MAX1792 500mA Low-Dropout Linear Regulator in µMAX General Description

MAX1792 500mA Low-Dropout Linear Regulator in µMAX General Description
MAX1792
500mA Low-Dropout
Linear Regulator in µMAX
General Description
Features
The MAX1792 low-dropout linear regulator operates
from a +2.5V to +5.5V supply and delivers a guaranteed 500mA load current with low 130mV dropout. The
high-accuracy (±1%) output voltage is preset at an
internally trimmed voltage (see Selector Guide) or can
be adjusted from 1.25V to 5.0V with an external resistive divider.
An internal PMOS pass transistor allows the low 80µA
supply current to remain independent of load, making
this device ideal for portable battery-operated equipment such as personal digital assistants (PDAs), cellular phones, cordless phones, base stations, and
notebook computers.
Other features include an active-low open-drain reset
output with a 4ms timeout period that indicates when
the output is out of regulation, a 0.1µA shutdown mode,
short-circuit protection, and thermal shutdown protection. The device is available in a miniature 1.3W, 8-pin
power-µMAX package with a metal pad on the underside of the package.
o Guaranteed 500mA Output Current
o Low 130mV Dropout at 500mA
o Up to ±1% Output Voltage Accuracy
________________________Applications
*Insert the desired two-digit suffix (see Selector Guide) into the
blanks to complete the part number.
+Denotes a lead(Pb)-free/RoHS-compliant package.
/V denotes an automotive qualified part.
Contact factory for other preset output voltages.
Notebook Computers
Cellular and Cordless Telephones
Preset at 1.5V, 1.8V, 2.5V, 3.3V, or 5.0V
Adjustable from 1.25V to 5.0V
o Reset Output with 4ms Timeout Period
o Low 80µA Ground Current
o 0.1µA Shutdown Current
o Thermal Overload Protection
o Output Current Limit
o Tiny 1.3W Power-µMAX Package
Ordering Information
PART*
TEMP RANGE
PIN-PACKAGE
MAX1792EUA_ _+
-40°C to +85°C
8 Power-μMAX
MAX1792EUA_ _/V+
-40°C to +85°C
8 Power-μMAX
Personal Digital Assistants (PDAs)
Selector Guide
Palmtop Computers
PART AND SUFFIX
Base Stations
V OUT
μMAX TOP MARK
USB Hubs
MAX1792EUA15+
1.5V or Adj.
AAAE
Docking Stations
MAX1792EUA18+
1.8V or Adj.
AAAA
MAX1792EUA25+
2.5V or Adj.
AAAB
MAX1792EUA33+
3.3V or Adj.
AAAC
MAX1792EUA50+
5.0V or Adj.
AAAD
MAX1792EUA33/V+
3.3V or Adj.
AACP
Typical Operating Circuit
VIN = +2.5V TO +5.5V
CIN
1µF
IN
NC
OUT
IN
OUT
Pin Configuration
VOUT
COUT
3.3µF
TOP VIEW
+
MAX1792
ON
SHDN
IN 1
RRST
100k
RST
OFF
IN 2
TO
µC
RST
3
SHDN 4
SET
MAX1792
EP
8
OUT
7
OUT
6
SET
5
GND
GND
POWER-µMAX
For pricing, delivery, and ordering information, please contact Maxim Direct
at 1-888-629-4642, or visit Maxim’s website at www.maximintegrated.com.
19-1699; Rev 2; 11/11
MAX1792
500mA Low-Dropout
Linear Regulator in µMAX
ABSOLUTE MAXIMUM RATINGS
IN, SHDN, RST, SET to GND ....................................-0.3V to +6V
OUT to GND ................................................-0.3V to (VIN + 0.3V)
Output Short-Circuit Duration ........................................Indefinite
Continuous Power Dissipation (TA = +70°C)
8-Pin Power-µMAX (derate 17mW/°C above +70°C) .......1.3W
Operating Temperature Range ...........................-40°C to +85°C
Junction Temperature ......................................................+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 = VOUT(NOM) + 500mV, or VIN = +2.5V (whichever is greater), SHDN = IN, TA = 0°C to +85°C, unless otherwise noted. Typical
values are at TA = +25°C.)
PARAMETER
Input Voltage
Input Undervoltage Lockout
SYMBOL
CONDITIONS
VIN
VUVLO
VOUT
Rising, 75mV hysteresis
2.0
+1
+1.5
IOUT = 100mA, TA = 0°C to +85°C
-2
+2
IOUT = 1mA to 500mA, VIN > VOUT + 0.5V,
TA = 0°C to +85°C
-3
+3
1.25
5
VIN = +2.7V,
VOUT set to 2.0V,
IOUT = 100mA
TA = +85°C
1.229
TA = 0°C to +85°C
1.219
IOUT
VIN 2.7V
500
Short-Circuit Current Limit
ILIM
VOUT = 0V, VIN 2.7V
0.55
SET Dual Mode™ Threshold
IOUT = 1mA
mARMS
0.8
100
80
IOUT = 500mA
1.8
A
A
150
mV
+100
nA
250
110
μA
VOUT = 5.0V
120
225
VOUT = 3.3V
130
250
VOUT = 2.5V
210
360
0
+0.15
%/V
IOUT = 1mA to 500mA
0.4
1.0
%
10Hz to 1MHz, C OUT = 3.3μF (ESR < 0.1)
115
SHDN = GND, VIN = 5.5V
0.1
IOUT = 500mA
Line Regulation
VLNR
VIN from (VOUT + 100mV) to 5.5V,
ILOAD = 5mA
Load Regulation
VLDR
Output Voltage Noise
V
1.281
-100
VIN VOUT
Dropout Voltage (Note 1)
%
1.271
1.6
50
VSET = 1.25V
1.250
%
V
VOUT > 96% of nominal value, VIN 2.7V
IQ
V
-1
Maximum Output Current
Ground-Pin Current
V
2.3
-1.5
VSET
ISET
UNITS
5.5
Preset VOUT 2.5V
SET Voltage Threshold
(Adjustable Mode)
SET Input Bias Current
2.15
MAX
Preset VOUT < 2.5V
Adjustable Output Voltage
Range
In-Regulation Current Limit
TYP
2.5
IOUT = 100mA,
TA = +85°C
Output Voltage Accuracy
(Preset Mode)
MIN
-0.15
mV
μVRMS
SHUTDOWN
Shutdown Supply Current
SHDN Input Threshold
SHDN Input Bias Current
IOFF
VIH
2.5V < VIN < 5.5V
VIL
2.5V < VIN < 5.5V
SHDN = IN or GND
15
1.6
0.6
10
100
μA
V
nA
Dual Mode is a trademark of Maxim Integrated Products.
2
Maxim Integrated
MAX1792
500mA Low-Dropout
Linear Regulator in µMAX
ELECTRICAL CHARACTERISTICS (continued)
(VIN = VOUT(NOM) + 500mV, or VIN = +2.5V (whichever is greater), SHDN = IN, TA = 0°C to +85°C, unless otherwise noted. Typical
values are at TA = +25°C.)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
0.01
0.1
V
5.5
V
100
nA
RESET OUTPUT
Reset Output Low Voltage
VOL
RST sinking 1mA
Operating Voltage Range for
Valid Reset
RST sinking 100μA
RST Output High Leakage
Current
VRST = +5.5V
RST Threshold
RST Release Delay
tRP
1.0
Rising edge, referred to VOUT(NOMINAL)
90
93
96
%
Rising edge of OUT to rising edge of RST
1.5
4.5
8
ms
THERMAL PROTECTION
Thermal Shutdown Temperature
TSHDN
170
°C
Thermal Shutdown Hysteresis
TSHDN
20
°C
ELECTRICAL CHARACTERISTICS
(VIN = VOUT(NOM) + 500mV, or VIN = +2.5V (whichever is greater), SHDN = IN, TA = -40°C to +85°C, unless otherwise noted.) (Note 2)
PARAMETER
Input Voltage
SYMBOL
CONDITIONS
MIN
MAX
2.5
5.5
V
Rising or falling
2.0
2.3
V
IOUT = 100mA
-2
+2
IOUT = 1mA to 500mA
-3
+3
1.25
5
V
1.212
1.288
V
VIN
Input Undervoltage Lockout
VUVLO
Output Voltage Accuracy
(Preset Mode)
VOUT
Adjustable Output Voltage
Range
SET Voltage Threshold
(Adjustable Mode)
VSET
Maximum Output Current
IOUT
Short-Circuit Current Limit
ILIM
IOUT = 100mA
500
VOUT = 0V
SET Dual Mode Threshold
SET Input Bias Current
Ground-Pin Current
ISET
VSET = 1.25V
IQ
IOUT = 1mA
0.55
1.8
A
50
150
mV
-100
+100
nA
250
μA
225
VOUT = 3.3V
250
VOUT = 2.5V
360
IOUT = 500mA
Line Regulation
VLNR
VIN from (VOUT + 100mV) to 5.5V,
ILOAD = 5mA
Load Regulation
VLDR
%
mARMS
VOUT = 5.0V
VIN VOUT
Dropout Voltage (Note 1)
UNITS
-0.15
mV
+0.15
%/V
IOUT = 1mA to 500mA
1.0
%
15
μA
SHUTDOWN
Shutdown Supply Current
IOFF
SHDN = GND, VIN = +5.5V
SHDN Input
Threshold
VIH
2.5V < VIN < 5.5V
VIL
2.5V < VIN < 5.5V
0.6
SHDN = IN or GND
100
SHDN Input Bias Current
Maxim Integrated
I SHDN
1.6
V
nA
3
MAX1792
500mA Low-Dropout
Linear Regulator in µMAX
ELECTRICAL CHARACTERISTICS (continued)
(VIN = VOUT(NOM) + 500mV, or VIN = +2.5V (whichever is greater), SHDN = IN, TA = -40°C to +85°C, unless otherwise noted.) (Note 2)
PARAMETER
SYMBOL
CONDITIONS
MIN
MAX
UNITS
0.1
V
5.5
V
100
nA
RESET OUTPUT
Reset Output Low Voltage
RST sinking 1mA
VOL
Operating Voltage Range for
Valid Reset
RST sinking 100μA
RST Output High Leakage
Current
V RST = +5.5V
RST Threshold
RST Release Delay
tRP
1.0
Rising edge, referred to VOUT(NOMINAL)
90
96
%
Rising edge of OUT to rising edge of RST
1.5
8
ms
Note 1: Dropout voltage is defined as VIN - VOUT, when VOUT is 100mV below the value of VOUT measured when VIN = VOUT(NOM)
+ 0.5V. Since the minimum input voltage is 2.5V, this specification is only meaningful when VOUT(NOM) ≥ 2.5V. For VOUT(NOM)
between 2.5V and 3.5V, use the following equations: Typical Dropout = -93mV/V VOUT(NOM) + 445mV; Guaranteed Maximum
Dropout = -137mV/V VOUT(NOM) + 704mV. For VOUT(NOM) ≥ 3.5V: Typical Dropout = 120mV; Guaranteed Maximum Dropout
= 225mV.
Note 2: Specifications to -40°C are guaranteed by design, not production tested.
Typical Operating Characteristics
(MAX1792EUA33, VIN = VOUT + 500mV, SHDN = IN, CIN = 1µF, COUT = 3.3µF, TA = +25°C, unless otherwise noted.)
OUTPUT VOLTAGE
OUTPUT VOLTAGE
OUTPUT VOLTAGE
vs. INPUT VOLTAGE
vs. TEMPERATURE
vs. LOAD CURRENT
1.5
1.0
3.29
0
3.0
3.5
4.0
4.5
5.0
5.5
3.29
-40
100 200 300 400 500 600 700 800
-15
10
35
60
INPUT VOLTAGE (V)
LOAD CURRENT (mA)
TEMPERATURE (°C)
DROPOUT VOLTAGE
vs. LOAD CURRENT
GROUND-PIN CURRENT
vs. INPUT VOLTAGE
GROUND-PIN CURRENT
vs. LOAD CURRENT
200
TA = +25°C
100
TA = -40°C
IOUT = 500mA
120
100
80
140
IOUT = 0A
60
40
130
GROUND-PIN CURRENT (μA)
TA = +85°C
140
GROUND-PIN CURRENT (μA)
250
150
3.30
3.27
0
MAX1792-04
2.5
3.31
3.28
3.27
2.0
MAX1792-03
MAX1792-02
3.30
3.28
0.5
DROPOUT VOLTAGE (mV)
3.31
VIN = 5.5V
85
MAX1792-06
2.0
VIN = VOUT + 500mV
IOUT = 0A
3.32
OUTPUT VOLTAGE (V)
IOUT = 500mA
3.33
MAX1792-05
OUTPUT VOLTAGE (V)
2.5
3.32
OUTPUT VOLTAGE (V)
IOUT = 0A
3.0
3.33
MAX1792-01
3.5
120
110
VIN = 3.8V
100
90
80
50
20
0
0
0
100 200 300 400 500 600 700 800
LOAD CURRENT (mA)
4
70
60
0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5
INPUT VOLTAGE (V)
0
100 200 300 400 500 600 700 800
LOAD CURRENT (mA)
Maxim Integrated
MAX1792
500mA Low-Dropout
Linear Regulator in µMAX
Typical Operating Characteristics (continued)
(MAX1792EUA33, VIN = VOUT + 500mV, SHDN = IN, CIN = 1µF, COUT = 3.3µF, TA = +25°C, unless otherwise noted.)
GROUND-PIN CURRENT
vs. TEMPERATURE
PSRR (dB)
80
75
-50
-40
-30
70
-20
-10
60
0
-15
10
35
60
85
0.01
0.1
1
10
100
TEMPERATURE (°C)
FREQUENCY (kHz)
OUTPUT SPECTRAL NOISE DENSITY
vs. FREQUENCY
OUTPUT NOISE DC TO 1MHz
10
COUT = 3.3μF
IOUT = 50mA
1000
MAX1792-09
-40
MAX1792-10
GROUND-PIN CURRENT (μA)
-60
85
65
OUTPUT SPECTRAL NOISE DENSITY (μV/√Hz)
COUT = 3.3μF
IOUT = 50mA
-70
MAX1792-08
VIN = VOUT + 500 mV
IOUT = 0A
90
-80
MAX1792-07
95
POWER-SUPPLY REJECTION RATIO
vs. FREQUENCY
1
VOUT
200μV/div
0.1
0.01
VOUT = 3.3V
ROUT = 66Ω (50mA)
0.001
0.1
1
10
100
1000
20ms/div
FREQUENCY (kHz)
REGION OF STABLE COUT ESR
vs. LOAD CURRENT
LOAD-TRANSIENT RESPONSE
MAX1792-12
MAX1792-11
100
IOUT
500mA/div
COUT ESR (Ω)
10
COUT = 3.3μF
1
VOUT
20mV/div
COUT = 10μF
STABLE REGION
0.1
VIN = VOUT + 500mV
CIN = 10μF
ROUT = 660Ω TO 6.6Ω (5mA TO 500mA)
0.01
0
100 200 300 400
500
600 700
800
10μs/div
LOAD CURRENT (mA)
Maxim Integrated
5
MAX1792
500mA Low-Dropout
Linear Regulator in µMAX
Typical Operating Characteristics (continued)
(MAX1792EUA33, VIN = VOUT + 500mV, SHDN = IN, CIN = 1µF, COUT = 3.3µF, TA = +25°C, unless otherwise noted.)
LOAD-TRANSIENT RESPONSE
NEAR DROPOUT
LINE-TRANSIENT RESPONSE
MAX1792-13
MAX1792-14
6V
IOUT
500mA/div
VIN
1V/div
3V
VOUT
50mV/div
VOUT
10mV/div
VIN = VOUT + 100mV
CIN = 10μF
ROUT = 660Ω TO 6.6Ω (5mA TO 500mA)
20μs/div
100μs/div
RST WAVEFORM
SHUTDOWN WAVEFORM
MAX1792-16
MAX1792-15
2V
5V
VSHDN
1V/div
0V
VIN
2.5V/div
0V
VOUT
2V/div
3V
VOUT
1V/div
0V
VRST
2V/div
0V
0V
ROUT = 6.6Ω (500mA)
ROUT = 66Ω (50mA)
20ms/div
20μs/div
Pin Description
6
PIN
NAME
FUNCTION
1, 2
IN
Regulator Input. Supply voltage can range from +2.5V to +5.5V. Bypass with a 1µF capacitor to GND (see
Capacitor Selection and Regulator Stability). Connect both input pins together externally.
3
RST
Open-Drain Active-Low Reset Output. RST remains low while the output voltage (VOUT) is below the reset
threshold and for at least 4ms after VOUT rises above the reset threshold. Connect a 100kΩ pullup resistor
to OUT to obtain an output voltage.
4
SHDN
Active-Low Shutdown Input. A logic low reduces supply current to 0.1µA. In shutdown, the RST output is
low and OUT is pulled low through an internal 5kΩ resistor. Connect to IN for normal operation.
5
GND
Ground. This pin and the exposed pad also function as a heatsink. Solder both to a large pad or to the
circuit-board ground plane to maximize power dissipation.
6
SET
Voltage-Setting Input. Connect to GND for preset output. Connect to a resistive divider between OUT and
GND to set the output voltage between 1.25V and 5.0V.
7, 8
OUT
Regulator Output. Sources up to 500mA. Bypass with a 3.3µF low-ESR capacitor to GND. Use a 4.7µF
capacitor for output voltages below 2V. Connect both output pins together externally.
—
EP
Exposed Pad. Solder to ground plane to maximize thermal performance. Not internally connected to
ground.
Maxim Integrated
MAX1792
500mA Low-Dropout
Linear Regulator in µMAX
VIN = +2.5V TO +5.5V
IN
CIN
1µF
IN
THERMAL
SENSOR
MOSFET
DRIVER WITH
I LIM
OUT
ON
VOUT = 1.25V TO 5.0V
SHDN
COUT
3.3µF
OUT
OFF
SHUTDOWN
LOGIC
5k
VREF
1.25V
ERROR
AMPLIFIER
LOGIC SUPPLY
VOLTAGE (VOUT)
RRST
100k
R1
MAX1792
RST
TO
µC
SET
DELAY
TIMER
R2
93% VREF
100mV
GND
Figure 1. Functional Diagram
Detailed Description
The MAX1792 is a low-dropout, low-quiescent-current
linear regulator designed primarily for battery-powered
applications. The device supplies loads up to 500mA
and is available with preset output voltages. As illustrated in Figure 1, the MAX1792 consists of a 1.25V reference, error amplifier, P-channel pass transistor, and
internal feedback voltage-divider.
The 1.25V reference is connected to the error amplifier,
which compares this reference with the feedback voltage and amplifies the difference. If the feedback voltage is lower than the reference voltage, the
pass-transistor gate is pulled lower, which allows more
current to pass to the output and increases the output
voltage. If the feedback voltage is too high, the passtransistor gate is pulled up, allowing less current to
pass to the output.
Maxim Integrated
The output voltage is fed back through either an internal resistive divider connected to OUT or an external
resistor network connected to SET. The Dual Mode
comparator examines VSET and selects the feedback
path. If VSET is below 50mV, the internal feedback path
is used and the output is regulated to the factory-preset
voltage.
Additional blocks include an output current limiter, thermal sensor, and shutdown logic.
Internal P-Channel Pass Transistor
The MAX1792 features a 0.25Ω P-channel MOSFET
pass transistor. Unlike similar designs using PNP pass
transistors, P-channel MOSFETs require no base drive,
which reduces quiescent current. PNP-based regulators also waste considerable current in dropout when
the pass transistor saturates, and use high base-drive
currents under large loads.
7
MAX1792
500mA Low-Dropout
Linear Regulator in µMAX
Reset Output
R1 = R2
IN
OUT
IN
OUT
VOUT
1.25V
V IN = +2.5V TO +5.5V
-1
VOUT
CIN
1µF
COUT
3.3µF
MAX1792
R1
ON
SHDN
SET
Current Limit
OFF
R2
RST
GND
Figure 2. Adjustable Output Using External Feedback
Resistors
The MAX1792 does not suffer from these problems and
consumes only 110µA of quiescent current under
heavy loads as well as in dropout.
Output Voltage Selection
The MAX1792’s Dual Mode operation allows operation
in either a preset voltage mode or an adjustable mode.
Connect SET to GND to select the preset output voltage. The two-digit part number suffix identifies the output voltage (see Selector Guide ). For example, the
MAX1792EUA33 has a preset 3.3V output voltage.
The output voltage may also be adjusted by connecting
a voltage-divider from OUT to SET to GND (Figure 2).
Select R2 in the 25kΩ to 100kΩ range. Calculate R1
with the following equation:
R1 = R2 [(VOUT / VSET) - 1]
where VSET = 1.25V and VOUT may range from 1.25V to
5.0V.
Shutdown
Pull SHDN low to enter shutdown. During shutdown, the
output is disconnected from the input and supply current
drops to 0.1µA. When in shutdown, RST pulls low and
OUT is discharged through an internal 5kΩ resistor. The
capacitance and load at OUT determine the rate at
which VOUT decays. SHDN can be pulled as high as
+6V, regardless of the input and output voltage.
8
The reset output (RST) pulls low when OUT is less than
93% of the nominal regulation voltage. Once OUT
exceeds 93% of the nominal voltage, RST goes high
impedance after 4ms. RST is an open-drain N-channel
output. To obtain a voltage output, connect a pullup
resistor from RST to OUT. A 100kΩ resistor works well for
most applications. RST can be used as a power-on-reset
(POR) signal to a microcontroller (µC), or drive an external LED to indicate power failure. When the MAX1792 is
shut down, RST is held low independent of the output
voltage. If unused, leave RST grounded or unconnected.
The MAX1792 monitors and controls the pass transistor’s gate voltage, limiting the output current to 0.8A
(typ). This current limit doubles when the output voltage
is within 4% of the nominal value to improve performance with large load transients. The output can be
shorted to ground for an indefinite period of time without damaging the part.
Thermal Overload Protection
Thermal overload protection limits total power dissipation in the MAX1792. When the junction temperature
exceeds TJ = +170°C, a thermal sensor turns off the
pass transistor, allowing the device to cool. The thermal
sensor turns the pass transistor on again after the junction temperature cools by 20°C, resulting in a pulsed
output during continuous thermal overload conditions.
Thermal overload protection protects the MAX1792 in
the event of fault conditions. For continuous operation,
do not exceed the absolute maximum junction-temperature rating of TJ = +150°C.
Operating Region and
Power Dissipation
The MAX1792’s maximum power dissipation depends on
the thermal resistance of the IC package and circuit
board, the temperature difference between the die junction and ambient air, and the rate of air flow. The power
dissipated in the device is P = IOUT x (VIN - VOUT). The
maximum allowed power dissipation is 1.3W or:
PMAX = (TJ(MAX) - TA) / ( θJC + θCA)
where TJ - TA is the temperature difference between
the MAX1792 die junction and the surrounding air, θJC
is the thermal resistance from the junction to the case,
and θ CA is the thermal resistance from the case
through the PC board, copper traces, and other materials to the surrounding air.
The MAX1792 package features an exposed thermal
pad on its underside. This pad lowers the thermal resistance of the package by providing a direct heat conMaxim Integrated
MAX1792
500mA Low-Dropout
Linear Regulator in µMAX
0.7
POWER-μMAX PACKAGE OPERATING
REGION AT TJ(MAX) = +150°C
TA = +50°C
CONTINUOUS CURRENT LIMIT
0.5
Noise, PSRR, and Transient Response
TYPICAL VDROPOUT LIMIT
MAXIMUM OUTPUT CURRENT (A)
0.6
0.1Ω or less to ensure stability and optimum transient
response. Surface-mount ceramic capacitors have very
low ESR and are commonly available in values up to
10µF. Connect CIN and COUT as close to the MAX1792
as possible to minimize the impact of PC board trace
inductance.
0.4
0.3
0.2
TA = +85°C
TA = +70°C
MAXIMUM SUPPLY
VOLTAGE LIMIT
(VOUT = 1.25V)
0.1
0
0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
INPUT-OUTPUT VOLTAGE DIFFERENTIAL (V)
Figure 3. Power Operating Regions: Maximum Output Current
vs. Supply Voltage
duction path from the die to the PC board. Additionally,
the MAX1792’s ground pin (GND) performs the dual
function of providing an electrical connection to system
ground and channeling heat away. Connect the
exposed backside pad and GND to the system ground
using a large pad or ground plane, or multiple vias to
the ground plane layer.
The MAX1792 delivers up to 0.5A(RMS) and operates
with input voltages up to 5.5V, but not simultaneously.
High output currents can only be sustained when inputoutput differential voltages are low, as shown in Figure 3.
Applications Information
Capacitor Selection
and Regulator Stability
Capacitors are required at the MAX1792’s input and
output for stable operation over the full temperature
range and with load currents up to 500mA. Connect a
1µF capacitor between IN and ground and a 3.3µF low
equivalent series resistance (ESR) capacitor between
OUT and ground. For output voltages less than 2V, use
a 4.7µF low-ESR output capacitor. The input capacitor
(CIN) lowers the source impedance of the input supply.
Reduce noise and improve load-transient response,
stability, and power-supply rejection by using larger
output capacitors such as 10µF.
The output capacitor’s (COUT) ESR affects stability and
output noise. Use output capacitors with an ESR of
Maxim Integrated
The MAX1792 is designed to operate with low dropout
voltages and low quiescent currents in battery-powered
systems while still maintaining good noise, transient
response, and AC rejection. See the Typical Operating
Characteristics for a plot of Power-Supply Rejection
Ratio (PSRR) vs. Frequency. When operating from
noisy sources, improved supply-noise rejection and
transient response can be achieved by increasing the
values of the input and output bypass capacitors and
through passive filtering techniques.
The MAX1792 load-transient response graphs (see
Typical Operating Characteristics) show two components of the output response: a DC shift from the output
impedance due to the load current change, and the
transient response. A typical transient response for a
step change in the load current from 5mA to 500mA is
18mV. Increasing the output capacitor’s value and
decreasing the ESR attenuates the overshoot.
Input-Output (Dropout) Voltage
A regulator’s minimum input-to-output voltage differential (dropout voltage) determines the lowest usable supply voltage. In battery-powered systems, this
determines the useful end-of-life battery voltage.
Because the MAX1792 uses a P-channel MOSFET pass
transistor, its dropout voltage is a function of drain-tosource on-resistance (RDS(ON)) multiplied by the load
current (see Typical Operating Characteristics):
VDROPOUT = VIN - VOUT = RDS(ON) x IOUT
The MAX1792 ground current remains below 150µA in
dropout.
Note: The MAX1792 has an exposed thermal pad on
the bottom side of the package.
Package 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.
PACKAGE
TYPE
PACKAGE
CODE
OUTLINE
NO.
LAND
PATTERN NO.
µMAX-EP
U8E+2
21-0107
90-0145
9
MAX1792
500mA Low-Dropout
Linear Regulator in µMAX
Revision History
REVISION
NUMBER
REVISION
DATE
DESCRIPTION
PAGES
CHANGED
0
9/00
Initial release
1
8/08
Updated Pin Description and Package Information
6, 10
—
2
11/11
Updated the Ordering Information and Selector Guide to include lead(Pb)-free and
automotive qualified parts; added the soldering information to the Absolute Maximum
Ratings section; added the Package Information table
1, 2, 9
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.
10 ________________________________Maxim Integrated 160 Rio Robles, San Jose, CA 95134 USA 1-408-601-1000
© 2011 Maxim Integrated Products, Inc.
Maxim Integrated and the Maxim Integrated logo are trademarks of Maxim Integrated Products, Inc.
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