MAX15009, MAX15011
19-0923; Rev 1; 2/08
KIT
ATION
EVALU
E
L
B
A
AVAIL
Automotive 300mA LDO Regulators with
Switched Output and Overvoltage Protector
Features
The MAX15009 includes a 300mA LDO regulator, a
switched output, and an overvoltage protection (OVP)
controller to protect downstream circuits from high-voltage load dump. The MAX15011 includes only the 300mA
LDO regulator and switched output. Both devices operate
over a wide supply voltage range from 5V to 40V and are
able to withstand load-dump transients up to 45V. The
MAX15009/MAX15011 feature short-circuit and thermalshutdown protection. These devices offer highly integrated power management solutions for automotive
applications such as instrument clusters, climate control,
and a variety of automotive power-supply circuits.
The 300mA LDO regulator consumes 67µA quiescent
current at light loads and is well suited to power
always-on circuits during “key off” conditions. The LDO
features independent enable and hold inputs, as well
as a microprocessor (µP) reset output with adjustable
reset timeout period.
The switched output of the MAX15009/MAX15011
incorporates a low RDS(ON) (0.28Ω, typ) pass transistor
switch internally connected to the output of the LDO
regulator. This switch features accurate current-limit
sensing circuitry and is capable of controlling remote
loads. The MAX15009/MAX15011 feature an adjustable
current limit and a programmable delay timer to set the
overcurrent detection blanking time of the switch and
autoretry timeout.
o 300mA LDO Regulator, Switched Output, and OVP
Controller (MAX15009)
The MAX15009 OVP controller operates with an external
enhancement mode n-channel MOSFET. While the monitored voltage remains below the adjustable threshold, the
MOSFET stays on. When the monitored voltage exceeds
the OVP threshold, the OVP controller quickly turns off the
external MOSFET. The OVP controller is configurable as a
load-disconnect switch or a voltage limiter.
The MAX15009/MAX15011 are available in a thermally
enhanced, 32-pin (5mm x 5mm), TQFN package and are
fully specified over the -40°C to +125°C automotive operating temperature range.
For tape and reel, add a T after “+.”
*EP = Exposed pad.
o OVP Controller Disconnects or Limits Output
Voltage During Battery Overvoltage Conditions
o LDO Regulator with Enable, Hold, and Reset
Features
o Internal 0.28Ω (typ) n-Channel Switch for
Switched Output
o 100mA Switched Output with Adjustable CurrentLimit Blanking/Autoretry Delay
Ordering Information
PART
PKG
CODE
MAX15009ATJ+ -40°C to +125°C
32 TQFN-EP*
T3255-4
MAX15011ATJ+ -40°C to +125°C
32 TQFN-EP*
T3255-4
+Denotes a lead-free package.
ILIM
OC_DELAY
OUT_LDO
OUT_LDO
IN
IN
EN_PROT
EN_SW
Pin Configurations
24
23
22
21
20
19
18
17
TOP VIEW
HOLD 25
16
EN_LDO
N.C. 26
15
FB_LDO
OUT_SW 27
14
N.C.
OUT_SW 28
13
SOURCE
12
GATE
MAX15009
N.C. 29
N.C. 30
N.C. 31
*EP
+
*EP = EXPOSED PAD
3
4
5
6
7
8
RESET
N.C.
2
PGND
Telematics Power Supply
1
SGND
N.C. 32
Multimedia Power Supply
Typical Operating Circuits and Selector Guide appear at end
of data sheet.
PINPACKAGE
TEMP RANGE
N.C.
AM/FM Radio Power Supply
o 67µA Quiescent Current LDO Regulator
N.C.
Climate Control
o 45V Load Dump Protection
N.C.
Instrument Clusters
o 5V to 40V Wide Operating Supply Voltage Range
N.C.
Applications
o 300mA LDO Regulator and Switched Output
(MAX15011)
11
N.C.
10
FB_PROT
9
CT
TQFN
(5mm x 5mm)
Pin Configurations continued at end of data sheet.
________________________________________________________________ Maxim Integrated Products
1
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.
MAX15009/MAX15011
General Description
MAX15009/MAX15011
Automotive 300mA LDO Regulators with
Switched Output and Overvoltage Protector
ABSOLUTE MAXIMUM RATINGS
(All pins referenced to SGND, unless otherwise noted.)
IN, GATE.................................................................-0.3V to +45V
EN_LDO, EN_SW, EN_PROT ......................-0.3V to (VIN + 0.3V)
SOURCE ......................................................-0.3V to (VIN + 0.3V)
OUT_LDO, FB_LDO, FB_PROT, RESET,
OC_DELAY .........................................................-0.3V to +12V
GATE to SOURCE ..................................................-0.3V to +12V
OUT_SW, ILIM, HOLD ......................-0.3V to (VOUT_LDO + 0.3V)
OUT_SW to OUT_LDO ...........................................-12V to +0.3V
CT to SGND............................................................-0.3V to +12V
SGND to PGND .....................................................-0.3V to +0.3V
IN, OUT_LDO Current .......................................................700mA
OUT_SW Current...............................................................350mA
Current Sink/Source (all remaining pins) ............................50mA
Continuous Power Dissipation (TA = +70°C)
32-Pin TQFN (derate 34.5mW/°C above +70°C) .............2.7W*
Thermal Resistance
θJA ..............................................................................29.0°C/W
θJC ................................................................................1.7°C/W
Operating Temperature Range .........................-40°C to +125°C
Junction Temperature ......................................................+150°C
Storage Temperature Range .............................-60°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C
*As per JEDEC 51 Standard, Multilayer Board (PCB).
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
ELECTRICAL CHARACTERISTICS
(VIN = +14V, VSGND = VPGND = 0V, CGATE = 6000pF, CIN = 10µF (ESR < 1.5Ω), COUT_LDO = 22µF (ceramic), COUT_SW = 1µF,
VOUT_LDO = 5V, CT = open, TA = TJ = -40°C to +125°C, unless otherwise noted. Typical values are at TA = +25°C.) (Note 1)
PARAMETER
Supply Voltage Range
SYMBOL
VIN
CONDITIONS
VIN ≥ VOUT + 1.5V
MAX15009
Supply Current
IIN
MAX15011
Shutdown Supply Current
ISHDN
IN Undervoltage Lockout
VUVLO
IN Undervoltage Lockout
Hysteresis
VUVLO_HYST
2
MIN
TYP
MAX
UNITS
40
V
5
EN_LDO = IN, EN_SW =
EN_PROT = 0V, IOUT_LDO
= 0µA, LDO on, switch off,
protector off, measured
from SGND
67
85
EN_LDO = EN_SW = IN,
EN_PROT = 0V, LDO ON,
IOUT_LDO = 100µA, switch
on, IOUT_SW = 0µA,
protector off, measured
from SGND
290
360
EN_LDO = EN_SW =
EN_PROT = IN, LDO ON,
IOUT_LDO = 100µA, switch
on, IOUT_SW = 0µA,
protector on, measured
from SGND
360
500
EN_LDO = EN_SW = IN,
LDO ON, IOUT_LDO =
100µA, switch on, IOUT_SW
= 0µA, measured from
SGND
268
360
16
30
EN_LDO = EN_SW =
EN_PROT = SGND,
measured from
SGND
µA
TA = -40°C to
+85°C
µA
TA = -40°C to
+125°C
VIN falling, GATE disabled
40
4.10
4.27
4.45
260
_______________________________________________________________________________________
V
mV
Automotive 300mA LDO Regulators with
Switched Output and Overvoltage Protector
(VIN = +14V, VSGND = VPGND = 0V, CGATE = 6000pF, CIN = 10µF (ESR < 1.5Ω), COUT_LDO = 22µF (ceramic), COUT_SW = 1µF,
VOUT_LDO = 5V, CT = open, TA = TJ = -40°C to +125°C, unless otherwise noted. Typical values are at TA = +25°C.) (Note 1)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
Thermal-Shutdown
Temperature
TSHDN
+160
°C
Thermal Hysteresis
THYST
20
°C
LDO
Output Voltage
VOUT_LDO
FB_LDO Set-Point Voltage
Dual Mode™ FB_LDO
Threshold
FB_LDO Input Current
VFB_LDO
VFB_LDO_TH
IFB_LDO
LDO Output Voltage
VLDO_ADJ
LDO Dropout Voltage
VDO
ILOAD = 1mA, FB_LDO = SGND
4.92
5.00
5.09
ILOAD = 300mA, VIN = 8V,
FB_LDO = SGND
4.88
5.00
5.11
With respect to SGND, ILOAD = 1mA,
VOUT_LDO = 5V, adjustable output option
1.21
1.235
1.26
FB_LDO rising
0.125
FB_LDO falling
0.064
VFB_LDO = 1V
Adjustable output option (Note 2)
+100
nA
11.0
V
ILOAD = 300mA (Note 3)
800
1500
ILOAD = 200mA (Note 3)
520
1000
(Note 4)
300
LDO Output Current Limit
ILIM_LDO
OUT_LDO = SGND, VIN = 6V
330
OUT_LDO Load Regulation
OUT_LDO Power-Supply
Rejection Ratio
OUT_LDO Startup Delay
Time
ΔVOUT/
ΔIOUT
PSRR
V
1.8
IOUT_LDO
OUT_LDO Line Regulation
V
-100
LDO Output Current
ΔVOUT/
ΔVIN
V
mV
mA
500
700
6V ≤ VIN ≤ 40V, ILOAD = 1mA,
VOUT_LDO = 5V
0.03
0.2
6V ≤ VIN ≤ 40V, ILOAD = 1mA,
FB_LDO = SGND, VOUT_LDO = 3.3V
0.03
0.1
6V ≤ VIN ≤ 40V, ILOAD = 20mA,
FB_LDO = SGND, VOUT_LDO = 5V
0.27
1
6V ≤ VIN ≤ 40V, ILOAD = 20mA,
VOUT_LDO = 3.3V
0.27
0.5
1mA to 300mA, VIN = 8V,
FB_LDO = SGND
0.054
0.15
mA
mV/V
mV/mA
1mA to 300mA, VIN = 6.3V,
VOUT_LDO = 3.3V
ILOAD = 10mA, f = 100Hz, 500mVP-P,
VOUT_LDO = 5V
IOUT_LDO = 0mA, from EN_LDO rising to
tSTARTUP_DELAY 10% of VOUT_LDO (nominal),
FB_LDO = SGND
0.038
0.100
60
dB
30
µs
Dual Mode is a trademark of Maxim Integrated Products, Inc.
_______________________________________________________________________________________
3
MAX15009/MAX15011
ELECTRICAL CHARACTERISTICS (continued)
MAX15009/MAX15011
Automotive 300mA LDO Regulators with
Switched Output and Overvoltage Protector
ELECTRICAL CHARACTERISTICS (continued)
(VIN = +14V, VSGND = VPGND = 0V, CGATE = 6000pF, CIN = 10µF (ESR < 1.5Ω), COUT_LDO = 22µF (ceramic), COUT_SW = 1µF,
VOUT_LDO = 5V, CT = open, TA = TJ = -40°C to +125°C, unless otherwise noted. Typical values are at TA = +25°C.) (Note 1)
PARAMETER
SYMBOL
OUT_LDO Overvoltage
Protection Threshold
VOV_TH
OUT_LDO Overvoltage
Protection Sink Current
IOV
CONDITIONS
MIN
1mA sink from OUT_LDO
VOUT_LDO = VOUT (nominal) x 1.15
8
TYP
MAX
UNITS
105
110
%VOUT_LDO
19
mA
ENABLE/HOLD INPUTS
EN_LDO to EN_PROT Input
Threshold Voltage
EN_LDO, EN_PROT, EN_SW
Input Pulldown Current
HOLD Input Threshold
Voltage
HOLD Input Pullup
VIH
2
VIL
IEN_PD
0.7
EN_ is internally pulled low to SGND
VIH
1
µA
1.4
0.4
VIL
IHOLD_PU
HOLD is internally pulled high to
OUT_LDO
V
0.6
V
µA
RESET
RESET Voltage Threshold
HIGH
RESET Voltage Threshold
LOW
VOUT_LDO to RESET Delay
CT Ramp Current
CT Ramp Threshold
RESET Output-Voltage Low
RESET Open-Drain
Leakage Current
V R ESET_H
VRESET_L
tRESET_FALL
FB_PROT Input Current
90.0
92.5
95.0
%VOUT_LDO
RESET goes HIGH when rising
VFB_LDO crosses this threshold
90.0
92.5
95.0
%VFB_LDO
RESET goes LOW when falling
VOUT_LDO crosses this threshold,
FB_LDO = SGND
88
90
92
%VOUT_LDO
RESET goes LOW when falling
VFB_LDO crosses this threshold
88
90
92
%VFB_LDO
VOUT_LDO falling, 0.1V/µs
µs
VCT = 0V
1.50
2
2.35
µA
VCT_TH
VCT rising
1.190
1.235
VOL
ILEAK_RESET
1.270
V
ISINK = 1mA, output asserted
0.1
V
Output not asserted
150
nA
1.27
V
FB_PROT rising
1.20
VHYST
IFB_PROT
1.235
4
VFB_PROT = 1.4V
Startup Response Time
tSTART
EN_PROT rising, EN_LDO = IN, to
VGATE = 0.5V
GATE Rise Time
tGATE
GATE rising to +8V, VSOURCE = 0V
4
19
ICT
LOAD DUMP PROTECTOR (MAX15009 only)
FB_PROT Threshold
VTH_PROT
Voltage
FB_PROT Threshold
Hysteresis
RESET goes HIGH when rising
VOUT_LDO crosses this threshold,
FB_LDO = SGND
-100
%VTH_PROT
+100
nA
20
µs
1
ms
_______________________________________________________________________________________
Automotive 300mA LDO Regulators with
Switched Output and Overvoltage Protector
(VIN = +14V, VSGND = VPGND = 0V, CGATE = 6000pF, CIN = 10µF (ESR < 1.5Ω), COUT_LDO = 22µF (ceramic), COUT_SW = 1µF,
VOUT_LDO = 5V, CT = open, TA = TJ = -40°C to +125°C, unless otherwise noted. Typical values are at TA = +25°C.) (Note 1)
PARAMETER
FB_PROT to GATE Turn-Off
Propagation Delay
GATE Output High Voltage
GATE Output Pulldown
Current
SYMBOL
tOV
VGATE - VIN
IGATEPD
GATE Charge-Pump
Current
IGATE
GATE-to-SOURCE Clamp
Voltage
VCLMP
CONDITIONS
MIN
TYP
FB_PROT rising from VTH_PROT 250mV to VTH_PROT + 250mV
MAX
UNITS
0.6
µs
VSOURCE = VIN = 5.5V,
RGATE to IN = 1MΩ
VIN +
3.2
VIN +
3.5
VIN +
3.8
VSOURCE = VIN; VIN ≥ 14V,
RGATE to IN = 1MΩ
VIN +
7.0
VIN +
8.1
VIN +
9.5
VGATE = 5V, VEN_PROT = 0V
63
100
GATE = SGND
45
12
V
mA
µA
16
18
V
36
70
mV
SWITCH
ΔVSW
Switch Dropout
Switch Current Limit
ISW_LIM
Current-Limit Selector ILIM
Voltage
OC_DELAY Timeout
Threshold
VILIM
ΔVSW = VOUT_LDO - VOUT_SW,
IOUT_SW = 100mA, VOUT_LDO = 5V,
no external MOSFET
ILIM = OUT_LDO, VIN = 8V
170
200
240
RLIM = 100kΩ to SGND,
VOUT_LDO = 5V, VIN = 8V
85
100
120
RLIM = 39kΩ to SGND,
VOUT_LDO = 5V, VIN = 8V
30
40
50
RLIM = 100kΩ
VOC_DELAY
OC_DELAY Timeout Pullup
Current
0.395
mA
V
1.194
1.235
1.270
V
IOC_DELAY_UP
VOC_DELAY = 0.5V rising
12.5
16.0
21.3
µA
OC_DELAY Timeout
Pulldown Current
IOC_DELAY_DOWN
VOC_DELAY = 0.5V, falling
0.75
1.00
1.40
µA
Minimum OC_DELAY
Timeout
tOC_DELAY_MIN
EN_SW to OUT_SW
Turn-On Time
EN_SW to OUT_SW
Turn-Off Propagation Delay
Note 1:
Note 2:
Note 3:
Note 4:
tOV_SW
COC_DELAY is unconnected
12
µs
OUT_SW rising to +0.5V,
ROUT_SW = 1kΩ
38
µs
EN_SW falling, VOUT_LDO - VOUT_SW
rising to +1V, ROUT_SW = 1kΩ,
VOUT_LDO = 5V
18
µs
Specifications to -40°C are guaranteed by design and not production tested.
1.8V is the minimum limit for proper HOLD functionality.
Dropout is defined as VIN - VOUT_LDO when VOUT_LDO is 98% of the value of VOUT_LDO for VIN = VOUT_LDO + 1.5V.
Maximum output current may be limited by the power dissipation of the package.
_______________________________________________________________________________________
5
MAX15009/MAX15011
ELECTRICAL CHARACTERISTICS (continued)
Typical Operating Characteristics
(VIN = VEN_LDO = VEN_PROT = VEN_SW = +14V, CIN = 10µF, COUT_LDO = 22µF, COUT_SW = 1µF, VOUT_LDO = +5V, FB_LDO = SGND,
TA = +25°C, unless otherwise specified.)
TA = +25°C
64
62
TA = +85°C
60
58
80
70
60
LOAD CURRENT (mA)
LOAD CURRENT (mA)
LDO POWER-SUPPLY
REJECTION RATIO vs. FREQUENCY
VIN UVLO HYSTERESIS
vs. TEMPERATURE
350
UVLO HYSTERESIS (mV)
LDO PSRR (dB)
-20
-30
-40
-50
-60
250
200
100k
5.02
5.00
4.98
4.94
4.92
IOUT_LDO = 10mA
10k
5.06
4.96
150
1k
5.08
5.04
300
-80
100
MAX15009 toc03
LDO LOAD REGULATION
-70
-90 10
20 40 60 80 100 120 140
5.10
VOUT_LDO (V)
-10
0
TEMPERATURE (°C)
400
MAX15009 toc04
0
0 -60 -40 -20
50 0 25 50 75 100 125 150 175 200 225 250 275 300
0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0
15
5
TA = +125°C
MAX15009 toc05
0
20
10
TA = +85°C
54
52
30
25
TA = -40°C
TA = +125°C
56
MAX15009 toc02
TA = +25°C
90
35
ISHDN (μA)
GROUND CURRENT (μA)
68
66
100
GROUND CURRENT (μA)
TA = -40°C
70
110
MAX15009 toc01
74
72
SHUTDOWN SUPPLY CURRENT
vs. TEMPERATURE
LDO GROUND CURRENT
vs. LOAD CURRENT
MAX15009 toc06
LDO GROUND CURRENT
vs. LOAD CURRENT
1M
100
4.90
-50
-25
0
25
50
75
100 125 150
FREQUENCY (Hz)
TEMPERATURE (°C)
LDO OUTPUT VOLTAGE
vs. INPUT VOLTAGE
LDO LOAD-TRANSIENT RESPONSE
0
100
200
MAX15009 toc07
6
IOUT_LDO = 10mA
5
IOUT_LDO = 300mA
(PULSED)
4
LDO LOAD-TRANSIENT RESPONSE
MAX15009 toc09
IOUT_LDO
100mA/div
IOUT_LDO
100mA/div
0A
3
0A
2
VOUT_LDO
5V, AC-COUPLED
100mV/div
VOUT_LDO
5V, AC-COUPLED
20mV/div
1
0
0
5
10
15
20
25
30
35
40
2ms/div
VIN (V)
6
300
IOUT_LDO (mA)
MAX15009 toc08
VOUT_LDO (V)
MAX15009/MAX15011
Automotive 300mA LDO Regulators with
Switched Output and Overvoltage Protector
_______________________________________________________________________________________
400μs/div
Automotive 300mA LDO Regulators with
Switched Output and Overvoltage Protector
LDO OUTPUT VOLTAGE
vs. TEMPERATURE
SWITCH LOAD-TRANSIENT RESPONSE
MAX15009 toc10
IOUT_LDO = 100μA
5.05
VOUT_LDO (V)
LINE-TRANSIENT RESPONSE
MAX15009 toc11
5.10
IOUT_LDO = 10mA
MAX15009 toc12
VIN
20V/div
IOUT_SW
100mA/div
VOUT_LDO
3.3V, AC-COUPLED
50mV/div
VOUT_SW
5V, AC-COUPLED
100mV/div
4.95
IOUT_LDO = 100mA
4.90
VOUT_SW
3.3V, AC-COUPLED
50mV/div
VOUT_LDO
5V, AC-COUPLED
100mV/div
IOUT_LDO = 300mA
4.85
0V
0A
5.00
IOUT_LDO = 100mA
IOUT_SW = 100mA
VIN = 8V
VOUT_PROT
20V/div
0V
4.80
-50
-25
0
25
50
75
100 125 150
400μs/div
40ms/div
LDO DROPOUT VOLTAGE
vs. LOAD CURRENT
SWITCH DROPOUT VOLTAGE
vs. LOAD CURRENT
TEMPERATURE (°C)
MAX15009 toc14
1000
LDO DROPOUT VOLTAGE (mV)
900
0V
VOUT_LDO
3.3V, AC-COUPLED
20mV/div
VOUT_SW
3.3V, AC-COUPLED
20mV/div
VOUT_PROT
10V/div
800
700
600
500
400
300
200
30
25
20
15
10
IOUT_LDO = 10mA
0
0
0
40ms/div
35
5
100
0V
40
MAX15009 toc15
MAX15009 toc13
VIN
10V/div
SWITCH DROPOUT VOLTAGE (mV)
LINE-TRANSIENT RESPONSE
100
200
0
300
IOUT_LDO (mA)
SWITCH DROPOUT VOLTAGE
vs. TEMPERATURE
100
STARTUP RESPONSE THROUGH VIN
MAX15009 toc17
MAX15009 toc16
60
IOUT_LDO = 10mA
SWITCH DROPOUT VOLTAGE (mV)
50
IOUT_SW (mA)
50
VIN
20V/div
0V
40
VRESET
5V/div
IOUT_SW = 100mA
30
IOUT_LDO = 100mA
IOUT_SW = 70mA
EN_LDO = EN_SW = IN
0V
VOUT_LDO
5V/div
20
IOUT_SW = 10mA
10
0V
VOUT_SW
5V/div
0V
0
-45
-20
5
30
55
80
105
130
20ms/div
TEMPERATURE (°C)
_______________________________________________________________________________________
7
MAX15009/MAX15011
Typical Operating Characteristics (continued)
(VIN = VEN_LDO = VEN_PROT = VEN_SW = +14V, CIN = 10µF, COUT_LDO = 22µF, COUT_SW = 1µF, VOUT_LDO = +5V, FB_LDO = SGND,
TA = +25°C, unless otherwise specified.)
Typical Operating Characteristics (continued)
(VIN = VEN_LDO = VEN_PROT = VEN_SW = +14V, CIN = 10µF, COUT_LDO = 22µF, COUT_SW = 1µF, VOUT_LDO = +5V, FB_LDO = SGND,
TA = +25°C, unless otherwise specified.)
SHUTDOWN RESPONSE THROUGH VIN
MAX15008 toc18
14V
VEN_LDO
5V/div
VIN
10V/div
0V
IOUT_LDO = 100mA
IOUT_SW = 70mA
VEN_LDO = VEN_SW
0V
VOUT_SW
5V/div
0V
0V
20ms/div
2ms/div
LDO, EN_LDO, AND HOLD TIMING
GROUND CURRENT DISTRIBUTION
HISTOGRAM (TA = -40°C)
MAX15009 toc21
VEN_LDO
5V/div
60
0V
HOLD PULLED UP
TO OUT_LDO
HOLD
5V/div
50
40
30
20
0V
0V
VOUT_LDO
5V/div
0V
VOUT_SW
5V/div
0V
90
80
70
60
50
40
30
20
10
RESET
5V/div
0V
IOUT_LDO = 100mA
IOUT_SW = 70mA
EN_LDO = EN_SW
VRESET
5V/div
NUMBER OF PARTS
0V
6V
GROUND CURRENT DISTRIBUTION
HISTOGRAM (TA = +125°C)
70
NUMBER OF PARTS
VOUT_LDO
5V/div
0V
VOUT_LDO
5V/div
0V
VOUT_SW
5V/div
0V
VRESET
5V/div
0V
VOUT_LDO
5V/div
IOUT_LDO = 100mA
IOUT_SW = 70mA
EN_LDO = VEN_SW = IN
MAX15008 toc20
VIN
20V/div
VEN_LDO
5V/div
MAX15009 toc22
VRESET
5V/div
SHUTDOWN RESPONSE THROUGH EN
MAX15008 toc19
MAX15009 toc23
STARTUP RESPONSE THROUGH EN
VIN
0V
10
0
0
67
200ms/div
69
71
73
75
79
77
81
51 53 55 57 59 61 63 65 67 69 71
GROUND CURRENT (μA)
PROTECTOR GATE VOLTAGE
vs. INPUT VOLTAGE (MAX15009 ONLY)
GROUND CURRENT (μA)
PROTECTOR STARTUP RESPONSE
MAX15009 toc25
MAX15009 toc24
50
45
40
GATE VOLTAGE (V)
MAX15009/MAX15011
Automotive 300mA LDO Regulators with
Switched Output and Overvoltage Protector
VIN
10V/div
0V
VGATE
35
30
VGATE
10V/div
25
20
0V
15
VOUT_PROT
10V/div
10
0V
VIN
5
IOUT_PROT = 1A
0
0
5
10
15
20
25
30
35
40
10ms/div
VIN (V)
8
_______________________________________________________________________________________
Automotive 300mA LDO Regulators with
Switched Output and Overvoltage Protector
MAX15009 toc26
MAX15009 toc27
7
6
RESET TIMEOUT DELAY (ms)
VIN
20V/div
0V
IOUT_PROT = 1A
VOV = 25V
0V
VGATE
20V/div
VGATE
20V/div
IOUT_PROT = 1A
OV THRESHOLD = 35V
0V
0V
5
4
3
2
VOUT_PROT
20V/div
VOUT_PROT
20V/div
1
0V
0V
400μs/div
0
0
40ms/div
2
4
6
8
10
CRESET (nF)
RESET TIMEOUT DELAY
vs. TEMPERATURE
CRESET = 2.2nF
1.4
1.2
1.0
0.8
0.6
0.4
0.2
160
140
120
TA = -40°C
100
TA = +85°C
80
60
TA = +25°C
40
0
20
-50
-25
0
25
50
75
100 125 150
20
40
60
80 100 120 140 160 180 200
TEMPERATURE (°C)
ILIM RESISTANCE (kΩ)
INTERNAL PRESET SWITCH CURRENT LIMIT
vs. TEMPERATURE
IOC_DELAY_UP AND IOC_DELAY_DOWN
vs. TEMPERATURE
MAX15009 toc31
250
240
PRESET CURRENT LIMIT (mA)
TA = +125°C
180
CRESET = 220pF
MAX15009 toc30
1.6
200
230
220
210
200
190
180
170
160
150
-50
-25
0
25
50
75
TEMPERATURE (°C)
100 125 150
18
16
MAX15009 toc32
RESET TIMEOUT DELAY (ms)
1.8
SWITCH CURRENT LIMIT (mA)
MAX15009 toc29
2.0
SWITCH CURRENT LIMIT
vs. ILIM RESISTANCE
OC_DELAY PULLUP/PULLDOWN CURRENT (μA)
VIN
10V/div
RESET TIMEOUT DELAY
vs. CRESET
OVERVOLTAGE LIMIT FAULT
MAX15009 toc28
OVERVOLTAGE SWITCH FAULT
IOC_DELAY_DOWN
14
12
10
8
6
4
IOC_DELAY_UP
2
0
-50
-25
0
25
50
75
100 125 150
TEMPERATURE (°C)
_______________________________________________________________________________________
9
MAX15009/MAX15011
Typical Operating Characteristics (continued)
(VIN = VEN_LDO = VEN_PROT = VEN_SW = +14V, CIN = 10µF, COUT_LDO = 22µF, COUT_SW = 1µF, VOUT_LDO = +5V, FB_LDO = SGND,
TA = +25°C, unless otherwise specified.)
MAX15009/MAX15011
Automotive 300mA LDO Regulators with
Switched Output and Overvoltage Protector
Pin Description
PIN
NAME
FUNCTION
MAX15009
MAX15011
1–4, 8, 11,
14, 26, 29–32
N.C.
—
1–4, 8,
10–14, 18,
26, 29–32
—
N.C.
5
SGND
SGND
Signal Ground
6
PGND
PGND
Ground. PGND is also the return path for the overvoltage protector pulldown current
for the MAX15009. In this case, connect PGND to SGND at the negative terminal of the
bypass capacitor connected to the source of the external MOSFET. For the
MAX15011, connect PGND to SGND together to the local ground plane.
7
RESET
RESET
Active-Low Open-Drain Reset Output. RESET is low while OUT_LDO is below the reset
threshold. Once OUT_LDO has exceeded the reset threshold, RESET remains low for
the duration of the reset timeout period then goes high.
9
CT
CT
Reset Timeout Adjust Input. Connect a capacitor (CRESET) from CT to ground to adjust
the reset timeout period. See the Setting the RESET Timeout Period section.
—
Overvoltage-Threshold Adjustment Input. Connect FB_PROT to an external resistive
voltage-divider network to adjust the desired overvoltage threshold. Use FB_PROT to
monitor a system input or output voltage. See the Setting the Overvoltage Threshold
(MAX15009 Only) section.
10
10
No Connection. Not internally connected.
FB_PROT
12
GATE
—
Protector Gate Drive Output. Connect GATE to the gate of an external n-channel
MOSFET. GATE is the output of a charge pump with a 45µA pullup current to 8.1V
(typ) above IN during normal operation. GATE is quickly turned off through a 63mA
internal pulldown during an overvoltage condition. GATE then remains low until
FB_PROT has decreased below 96% of the overvoltage threshold. GATE pulls low
when EN_PROT is low.
13
SOURCE
—
Output-Voltage Sense Input. Connect SOURCE to the source of the external n-channel
MOSFET.
______________________________________________________________________________________
Automotive 300mA LDO Regulators with
Switched Output and Overvoltage Protector
PIN
15
NAME
FUNCTION
MAX15009
MAX15011
FB_LDO
FB_LDO
LDO Voltage Feedback Input. Connect FB_LDO to SGND to select the preset +5V
output voltage. Connect FB_LDO to an external resistive voltage-divider for adjustable
output operation. See the Setting the Output Voltage section.
16
EN_LDO
EN_LDO
Active-High LDO Enable Input. Connect EN_LDO to IN or to a logic-high voltage to
turn on the regulator. To place the LDO in shutdown, pull EN_LDO low or leave
unconnected and leave HOLD unconnected. EN_LDO is internally pulled to SGND
through a 1µA current sink. See the Control Logic section.
17
EN_SW
EN_SW
Active-High Switch Enable Input. Connect EN_SW to IN or to a logic-high voltage to
turn on the switch. Pull EN_SW low or leave unconnected to place the switch in
shutdown. EN_SW is internally pulled to SGND through a 1µA current sink.
18
EN_PROT
—
Protector Enable Input. Drive EN_PROT low to force GATE low and turn off the external
n-channel MOSFET. EN_PROT is internally pulled to SGND by a 1µA sink current.
Connect EN_PROT to IN for normal operation.
19, 20
IN
IN
Regulator Input. Bypass IN to SGND with a 10µF capacitor with an ESR < 1.5Ω.
21, 22
OUT_LDO
OUT_LDO
LDO Regulator Output. Bypass OUT_LDO to SGND with a ceramic capacitor with a
minimum value of 22µF. OUT_LDO has a fixed 5V output or can be adjusted from1.8V
to 11V. See the Setting the Output Voltage section.
OC_DELAY
Switch Overcurrent Blanking Time Programming Input. Leave OC_DELAY
unconnected to select the minimum delay timeout before turning the switch off.
OC_DELAY is internally pulled to SGND through a 1µA current source. See the
Programming the Switch Overcurrent Blanking Time section.
23
24
OC_DELAY
ILIM
ILIM
Switch Current-Limit Set Input. Connect a 10kΩ to 200kΩ resistor from ILIM to SGND to
select the current limit for the internal switch. Connect ILIM to OUT_LDO to select the
internal 170mA (min) current-limit threshold. Do not leave ILIM unconnected. See the
Setting the Switch Current Limit section.
Active-Low Hold Input. If EN_LDO is high when HOLD is forced low, the regulator
latches the state of the EN_LDO input and allows the regulator to remain turned on
when EN_LDO is subsequently pulled low. To shut down the regulator, release HOLD
after EN_LDO is pulled low. If HOLD functionality is unused, connect HOLD to
OUT_LDO or leave unconnected. HOLD is internally pulled up to OUT_LDO through a
0.6µA current source. See the Control Logic section.
25
HOLD
HOLD
27, 28
OUT_SW
OUT_SW
—
EP
EP
Switch Output. Bypass OUT_SW to SGND with a minimum 0.1µF ceramic capacitor.
Exposed Pad. Connect EP to SGND plane. EP also functions as a heatsink to maximize
thermal dissipation. Do not use as the main ground connection.
______________________________________________________________________________________
11
MAX15009/MAX15011
Pin Description (continued)
Automotive 300mA LDO Regulators with
Switched Output and Overvoltage Protector
MAX15009/MAX15011
Functional Diagram
IN
VIN
ENABLE LDO
HOLD
LDO
IN
VREF 1.235V
BIAS AND VOLTAGE
REFERENCE
EN_LDO
HOLD
CONTROL
LOGIC
5V LDO
OUTPUT
OUT_LDO
M
U
X
FB_LDO
0.124V
2μA
CT
0.925 x VREF
RESET
VREF
RESET
OUTPUT
OUT_LDO
ILIM
SWITCH
16μA
OUT_SW
VGATE
SWITCH
OUTPUT
OUT_SW
VREF
S
ENABLE SWITCH
EN_SW
Q
0.1V
R
OC_DELAY
1μA
IN
GATE UVLO
4.75V
VIN
GATE
VREF
ENABLE
PROTECTOR
EN_PROT
SOURCE
OVERVOLTAGE PROTECTOR
(MAX15009 ONLY)
EP
12
SGND
PROTECTOR
OUTPUT
FB_PROT
PGND
______________________________________________________________________________________
Automotive 300mA LDO Regulators with
Switched Output and Overvoltage Protector
The MAX15009/MAX15011 integrate a 300mA LDO
voltage regulator, a current-limited switched output,
and an OVP controller (MAX15009 only). These devices
operate over a wide supply voltage range from 5V to
40V and are able to withstand load-dump transients up
to 45V.
The MAX15009/MAX15011 feature a 300mA LDO regulator that consumes 70µA of current under light-load
conditions and feature a fixed 5V or an adjustable output voltage (1.8V to 11V). Connect FB_LDO to ground
to select a fixed 5V output voltage or select the LDO
output voltage by connecting an external resistive voltage-divider at FB_LDO. The regulator sources at least
300mA of current and includes a current limit of 330mA
(min). Enable the LDO by pulling EN_LDO high.
The switch features accurate current-limit sensing circuitry and is capable of controlling remote loads. Once
enabled, an internal charge pump generates the overdrive voltage for an internal MOSFET. The switch then
starts to conduct and OUT_SW is charged up to
VOUT_LDO. The switch is enabled when the output voltage of the LDO is above the RESET threshold voltage
(92.5% of the LDO nominal output value).
An overcurrent condition exists when the current at
OUT_SW, IOUT_SW, exceeds the 200mA (typ) internal
factory-set current-limit threshold or the externally
adjustable current-limit threshold. During a continuous
overcurrent event, the capacitor connected at
OC_DELAY, COC_DELAY, is charged up to a voltage of
1.235V with a current, IOC_DELAY_UP. When this voltage
is reached, an overcurrent latch is set and the gate of
the internal MOSFET is discharged, reducing IOUT_SW.
COC_DELAY is then discharged through a pulldown current, IOC_DELAY_DOWN (IOC_DELAY_UP / 16) and the
internal MOSFET remains off until COC_DELAY has been
discharged to 0.1V. After this user-programmable turnoff delay, the switch turns back on. This charge/
discharge is repeated if the overcurrent condition persists. The switch returns to normal operation once the
overcurrent condition has been removed.
The OVP controller (MAX15009 only) relies on an external MOSFET with adequate voltage rating (VDSS) to
protect downstream circuitry from overvoltage transients. The OVP controller drives the gate of the external n-channel MOSFET, and is configurable to operate
as an overvoltage protection switch or as a closed-loop
voltage limiter.
GATE Voltage (MAX15009 Only)
The MAX15009 uses a high-efficiency charge pump to
generate the GATE voltage for the external n-channel
MOSFET. Once the input voltage, VIN, exceeds the
undervoltage lockout (UVLO) threshold, the internal
charge pump fully enhances the external n-channel
MOSFET. An overvoltage condition occurs when the
voltage at FB_PROT goes above the threshold voltage,
VTH_PROT. After VTH_PROT is exceeded, GATE is quickly pulled to PGND with a 63mA pulldown current. The
MAX15009 includes an internal clamp from GATE to
SOURCE that ensures that the voltage at GATE never
exceeds one diode drop below SOURCE during gate
discharge. The voltage clamp also prevents the GATEto-SOURCE voltage from exceeding the absolute maximum rating for the VGS of the external MOSFET in case
the source terminal is accidentally shorted to 0V.
Overvoltage Monitoring (MAX15009 Only)
The OVP controller monitors the voltage at FB_PROT
and controls an external n-channel MOSFET, isolating,
or limiting the load during an overvoltage condition.
Operation in OVP switch mode or limiter mode
depends on the connection between FB_PROT and the
external MOSFET.
Overvoltage Switch Mode
When operating in OVP switch mode, the FB_PROT
divider is connected to the drain of the external MOSFET. The feedback path consists of the voltage-divider
tapped at FB_PROT, FB_PROT’s internal comparator,
the internal gate charge pump/gate pulldown, and the
external n-channel MOSFET (Figure 1). When the programmed overvoltage threshold is exceeded, the internal comparator quickly pulls GATE to ground and turns
VIN
IN
GATE
MAX15009
FB_PROT
PROTECTOR
OUTPUT
SOURCE
SGND
Figure 1. Overvoltage-Limiter Switch Configuration (MAX15009)
______________________________________________________________________________________
13
MAX15009/MAX15011
Detailed Description
MAX15009/MAX15011
Automotive 300mA LDO Regulators with
Switched Output and Overvoltage Protector
off the external MOSFET, disconnecting the power
source from the load. In this configuration, the voltage
at the source of the MOSFET is not monitored. When
the voltage at FB_PROT decreases below the overvoltage threshold, the MAX15009 raises the voltage at
GATE, reconnecting the load to the power source.
Overvoltage-Limiter Mode (MAX15009 Only)
When operating in overvoltage-limiter mode, the feedback path consists of SOURCE, FB_PROT’s internal
comparator, the internal gate charge pump/gate pulldown, and the external n-channel MOSFET (Figure 2).
This configuration results in the external MOSFET operating as a hysteretic voltage regulator.
During normal operation, GATE is enhanced 8.1V above
VIN. The external MOSFET source voltage is monitored
through a resistive voltage-divider between SOURCE
and FB_PROT. When VSOURCE exceeds the adjustable
overvoltage threshold, an internal pulldown switch
discharges the gate voltage and quickly turns the
MOSFET off. Consequently, the source voltage begins
to fall. The VSOURCE fall time is dependent on the MOSFET’s gate charge, the internal charge-pump current,
the output load, and any load capacitance at SOURCE.
When the voltage at FB_PROT is below the overvoltage
threshold by an amount equal to the hysteresis, the
charge pump restarts and turns the MOSFET back on.
In this way, the OVP controller attempts to regulate
VSOURCE around the overvoltage threshold. SOURCE
remains high during overvoltage transients and the
MOSFET continues to conduct during an overvoltage
event. The hysteresis of the FB_PROT comparator and
the gate turn-on delay force the external MOSFET to
operate in a switched on/off sequence during an overvoltage event.
Exercise caution when operating the MAX15009 in voltage-limiting mode for long durations. Care must be
taken against prolonged or repeated exposure to overvoltage events while delivering large amounts of load
current as the power dissipation in the external MOSFET may be high under these conditions. To prevent
damage to the MOSFET, implement proper heatsinking.
The capacitor tied between SOURCE and ground may
also be damaged if the ripple current rating for the
capacitor is exceeded.
14
VIN
IN
GATE
MAX15009
PROTECTOR
OUTPUT
SOURCE
FB_PROT
SGND
Figure 2. Overvoltage Limiter (MAX15009)
As the transient voltage decreases, the voltage at
SOURCE falls. For fast-rising transients and very large
MOSFETs, connect an additional capacitor from GATE
to PGND. This capacitor acts as a voltage-divider working against the MOSFET’s drain-to-gate capacitance. If
using a very low gate charge MOSFET, additional
capacitance from GATE to ground might be required to
reduce the switching frequency.
Control Logic
The MAX15009/MAX15011 LDO features two logic
inputs, EN_LDO and HOLD, making these devices suitable for automotive applications. For example, when
the ignition key signal drives EN_LDO high, the regulator turns on and remains on even if EN_LDO goes low,
as long as HOLD is forced low and stays low after initial
regulator power-up. In this state, releasing HOLD turns
the regulator output (OUT_LDO) off. This feature makes
it possible to implement a self-holding circuit without
external components. Forcing EN_LDO low and HOLD
high (or unconnected) places the regulator into shutdown mode, reducing the supply current to less than
16µA. Table 1 shows the state of OUT_LDO with
respect to EN_LDO and HOLD. Leave HOLD unconnected or connect directly to OUT_LDO to allow the
EN_LDO input to act as a standard on/off logic input for
the regulator.
______________________________________________________________________________________
Automotive 300mA LDO Regulators with
Switched Output and Overvoltage Protector
EN_LDO
HOLD
OUT_LDO
Initial State
Low
Don’t care
OFF
EN_LDO is pulled to SGND through an internal pulldown. HOLD
is unconnected and is internally pulled up to OUT_LDO. The
regulator is disabled.
Turn-On State
High
Don’t care
ON
EN_LDO is externally driven high turning regulator on. HOLD is
pulled up to OUT_LDO.
Hold Setup State
High
Low
ON
HOLD is externally pulled low while EN_LDO remains high
(latches EN_LDO state).
Hold State
Low
Low
ON
EN_LDO is driven low or left unconnected. HOLD remains
externally pulled low keeping the regulator on.
Off State
Low
High or
unconnected
OFF
HOLD is driven high or left unconnected while EN_LDO is low.
The regulator is turned off and EN_LDO/HOLD logic returns to the
initial state.
OPERATION STATE
COMMENT
Applications Information
Load Dump
Most automotive applications run off a multicell 12V
lead-acid battery with a nominal voltage that swings
between 9V and 16V, depending on load current,
charging status, temperature, and battery age, etc. The
battery voltage is distributed throughout the automobile
and is locally regulated down to voltages required by
the different system modules. Load dump occurs when
the alternator is charging the battery and the battery
becomes disconnected. Power in the alternator (behaving now essentially as an inductor) flows into the distributed power system and elevates the voltage seen at
each module. The voltage spikes have rise times typically greater than 5ms and decay within several hundred milliseconds but can extend out to 1s or more
depending on the characteristics of the charging system. These transients are capable of destroying semiconductors on the first fault event.
The MAX15009/MAX15011 feature load-dump transient
protection up to +45V.
Setting the Output Voltage
The MAX15009/MAX15011 feature dual-mode operation: these devices operate in either a preset voltage
mode or an adjustable mode. In preset voltage mode,
internal feedback resistors set the linear regulator output voltage (VOUT_LDO) to 5V. To select the preset 5V
output voltage, connect FB_LDO to SGND.
To select an adjustable output voltage between 1.8V
and 11V, use two external resistors connected as a
voltage-divider to FB_LDO (Figure 3). Set the output
voltage using the following equation:
VIN
IN
OUT_LDO
R1
MAX15009
MAX15011
FB_LDO
R2
SGND
Figure 3. Setting the LDO Output Voltage
VOUT_LDO = VFB_LDO x (R1 + R2) / R2
where VFB_LDO = 1.235V and R2 ≤ 50kΩ.
Setting the RESET Timeout Period
The reset timeout period is adjustable to accommodate
a variety of applications. Set the reset timeout period by
connecting a capacitor, C RESET , between CT and
SGND. Use the following formula to select the reset
timeout period, tRESET:
tRESET = CRESET x VCT_TH / ICT
where t RESET is in seconds and C RESET is in µF.
VCT_TH is the CT ramp threshold in volts and ICT is the
CT ramp current in µA, as described in the Electrical
Characteristics table.
______________________________________________________________________________________
15
MAX15009/MAX15011
HOLD Truth/State Table
Table 1. EN_LDO/H
MAX15009/MAX15011
Automotive 300mA LDO Regulators with
Switched Output and Overvoltage Protector
Leave CT open to select a typical reset timeout of 19µs.
To maintain reset accuracy, use a low-leakage type of
capacitor.
Setting the Switch Current Limit
The switch block features accurate current-limit sensing circuitry. A resistor connected from ILIM to SGND
can be used to select the current-limit threshold using
the following relationship:
ISW_LIM (mA) = RILIM (kΩ) x 1mA / kΩ
where 20kΩ ≤ RILIM ≤ 200kΩ.
Connect ILIM to OUT_LDO to select the default current
limit of 200mA (typ).
Programming the Switch
Overcurrent Blanking Time
The switch provides an adjustable overcurrent blanking
time to allow the safe charge of large capacitive loads.
When an overcurrent event is detected, a delay period
elapses before the condition is latched and the internal
MOSFET is turned off. This period is the overcurrent
delay, tOC_DELAY. Set the overcurrent delay using the
following equation:
tOC_DELAY = COC_DELAY x VOC_DELAY / IOC_DELAY_UP
where tOC_DELAY is in seconds and COC_DELAY is in
µF. VOC_DELAY is the overcurrent delay timeout threshold voltage in volts and IOC_DELAY_UP is the overcurrent delay timeout pullup current in µA as seen in the
Electrical Characteristics table.
Ensure that the switch is not disabled due to a large
startup inrush current by selecting a large enough
value for overcurrent blanking time. Assume that the
current available for charging the total switch output
capacitance, COUT_SW, is the difference between the
current-limit threshold value, ISW_LIM, and the nominal
IN
VIN
PROTECTOR
OUTPUT
MAX15009
FB_PROT
COC_DELAY ≥
IOC_DELAY_UP × VOUT_LDO × COUT_SW
VOC_DELAY × (ISW_LIM − IOUT_SW_NOM)
COC_DELAY also affects the length of time before the
MAX15009/MAX15011 attempt to turn the switch back
on. Set the autoretry delay using the following equation:
tOC_RETRY = COC_DELAY x
VOC_DELAY/IOC_DELAY_DOWN
where tOC_RETRY is in seconds, COC_DELAY is in µF,
VOC_DELAY is in volts, and IOC_DELAY_DOWN is in µA.
COC_DELAY should be a low-leakage type of capacitor
with a minimum value of 100pF.
Setting the Overvoltage Threshold
(MAX15009 Only)
The MAX15009 provides an accurate means to set the
overvoltage threshold for the OVP controller using
FB_PROT. Use a resistive voltage-divider to set the
desired overvoltage threshold (Figure 4). FB_PROT has
a rising 1.235V threshold with a 4% falling hysteresis.
Begin by selecting the total end-to-end resistance,
RTOTAL = R3 + R4. Choose RTOTAL to yield a total current
equivalent to a minimum of 100 x IFB_PROT (FB_PROT’s
input maximum bias current) at the desired overvoltage
threshold. See the Electrical Characteristics table.
For example:
With an overvoltage threshold (VOV) set to 20V, RTOTAL
< 20V / (100 x IFB_PROT), where IFB_PROT is FB_PROT’s
maximum 100nA bias current:
RTOTAL < 2MΩ
VIN
GATE
R5
DC load current at OUT_SW, IOUT_SW_NOM and select
the COC_DELAY using the following relationship:
IN
GATE
PROTECTOR
OUTPUT
MAX15009
SOURCE
SOURCE
R3
R6
FB_PROT
SGND
SGND
Figure 4. Setting the Overvoltage Threshold (MAX15009)
16
______________________________________________________________________________________
R4
Automotive 300mA LDO Regulators with
Switched Output and Overvoltage Protector
where VTH_PROT is the 1.235V FB_PROT rising threshold
and VOV is the desired overvoltage threshold. R4 = 124kΩ:
RTOTAL = R3 + R4
where R3 = 1.88MΩ. Use a standard 1.87MΩ resistor.
A lower value for total resistance dissipates more
power, but provides better accuracy and robustness
against external disturbances.
Input Transients Clamping
When the external MOSFET is turned off during an
overvoltage event, stray inductance in the power path
may cause additional input-voltage spikes that exceed
the VDSS rating of the external MOSFET or the absolute
maximum rating for the MAX15009. Minimize stray
inductance in the power path using wide traces and
minimize the loop area included by the power traces
and the return ground path.
For further protection, add a zener diode or transient
voltage suppressor (TVS) rated below the absolute
maximum rating limits (Figure 5).
Select the external MOSFET with adequate voltage rating,
VDSS, to withstand the maximum expected load-dump
input voltage. The on-resistance of the MOSFET,
RDS(ON), should be low enough to maintain a minimal
voltage drop at full load, limiting the power dissipation
of the MOSFET.
During regular operation, the power dissipated by the
MOSFET is:
PNORMAL = ILOAD2 x RDS(ON)
Normally, this power loss is small and is safely handled
by the MOSFET. However, when operating the
MAX15009 in overvoltage limiter mode under prolonged or frequent overvoltage events, select an external MOSFET with an appropriate power rating.
During an overvoltage event, the power dissipation in
the external MOSFET is proportional to both load current and to the drain-source voltage, resulting in high
power dissipated in the MOSFET (Figure 6). The power
dissipated across the MOSFET is:
POV_LIMITER = VQ1 x ILOAD
where VQ1 is the voltage across the MOSFET’s drain
and source during overvoltage limiter operation, and
ILOAD is the load current.
VMAX
VOV
VIN
+ VQ1 -
VSOURCE
ILOAD
IN
IN
GATE
MAX15009
MAX15009
TVS
VSOURCE
LOAD
TVS
GATE
SOURCE
LOAD
SOURCE
FB_PROT
SGND
Figure 5. Protecting the MAX15009 Input from High-Voltage
Transients
SGND
Figure 6. Power Dissipated Across MOSFETs During an
Overvoltage Fault (Overvoltage Limiter Mode)
______________________________________________________________________________________
17
MAX15009/MAX15011
External MOSFET Selection
Use the following formula to calculate R4:
R4 = VTH_PROT x RTOTAL / VOV
MAX15009/MAX15011
Automotive 300mA LDO Regulators with
Switched Output and Overvoltage Protector
Calculate the discharge time, t1, using the following
equation:
0.04 × VOV
t1 = CSOURCE ×
ILOAD + IGATEPD
GATE
SOURCE
t2
t3
t1
tOVP
Figure 7. MAX15009 Timing Diagram
Overvoltage-Limiter Mode
Switching Frequency
When the MAX15009 is configured in overvoltagelimiter mode, the external n-channel MOSFET is subsequently switched on and off during an overvoltage
event. The output voltage at OUT_PROT resembles a
periodic sawtooth waveform. Calculate the period of
the waveform, tOVP, by summing three time intervals
(Figure 7):
tOVP = t1 + t2 + t3
where t1 is the VSOURCE output discharge time, t2 is the
GATE delay time, and t3 is the VSOURCE output charge
time.
During an overvoltage event, the power dissipated
inside the MAX15009 is due to the gate pulldown current, I GATEPD . This amount of power dissipation is
worse when ISOURCE = 0 (CSOURCE is discharged only
by the internal current sink).
The worst-case internal power dissipation contribution
in overvoltage limiter mode, P OVP , in watts can be
approximated using the following equation:
t
POVP = VOV × 0.98 × IGATEPD × 1
t OVP
where VOV is the overvoltage threshold voltage in volts
and IGATEPD is 100mA (max) GATE pulldown current.
Output Discharge Time (t1)
When the voltage at SOURCE exceeds the adjusted
overvoltage threshold, GATE’s internal pulldown is
enabled until VSOURCE drops by 4%. The internal current sink, I GATEPD , and the external load current,
I LOAD , discharge the external capacitance from
SOURCE to ground.
18
where t 1 is in ms, V OV is the adjusted overvoltage
threshold in volts, ILOAD is the external load current in
mA, and IGATEPD is the 100mA (max) internal pulldown
current of GATE. CSOURCE is the value of the capacitor
connected between the source of the MOSFET and
PGND in µF.
GATE Delay Time (t2)
When SOURCE falls 4% below the overvoltage-threshold
voltage, the internal current sink is disabled and the
internal charge pump begins recharging the external
GATE voltage. Due to the external load, the SOURCE
voltage continues to drop until the gate of the MOSFET is
recharged. The time needed to recharge GATE and reenhance the external MOSFET is approximately:
t 2 = Ciss ×
VGS( TH) + VF
IGATE
where t2 is in µs, Ciss is the input capacitance of the
MOSFET in pF, and VGS(TH) is the GATE-to-SOURCE
threshold voltage of the MOSFET in volts. VF is the 0.7V
(typ) internal clamp diode forward voltage of the MOSFET in volts, and IGATE is the charge-pump current
45µA (typ). Any external capacitance between GATE
and PGND adds up to Ciss.
During t2, the SOURCE capacitance, CSOURCE, loses
charge through the output load. The voltage across
CSOURCE, ΔV2, decreases until the MOSFET reaches
its VGS(TH) threshold. Approximate ΔV2 using the following formula:
I
×t
ΔV2 = LOAD 2
CSOURCE
SOURCE Output Charge Time (t3)
Once the GATE voltage exceeds the GATE-to-SOURCE
threshold, VGS(TH), of the external MOSFET, the MOSFET turns on and the charge through the internal
charge pump with respect to the drain potential, QG,
determines the slope of the output voltage rise. The
time required for the SOURCE voltage to rise again to
the overvoltage threshold is:
t3 =
Crss × ΔVSOURCE
IGATE
______________________________________________________________________________________
Automotive 300mA LDO Regulators with
Switched Output and Overvoltage Protector
Power Dissipation/Junction Temperature
During normal operation, the MAX15009/MAX15011
have two main sources of internal power dissipation:
the LDO and the switched output.
The internal power dissipation due to the LDO can be
calculated as:
PLDO = (VIN − VOUT_LDO ) × (IOUT_LDO + IOUT_SW )
where VIN is the LDO input supply voltage in volts,
VOUT_LDO is the output voltage of the LDO in volts,
I OUT_LDO is the LDO total load current in mA, and
IOUT_SW is the switch load current in mA.
Calculate the power dissipation due to the switch as:
PSW = ΔVSW × IOUT _ SW
where ΔVSW is the switch dropout voltage in volts for
the given IOUT_SW current in mA.
The total power dissipation PDISS in mW as:
PDISS = PLDO + PSW
For prolonged exposure to overvoltage events, use the
VIN voltage expected during overvoltage conditions.
Under these circumstances the corresponding internal
power dissipation contribution, POVP, calculated in the
previous section should also be included in the total
power dissipation, PDISS.
For a given ambient temperature, T A, calculate the
junction temperature, TJ, as follows:
TJ = TA + PDISS x θJA
where TJ and TA are in °C and θJA is the junction-toambient thermal resistance in °C/W as listed in the
Absolute Maximum Ratings section.
The junction temperature should never exceed +150°C
during normal operation.
Thermal Protection
When the junction temperature exceeds TJ = +160°C,
the MAX15009/MAX15011 shut down to allow the
device to cool. When the junction temperature drops to
+140°C, the thermal sensor turns all enabled blocks on
again, resulting in a cycled output during continuous
thermal-overload conditions. Thermal protection protects the MAX15009/MAX15011 from excessive power
dissipation. For continuous operation, do not exceed
the absolute maximum junction temperature rating of
+150°C.
______________________________________________________________________________________
19
MAX15009/MAX15011
where VSOURCE = (VOV x 0.04) + V2 in volts, and Crss
is the MOSFET’s reverse transfer capacitance in pF.
Any external capacitance between GATE and PGND
adds up to Crss.
Automotive 300mA LDO Regulators with
Switched Output and Overvoltage Protector
MAX15009/MAX15011
Typical Operating Circuits
VOUT1
DC-DC
MAX5073
VOUT2
CSOURCE
5V TO 40V INPUT
GATE
SOURCE
FB_PROT
PGND
IN
SGND
CIN
SWITCH OUTPUT
OUT_SW
LDO ON/OFF
COUT_SW
EN_LDO
MAX15009
SWITCH ON/OFF
PROTECTOR ON/OFF
HOLD
5V
300mA
EN_SW
OUT_LDO
EN_PROT
FB_LDO
HOLD
μC
RPU
ILIM
RESET/EN
I/O
RESET
CT
RILIM
VCC
COUT_LDO
OC_DELAY
CRESET
COC_DELAY
5V TO 40V INPUT
IN
LDO ON/OFF
SWITCH ON/OFF
HOLD
COUT_SW
EN_LDO
MAX15011
VCC
COUT_LDO
EN_SW
FB_LDO
RPU
μC
HOLD
RESET
CT
OC_DELAY
CRESET
20
5V
300mA
OUT_LDO
ILIM
RILIM
SWITCH OUTPUT
OUT_SW
CIN
RESET/EN
I/O
PGND SGND
COC_DELAY
______________________________________________________________________________________
Automotive 300mA LDO Regulators with
Switched Output and Overvoltage Protector
ILIM
OC_DELAY
OUT_LDO
OUT_LDO
IN
IN
N.C.
EN_SW
23
22
21
20
19
18
17
HOLD 25
16
EN_LDO
N.C. 26
15
FB_LDO
OUT_SW 27
14
N.C.
13
N.C.
12
N.C.
OUT_SW 28
MAX15011
N.C. 29
N.C. 30
N.C. 31
*EP
+
4
5
6
7
8
N.C.
SGND
PGND
RESET
N.C.
N.C.
3
N.C.
2
N.C.
N.C. 32
1
LDO
SWITCHED
OUTPUT
MAX15009
√
√
√
MAX15011
√
√
—
PART
24
TOP VIEW
Selector Guide
11
N.C.
10
N.C.
9
CT
OVP
CONTROLLER
Chip Information
PROCESS: BiCMOS
TQFN
(5mm x 5mm)
*EP = EXPOSED PAD
______________________________________________________________________________________
21
MAX15009/MAX15011
Pin Configurations (continued)
Package Information
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information
go to www.maxim-ic.com/packages.)
QFN THIN.EPS
MAX15009/MAX15011
Automotive 300mA LDO Regulators with
Switched Output and Overvoltage Protector
22
______________________________________________________________________________________
Automotive 300mA LDO Regulators with
Switched Output and Overvoltage Protector
______________________________________________________________________________________
23
MAX15009/MAX15011
Package Information (continued)
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information
go to www.maxim-ic.com/packages.)
MAX15009/MAX15011
Automotive 300mA LDO Regulators with
Switched Output and Overvoltage Protector
Revision History
REVISION
NUMBER
REVISION
DATE
0
8/07
Initial release
1
1/08
Removed future product asterisks, updated Electrical Characteristics table and
Typical Operating Characteristics section.
DESCRIPTION
PAGES
CHANGED
—
1, 2, 6, 8
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are
implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
24 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600
© 2008 Maxim Integrated Products
is a registered trademark of Maxim Integrated Products, Inc.
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