EVALUATION KIT AVAILABLE
MAX6791–MAX6796
High-Voltage, Micropower, Single/Dual
Linear Regulators with Supervisory Functions
General Description
The
MAX6791–MAX6796
ultra-low-quiescentcurrent, single/dual-output linear regulators are ideal for
automotive applications. The devices offer a wide 5V to
72V operating input range, allowing them to withstand
automotive load-dump conditions while consuming only
68μA. The MAX6791–MAX6794 are dual-output regulators
capable of supplying up to 150mA per output. The
MAX6795/MAX6796 offer a single output capable of
delivering up to 300mA. These devices offer standard
output-voltage options (5V, 3.3V, 2.5V, or 1.8V) and
can be adjusted to any voltage from 1.8V to 11V. The
MAX6791–MAX6794 also offer a fixed 5V output.
All devices feature a push-pull or open-drain, activelow RESET output with a fixed output reset threshold
that is 92.5%/87.5% of the regulator output OUT/OUT1.
The reset output asserts low when OUT/OUT1 drops
below the reset threshold and remains low for the fixed
or capacitor-adjustable reset timeout period after OUT/
OUT1 exceeds the reset threshold.
The MAX6791–MAX6796 provide a watchdog input that
monitors a pulse train from the microprocessor (μP) and
generates reset pulses if the watchdog input remains high
or low for a duration longer than the watchdog timeout
period. All devices are available with either a fixed watchdog timeout period of 280ms (min) or a period adjustable
with an external capacitor. The MAX6791/MAX6792
feature a windowed watchdog timeout period with selectable
window ratio. The watchdog feature can be disabled.
The MAX6791–MAX6794 provide dual enable inputs
(ENABLE1 and ENABLE2) that control each regulator
independently. The single-output MAX6795/MAX6796
feature one enable input (ENABLE).
All devices include a hold input (HOLD) that aids the
implementation of a self-holding circuit without requiring
external components. Once the regulator is enabled,
setting HOLD low forces the regulator to remain on even
if ENABLE/ENABLE1 is subsequently set low. Releasing
HOLD shuts down the regulator.
The MAX6791–MAX6796 are available in a small,
thermally enhanced TQFN package. The 5mm x 5mm
package dissipates up to 2.7W, supporting continuous
regulator operation during high ambient temperatures,
high battery voltage, and high load-current conditions.
The MAX6791–MAX6796 are specified for a -40°C to
+125°C operating temperature range.
Applications
● Automotive
19-3875; Rev 3; 10/17
Benefits and Features
● Low 68μA Quiescent Current
● Wide 5V to 72V Supply Voltage Range
● Output Current
• Single Output Up to 300mA
• Dual Outputs Up to 150mA per Output
● Low Dropout Voltage
• 420mV (typ) at 100mA (Single)
• 840mV (typ) at 100mA (Dual)
● Fixed Output-Voltage Options: 5V, 3.3V, 2.5V, 1.8V,
or Adjustable Output (From 1.8V to 11V)
● ENABLE and HOLD Functionality
● RESET Output: Open-Drain or Push-Pull
● Internally Fixed (35μs, 3.125ms, 12.5ms, 50ms, or
200ms) or Capacitor-Adjustable Reset Timeout Periods
● Internally Fixed or Capacitor-Adjustable
Watchdog Timeout Periods
● Windowed (Minimum/Maximum) Watchdog Timer
Options (MAX6791/MAX6792)
● Watchdog Disable Feature
● Thermal, Short-Circuit, and Output Overvoltage
Protection
● Fully Specified from -40°C to +125°C
● Small, Thermally Enhanced, 5mm x 5mm TQFN
● AEC-Q100 Qualified MAX6795TPLD2/V+,
MAX6795TPSD2/V+
Ordering Information
PART
MAX6791TP_D _+
MAX6792TP_D _+
MAX6793TP_ D_+
MAX6794TP_ D_+
MAX6795TP_ D_+
MAX6795TP_D _/V+
MAX6795TPLD2/V+
MAX6795TPSD2/V+
MAX6796TP_D _+
TEMP RANGE
-40°C to +125°C
-40°C to +125°C
-40°C to +125°C
-40°C to +125°C
-40°C to +125°C
-40°C to +125°C
-40°C to +125°C
-40°C to +125°C
-40°C to +125°C
PIN-PACKAGE
20 TQFN-EP*
20 TQFN-EP*
20 TQFN-EP*
20 TQFN-EP*
20 TQFN-EP*
20 TQFN-EP*
20 TQFN-EP*
20 TQFN-EP*
20 TQFN-EP*
+Denotes lead-free package.
For tape-and-reel, add a T after the “+.” Tape-and-reel are
offered in 2.5k increments. The first placeholder “_” designates
preset output-voltage option and preset reset threshold level;
see Table 1. The second placeholder “_” designates the reset
timeout period; see Table 2. For example, the MAX6791TPSD3+
indicates a 3.3V output voltage with a reset threshold of 87.5%
at nominal voltage and a 50ms reset timeout period. Samples
are generally held in stock. Nonstandard versions require a 2.5k
minimum order quantity.
/V Denotes an automotive-qualified part.
*EP = Exposed pad.
Typical Application Circuit, Pin Configurations, and
Selector Guide appear at end of data sheet.
MAX6791–MAX6796
High-Voltage, Micropower, Single/Dual
Linear Regulators with Supervisory Functions
Absolute Maximum Ratings
(All pins referenced to GND, unless otherwise noted.)
IN to GND...............................................................-0.3V to +80V
ENABLE, ENABLE1, ENABLE2, PFI,
GATEP to GND........................................-0.3V to (VIN + 0.3V)
GATEP to IN...........................................................-12V to +0.3V
OUT, OUT1, OUT2, PFO, RESET (open-drain versions),
CSRT, CSWT......................................................-0.3V to +12V
HOLD, RESET (push-pull versions), WDI, WDS0, WDS1,
WD-DIS, SET, SET1...................-0.3V to (VOUT/OUT1 + 0.3V)
OUT, OUT1, OUT2 Short Circuit to GND...................Continuous
Maximum Current (all pins except IN and OUT_)...............50mA
Continuous Power Dissipation (TA = +70°C)
20-Pin TQFN (derate 33.3mW/°C above +70°C)....2666.7mW
Operating Temperature Range (TA).................. -40°C to +125°C
Junction Temperature (TJ).................................................. 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 = 14V, CIN = 1μF, COUT = 10μF, TA = TJ = -40°C to +125°C, unless otherwise noted. Typical values are at TA = TJ = +25°C.)
(Note 1)
PARAMETER
Supply Voltage Range
SYMBOL
CONDITIONS
VIN
Shutdown Supply Current
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IIN
ISHDN
TYP
5
Regulators on (ILOAD = 0mA), VIN = 8V
Supply Current
MIN
MAX
UNITS
72
V
68
85
VIN = 8V, ILOAD = 300mA
(MAX6795/MAX6796)
130
220
VIN = 14V, ILOAD = 100mA
(MAX6795/MAX6796)
100
160
VIN = 8V, ILOAD1 =
ILOAD2 = 150mA
(MAX6791–MAX6794)
130
220
VIN = 14V, ILOAD1 =
ILOAD2 = 50mA
(MAX6791–MAX6794)
100
160
Regulators on (ILOAD = 0mA), VIN = 42V
74
95
Regulators on (ILOAD = 20mA, total)
OUT1/OUT2/OUT = 5V, VIN = 42V
100
170
Regulators off, VIN = 14V
27
45
Regulators on,
VOUT/OUT1 =
VOUT2 = 5V
µA
µA
Maxim Integrated │ 2
MAX6791–MAX6796
High-Voltage, Micropower, Single/Dual
Linear Regulators with Supervisory Functions
Electrical Characteristics (continued)
(VIN = 14V, CIN = 1μF, COUT = 10μF, TA = TJ = -40°C to +125°C, unless otherwise noted. Typical values are at TA = TJ = +25°C.)
(Note 1)
PARAMETER
Output Voltage
Output Voltage
(MAX6791–MAX6794)
SYMBOL
VOUT/
VOUT1
VOUT2
SET/SET1 Threshold Voltage
VSET
Adjustable Output Voltage
VOUT
Dual-Mode™ SET Threshold
SET/SET1 Input Current
CONDITIONS
MIN
TYP
MAX
L/M, ILOAD = ILOAD1 = 1mA
4.858
4.974
5.090
L/M, ILOAD = 150mA (MAX6791–MAX6794),
VIN = 8V
4.811
4.945
5.078
L/M, ILOAD = 300mA (MAX6795/MAX6796),
VIN = 8V
4.850
5
5.150
T/S, ILOAD = ILOAD1 = 1mA
3.206
3.282
3.360
T/S, ILOAD = 150mA (MAX6791–MAX6794),
VIN = 6V
3.175
3.263
3.351
T/S, ILOAD = 300mA (MAX6795/MAX6796),
VIN = 6V
3.201
3.3
3.399
Z/Y, ILOAD = ILOAD1 = 1mA
2.429
2.487
2.546
Z/Y, ILOAD = 150mA (MAX6791–MAX6794),
VIN = 5.5V
2.405
2.472
2.539
Z/Y, ILOAD = 300mA (MAX6795/MAX6796),
VIN = 5.5V
2.425
2.5
2.575
W/V, ILOAD = ILOAD1 = 1mA
1.748
1.791
1.832
W/V, ILOAD = 150mA (MAX6791–MAX6794),
VIN = 5V
1.731
1.780
1.828
W/V, ILOAD = 300mA (MAX6795/MAX6796),
VIN = 5V
1.746
1.8
1.854
ILOAD2 = 1mA
4.858
4.974
5.090
ILOAD2 = 150mA
4.811
4.945
5.079
ILOAD = ILOAD1 = 1mA, VOUT/OUT1 = 5V
1.207
1.2315
1.256
V
11.0
V
1.8
SET/SET1 rising
124
SET/SET1 falling
62
SET/SET1 = 1V, VIN = 11V
(MAX6795/
MAX6796)
Dropout Voltage
ΔVDO
(MAX6791–
MAX6794)
Guaranteed Output Current
(Note 4)
-100
+100
84
130
L/M, ILOAD = 300mA (Note 2)
1200
1800
T/S, ILOAD = 300mA (Note 3)
1700
2400
L/M, ILOAD = 150mA (Note 2)
1000
1800
L/M, ILOAD = 10mA (Note 2)
84
130
T/S, ILOAD = 150mA (Note 3)
1700
2400
300
MAX6791–MAX6794, inferred from dropout test
150
V
V
mV
L/M, ILOAD = 20mA (Note 2)
L/M, ILOAD = 300mA (Note 2)
T/S, ILOAD = 300mA (Note 3)
MAX6795/MAX6796, inferred from dropout test
UNITS
nA
mV
mA
Dual Mode is a trademark of Maxim Integrated Products, Inc.
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Maxim Integrated │ 3
MAX6791–MAX6796
High-Voltage, Micropower, Single/Dual
Linear Regulators with Supervisory Functions
Electrical Characteristics (continued)
(VIN = 14V, CIN = 1μF, COUT = 10μF, TA = TJ = -40°C to +125°C, unless otherwise noted. Typical values are at TA = TJ = +25°C.)
(Note 1)
PARAMETER
SYMBOL
Short-Circuit Output Current Limit
(Note 4)
MIN
TYP
MAX6795/MAX6796, output shorted,
VIN = 6V
CONDITIONS
400
480
MAX6791–MAX6794, output shorted,
VIN = 6V
200
Thermal-Shutdown Hysteresis
Load Regulation (Note 5)
Power-Supply Rejection Ratio
Startup Response Time
Output Overvoltage Protection
Threshold
PSRR
tSTART
OVTH
°C
IOUT = 1mA to 300mA
(MAX6795/MAX6796)
2
IOUT = 1mA to 150mA
(MAX6791–MAX6794)
1.5
69
ILOAD = 300mA, VOUT = 5V,
VOUT = 90% of its nominal value
180
ILOAD = 150mA, VOUT = 5V,
VOUT1/OUT2 = 90% of its nominal value
360
dB
µs
1.05 x
VOUT
ISINK = 1mA from OUT/OUT1/OUT2
IGATEP = 0A, VIN = 20V
% of
VOUT
%
ILOAD = 10mA, f = 100Hz, VIN = 500mVP-P
IN to GATEP Drive Voltage
VIH
20
1
IGATEP = -100µA, VIN = 20V
ENABLE/ENABLE1/ENABLE2/
HOLD Input-Voltage High
°C
8V ≤ VIN ≤ 72V, ILOAD = 10mA
IN to GATEP Clamp Voltage
VIL
+165
1
VOUT = VOUT (nominal) x 1.15
ENABLE/ENABLE1/ENABLE2/
HOLD Input-Voltage Low
240
8V ≤ VIN ≤ 72V, ILOAD = 1mA
Output Overvoltage Protection
Sink Current
UNITS
mA
Thermal-Shutdown Temperature
Line Regulation
MAX
1.1 x
VOUT
V
5
10
13.8
16.3
18.8
V
8
10
12
V
0.4
V
1.4
mA
V
ENABLE/ENABLE1/ENABLE2
Input Pulldown Current
Enable is internally pulled down to GND
0.5
µA
HOLD Input Pullup Current
HOLD is internally pulled to OUT/OUT1
2
µA
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Maxim Integrated │ 4
MAX6791–MAX6796
High-Voltage, Micropower, Single/Dual
Linear Regulators with Supervisory Functions
Electrical Characteristics (continued)
(VIN = 14V, CIN = 1μF, COUT = 10μF, TA = TJ = -40°C to +125°C, unless otherwise noted. Typical values are at TA = TJ = +25°C.)
(Note 1)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
L
4.500
4.625
4.750
M
4.250
4.375
4.500
T
2.970
3.053
3.135
S
2.805
2.888
2.970
Z
2.250
2.313
2.375
Y
2.125
2.188
2.250
W
1.620
1.665
1.710
V
1.530
1.575
1.620
L/T/Z/W
0.90 x
VOUT
0.925 x
VOUT
0.95 x
VOUT
M/S/Y/V
0.85 x
VOUT
0.875 x
VOUT
0.90 x
VOUT
UNITS
RESET OUTPUT
Reset Threshold (Preset Output
Voltage)
SET/SET1 = GND
Reset Threshold (Adjustable
Output Voltage)
OUT to Reset Delay
VOUT1/VOUT falling
D0
Reset Timeout Period
(CSRT = OUT/OUT1)
tRP
V
V
35
µs
35
µs
D1
2.187
3.125
4.063
D2
8.75
12.5
16.25
D3
35
50
65
D4
140
200
260
800
1000
1250
nA
1.185
1.218
1.255
V
280.0
400.0
520.0
CSWT = 1500pF (adjustable)
170
236.2
290
CSWT = OUT/OUT1 (fixed)
37.5
50.0
62.5
CSWT = 1500pF (adjustable)
21.95
29.52
36.90
CSWT = OUT/OUT1 (fixed)
18.75
25.0
31.25
CSWT = 1500pF (adjustable)
10.80
14.76
18.45
CSWT = OUT/OUT1 (fixed)
4.68
6.25
7.81
CSWT = 1500pF (adjustable)
2.52
3.69
4.62
VOUT1/VOUT rising
CSRT Ramp Current
CSRT Ramp Threshold
ms
WATCHDOG INPUT
Normal Watchdog Timeout
Period
tWD2
Fast Watchdog Timeout Period
SET Ratio = 8
tWD1
Fast Watchdog Timeout Period
SET Ratio = 16
tWD1
Fast Watchdog Timeout Period
SET Ratio = 64
tWD1
Fast Watchdog Minimum Period
tWD0
CSWT = OUT/OUT1 (fixed)
2000
ms
ms
ms
ms
ns
CSWT Ramp Current
Adjustable timeout
800
1000
1250
nA
CSWT Ramp Threshold
Adjustable timeout
1.185
1.218
1.255
V
Undercurrent Threshold for
Watchdog Enable
7.0
10
13.8
mA
Undercurrent Threshold for
Watchdog Disable
3
5
7
mA
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Maxim Integrated │ 5
MAX6791–MAX6796
High-Voltage, Micropower, Single/Dual
Linear Regulators with Supervisory Functions
Electrical Characteristics (continued)
(VIN = 14V, CIN = 1μF, COUT = 10μF, TA = TJ = -40°C to +125°C, unless otherwise noted. Typical values are at TA = TJ = +25°C.)
(Note 1)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
0.4
V
LOGIC INPUT (WDS0, WDS1, WD-DIS, WDI)
Input-Voltage Low
VIL
Input-Voltage High
VIH
Input Current
1.4
Inputs connected to OUT/OUT1 or GND
V
-100
+100
nA
1.263
V
POWER-FAIL COMPARATOR
PFI Threshold
VPFI
1.199
PFI Hysteresis
0.5
PFI Input Current
VPFI = 14V
PFI to PFO Delay
(VPFI + 50mV) to (VPFI - 50mV)
LOGIC OUTPUT (RESET, PFO)
Output-Voltage Low (Open-Drain
or Push-Pull)
Output-Voltage High (Push-Pull)
Open-Drain Leakage
Note
Note
Note
Note
Note
1.231
VOL
VOH
-100
%
+100
35
µs
ISINK = 50µA (output asserted)
0.3
ISINK = 3.2mA (output asserted)
0.4
VOUT ≥ 1.0V, ISOURCE = 10µA
(output not asserted)
0.8 x
VOUT
VOUT ≥ 1.5V, ISOURCE = 100µA
(output not asserted)
0.8 x
VOUT
VOUT ≥ 2.2V, ISOURCE = 500µA
(output not asserted)
0.8 x
VOUT
VRESET = VPFO = 12V (output not asserted)
nA
V
V
100
nA
1: All devices are 100% production tested at TJ = +25°C and +125°C. Limits at -40°C are guaranteed by design.
2: Dropout voltage is defined as (VIN - VOUT) when VOUT is 98% of VOUT for VIN = 8V.
3: Dropout voltage is defined as (VIN - VOUT) when VOUT is 98% of VOUT for VIN = 6V.
4: Operation beyond the absolute maximum power dissipation is not guaranteed and may damage the part.
5: Test at VIN = 8V (L/M), VIN = 6V (T/S), VIN = 5V (Z/Y/W/V).
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Maxim Integrated │ 6
MAX6791–MAX6796
High-Voltage, Micropower, Single/Dual
Linear Regulators with Supervisory Functions
Typical Operating Characteristics
(VIN = VEN = 14V, CIN = 0.1μF, COUT = 10μF, TJ = TA = +25°C, unless otherwise noted.)
55
50
15
25
35
45
55
65
MAX6791 toc02
10
-40 -25 -10 5 20 35 50 65 80 95 110 125
5
15
25
35
45
55
NORMALIZED RESET THRESHOLD
vs. TEMPERATURE
DROPOUT VOLTAGE
vs. TEMPERATURE
MAX6796
1.010
1.000
0.990
-40 -25 -10 5 20 35 50 65 80 95 110 125
0.980
DROPOUT VOLTAGE
vs. TEMPERATURE
OUTPUT VOLTAGE
vs. INPUT VOLTAGE
ILOAD = 150mA
ILOAD = 100mA
200
ILOAD = 10mA
-40 -25 -10 5 20 35 50 65 80 95 110 125
TEMPERATURE (°C)
www.maximintegrated.com
ILOAD = 100mA
800
600
400
0
6.0
ILOAD = 10mA
-40 -25 -10 5 20 35 50 65 80 95 110 125
4.986
4.985
4.984
OUTPUT VOLTAGE vs. LOAD CURRENT
MAX6796
VIN = 14V
5.5
VOUT = 5V
5.0
4.987
4.5
4.0
VOUT = 3.3V
3.5
4.983
3.0
4.982
400
ILOAD = 150mA
1000
VOUT (V)
1200
4.988
75
TEMPERATURE (°C)
MAX6795
PRESET VOLTAGE,
NO LOAD
4.989
OUTPUT VOLTAGE (V)
1400
1000
4.990
65
1200
-40 -25 -10 5 20 35 50 65 80 95 110 125
TEMPERATURE (°C)
ILOAD = 300mA
MAX6792
VOUT = 5V
1400
200
TEMPERATURE (°C)
MAX6796
1600
DROPOUT VOLTAGE (mV)
MAX6791toc05
MAX6791toc04
1.020
MAX6791toc07
SHUTDOWN SUPPLY CURRENT (µA)
DROPOUT VOLTAGE (mV)
15
MAX6791
SHUTDOWN SUPPLY CURRENT
vs. TEMPERATURE
1600
0
20
SUPPLY VOLTAGE (V)
25
600
25
TEMPERATURE (°C)
30
800
50
75
35
1800
70
30
SUPPLY VOLTAGE (V)
MAX6795
VIN = 14V
2000
ILOAD = 0A
NORMALIZED RESET THRESHOLD
5
40
20
ILOAD = 1mA
80
60
45
40
90
MAX6791toc06
60
ILOAD = 50mA
MAX6791-96 toc09
MAX6791
NO LOAD
65
ILOAD = 100mA
100
MAX6793/MAX6794
35
SUPPLY CURRENT (µA)
70
110
40
MAX6791-96toc08
SUPPLY CURRENT (µA)
75
120
SUPPLY CURRENT (µA)
MAX6791-96 toc01
80
SHUTDOWN SUPPLY CURRENT
vs. SUPPLY VOLTAGE
SUPPLY CURRENT vs. TEMPERATURE
MAX6791-96toc03
SUPPLY CURRENT
vs. SUPPLY VOLTAGE
4.981
2.5
4.980
2.0
5
15
25
35
45
55
INPUT VOLTAGE (V)
65
75
SET EXTERNALLY
0
50
100
150
200
250
300
LOAD CURRENT (mA)
Maxim Integrated │ 7
MAX6791–MAX6796
High-Voltage, Micropower, Single/Dual
Linear Regulators with Supervisory Functions
Typical Operating Characteristics (continued)
(VIN = VEN = 14V, CIN = 0.1μF, COUT = 10μF, TJ = TA = +25°C, unless otherwise noted.)
MAX6796
1.02
-55
PSRR (dB)
1.00
-60
-65
-70
0.99
-75
-80
-40 -25 -10 5 20 35 50 65 80 95 110 125
10
100
10k
1k
100k
TEMPERATURE (°C)
FREQUENCY (Hz)
NORMALIZED WATCHDOG TIMEOUT PERIOD
vs. TEMPERATURE
NORMALIZED PFI THRESHOLD
vs. TEMPERATURE
1.015
1.010
1.000
0.998
0.995
0.997
0.990
0.996
0.985
-40 -25 -10 5 20 35 50 65 80 95 110 125
3.0
2.5
2.0
1.5
1.0
MAX6796
0.9
RESET OUTPUT VOLTAGE (V)
3.5
1.0
MAX6791-96toc15
TEMPERATURE (°C)
RESET OUTPUT VOLTAGE
vs. SINK CURRENT
MAX6796
4.0
-40 -25 -10 5 20 35 50 65 80 95 110 125
RESET OUTPUT
vs. SOURCE CURRENT
MAX6791-96toc14
4.5
0.995
TEMPERATURE (°C)
5.0
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0.5
0
MAX6796
1.000
0.999
1.005
0.980
1.001
MAX6791toc13
MAX6796
NORMALIZED PFI THRESHOLD
MAX6791toc12
NORMALIZED WATCHDOG TIMEOUT PERIOD
1.020
RESET OUTPUT (V)
VIN = 6V
VOUT = 1.8V
ILOAD = 10mA
-45
-50
1.01
0.98
PSRR vs. FREQUENCY
-40
MAX6791toc10
NORMALIZED RESET TIMEOUT PERIOD
1.03
MAX6791toc11
NORMALIZED RESET TIMEOUT PERIOD
vs. TEMPERATURE
0
2
4
6
8
10
SOURCE CURRENT (mA)
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12
14
0
0
1
2
3
4
5
6
7
8
9
10
SINK CURRENT (mA)
Maxim Integrated │ 8
MAX6791–MAX6796
High-Voltage, Micropower, Single/Dual
Linear Regulators with Supervisory Functions
Typical Operating Characteristics (continued)
(VIN = VEN = 14V, CIN = 0.1μF, COUT = 10μF, TJ = TA = +25°C, unless otherwise noted.)
100,000
1000
WATCHDOG TIMEOUT PERIOD
MAX6791-96toc16
10,000
100
10
1
0.1
0.0001
0.001
0.01
0.1
1000
100
10
1
0.0001
1
0.001
LOAD-TRANSIENT RESPONSE
0.1
LOAD-TRANSIENT RESPONSE
MAX6791-96toc18
MAX6796
COUT = 10µF
VOUT = 5V
VIN = 14V
IOUT1
0.01
CCSWT (µF)
CCSRT (µF)
MAX6796
VIN = 14V
VOUT = 5V
IOUT
100mA/div
100mA/div
1mA
OUT1
MAX6791-96toc19
RESET TIMEOUT PERIOD (ms)
10,000
WATCHDOG TIMEOUT PERIOD
vs. CCSWT
MAX6791-96toc17
RESET TIMEOUT PERIOD
vs. CCSRT
1mA
1V/div
500mV/div
OUT
VOUT ACCOUPLED
OUT ACCOUPLED
400µs/div
400µs/div
LINE-TRANSIENT RESPONSE
MAX6791-96toc20
MAX6796
ILOAD = 10mA
VIN
OUT
10V/div
(AC-COUPLED)
20mV/div
OUT ACCOUPLED
1ms/div
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Maxim Integrated │ 9
MAX6791–MAX6796
High-Voltage, Micropower, Single/Dual
Linear Regulators with Supervisory Functions
Typical Operating Characteristics (continued)
(VIN = VEN = 14V, CIN = 0.1μF, COUT = 10μF, TJ = TA = +25°C, unless otherwise noted.)
LOAD-TRANSIENT RESPONSE
LOAD-TRANSIENT RESPONSE
MAX6791-96toc22
MAX6791-96toc21
100mA/div
IOUT1
100mA/div
IOUT1
20mA
1mA
OUT1
AC-COUPLED
MAX6792
VOUT1 = 5V
COUT = 10µF
500mV/div
OUT1
AC-COUPLED
MAX6792
VOUT1 = 5V
COUT = 10µF
500mV/div
1ms/div
1ms/div
Pin Description
PIN
MAX6791/ MAX6793/ MAX6795/
MAX6792 MAX6794 MAX6796
NAME
FUNCTION
1, 2
1, 2
—
OUT1
Regulator 1 Output. Fixed (+1.8V, +2.5V, +3.3V, or +5V) or adjustable
(+1.8V to +11V). VOUT1 = 150mA (max). Connect a 10µF (min) capacitor
from OUT1 to GND.
3
3
—
SET1
Feedback Input for Setting the OUT1 Voltage. Connect SET1 to GND to
select the preset output voltage. Connect to an external resistive divider for
adjustable output operation.
4
4
4
PFO
Active-Low, Open-Drain, Power-Fail Comparator Output. PFO asserts low
when PFI is below the internal 1.231V threshold. PFO deasserts when
PFI is above the internal 1.231V threshold.
5
5
5
CSWT
Watchdog Timeout Period Adjust Input. Connect CSWT to OUT1/OUT for
the internally fixed watchdog timeout period. For adjustable watchdog
timeout period, connect a capacitor from CSWT to GND.
See the Selecting Watchdog Timeout Period section for more details.
6
6
6
CSRT
Reset Timeout Period Adjust Input. Connect CSRT to OUT1/OUT for the
internally fixed timeout period. For adjustable timeout, connect a capacitor
from CSRT to GND. See the Reset Output section for more details.
7
7
7
GND
Ground
8
8
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8
RESET
Active-Low Reset Output. RESET remains low while OUT1/OUT is below
the reset threshold. RESET remains low for the duration of the reset timeout
period after the reset conditions end. RESET is available in push-pull and
open-drain options.
Maxim Integrated │ 10
MAX6791–MAX6796
High-Voltage, Micropower, Single/Dual
Linear Regulators with Supervisory Functions
Pin Description (continued)
PIN
MAX6791/ MAX6793/ MAX6795/
MAX6792 MAX6794 MAX6796
NAME
9
—
—
WDS1
10
—
—
WDS0
11
11
11
FUNCTION
Min/Max Watchdog Logic-Select Input. WDS0 and WDS1 select the
watchdog window ratio or disable the watchdog timer. Drive WDS0 and
WDS1 high or low to select the desired ratio, see Table 4.
WDI
Watchdog Input.
MAX6793–MAX6796: A falling or rising transition must occur on WDI within the
selected watchdog timeout period or a reset pulse occurs. The watchdog timer
clears when a transition occurs on WDI or whenever RESET is asserted.
MAX6791/MAX6792: WDI falling and rising transitions within periods shorter
than tWD1 or longer than tWD2 force RESET to assert low for the reset timeout
period. The watchdog timer begins to count after RESET is deasserted.
The watchdog timer clears when a valid transition occurs on WDI or whenever
RESET is asserted. Connect WDS0 high and WDS1 low to disable the
watchdog timer function. See the Watchdog Timer section.
12
12
12
HOLD
Active-Low Regulator Hold Input. When HOLD is forced low, OUT1/OUT
remains ON even if ENABLE1/ENABLE is pulled low. To shut down the
output of the regulator (OUT/OUT1), release HOLD after ENABLE1/ENABLE
is pulled low. Connect HOLD to OUT1/OUT or leave unconnected if unused.
HOLD is internally connected to OUT/OUT1 through a 2µA current source.
13, 14
13, 14
—
OUT2
Regulator 2 Output. OUT2 is a fixed +5V output. Connect a 10µF (min)
capacitor from OUT2 to GND.
15
15
—
ENABLE2
16
16
16
PFI
Adjustable Power-Fail Comparator Input. Connect PFI to a resistive-divider
to set the desired PFI threshold. The PFI input is referenced to an accurate
1.231V threshold.
17, 18
17, 18
17, 18
IN
Regulator Inputs. Bypass IN with a 1µF capacitor to GND.
19
19
19
GATEP
pFET Gate Drive. Connect GATEP to the gate of a p-channel MOSFET to
provide low drop reverse-battery voltage protection.
20
20
—
ENABLE1
Active-High Enable Input 1. Drive ENABLE1 high to turn on OUT1.
ENABLE1 is internally connected to ground through a 0.5µA current sink.
—
9
9
WD-DIS
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Active-High Enable Input 2. Drive ENABLE2 high to turn on OUT2.
ENABLE2 is internally connected to ground through a 0.5µA current sink.
Watchdog Disable Input. Drive WD-DIS low to disable the watchdog timer.
Drive WD-DIS high or connect to OUT/OUT1 to enable the watchdog timer.
The watchdog timer clears when reset asserts.
Maxim Integrated │ 11
MAX6791–MAX6796
High-Voltage, Micropower, Single/Dual
Linear Regulators with Supervisory Functions
Pin Description (continued)
PIN
MAX6791/ MAX6793/ MAX6795/
MAX6792 MAX6794 MAX6796
NAME
FUNCTION
—
10
10, 13,
14, 15
N.C.
Not Internally Connected
—
—
1, 2
OUT
Regulator Output. Fixed +5V, +3.3V, +2.5V, +1.8V, or adjustable output
(+1.8V to +11V). Connect a 10µF (min) capacitor from OUT to GND.
—
—
3
SET
Feedback Input for Setting the OUT Voltage. Connect SET to GND to
select the preset output voltage. Connect to an external resistive-divider
for adjustable output operation.
—
—
20
ENABLE
Active-High Enable Input. Drive ENABLE high to turn on the regulator.
ENABLE is internally connected to ground through a 0.5µA current sink.
—
—
—
EP
Exposed Pad. EP is internally connected to GND. Connect EP to the ground
plane to provide a low thermal-resistance path from the IC junction to the PC
board. Do not use as the electrical connection to GND.
Detailed Description
The MAX6791–MAX6796 ultra-low-quiescent-current,
single-/dual-output, high-input-voltage linear regulators
operate from 5V to 72V. The MAX6791–MAX6794 feature
dual regulators that deliver up to 150mA of load current
per output. One output is available with preset outputvoltage options (+1.8V, +2.5V, +3.3V, and +5.0V) and
can be adjusted to any voltage between +1.8V to +11V
using an external resistive-divider at SET1. The other
output provides a fixed 5V output voltage. The MAX6795/
MAX6796 feature a single regulator that delivers up to
300mA of current with preset output-voltage options
(+1.8V, +2.5V, +3.3V, and +5.0V) or can be adjusted to
any voltage between +1.8V to +11V.
All devices include an integrated µP reset circuit with a
fixed/adjustable reset and watchdog timeout period. The
MAX6791–MAX6796 monitor OUT/OUT1 and assert
a reset output when the output falls below the reset
threshold.
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Regulators
The single and dual regulators accept an input voltage
from 5V to 72V. The MAX6791–MAX6796 offer fixed
preset output voltages of +1.8V, +2.5V, +3.3V, and
+5V, or an adjustable output voltage of +1.8V to +11V,
selected using an external resistive-divider network
connected between OUT1/OUT, SET1/SET, and GND
(see Figure 1). In addition to an adjustable output, the
MAX6791–MAX6794 feature a fixed 5V output voltage.
Reset Output
The reset output is typically connected to the reset input
of a µP. A µP’s reset input starts or restarts the µP in
a known state. The MAX6791–MAX6796 supervisory
circuits provide the reset logic output to prevent codeexecution errors during power-up, power-down, and
brownout conditions (see the Typical Application
Circuit). RESET changes from high to low whenever the
monitored output voltage drops below the reset threshold
voltage or the watchdog timeout expires. Once the
monitored voltage exceeds its respective reset threshold
voltage, RESET remains low for the reset timeout period,
then goes high.
Maxim Integrated │ 12
MAX6791–MAX6796
High-Voltage, Micropower, Single/Dual
Linear Regulators with Supervisory Functions
Functional Diagrams
ENABLE2
MAX6791/MAX6792
OUT2
THERMAL
PROTECTION
OUT1
IN
GATEP
ENABLE1
HOLD
OVERCURRENT
PROTECTION
CONTROL
LOGIC
1.23V
SET1
124mV
1.138V
OR
1.076V
RESET
RESET
TIMEOUT
RESET
CSRT
WATCHDOG
TIMEOUT
WDI
CSWT
WDS0
WDS1
PFO
GND
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PFI
Maxim Integrated │ 13
MAX6791–MAX6796
High-Voltage, Micropower, Single/Dual
Linear Regulators with Supervisory Functions
Functional Diagrams (continued)
ENABLE2
MAX6793/MAX6794
OUT2
THERMAL
PROTECTION
OUT1
IN
GATEP
ENABLE1
HOLD
OVERCURRENT
PROTECTION
CONTROL
LOGIC
1.23V
SET1
124mV
1.138V
OR
1.076V
RESET
RESET
TIMEOUT
RESET
CSRT
WATCHDOG
TIMEOUT
WDI
CSWT
WD-DIS
PFO
GND
www.maximintegrated.com
PFI
Maxim Integrated │ 14
MAX6791–MAX6796
High-Voltage, Micropower, Single/Dual
Linear Regulators with Supervisory Functions
Functional Diagrams (continued)
THERMAL
PROTECTION
MAX6795/MAX6796
OUT
IN
GATEP
ENABLE
HOLD
OVERCURRENT
PROTECTION
CONTROL
LOGIC
1.23V
SET
124mV
1.138V
OR
1.076V
RESET
RESET
TIMEOUT
RESET
CSRT
WATCHDOG
TIMEOUT
WDI
CSWT
WD-DIS
PFO
GND
www.maximintegrated.com
PFI
Maxim Integrated │ 15
MAX6791–MAX6796
High-Voltage, Micropower, Single/Dual
Linear Regulators with Supervisory Functions
Watchdog Timer
The MAX6791–MAX6796 include a watchdog timer that
asserts RESET if the watchdog input (WDI) does not
toggle high to low or low to high within the watchdog
timeout period tWD (280ms min or externally adjustable).
RESET remains low for the fixed or user-adjustable reset
timeout period, tRP. If the watchdog is not updated for
lengthy periods of time, the reset output appears as a
pulse train, asserted for tRP, deasserted for tWD, until
WDI is toggled again. Once RESET asserts, it stays
low for the entire reset timeout period ignoring any WDI
transitions that may occur. To prevent the watchdog from
asserting RESET, toggle WDI with a valid rising or falling
edge before tWD from the last edge. The watchdog counter clears when WDI toggles prior to tWD from the last
edge or when RESET asserts. The watchdog resumes
counting after RESET deasserts.
The MAX6791/MAX6792 have a windowed watchdog
timer that asserts RESET for the adjusted reset timeout
period when the watchdog recognizes a fast watchdog
fault (tWDI < tWD1), or a slow watchdog fault (tWDI >
tWD2). The reset timeout period is adjusted independently
of the watchdog timeout period.
Enable and Hold Inputs
The MAX6791–MAX6796 support two logic inputs,
ENABLE1/ENABLE and HOLD, making these devices
suitable for automotive applications. For example, when
the ignition key signal drives ENABLE1/ENABLE high,
the regulator turns on and remains on even if ENABLE1/
ENABLE 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/OUT1)
off. This feature makes it possible to implement a selfholding circuit without external components. Forcing
ENABLE1/ENABLE low and HOLD high or unconnected
places the MAX6791–MAX6796 into shutdown mode in
which the MAX6791–MAX6796 draw less than 27µA of
supply current.
Table 3 shows the state of the regulator output with respect
to the voltage level at ENABLE1/ENABLE and HOLD.
Connect HOLD to OUT1/OUT or leave it unconnected to
allow the ENABLE1/ENABLE input to act as a standard
ON/OFF switch for the regulator output (OUT/OUT1).
Power-Fail Comparator
PFI is the noninverting input to a comparator. If PFI is
less than VPFI (1.231V), PFO goes low. Common uses
for the power-fail comparator include monitoring the
www.maximintegrated.com
preregulated input of the power supply (such as a battery)
or providing an early power-fail warning so software can
conduct an orderly system shutdown. Set the power-fail
threshold with a resistive-divider, as shown in Figure 5.
The typical comparator delay is 35µs from PFI to PFO.
Connect PFI to GND or IN if unused.
Reverse-Battery Protection Circuitry
The MAX6791–MAX6796 include an overvoltage
protection circuit that is capable of driving a p-channel
MOSFET to protect against reverse-battery conditions.
This MOSFET eliminates the need for external diodes,
thus minimizing the input voltage drop. See the Typical
Application Circuit. The low p-channel MOSFET onresistance of 30mΩ or less yields a forward-voltage drop
of only a few millivolts versus hundreds of millivolts for
a diode, thus improving efficiency in battery-operated
devices. Connecting a positive battery voltage to the drain
of Q1 (see the Typical Application Circuit) forward biases
its body diode. When the source voltage exceeds Q1’s
threshold voltage, Q1 turns on. Once the FET is on, the
battery is fully connected to the system and can deliver
power to the device and the load. An incorrectly inserted
battery reverse-biases the FET’s body diode. The gate
remains at the ground potential. The FET remains off and
disconnects the reversed battery from the system. The
internal zener diode and resistor combination at GATEP
prevent damage to the p-channel MOSFET during an
overvoltage condition. See the Functional Diagrams.
Thermal Protection
When the junction temperature exceeds TJ = +165°C,
the internal protection circuit turns off the internal pass
transistor and allows the IC to cool. The thermal sensor turns the pass transistor on again after the junction
temperature drops to +145°C, resulting in a cycled
output during continuous thermal-overload conditions.
Thermal protection protects the MAX6791–MAX6796 in
the event of fault conditions. For continuous operation, do
not exceed the absolute maximum junction temperature
rating of +150°C.
Proper Soldering of Package Heatsink
The MAX6791–MAX6796 package features an exposed
thermal pad on its underside that should be used as
a heatsink. This pad lowers the package’s thermal
resistance by providing a direct heat-conduction path from
the die to the PC board. Connect the exposed pad and
GND to the system ground using a large pad or ground
plane, or multiple vias to the ground plane layer.
Maxim Integrated │ 16
MAX6791–MAX6796
High-Voltage, Micropower, Single/Dual
Linear Regulators with Supervisory Functions
Applications Information
Output Voltage Selection
The MAX6791–MAX6796 feature dual-mode operation:
these devices operate in either a preset voltage mode
or an adjustable mode. In preset voltage mode, internal
trimmed feedback resistors set the internal linear regulator to +1.8V, +2.5V, +3.3V, or +5V (see the Selector
Guide). Select preset voltage mode by connecting SET1
(MAX6791–MAX6794)/SET(MAX6795/MAX6796) to
GND. In adjustable mode, select an output voltage
between +1.8V and +11V using two external resistors
connected as a voltage-divider to SET1/SET (see Figure
1). Set the output voltage using the following equation:
R1
=
VOUT VSET 1 +
R 2
where VSET = 1.2315V and R1, R2 ≤ 200kΩ.
Selecting Reset Timeout Period
The reset timeout period is adjustable to accommodate a
variety of µP applications. Adjust the reset timeout period
by connecting a capacitor between CSRT and GND. Use
the following formula to set the reset time period:
V
=
t RP C CSRT 1.218 × 10 6
A
where tRP is in seconds and CCSRT is in Farads.
Connect CSRT to OUT1 (MAX6791–MAX6794) or to
OUT (MAX6795/MAX6796) to select an internally fixed
timeout period. Connect CSRT to GND to force RESET
low. CCSRT must be a low-leakage (< 10nA) type capacitor. Ceramic capacitors are recommended; do not use
capacitors lower than 100pF to avoid the influence of
parasitic capacitances.
Available Output-Current Calculation
www.maximintegrated.com
VIN
IN
OUT1/OUT
MAX6791–MAX6796
R1
SET1/SET
R2
GND
Figure 1. Setting the Output Voltage Using a Resistive-Divider
IOUT vs. (VIN - VOUT)
350
VOUT = 1.8V
300
+70°C SAFE OPERATION REGION FOR
EACH TEMPERATURE POINT IS
UNDER THE CURVE
250
IOUT (mA)
The MAX6791–MAX6794 provide up to 150mA per
output, and the MAX6795/MAX6796 provide up to 300mA
of load current. Since the input voltage can be as high
as +72V, package power dissipation limits the amount
of output current available for a given input/output
voltage and ambient temperature. Figure 2 shows the
maximum power-dissipation curve for the MAX6791–
MAX6796. The graph assumes that the exposed metal
pad of the device package is soldered to a solid 1in2
section of PC board copper. Use Figure 2 to determine
the allowable package dissipation for a given ambient
temperature. Alternately, use the following formula to
calculate the allowable package dissipation:
PDMAX = Maximum Power Dissipation
PDMAX = 2.666W, for TA ≤ +70°C
PDMAX = [2.666W - 0.0333W x (TA - 70°C)], for +70°C
< TA ≤ +125°C
where 0.0333W is the MAX6791–MAX6796 package
thermal derating in W/°C and TA is the ambient temperature in °C.
After determining the allowable package dissipation,
calculate the maximum output current using the following
formula:
PD = Power Dissipation
PD < PDMAX where PD = [(IN - OUT1) x IOUT1] + [(IN OUT2) x IOUT2], for MAX6791–MAX6794.
Also, IOUT1 should be ≤ 150mA and IOUT2 should be
≤ 150mA in any case.
PD < PDMAX where PD = [(IN - OUT) x IOUT], for
MAX6795/MAX6796.
Also, IOUT should be ≤ 300mA in any case.
+85°C
200
150
+125°C
100
50
0
0
10
20
30
40
50
60
70 75
(VIN - VOUT) (V)
Figure 2. Maximum Power Dissipation for MAX6791–MAX6796
Maxim Integrated │ 17
MAX6791–MAX6796
High-Voltage, Micropower, Single/Dual
Linear Regulators with Supervisory Functions
Selcting Watchdog Timeout Period
The watchdog timeout period is adjustable to accommodate a variety of µP applications. With this feature,
the watchdog timeout can be optimized for software
execution. The programmer can determine how often the
watchdog timer should be serviced. Adjust the watchdog
timeout period (tWD) by connecting a capacitor between
CSWT and GND. For normal-mode operation, calculate
the watchdog timeout capacitor as follows:
V
=
t WD2 C CSWT 155 × 10 6
A
where tWD is in seconds and CCSWT is in Farads.
To select the internally fixed watchdog timeout period for
the MAX6791–MAX6794, connect CSWT to OUT1. To
select the internally fixed watchdog timeout period for the
MAX6795/MAX6796, connect CSWT to OUT.
CCSWT must be a low-leakage (< 10nA) type capacitor.
Ceramic capacitors are recommended; do not use capacitors lower than 100pF to avoid the influence of parasitic
capacitances.
The MAX6791/MAX6792 have a windowed watchdog
timer that asserts RESET for tRP when the watchdog
recognizes a fast watchdog fault (time between transitions < tWD1), or a slow watchdog fault (time between
transitions > tWD2). The reset timeout period is adjusted
independently of the watchdog timeout period. The slow
watchdog period, tWD2, is calculated as follows:
V
=
t WD2 C CSWT 155 × 10 6
A
where tWD2 is in seconds and CCSWT is in Farads.
tWD0
RESET:
WDI INPUT:
MIN
GUARANTEED
TO ASSERT
tWD1
MAX
UNDETERMINED
The fast watchdog period, tWD1, is selectable as a ratio
from the slow watchdog fault period (tWD2). Select the
fast watchdog period by connecting WDS0 and WDS1 to
OUT/OUT1 or GND according to Table 4, which illustrates
the settings for the 8, 16, and 64 window ratios (tWD2/
tWD1). For example, if CCSWT is 2000pF, and WDS0 and
WDS1 are low, then tWD2 is 318ms (typ) and tWD1 is
40ms (typ). RESET asserts if the watchdog input has two
edges too close to each other (faster than tWD1); or has
edges that are too far apart (slower than tWD2).
All WDI inputs are ignored while RESET is asserted.
The watchdog timer begins to count after RESET is
deasserted. If the time difference between two transitions on WDI is shorter than tWD1 or longer than tWD2,
RESET is forced to assert low for the reset timeout period.
If the time difference between two transitions on WDI
is between tWD1 (min) and tWD1 (max) or tWD2 (min)
and tWD2 (max), RESET is not guaranteed to assert or
deassert; see Figure 3. To guarantee that the window
watchdog does not assert RESET, strobe WDI between
tWD1 (max) and tWD2 (min). The watchdog timer is
cleared when RESET is asserted. Disable the watchdog
timer by connecting WDS0 high and WDS1 low.
There are several options available to disable the watchdog timer (for system development or test purposes or when the µP is in a low-power sleep mode).
One way to disable the watchdog timer is to drive
WD-DIS low for the MAX6793–MAX6796 and drive
WDS0 high and WDS1 low for the MAX6791/MAX6792.
This prevents the capacitor from ramping up. Finally,
reducing the OUT/OUT1 regulator current below the
specified regulator current watchdog-disable threshold (3mA min) also disables the watchdog timer.
MIN
GUARANTEED
TO NOT ASSERT
tWD2
MAX
UNDETERMINED
GUARANTEED
TO ASSERT
FAST
FAULT
NORMAL
OPERATION
SLOW
FAULT
Figure 3. Windowed Watchdog Timing Diagram
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Maxim Integrated │ 18
MAX6791–MAX6796
High-Voltage, Micropower, Single/Dual
Linear Regulators with Supervisory Functions
The watchdog re-enables immediately when any of these
conditions are removed (as long as the RESET is not
asserted). Note that the output current threshold limit
includes hysteresis so that output current must exceed
13.8mA (max) to reenable the watchdog timer.
VIN
IN
MAX6792
MAX6794
MAX6796
Capacitor Selection and Regulator Stability
For stable operation over the full temperature range
and with load currents up to 150mA, use a 10µF (min)
output capacitor with an ESR < 0.5Ω. To reduce noise and
improve load-transient response and power-supply rejection, use larger output-capacitor values. Some ceramic
dielectrics exhibit large capacitance and ESR variation
with temperature. For these types of capacitors (such as
Z5U and Y5V), much higher-value capacitors are required
to maintain stability over the temperaure range. With
X7R dielectrics, a 10µF capacitor should be sufficient
at all operating temperatures. To improve power-supply
rejection and transient response, increase the capacitor
between IN and GND.
RESET
GND
Figure 4. Ensuring RESET Valid to VIN = 0V
VIN
Ensuring a Valid RESET Output
Down to VIN = 0V
When VIN falls below 1V, RESET current-sinking
capabilities decline drastically. High-impedance CMOSlogic inputs connected to RESET can drift to undetermined voltages. This presents no problems in most
applications, since most µPs and other circuitry do not
operate with a supply voltage below 1V. In those applications where RESET must be valid down to 0V, adding a
pulldown resistor between RESET and GND sinks any
stray leakage currents, holding RESET low (Figure 4).
The value of the pulldown resistor is not critical; 100kΩ
is large enough not to load RESET and small enough to
pull RESET to ground. Open-drain RESET versions are
not recommended for applications requiring valid logic for
VIN down to 0V.
IN
R5
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MAX6791
PFI
PFO
R6
GND
Figure 5. Setting Power-Fail Comparator to Monitor VIN
VIN
Adding Hysteresis to PFI
The power-fail comparator has a typical input hysteresis
of 0.5% (of VTH). This is sufficient for most applications
where a power-supply line is being monitored through an
external resistive-divider (Figure 5). Figure 6 shows how
to add hysteresis to the power-fail comparator. Select the
ratio of R5 and R6 so PFI sees 1.23V when VIN falls to
the desired trip point (VTRIP). Since PFO is an open-drain
output, resistors R7 and R8 add hysteresis. R7 typically is
an order of magnitude greater than R5 or R6. The current
through R5 and R6 should be at least 10µA to ensure that
the 100nA (max) PFI input current does not shift the trip
point. R7 should be larger than 50kΩ to prevent it from
loading down the PFO.
VTERM
R7
VTERM
IN
R8
MAX6791
R5
PFI
PFO
R6
GND
Figure 6. Adding Hysteresis Power-Fail Comparator
Maxim Integrated │ 19
MAX6791–MAX6796
High-Voltage, Micropower, Single/Dual
Linear Regulators with Supervisory Functions
Table 1. Preset Output Voltage and Reset
Threshold
PART
SUFFIX (_)
OUTPUT
VOLTAGE (V)
RESET THRESHOLD
(NOMINAL)
L
5.0
4.625
M
5.0
4.375
T
3.3
3.053
S
3.3
2.888
Z
2.5
2.313
Y
2.5
2.188
W
1.8
1.665
V
1.8
1.575
Use the following formulas to determine the high/low
threshold levels and the hysteresis:
VL-H = VPFI x (1 + R5 / R6 +R5 / R7)
VH-L = VPFI x (1 + R5 / R6 ) + (VPFI - VTERM) [R5 / (R7
+ R8)]
VHYS = VPFI x (R5 / R7 ) - (VPFI - VTERM) [R5 / (R7 +
R8)]
where VL-H is the threshold level for the monitored
voltage rising and VH-L is the threshold level for the
monitored voltage falling.
Chip Information
PROCESS: BiCMOS
Table 2. Preset Timeout Period
PART
SUFFIX (_)
RESET TIMEOUT PERIOD
(NOMINAL)
D0
35µs
D1
3.125ms
D2
12.5ms
D3
50ms
D4
200ms
Table 3. ENABLE/ENABLE1 and HOLD Truth Table/State Table
OPERATING
STATE
ENABLE1
ENABLE
HOLD
REGULATOR 1
OUTPUT
Initial state
Low
Don’t care
Off
ENABLE/ENABLE1 is pulled to GND through internal pulldown.
OUT/OUT1 is disabled.
Turn-on state
High
Don’t care
On
ENABLE/ENABLE1 is externally driven high turning OUT/OUT1
on. HOLD is pulled up to OUT/OUT1.
Hold setup state
High
Low
On
HOLD is externally pulled low while ENABLE/ENABLE1 remains
high, and the regulator latches on.
Hold state
Low
Low
On
ENABLE/ENABLE1 is driven low (or allowed to float low by an
internal pulldown). HOLD remains externally pulled low keeping
OUT/OUT1 on.
Off state
Low
High
Off
HOLD is driven high (or pulled high by the internal pullup) while
ENABLE/ENABLE1 is low. OUT/OUT1 is turned off and ENABLE/
ENABLE1 and HOLD logic returns to the initial state.
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COMMENT
Maxim Integrated │ 20
MAX6791–MAX6796
High-Voltage, Micropower, Single/Dual
Linear Regulators with Supervisory Functions
Table 4. MIN/MAX Watchdog Setting
WDS0
WDS1
RATIO
0
0
8
0
1
16
1
0
Watchdog disabled
1
1
64
Table 5. Standard Version Part Number
PART NUMBER
OUTPUT VOLTAGE
(V)
RESET TIMEOUT PERIOD (ms)
(NOMINAL)
RESET THRESHOLD (V)
(NOMINAL)
MAX6791TPLD2+
5.0
12.5
4.625
MAX6791TPSD2+
3.3
12.5
2.888
MAX6792TPLD2+
5.0
12.5
4.625
MAX6792TPSD2+
3.3
12.5
2.888
MAX6793TPLD2+
5.0
12.5
4.625
MAX6793TPSD2+
3.3
12.5
2.888
MAX6794TPLD2+
5.0
12.5
4.625
MAX6794TPSD2+
3.3
12.5
2.888
MAX6795TPLD2+
5.0
12.5
4.625
MAX6795TPSD2+
3.3
12.5
2.888
MAX6796TPLD2+
5.0
12.5
4.625
MAX6796TPSD2+
3.3
12.5
2.888
+Denotes lead-free package.
Selector Guide
PART
RESET OUTPUT
NUMBER OF
OUTPUTS
WINDOWED
WATCHDOG TIMEOUT
ENABLE
INPUTS
WATCHDOG
DISABLE INPUT
MAX6791TP_D_
Open drain
2
ü
Dual
ü
MAX6792TP_D_
Push-pull
2
ü
Dual
ü
MAX6793TP_D_
Open drain
2
—
Dual
ü
MAX6794TP_D_
Push-pull
2
—
Dual
ü
MAX6795TP_D_
Open drain
1
—
Single
ü
MAX6796TP_D_
Push-pull
1
—
Single
ü
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Maxim Integrated │ 21
MAX6791–MAX6796
High-Voltage, Micropower, Single/Dual
Linear Regulators with Supervisory Functions
Typical Application Circuit
12V
BATT
TO OTHER CIRCUITRY
GATEP
IN
IN
ENABLE1
OUT1
PFI
ENABLE2
SET1
OUT2
MAX6791/MAX6792
CSWT
PFO
WDI
CSRT GND
RESET HOLD
RESET
VCC
INT
I/O
WDS1
I/O
WDS0
TXD
C
VCC INH
BATT
CANH
XCVR
RXD
CANL
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.
20 TQFN-EP
T2055+4
21-0140
90-0009
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Maxim Integrated │ 22
MAX6791–MAX6796
High-Voltage, Micropower, Single/Dual
Linear Regulators with Supervisory Functions
IN 17
MAX6791/
MAX6792
IN 18
GATEP 19
9
WDS1
IN 17
8
RESET
IN 18
7
GND
6
CSRT
HOLD
WDI
11
MAX6793/
MAX6794
GATEP 19
ENABLE1 20
2
3
4
5
1
CSWT
OUT1
+
PFO
OUT1
1
PFI 16
12
SET1
+
WDS0
13
OUT1
ENABLE1 20
10
14
THIN QFN
5mm x 5mm
2
3
4
5
CSWT
PFI 16
15
PFO
11
OUT2
12
SET1
WDI
13
OUT2
HOLD
14
OUT1
OUT2
15
TOP VIEW
ENABLE2
OUT2
TOP VIEW
ENABLE2
Pin Configurations
10
N.C.
9
WD-DIS
8
RESET
7
GND
6
CSRT
N.C.
N.C.
HOLD
WDI
TOP VIEW
N.C.
THIN QFN
5mm x 5mm
15
14
13
12
11
PFI 16
IN 17
MAX6795/
MAX6796
IN 18
GATEP 19
2
3
4
5
PFO
CSWT
OUT
1
SET
+
OUT
ENABLE 20
10
N.C.
9
WD-DIS
8
RESET
7
GND
6
CSRT
THIN QFN
5mm x 5mm
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Maxim Integrated │ 23
MAX6791–MAX6796
High-Voltage, Micropower, Single/Dual
Linear Regulators with Supervisory Functions
Revision History
REVISION
NUMBER
REVISION
DATE
0
10/05
Initial release
1
8/06
Correct text in data sheet.
2
10/11
Added /V automotive-qualified part to data sheet
1
3
10/17
Added MAX6795TPLD2/V+ to Ordering Information
1
DESCRIPTION
PAGES
CHANGED
—
10, 11, 18, 19
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.
© 2017 Maxim Integrated Products, Inc. │ 24
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