Low-Noise 500mA LDO Regulators MAX8902A/MAX8902B in a 2mm x 2mm TDFN Package

Low-Noise 500mA LDO Regulators MAX8902A/MAX8902B in a 2mm x 2mm TDFN Package
EVALUATION KIT AVAILABLE
Low-Noise 500mA LDO Regulators
in a 2mm x 2mm TDFN Package
MAX8902A/MAX8902B
General Description
Features
The MAX8902A/MAX8902B low-noise linear regulators
deliver up to 500mA of output current with only
16µVRMS of output noise in a 100kHz bandwidth. These
regulators maintain their output voltage over a wide
input range, requiring only 100mV of input-to-output
headroom at full load.
These LDOs maintain a low 80µA typical supply current, independent of the load current and dropout voltage. The regulator control circuitry includes a
programmable soft-start circuit and short circuit,
reverse current, and thermal-overload protection. Other
features include an enable input and a power-OK output (MAX8902B only).
The MAX8902A output voltage can be set to 1.5V, 1.8V,
2.0V, 2.5V, 3.0V, 3.1V, 3.3V, 4.6V, or 4.7V using the
SELA and SELB inputs. The MAX8902B output voltage
can be set between 0.6V and 5.3V with an external
resistor voltage-divider.
•
•
•
•
•
•
•
Applications
•
•
•
•
•
•
1.7V to 5.5V Input Voltage Range
0.6V to 5.3V Output Voltage Range
16µVRMS Output Noise, 10Hz to 100kHz
80µA Operating Supply Current
92dB PSRR at 5kHz
Guaranteed 500mA Output Current
±1.5% Output Accuracy Over Load, Line, and
Temperature
100mV (max) Dropout at 500mA Load
< 1µA Shutdown Supply Current
700mA Short-Circuit Protection
Thermal-Overload Protection
Output-to-Input Reverse Current Protection
2mm x 2mm x 0.8mm TDFN Package
Ordering Information
FEATURES
TOP
MARK
MAX8902AATA+
Pin-selectable output
voltage
ABG
MAX8902AATA/V+
Pin-selectable output
voltage
BRP
MAX8902BATA+
Adjustable output voltage
ABH
MAX8902BATA/V+
Adjustable output voltage
ADL
PART
Notebook Computers
MP3 and Portable Media Players
Wireless Headphones
GPS Portable Navigation Devices
Smartphones
+Denotes a lead(Pb)-free/RoHS-compliant package.
/V denotes an automotive qualified part.
Note: All devices are in an 8-pin, 2mm x 2mm TDFN package
with an exposed paddle and operate over the -40°C to +125°C
automotive temperature range.
Typical Operating Circuits
INPUT
4.7V TO 5.5V
INPUT
1.7V TO 5.5V
OUTPUT
4.6V
MAX8902A
EN
ON
OFF
OUT
IN
OUT
IN
10μF
OUTPUT ADJUSTABLE
0.6V TO 5.3V
0.01μF
BYP
10μF
10μF
0.01μF
BYP
ON
OFF
OUTS
MAX8902B
10μF
R1
EN
FB
LOGIC
SUPPLY
R2
SELA
R3
100kΩ
SELB
TO μC
EP
GND
Pin Configurations appear at end of data sheet.
19-0990; Rev 6; 1/15
GS
POK
EP
GND
Low-Noise 500mA LDO Regulators
in a 2mm x 2mm TDFN Package
MAX8902A/MAX8902B
Absolute Maximum Ratings
BYP, EN, IN, OUT, SELA, SELB, POK to GND, GS to GND, FB,
OUTS to GND .....................................................-0.3V to +6.0V
Output Short-Circuit Duration.....................................Continuous
Continuous Power Dissipation (TA = +70°C)
TDFN (derate 11.9mW/°C above +70°C)...................953.5mW
Operating Temperature Range .........................-40°C to +125°C
Junction Temperature Range ............................-40°C to +150°C
Storage Temperature Range .............................-65°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C
Soldering Temperature (reflow) .......................................+260°C
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 = VEN = 5V, OUTS = OUT, circuit of Figure 2 (MAX8902A) and Figure 3 (MAX8902B), TA = -40°C to +125°C, unless otherwise
noted.) (Note 1)
PARAMETER
CONDITIONS
MIN
TYP
MAX
UNITS
5.5
V
1.7
V
IN
Input Voltage Range
Input Undervoltage Lockout
1.7
VIN rising, 100mV typical hysteresis
1.5
1.6
Output Voltage Range
VIN VOUT + 0.1V
0.6
5.3
V
Output Voltage Accuracy
VIN = 1.7V to 5.5V for VOUT 1.4V,
VIN = (VOUT + 0.3V) to 5.5V for VOUT > 1.4V,
I OUT = 0.1mA to 500mA
-1.5
+1.5
%
Load Regulation
I OUT = 0.1mA to 500mA
0.02
%
Line Regulation
VIN = 1.7V to 5.5V for VOUT 1.4V,
VIN = (VOUT + 0.3V) to 5.5V for VOUT > 1.4V,
I OUT = 200mA
0.04
%
Dropout Voltage
(Note 2)
I OUT = 500mA
OUT
Current Limit
Output Noise
Power-Supply Rejection Ratio
VIN 3.6V, TA +85°C
VIN 3.6V, TA +125°C
VIN = 1.7V
VOUT = 95% of regulation, VIN = V OUT + 0.5V
I OUT = 100mA, f = 10Hz to 100kHz, CBYP = 0.01μF
I OUT = 10mA
50
100
120
mV
800
mA
150
600
700
16
f = 5kHz
92
f = 10kHz
85
f = 100kHz
62
μVRMS
dB
OUTS (MAX8902A only)
OUTS Input Bias Current
In regulation
0.5
7.0
μA
V
FB (MAX8902B only)
FB Threshold Accuracy
VIN = 1.7V to 5.5V, IOUT = 0.1mA to 500mA
FB Input Bias Current
VFB = 0.6V
TA = +25°C
0.591
0.600
0.609
-0.1
0.02
+0.1
TA = -40°C
0.03
μA
BYP
BYP Capacitor Range
Regulator remains stable
BYP Startup Current
From BYP to GND during startup
www.maximintegrated.com
1
100
50
nF
μA
Maxim Integrated | 2
Low-Noise 500mA LDO Regulators
in a 2mm x 2mm TDFN Package
MAX8902A/MAX8902B
Electrical Characteristics (continued)
(VIN = VEN = 5V, OUTS = OUT, circuit of Figure 2 (MAX8902A) and Figure 3 (MAX8902B), TA = -40°C to +125°C, unless otherwise
noted.) (Note 1)
PARAMETER
CONDITIONS
MIN
TYP
MAX
80
120
160
+1
UNITS
GND
GND Supply Current
I OUT = 0mA
GND Shutdown Current
VIN = 5.5V, EN = 0V
TA < +85°C
TA < +125°C
TA = +25°C
0.001
TA = +85°C
0.01
μA
μA
SELA/SELB (MAX8902A only)
Select Input Resistance
Select Input Capacitance
When shorted to GND or VIN
500
When open
1
M
When open
10
pF
EN
Enable Input Threshold
Enable Input Bias Current
VIN = 1.7V to 5.5V
VEN = 0V to 5.5V
EN rising
EN falling, TA < +85°C
0.4
0.8
0.7
EN falling, TA < +125°C
0.38
0.7
-1
0.001
TA = +25°C
TA = +85°C
1.2
V
+1
0.01
μA
POK (MAX8902B only)
POK Threshold
OUT voltage when POK
switches
POK Voltage, Low
I POK = 1mA
POK Leakage Current
POK = 5.5V, VEN = 0V
OUT rising
88
OUT falling
TA = +25°C
TA = +85°C
91
94
%
10
100
mV
0.001
+1
88
-1
0.01
%
μA
THERMAL SHUTDOWN
Thermal Shutdown Threshold
TJ rising
165
TJ falling
150
°C
OUTPUT TRANSIENT
Load Transient
I OUT = 50mA to 500mA to 50mA, tRISE = tFALL= 1μs
25
mV/ P-P
Line Transient
VIN = 4V to 5V to 4V, tRISE = tFALL = 5μs, I OUT = 500mA
3
mV/ P-P
IN-to-OUT Reverse Voltage
Turnoff Threshold
IN falling below OUT
10
mV
Note 1: All devices are production tested at TA = +25°C. Specifications over the operating temperature range are guaranteed by
design and characterization.
Note 2: The dropout voltage is defined VIN - VOUT, when VOUT is 5% lower than the value of VOUT when VIN = VOUT + 0.5V.
www.maximintegrated.com
Maxim Integrated | 3
Low-Noise 500mA LDO Regulators
in a 2mm x 2mm TDFN Package
MAX8902A/MAX8902B
Typical Operating Characteristics
(MAX8902A, VIN = 3.6V, VOUT = 2.5V, TA = +25°C, unless otherwise noted.)
80
60
40
2.504
2.503
2.502
20
2.501
0
2.500
2.510
200mA LOAD
2.508
2.506
OUTPUT VOLTAGE (V)
3.6V INPUT
2.505
OUTPUT VOLTAGE (V)
100
MAX8902A/02B toc02
2.506
MAX8902A/02B toc01
120
INPUT CURRENT (μA)
LINE REGULATION
LOAD REGULATION
140
MAX8902A/02B toc03
QUIESCENT CURRENT
EN = HIGH, NO LOAD
2.504
2.502
2.500
2.498
2.496
2.494
2.492
0
1
2
3
4
2.490
0
5
100
200
300
400
500
1.5
2.5
LOAD CURRENT (mA)
INPUT VOLTAGE (V)
LOAD TRANSIENT RESPONSE
50mA TO 500mA TO 50mA
3.5
4.5
STARTUP WAVEFORM
LINE TRANSIENT RESPONSE
MAX8902A/02B toc05
MAX8902A/02B toc04
5.5
INPUT VOLTAGE (V)
MAX8902A/02B toc06
2V/div
5V
100mV/div
VOUT
5V
VEN
500mV/div
2V/div
VIN
4V
200mA/div
2mV/div
VOUT
VOUT
200mA/div
IOUT
5Ω LOAD
CBYP = 0.01μF
40ms/div
10μs/div
100μs/div
DROPOUT VOLTAGE vs. LOAD CURRENT
PSRR vs. FREQUENCY
MAX8902A LDO OUTPUT-NOISE SPECTRAL
DENSITY vs. FREQUENCY
-30
PSRR (dB)
50
-20
40
30
-40
-50
-60
1E+3
100E+0
-70
20
10E+3
MAX8902A/02B toc09
60
MAX8902A/02B toc08
70
0
-10
NOISE DENSITY (nV √Hz)
3.6V INPUT, 4.6V OUTPUT PRESET
THE SLOPE OF THE LINE INDICATES
A 129mΩ ON-RESISTANCE IN
DROPOUT
MAX8902A/02B toc07
80
DROPOUT VOLTAGE (mV)
IIN
2.5V OUTPUT
5Ω LOAD
tRISE = tFALL = 1μs
-80
10
-90
-100
0
0
100
200
300
LOAD CURRENT (mA)
www.maximintegrated.com
400
500
10E+0
10
100
1k
FREQUENCY (Hz)
10k
100k
10
100
1k
10k
100k
1M
FREQUENCY (Hz)
Maxim Integrated | 4
MAX8902A/MAX8902B
Low-Noise 500mA LDO Regulators
in a 2mm x 2mm TDFN Package
Pin Description
PIN
NAME
FUNCTION
MAX8902A
MAX8902B
1
IN
IN
2
GND
GND
3
EN
EN
Enable Input. A logic-low drives the output low through a 3k resistor and reduces the supply
current to less than 1μA. Drive logic-high or connect to IN for normal operation.
SELA
—
Output Voltage Select Input. Connect SELA to GND, IN, or leave unconnected. The states of
SELA and SELB are sampled when the regulator turns on and the output voltage is set as
shown in Table 2.
—
GS
Internally Used. Connect GS to GND.
SELB
—
Output Voltage Select Input. Connect SELB to GND, IN, or leave unconnected. The states of
SELA and SELB are sampled when the regulator turns on and the output voltage is set as
shown in Table 2.
—
POK
Power-OK Output. Open-drain output that goes low when the output is above 91% of the
nominal regulation voltage. POK is high impedance in shutdown or when the output is below
the regulation voltage.
OUTS
—
Output Sense Input. Connect OUTS to the load at a point where accurate regulation is
required, or connect OUTS directly to OUT.
—
FB
Feedback Input. Connect FB to the center of a resistor voltage-divider connected between
OUT and GND to set the output voltage. VFB regulates to 0.6V.
4
Regulator Power Input. Connect IN to a supply from 1.7V to 5.5V. Bypass IN with a 10μF
ceramic capacitor to GND.
Ground
5
6
7
BYP
BYP
Bypass Input. Connect a 0.01μF ceramic capacitor from BYP to OUT to achieve 16μVRMS
output noise. Adjust the value of this capacitor to control the output slew rate during startup.
Slew Rate = (5V / ms) x (0.01μF / CBYP)
8
OUT
OUT
—
EP
EP
Regulator Output. Sources up to 500mA at the output regulation voltage. Bypass with a 10μF
(< 0.03 ESR) capacitor to GND.
Exposed Paddle. Connect the exposed paddle to a ground plane to provide heat sinking.
Detailed Description
The MAX8902A/MAX8902B low-noise, low-dropout linear regulators deliver up to 500mA of output current
with only 16µVRMS of output noise in a 100kHz bandwidth. These regulators maintain their output voltage
over a wide input range, requiring only 100mV of inputto-output headroom at full load.
The MAX8902 maintains a low 80µA typical supply current, independent of the load current and dropout voltage. The regulator control circuitry includes a
programmable soft-start circuit and short circuit,
reverse current, and thermal-overload protection. Other
features include an enable input and a power-OK
www.maximintegrated.com
(POK) output (MAX8902B only). A simplified functional
diagram is shown in Figure 1.
The MAX8902A output voltage can be set to 1.5V, 1.8V,
2.0V, 2.5V, 3.0V, 3.1V, 3.3V, 4.6V, or 4.7V using the
SELA and SELB inputs. The MAX8902B output voltage
can be set between 0.6V and 5.3V with an external
resistor voltage-divider.
Enable (EN)
The MAX8902A/MAX8902B include an enable input,
EN. Pull EN low to shut down the output, or drive EN
high to enable the output. If shutdown is not needed,
connect EN to IN.
Maxim Integrated | 5
Low-Noise 500mA LDO Regulators
in a 2mm x 2mm TDFN Package
MAX8902A/MAX8902B
THERMAL
PROTECTION
IN
CURRENT
LIMIT
EN
REVERSE
CURRENT
PROTECTION
CONTROL
OUT
BYP
BYP
GND
REF
0.6V
EA
POK
MAX8902A
MAX8902B
0.54V
FB
MAX8902B ONLY
OUTS
MAX8902A ONLY
SELA
990kΩ
VOLTAGE
SELECT
SELB
Figure 1. Simplified Functional Diagram
Bypass (BYP)
The capacitor connected from BYP to OUT filters the
noise of the reference, feedback resistors, and regulator input stage and provides a high-speed feedback
path for improved transient response. A 0.01µF capacitor rolls off input noise at approximately 32Hz.
www.maximintegrated.com
The slew rate of the output voltage during startup is
also determined by the BYP capacitor. A 0.01µF
capacitor sets the slew rate to 5V / ms. This startup rate
results in a 50mA slew current drawn from the input at
startup to charge the 10µF output capacitance.
Maxim Integrated | 6
MAX8902A/MAX8902B
The BYP capacitor value can be adjusted from 0.001µF
to 0.1µF to change the startup slew rate according to
the following formula:
Startup slew rate = (5V / ms) x (0.01µF / CBYP)
Note that this slew rate applies only at startup, and that
recovery from a short circuit occurs at a slew rate
approximately 500 times slower.
Also note that, being a low-frequency filter node, BYP is
sensitive to leakage. BYP leakage currents above 10nA
cause measurable inaccuracy at the output and should
be avoided.
Low-Noise 500mA LDO Regulators
in a 2mm x 2mm TDFN Package
Table 1. 2mm x 2mm TDFN Package
Thermal Characteristics
CONTINUOUS POWER
DISSIPATION
953.5mW DERATE 11.9mW/°C
ABOVE +70°C
JA*
83.9°C/W
JC
10.8°C/W
*θJA is specified according to the JESD51 standard with the
part mounted on a multilayer PCB.
Table 2. MAX8902A Output Voltages
Protection Features
The MAX8902A/MAX8902B are fully protected from an
output short circuit by a current-limiting and thermaloverload circuit. If the output is shorted to GND, the
output current is limited to 700mA (typ). Under these
conditions, the part quickly heats up. When the junction
temperature reaches +165°C, a thermal-limit circuit
shuts off the output device. When the junction cools to
+150°C, the output turns back on in an attempt to
reestablish regulation. While the fault persists, the output current cycles on and off, as the junction temperature slews between +150°C and +165°C.
The MAX8902A/MAX8902B are also protected against
reverse current when the output voltage is higher than
the input. In the event that extra output capacitance is
used at the output, a power-down transient at the input
would normally cause a large reverse current through a
conventional regulator. The MAX8902A/MAX8902B
include a reverse voltage detector that trips when IN
drops 10mV below OUT, shutting off the regulator and
opening the pMOS body diode connection, preventing
any reverse current.
Thermal Considerations
The MAX8902A/MAX8902B are packaged in an 8-pin,
2mm x 2mm TDFN package with an exposed paddle.
The exposed paddle is the main path for heat to leave
the IC, and therefore, must be connected to a ground
plane with thermal vias to allow heat to dissipate from
the device. Thermal properties of the IC package are
given in Table 1.
OUTPUT VOLTAGE
(V)
SELA STATE
SELB STATE
1.5
IN
Unconnected
1.8
Unconnected
GND
2.0
Unconnected
IN
2.5
Unconnected
Unconnected
3.0
GND
GND
3.1
GND
IN
3.3
GND
Unconnected
4.6
IN
GND
4.7
IN
IN
are sampled only at startup. The regulation voltage can
be set to a different level by cycling EN or IN momentarily to GND.
Setting the Output Voltage (MAX8902B)
The MAX8902B uses external feedback resistors to set
the output regulation voltage as shown in Figure 3. The
output can be set from 0.6V to 5.3V. Set the lower feedback resistor (R2) to 120kΩ or less to minimize FB input
bias current error. Then calculate the value of the upper
feedback resistor (R1) as follows:
⎛V
⎞
R1 = R2 × ⎜ OUT − 1⎟
⎝ VFB
⎠
where VFB is the feedback regulation voltage of 0.6V.
Selecting the Output Voltage (MAX8902A)
Power-OK (MAX8902B)
The MAX8902A output can be set to one of nine voltages by shorting or opening the SELA and SELB
inputs, as shown in Table 2. SELA and SELB should be
connected to GND, IN, or left unconnected.
Alternatively, they may be driven high, low, or open with
external logic; however, the states of SELA and SELB
The MAX8902B includes an additional open-drain output, POK, that pulls low to indicate the output voltage is
in regulation. During startup, POK is high impedance
until the output voltage rises to 91% of its regulation
level. If an overload occurs at the output, or the output
is shut down, POK is high impedance.
www.maximintegrated.com
Maxim Integrated | 7
Low-Noise 500mA LDO Regulators
in a 2mm x 2mm TDFN Package
MAX8902A/MAX8902B
INPUT
4.7V TO 5.5V
INPUT
1.7V TO 5.5V
OUTPUT
4.6V
10μF
MAX8902A
EN
ON
OUTPUT ADJUSTABLE
0.6V TO 5.3V
OUT
IN
OFF
OUT
IN
0.01μF
10μF
10μF
BYP
MAX8902B
ON
OFF
10μF
R1
EN
FB
LOGIC
SUPPLY
OUTS
0.01μF
BYP
R2
SELA
R3
100kΩ
SELB
TO μC
EP
GS
POK
GND
EP
GND
Figure 2. MAX8902A Fixed-Output Application Circuit
Figure 3. MAX8902B Adjustable-Output Application Circuit
Input Capacitor
Pin Configurations
A 10µF ceramic capacitor is recommended for the
input. Select a capacitor that maintains its capacitance
over temperature and DC bias. Capacitors with X5R or
X7R temperature characteristics generally perform well.
Output Capacitor
TOP VIEW
IN 1
A minimum of 10µF of capacitance is required at OUT
to ensure stability. Select a ceramic capacitor that
maintains its capacitance over temperature and DC
bias. Capacitors with X5R or X7R temperature characteristics generally perform well.
GND 2
EN 3
SELA 4
+
MAX8902A
8 OUT
IN 1
7 BYP
GND 2
6 OUTS
EN 3
5 SELB
GS 4
EP
TDFN
(2mm x 2mm)
+
8 OUT
MAX8902B
EP
7 BYP
6 FB
5 POK
TDFN
(2mm x 2mm)
EP = EXPOSED PADDLE.
Package Information
Chip Information
For the latest package outline information and land patterns (footprints), go to www.maximintegrated.com/packages. Note that a
“+”, “#”, or “-” in the package code indicates RoHS status only.
Package drawings may show a different suffix character, but the
drawing pertains to the package regardless of RoHS status.
PROCESS: BiCMOS
PACKAGE
TYPE
PACKAGE
CODE
OUTLINE
NO.
LAND
PATTERN NO.
8 TDFN-EP
T822+1
21-0168
90-0064
www.maximintegrated.com
Maxim Integrated | 8
Low-Noise 500mA LDO Regulators
in a 2mm x 2mm TDFN Package
MAX8902A/MAX8902B
Revision History
REVISION
NUMBER
REVISION
DATE
PAGES
CHANGED
0
9/07
Initial release
1
1/08
Changed input capacitor value from 4.7µF to 10µF
1, 5, 8
2
2/08
Changed BP to BYP
2, 4–8
3
5/08
Updated TOC 5 title
4
4
4/11
Added the MAX8902BATA/V+ part to the Ordering Information table
1
5
10/12
Updated θJC specification in Table 1
7
6
1/15
Added MAX8902AATA/V+ to Ordering Information
1
DESCRIPTION
—
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642, or visit Maxim Integrated’s website at www.maximintegrated.com.
Maxim Integrated cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim Integrated product. No circuit patent
licenses are implied. Maxim Integrated reserves the right to change the circuitry and specifications without notice at any time. The parametric values (min and
max limits) shown in the Electrical Characteristics table are guaranteed. Other parametric values quoted in this data sheet are provided for guidance.
Maxim Integrated and the Maxim Integrated logo are trademarks of Maxim Integrated Products, Inc.
© 2015 Maxim Integrated Products, Inc. | 9
Was this manual useful for you? yes no
Thank you for your participation!

* Your assessment is very important for improving the work of artificial intelligence, which forms the content of this project

Download PDF

advertisement