General Description
The MAX5091 high-voltage linear regulator is designed
to operate from a +5V to +28V input voltage, and with-
stands up to 40V transients. The device consumes only
45µA of quiescent current at 100µA output current. The
MAX5091 delivers up to 100mA of output current with
low 50mV maximum dropout voltage. The MAX5091
provides an active-low open-drain microprocessor
RESET output. The reset timeout period is programma-
ble and can be set with an external capacitor. The
MAX5091 includes an uncommitted comparator for
input voltage monitoring/power-fail indication. The
device is available with a fixed +5V (MAX5091A) or
+3.3V (MAX5091B) output. The MAX5091 is short-cir-
cuit protected and includes thermal shutdown.
The MAX5091 operates over the -40°C to +125°C auto-
motive temperature range and is available in 8-pin,
thermally enhanced TDFN and SO-EP packages.
Applications
Features
♦+5V to +28V Wide Operating Input Voltage Range
♦Withstands 40V Input Voltage Transients
♦Guaranteed 100mA Output Current
♦45µA Typical Quiescent Current at 100µA Output
Current
♦Preset +5V (MAX5091A) or +3.3V (MAX5091B)
Output Voltage
♦Stable with Only 10µF Output Capacitance
♦RESET Output with Adjustable Timeout Period
♦Uncommitted Comparator for Voltage
Monitoring/Power-Fail Indication
♦Output Overload and Short-Circuit Protection
♦Thermal Shutdown
♦Available in 8-Pin TDFN (1.95W at TA= +70°C) and
8-Pin SO (1.5W at TA= +70°C)
♦Operates Over -40°C to +125°C Automotive
Temperature Range
MAX5091
28V, 100mA, Low-Quiescent-Current LDO
with Reset and Power-Fail Input/Output
________________________________________________________________ Maxim Integrated Products 1
134
8
+
65
VOUT RES GND
MAX5091
EXPOSED PADDLE
2
7
SO
VSEN CTSI
TDFN
(3mm x 3mm)
TOP VIEW
Pin Configurations
Ordering Information
μC
RESET
CT
SI
+5V TO +28V
RH
288kΩ
CIN
10μF
CCT
0.1μF
COUT
10μF
RL
100kΩ
+5V (MAX5091A)/
+3.3V (MAX5091B)
100mA
SO
GND
EN
RRES
10kΩ
V
OUT
RES
POWER-
FAIL
V
S
ON
OFF
V
IN
MAX5091
RSO
10kΩ
Typical Application Circuit
19-0654; Rev 0; 11/06
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.
Note: All devices specified for -40°C to +125°C operating temperature range.
+Denotes lead-free package. *EP = Exposed paddle.
PART PIN-
PACKAGE
PRESET VOUT
(V)
PKG
CODE
TOP
MARK
MAX5091AATA+T 8 TDFN-8 5 T833-2 +APB
MAX5091AASA+ 8 SO-EP* 5 S8E-14 —
MAX5091BATA+T 8 TDFN-8 3.3 T833-2 +APC
MAX5091BASA+ 8 SO-EP* 3.3 S8E-14 —
Pin Configurations continued at end of data sheet.
Automotive
Industrial
Home Security/Safety
Telecom/Networking
MAX5091
28V, 100mA, Low-Quiescent-Current LDO
with Reset and Power-Fail Input/Output
2 _______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS (MAX5091A)
(VS= +14V, VOUT = 5V, EN unconnected, TA = TJ = -40°C to +125°C, CIN = 10µF, COUT = 10µF, unless otherwise noted. Typical
specifications are at TA= +25°C.) (Note 1)
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.
VSto GND ..............................................................-0.3V to +28V
VSto GND (t ≤1s) ..................................................-0.3V to +40V
VOUT to GND ..........................................................-0.3V to +20V
VSto OUT ...............................................................-0.3V to +28V
RES, SO to GND.....................................................-0.3V to +20V
RES, SO Output Sink Current................................................5mA
VOUT Short Circuit (VS≤16V)………… ......................Continuous
EN, SI to GND.........................................................-0.3V to +12V
CT to GND.............................-0.3V to the lower of VOUT or +12V
Continuous Power Dissipation (TA= +70°C)
8-Pin SO-EP (derate 19.2mW/°C above +70°C) .........1538mW*
Thermal Resistance (θJA)................................................52°C/W
Thermal Resistance (θJC)..................................................6°C/W
8-Pin TDFN-EP (derate 24.4mW/°C above +70°C).....1951mW**
Thermal Resistance (θJA)................................................41°C/W
Thermal Resistance (θJC)...............................................8.3°C/W
Operating Junction Temperature Range...........-40°C to +125°C
Maximum Junction Temperature .....................................+150°C
Storage Temperature Range .............................-60°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
TA = +25°C, IOUT = 1mA 4.95 5 5.05
5.6V ≤ VS ≤ 28V, IOUT = 1mA to 50mA (Note 2) 4.90 5 5.10
5.6V ≤ VS ≤ 40V, t ≤ 1s, IOUT = 1mA to 30mA
(Note 2) 4.9 5 5.1
Output Voltage VOUT
VS = +8V, IOUT = 1mA to 100mA 4.9 5 5.1
V
IOUT = 10mA 0.1 0.25
IOUT = 50mA 0.2 0.4
Dropout Voltage VDP VS = +4.75V
IOUT = 100mA 0.3 0.5
V
VS to VOUT Difference in
Undervoltage VIO VS = +4V, IOUT = 35mA 0.4 V
Line Regulation VOL +5.5V ≤ VS ≤ +28V, IOUT = 1mA 0.6 5 mV
Load Regulation VOLO 1mA ≤ IOUT ≤ 100mA 17 50 mV
Current Limit ILIM 160 260 400 mA
IOUT = 100µA 46 100
IOUT = 300µA 45 100 µA
Quiescent Current IQ
IOUT = 100mA 4.5 10 mA
Shutdown Supply Current ISHDN VEN ≤ +0.4V 17 30 µA
Thermal-Shutdown
Temperature TJ
(
SHDN
)
Temperature rising +165 °C
Thermal-Shutdown
Hysteresis ΔTJ
(
SHDN
)
20 °C
*As per JEDEC51 Standard (single-layer board).
**As per JEDEC51 Standard (multilayer board).
MAX5091
28V, 100mA, Low-Quiescent-Current LDO
with Reset and Power-Fail Input/Output
_______________________________________________________________________________________ 3
ELECTRICAL CHARACTERISTICS (MAX5091A) (continued)
(VS= +14V, VOUT = 5V, EN unconnected, TA = TJ = -40°C to +125°C, CIN = 10µF, COUT = 10µF, unless otherwise noted. Typical
specifications are at TA= +25°C.) (Note 1)
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
RESET
Reset Threshold Voltage VRT VOUT falling 85 90 94.5 %VOUT
Reset Threshold
Hysteresis VRTH 30 65 100 mV
Reset Pulse Delay tRD CCT = 100nF, tR ≥ 100µs 55 110 180 ms
RES Output Low Voltage VRL VS ≥ +1.5V,RRES = 10kΩ to VOUT 0.4 V
RES Output High
Leakage Current IRH VRES = 5V 1.0 µA
Delay Comparator
Threshold VCTTH VCT rising 1.9 2.1 2.4 V
Delay Comparator
Threshold Hysteresis 100 mV
SENSE
Sense Threshold VST VSI falling 1.10 1.16 1.24 V
Sense Threshold
Hysteresis 50 100 150 mV
Sense Output
Low Voltage VSL VSI ≤ 1.10V, VS ≥ 4V, RSO = 10kΩ to VOUT 0.4 V
Sense Output
Leakage Current ISH VSO = 5V, VSI ≥ 1.5V 1 µA
Sense Input Current ISI VSI = 3.3V -1 +1 µA
ENABLE
EN = high, regulator on 2.4
Enable Voltage VEN EN = low, regulator off 0.4 V
Enable Internal
Pullup Current IEN EN is internally pulled up to 3.6V (max) 3 µA
MAX5091
28V, 100mA, Low-Quiescent-Current LDO
with Reset and Power-Fail Input/Output
4 _______________________________________________________________________________________
ELECTRICAL CHARACTERISTICS (MAX5091B)
(VS= +14V, VOUT = 3.3V, EN unconnected, TA= TJ= -40°C to +125°C, CIN = 10µF, COUT = 10µF, unless otherwise noted. Typical
specifications are at TA= +25°C.) (Note 1)
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
TA = +25°C, IOUT = 1mA 3.267 3.3 3.333
5V ≤ VS ≤ 28V, IOUT = 1mA to 50mA (Note 2) 3.234 3.3 3.366
5V ≤ VS ≤ 40V, t < 1s, IOUT = 1mA to 30mA
(Note 2) 3.234 3.3 3.366
Output Voltage VOUT
VS = +8V, IOUT = 1mA to 100mA 3.234 3.3 3.366
V
VS to VOUT Difference in
Undervoltage VIO VS = 3.5V, IOUT = 35mA 0.2 0.4 V
Line Regulation VOL 5V ≤ VS ≤ 28V, IOUT = 1mA 0.6 5 mV
Load Regulation VOLO 1mA ≤ IOUT ≤ 100mA 11 40 mV
Current Limit ILIM 160 260 400 mA
IOUT = 100µA 45 100
IOUT = 300µA 45 100 µA
Quiescent Current IQ
IOUT = 100mA 4.4 10 mA
Shutdown Supply
Current ISHDN VEN ≤ 0.4V 17 30 µA
Thermal-Shutdown
Temperature TJ
(
SHDN
)
Temperature rising +165 °C
Thermal-Shutdown
Hysteresis ΔTJ
(
SHDN
)
20 °C
RESET CIRCUIT
Reset Threshold Voltage VRT VOUT falling 85 90 94.5 %VOUT
Reset Threshold
Hysteresis VRTH 20 45 80 mV
Reset Pulse Delay tRD CCT = 100nF, tR ≥ 100µs 55 105 180 ms
RES Output-Low Voltage VRL VS ≥ 1.5V, RRES = 4kΩ to VOUT 0.4 V
RES Output-High
Leakage Current IRH VRES = 3.3V 1.0 µA
Delay Comparator
Threshold VCTTH VCT rising 1.9 2.1 2.4 V
Delay Comparator
Threshold Hysteresis 100 mV
MAX5091
28V, 100mA, Low-Quiescent-Current LDO
with Reset and Power-Fail Input/Output
_______________________________________________________________________________________ 5
Note 1: Limits at TA= -40°C are guaranteed by design and not production tested.
Note 2: Maximum output current is limited by the power dissipation capability of the package.
ELECTRICAL CHARACTERISTICS (MAX5091B) (continued)
(VS= +14V, VOUT = 3.3V, EN unconnected, TA= TJ= -40°C to +125°C, CIN = 10µF, COUT = 10µF, unless otherwise noted. Typical
specifications are at TA= +25°C.) (Note 1)
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
SENSE
Sense Threshold VST VSI falling 1.09 1.15 1.23 V
Sense Threshold
Hysteresis 50 100 150 mV
Sense Output-Low
Voltage VSL VSI ≤ 1.09V, VS ≥ 4V, RSO = 10kΩ to VOUT 0.4 V
Sense Output
Leakage Current ISH VSO = 3.3V, VSI ≥ 1.5V 1 µA
Sense Input Current ISI VSI = 3.3V -1 +1 µA
ENABLE
EN = high, regulator on 2.4
Enable Voltage VEN EN = low, regulator off 0.4 V
Enable Internal
Pullup Current IEN EN is internally pulled up to 3.6V (max) 3 µA
Typical Operating Characteristics
(Typical Application Circuit, VS= +14V, CIN = 10µF, COUT = 10µF, VSI = 0V, VEN = +2.4V, VOUT = +5V, TA= +25°C, unless other-
wise noted.)
OUTPUT VOLTAGE vs. INPUT VOLTAGE
MAX5091 toc01
VS (V)
VOUT (V)
10
515
3
4
5
6
2
0
MAX5091AVOUT AT NO LOAD, 100μA,
1mA, 10mA, 100mA
OUTPUT VOLTAGE vs. INPUT VOLTAGE
MAX5091 toc02
VS (V)
VOUT (V)
54321
1
2
3
4
0
06
MAX5091BVOUT AT NO LOAD, 100μA,
1mA, 10mA, 100mA
OUTPUT VOLTAGE vs. OUTPUT CURRENT
MAX5091 toc03
IOUT (mA)
VOUT (V)
1010.1
4.92
4.94
4.96
4.98
5.00
5.02
5.04
4.90
0.01 100
MAX5091A
VS = 14V
VS = 6V
MAX5091
28V, 100mA, Low-Quiescent-Current LDO
with Reset and Power-Fail Input/Output
6 _______________________________________________________________________________________
Typical Operating Characteristics (continued)
(Typical Application Circuit, VS= +14V, CIN = 10µF, COUT = 10µF, VSI = 0V, VEN = +2.4V, VOUT = +5V, TA= +25°C, unless other-
wise noted.)
OUTPUT VOLTAGE
vs. TEMPERATURE
MAX5091 toc04
TEMPERATURE (°C)
VOUT (V)
11085603510-15
4.925
4.950
4.975
5.000
5.025
5.050
4.900
-40 135
MAX5091A
IOUT = 100μA
IOUT = 1mA
IOUT = 10mA
IOUT = 100mA
QUIESCENT CURRENT
vs. INPUT VOLTAGE
MAX5091 toc05
VS (V)
IQ (μA)
26221814106
10
100
1000
12303834
EN = OPEN
IOUT = NO LOAD
TA = +25°C, +85°CTA = +125°C
TA = -40°C
QUIESCENT CURRENT
vs. INPUT VOLTAGE
MAX5091 toc06
VS (V)
IQ (μA)
26221814106
10
100
1000
12303834
EN = OPEN
IOUT = 100μA
TA = +25°C, +85°C
TA = +125°C
TA = -40°C
RESET OUTPUT LOW
vs. TEMPERATURE
MAX5091 toc07
TEMPERATURE (°C)
RESET OUTPUT LOW (V)
1109580655035205-10-25
0.05
0.10
0.15
0.20
0.25
0
-40 125
RRES = 4kΩ
RRES = 10kΩ
QUIESCENT CURRENT
vs. OUTPUT CURRENT
MAX5091 toc08
IOUT (mA)
IQ (mA)
110
0.1
1
10
0.01
0.1 100
VS = 14V
TA = +25°C
SHUTDOWN SUPPLY CURRENT
vs. INPUT VOLTAGE
MAX5091 toc09
VS (V)
ISHDN (μA)
302010
10
20
30
40
0
040
VS = 14V
TA = +25°C
EN = 0V
SHUTDOWN SUPPLY CURRENT
vs. TEMPERATURE
MAX5091 toc10
TEMPERATURE (°C)
ISHDN (μA)
10065-30-5
15
16
17
18
19
20
14
-40 135
VS = 14V
EN = 0V
DROPOUT VOLTAGE
vs. LOAD CURRENT
MAX5091 toc11
IOUT (mA)
DROPOUT VOLTAGE (mV)
101
25
50
75
100
125
150
175
200
225
250
275
300
325
0
0.1 100
MAX5091A
VS = 4.75V
DROPOUT VOLTAGE
vs. LOAD CURRENT
MAX5091 toc12
IOUT (mA)
DROPOUT VOLTAGE (mV)
101
25
50
75
100
125
150
175
200
225
250
275
300
0
0.1 100
MAX5091B
VS = 3.3V
MAX5091
28V, 100mA, Low-Quiescent-Current LDO
with Reset and Power-Fail Input/Output
_______________________________________________________________________________________ 7
DROPOUT VOLTAGE
vs. TEMPERATURE
MAX5091 toc13
TEMPERATURE (°C)
DROPOUT VOLTAGE (mV)
10065-5 30
50
100
150
200
250
300
350
400
0
-40 135
MAX5091A
VS = 4.75V
IOUT = 10mA
IOUT = 100mA
RESET THRESHOLD
vs. TEMPERATURE
MAX5091 toc14
TEMPERATURE (°C)
RESET THRESHOLD VOLTAGE (V)
1006530-5
4.42
4.44
4.46
4.48
4.50
4.52
4.54
4.56
4.58
4.60
4.40
-40 135
MAX5091A
VOUT FALLING
VOUT RISING
RESET VOLTAGE
vs. OUTPUT VOLTAGE
MAX5091 toc15
VOUT (V)
VRES (V)
4.64.54.4
1
2
3
4
5
0
4.3 4.7
MAX5091A
RRES = 10kΩ TO OUT
VOUT FALLING VOUT RISING
SENSE THRESHOLD
vs. TEMPERATURE
MAX5091 toc16
TEMPERATURE (°C)
SENSE THRESHOLD (V)
1006530-5
1.05
1.10
1.15
1.20
1.25
1.30
1.35
1.40
1.45
1.50
1.00
-40 135
SI INPUT FALLING
SI INPUT RISING
SENSE OUTPUT
vs. SENSE INPUT
MAX5091 toc17
SENSE INPUT (V)
SENSE OUTPUT (V)
1.31.21.1
1
2
3
4
5
0
1.0 1.4
VSI FALLING
VSI RISING
POWER-SUPPLY REJECTION RATIO
vs. SUPPLY CURRENT
MAX5091 toc18
FREQUENCY (kHz)
PSRR (dB)
1010.1
-70
-60
-50
-40
-30
-20
-10
0
-80
0.01 100
VIN = 14V
IOUT = 10mA
500mVP-P
LOAD-TRANSIENT RESPONSE
MAX5091 toc19
200μs/div
VOUT
5V AC-COUPLED
100mV/div
IOUT
20mA/div
50mA
100μA
C
IN
= 10μF
C
OUT
= 10μF/10mΩ ESR
I
STEP
= 100μA TO 50mA
LINE-TRANSIENT RESPONSE
MAX5091 toc20
200μs/div
VOUT
5V AC-COUPLED
200mV/div
IOUT = 1mA
VS
10V/div
40V
14V
Typical Operating Characteristics (continued)
(Typical Application Circuit, VS= +14V, CIN = 10µF, COUT = 10µF, VSI = 0V, VEN = +2.4V, VOUT = +5V, TA= +25°C, unless other-
wise noted.)
MAX5091
28V, 100mA, Low-Quiescent-Current LDO
with Reset and Power-Fail Input/Output
8 _______________________________________________________________________________________
Pin Description
PIN
NAME
FUNCTION
1V
SRegulator Input. Operating supply range is from +5V to +28V and withstands 40V transients. Bypass
VS to GND with a 10µF capacitor.
2SI
Voltage Sense/Power-Fail Comparator Input. SI is the noninverting input of an uncommitted comparator. SO
asserts low if VSI drops below the reference level, VST.
3EN
Enable Input. Leave unconnected (or pull EN high) to turn on the regulator. Pull EN low to place the device in
shutdown mode. EN is internally pulled up to 3.6V.
4CT
Reset Timeout Delay Capacitor Connection. Connect a capacitor from CT to GND to program the reset
timeout period/reset pulse delay. During regulation, CT is pulled up to VOUT. CT is pulled low during reset,
when EN is low, or when in thermal shutdown.
5 GND Ground. Bypass the input and output capacitors to the GND plane. Solder to large pads or the circuit-board
ground plane to maximize thermal dissipation.
6RES
Active-Low Reset Output. Pull up externally to VOUT. Open-drain RES goes low when VOUT is below the reset
threshold. Once output voltage is in regulation, RES goes high after the programmed reset timeout period is
over. RES is low when EN is low or in thermal shutdown.
7SO
Voltage Sense/Power-Fail Comparator Output. Pull up externally to VOUT. Open-drain SO asserts
low when VSI drops below the reference level, VST. SO also asserts low when EN is low or in thermal
shutdown.
8
VOUT
Regulator Output. Fixed at +5V (MAX5091A) or +3.3V (MAX5091B). Bypass with a 10µF ceramic capacitor to
GND.
EP EP E xp osed P ad d l e. E P i s i nter nal l y connected to GN D . C onnect E P to GN D to p r ovi d e a l ow ther m al - r esi stance
p ath fr om the IC j uncti on to the P C b oar d . D o not use as the onl y el ectr i cal connecti on to G N D .
Typical Operating Characteristics (continued)
(Typical Application Circuit, VS= +14V, CIN = 10µF, COUT = 10µF, VSI = 0V, VEN = +2.4V, VOUT = +5V, TA= +25°C, unless other-
wise noted.)
VOUT STARTUP RESPONSE
MAX5091 toc21
10ms/div
VOUT
2V/div
VS
5V/div
0V
0V
IOUT = 10mA
ENABLE RESPONSE
MAX5091 toc22
200μs/div
VOUT
5V/div
EN
5V/div
0V
0V
IOUT = 100mA
SHUTDOWN RESPONSE
MAX5091 toc23
200μs/div
VOUT
2V/div
EN
2V/div
0V
0V
IOUT = 100mA
MAX5091
28V, 100mA, Low-Quiescent-Current LDO
with Reset and Power-Fail Input/Output
_______________________________________________________________________________________ 9
N
MAX5091
PASS
ELEMENT
DELAY
COMPARATOR
PREREGULATOR
ALWAYS-ON
FAULT
DETECTION
(TEMP AND SC)
VREF
1.25V
VREF
VINT
3.6V (MAX)
VREF
SCLIM
SD
VOUT
VS
CT
SI
EN
0.9 x VREF
2.1V
N
ICT
2μA
ENABLE
VINT
3μA
MAX
ALWAYS-ON
GND
RES
LDO
VOUT
VREF
N
SO
Figure 1. Functional Diagram
MAX5091
28V, 100mA, Low-Quiescent-Current LDO
with Reset and Power-Fail Input/Output
10 ______________________________________________________________________________________
Detailed Description
Regulator
The MAX5091 high-voltage, LDO regulator operates
from +5V to +28V input voltage. The device withstands
up to 40V transients, providing protection against tem-
porary overvoltage conditions like load dump. The
MAX5091 incorporates internal feedback resistors for
factory-preset voltages of either +5V (MAX5091A) or
+3.3V (MAX5091B). The regulator is capable of driving
up to 100mA of load current and features a typical cur-
rent limit of 260mA. The regulator uses a pnp pass ele-
ment and provides low 0.5V dropout while delivering
100mA load current. The output of the regulator follows
closely to the input during turn-on. See the Output
Voltage vs. Input Voltage graph in the Typical
Operating Characteristics. This makes the usable input
voltage range for 3.3V and 5V output down to 3.7V and
5.5V, respectively. The MAX5091 is designed to oper-
ate with very low quiescent current during always-on
operation when not in dropout. The regulator is stable
with a wide variety of capacitors including low-ESR
ceramic 10µF (0603 case size). The load-transient
response curves depict the stability of the LDO when
using different capacitance and ESR ranges. See the
Capacitor Selection and Regulator Stability section in
the Applications Information.
Reset Output (
RES
)
The MAX5091 integrates a power-on-reset circuit. RES
is an open-drain output that requires a pullup resistor to
VOUT. The open-drain MOSFET can sink up to 825µA
current while keeping the RES voltage below 0.4V. The
internal reset circuit monitors the regulator output volt-
age and RES asserts an active-low output when the
regulator output falls below a reset threshold of typical-
ly 0.9 x VOUT. The RES output remains low when VOUT
is below the reset threshold, and remains low for the
duration of the reset timeout period (tRD). The reset
timeout period is programmable and can be set with an
external capacitor connected from CT to ground. The
duration of the delay as a function of CT is:
The default reset timeout period is 35µs when no
capacitor is connected from CT to ground.
SI/SO Comparator
The MAX5091 includes an uncommitted comparator for
monitoring the input voltage or for detecting power-fail
conditions. The input SI is the noninverting input of the
comparator. The open-drain output SO asserts low
when voltage at the input SI drops below the threshold
voltage, VST (see Figure 1). The sense comparator typi-
cally has a hysteresis of 100mV. Use the following
equation to calculate the resistor-divider for program-
ming the trip voltage (VTRIP) during power-fail. See the
Typical Application Circuit.
where VST = 1.16V (typ). Choose RLbetween 100kΩto
300kΩ.
Enable Input
The enable (EN) is a TTL-compatible logic input. Logic
low at EN turns off the regulator and reduces the cur-
rent consumption to 17µA (typ). It is internally pulled up
to a logic-high voltage (3.6V max) by an internal resis-
tor. Thus, the MAX5091 is enabled by default when VS
is applied and EN is left unconnected. The regulator,
reset supervisor circuit, and the sense comparator can
be manually shut down by pulling EN low. For shut-
down operation, the pulldown network must be capable
of sinking 3µA max, since the internal pullup resistor
sets the maximum pullup current at 3µA. The external
pulldown device should not leak more than 1µA current
when it is in the off-state.
Current Limit
The MAX5091 features a current limiter that monitors
the output current and controls the pass transistor’s
gate voltage, limiting the output current to typically
260mA. The output can be continuously shorted to
ground without damaging the device at VS≤16V. Note
that the output short-circuit current may increase the
power dissipation significantly and raise the junction
temperature to its thermal-shutdown threshold. In such
a case, the MAX5091 is temporarily turned off.
Thermal Shutdown
When the junction temperature exceeds TJ= +165°C
(typ), an internal thermal sensor signals the shutdown
logic to turn off the pass transistor and allow the IC to
cool. The thermal sensor turns the pass transistor on
again after the IC’s junction temperature cools by
+20°C (typ), resulting in a cycled output during contin-
uous thermal-overload conditions. Thermal shutdown
protects the MAX5091 in the event of fault conditions.
For continuous operation, do not exceed the absolute
maximum junction temperature of TJ= +150°C.
MAX5091
28V, 100mA, Low-Quiescent-Current LDO
with Reset and Power-Fail Input/Output
______________________________________________________________________________________ 11
Applications Information
Available Output Current Calculation
The MAX5091 high-voltage regulator provides up to
100mA of output current. The input voltage extends to
+28V. Package power dissipation limits the amount of
output current available for a given input/output voltage
and ambient temperature. Figure 2 depicts the maxi-
mum power dissipation curve for the 8-pin SO-EP pack-
age. The graph assumes that the exposed metal back
of the MAX5091 package is soldered to copper on a
single layer PCB according to the JEDEC51 standard.
Use Figure 2 to determine the allowable package dissi-
pation for a given ambient temperature. Alternately, use
the following formula to calculate the allowable pack-
age dissipation:
After determining the allowable package dissipation, cal-
culate the maximum output current using the following
formula:
The above equations do not include the power dissipation
from self-heating due to the IC ground current.
The junction-to-ambient thermal impedance depends
on the area of the copper plane, its thickness, and the
number of copper layers on PCB. For the higher power
dissipation requirement, use multiple-layered PCBs
with 2oz copper and a large copper area.
Capacitor Selection and
Regulator Stability
For stable operation over the full temperature range and
with load currents up to 100mA, use a 10µF output
capacitor with a low ESR. Table 1 shows a list of recom-
mended output capacitor ESR for various load conditions.
Figure 2. 8-Pin SO-EP Maximum Power Dissipation vs.
Temperature
MAX5091 fig02
TEMPERATURE (°C)
PD (W)
130
12010011030 40 50 60 70 80 9010 20
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1.8
2.0
0
140
150
1.538W
DERATE
19.23mW/°C
8-PIN SO-EP
Table 1. Recommended Output Capacitor
ESR
RECOMMENDED COUT ESR
IOUT VOUT = 3.3V VOUT = 5.0V
IOUT ≤ 10mA CESR < 0.66ΩCESR < 1Ω
IOUT ≤ 50mA CESR < 0.132ΩCESR < 0.2Ω
IOUT ≤ 100mA CESR < 66mΩCESR < 0.1Ω
MAX5091
28V, 100mA, Low-Quiescent-Current LDO
with Reset and Power-Fail Input/Output
12 ______________________________________________________________________________________
Chip Information
PROCESS: BiCMOS
RES
GND
EXPOSED PADDLE
CT
1+
2
8
7
VOUT
SOSI
EN
VS
SO-EP
TOP VIEW
3
4
6
5
MAX5091
Pin Configurations (continued)
MAX5091
28V, 100mA, Low-Quiescent-Current LDO
with Reset and Power-Fail Input/Output
______________________________________________________________________________________ 13
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.)
8L, SOIC EXP. PAD.EPS
C11
21-0111
PACKAGE OUTLINE
8L SOIC, .150" EXPOSED PAD
MAX5091
28V, 100mA, Low-Quiescent-Current LDO
with Reset and Power-Fail Input/Output
14 ______________________________________________________________________________________
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.)
6, 8, &10L, DFN THIN.EPS
H
12
21-0137
PACKAGE OUTLINE, 6,8,10 & 14L,
TDFN, EXPOSED PAD, 3x3x0.80 mm
MAX5091
28V, 100mA, Low-Quiescent-Current LDO
with Reset and Power-Fail Input/Output
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.
Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 ____________________ 15
© 2006 Maxim Integrated Products is a registered trademark of Maxim Integrated Products, Inc.
Heaney
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.)
COMMON DIMENSIONS
SYMBOL MIN. MAX.
A 0.70 0.80
D 2.90 3.10
E 2.90 3.10
A1 0.00 0.05
L 0.20 0.40
PKG. CODE N D2 E2 eJEDEC SPEC b[(N/2)-1] x e
PACKAGE VARIATIONS
0.25 MIN.k
A2 0.20 REF.
2.30±0.101.50±0.106T633-1 0.95 BSC MO229 / WEEA 1.90 REF0.40±0.05
1.95 REF0.30±0.050.65 BSC2.30±0.108T833-1
2.00 REF0.25±0.050.50 BSC2.30±0.1010T1033-1
2.40 REF0.20±0.05- - - - 0.40 BSC1.70±0.10 2.30±0.1014T1433-1
1.50±0.10
1.50±0.10
MO229 / WEEC
MO229 / WEED-3
0.40 BSC - - - - 0.20±0.05 2.40 REFT1433-2 14 2.30±0.101.70±0.10
T633-2 6 1.50±0.10 2.30±0.10 0.95 BSC MO229 / WEEA 0.40±0.05 1.90 REF
T833-2 8 1.50±0.10 2.30±0.10 0.65 BSC MO229 / WEEC 0.30±0.05 1.95 REF
T833-3 8 1.50±0.10 2.30±0.10 0.65 BSC MO229 / WEEC 0.30±0.05 1.95 REF
-DRAWING NOT TO SCALE-
H
22
21-0137
PACKAGE OUTLINE, 6,8,10 & 14L,
TDFN, EXPOSED PAD, 3x3x0.80 mm
2.30±0.10 MO229 / WEED-3 2.00 REF0.25±0.05
0.50 BSC
1.50±0.1010T1033-2