For price, delivery, and to place orders, please contact Maxim Distribution at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.
MAX836/MAX837
4-Pin Micropower Voltage Monitors
________________________________________________________________ Maxim Integrated Products 1
TOP VIEW
1
2
4
3
OUT
INVCC
GND
SOT143
MAX836
MAX837
___________________Pin Configuration
GND
1.204V
REF
OUT
MAX836
ONLY
IN
MAX836
MAX837
VCC
VCC
VCC
0.1µF
__________Typical Operating Circuit
19-1137; Rev 2; 12/05
______________General Description
The MAX836/MAX837 micropower voltage monitors
contain a 1.204V precision bandgap reference and a
comparator in a SOT143 package. The MAX836 has an
open-drain, n-channel output driver, while the MAX837
has a push-pull output driver. Two external resistors set
the trip threshold voltage.
________________________Applications
Precision Battery Monitor
Load Switching
Battery-Powered Systems
Threshold Detectors
____________________________Features
♦±1.25% Precision Voltage Threshold
♦SOT143 Package
♦Low Cost
♦< 5µA Typical Supply Current
♦Open-Drain Output (MAX836)
Push-Pull Output (MAX837)
_______________Ordering Information
*All devices available in tape-and-reel only. Contact factory for
availability.
Devices are available in both leaded and lead-free packaging.
Specify lead-free by replacing “-T” with “+T” when ordering.
PART* TEMP RANGE PIN-
PACKAGE
TOP
MARK
MAX836EUS-T -40°C to +85°C 4 SOT143-4 EQAA
MAX837EUS-T -40°C to +85°C 4 SOT143-4 EQAA
MAX836/MAX837
4-Pin Micropower Voltage Monitors
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS
(VCC = +2.5V to +11.0V, TA= TMIN to TMAX, unless otherwise noted. Typical values are at TA= +25°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.
VCC, OUT to GND (MAX836)....................................-0.3V to 12V
IN, OUT to GND (MAX837).........................-0.3V to (VCC + 0.3V)
Input Current
VCC .................................................................................20mA
IN.....................................................................................10mA
Output Current, OUT...........................................................20mA
Rate of Rise, VCC ............................................................100V/µs
Continuous Power Dissipation
SOT143 (derate 4mW/°C above +70°C)......................320mW
Operating Temperature Range ...........................-40°C to +85°C
Storage Temperature Range .............................-65°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C
Note 1: The voltage-detector output remains in the direct state for VCC down to 1.2V when VIN ≤VCC / 2.
Note 2: Supply current has a monotonic dependence on VCC (see the Typical Operating Characteristics).
Note 3: IN leakage current has a monotonic dependence on VCC (see the Typical Operating Characteristics).
Note 4: The MAX836 open-drain output can be pulled up to a voltage greater than VCC, but may not exceed 11V.
2 ______________________________________________________________________________________
TA= -40°C to +85°C
VCC = full operating range
VIN = 1.25V,
OUT = high
13
TA= TMIN to TMAX 8.0
VCC = 3.6V TA= +25°C 2.0 5.0
VCC = full operating range
ICC
VIN = 1.16V,
OUT = low
15
Supply Current (Note 2)
3.5 6.5
µA
TA= +25°C
CONDITIONS
VCC = 5.0V, 50mV overdrive
TA= +25°C
VCC = 5.0V, 100mV overdrive
VCC = 5V, IN = low to high
VCC = 5.0V, no load (MAX837 only)
VCC = 5.0V, no load (MAX836 pull-up = 10kΩ)
VIN = VTH
VIN > VTHMAX (MAX836 only)
VIN > VTHMAX, ISOURCE = 500µA (MAX837 only)
VIN < VTHMIN, ISINK = 500µA
TA= TMIN to TMAX
VIN falling
10
VCC = 3.6V
PARAMETER SYMBOL MIN TYP MAX UNITS
1.169 1.204 1.231
Trip Threshold Voltage VTH
1.185 1.204 1.215 V
Trip Threshold Voltage
Hysteresis VHYST 6mV
IN Operating Voltage Range
(Note 1) VIN VCC -1 V
IN Leakage Current (Note 3) IIN nA±3 ±12
Operating Voltage Range
(Note 1) VCC 2.5 11.0 V
Propagation Delay tPL 80 µs
Glitch Immunity 35 µs
OUT Rise Time tRT 260 ns
OUT Fall Time tFT 680 ns
Output Leakage Current
(Note 4) ILOUT ±1 µA
Output-Voltage High VOH VCC - 0.5 V
Output-Voltage Low VOL 0.4 V
MAX836/MAX837
4-Pin Micropower Voltage Monitors
_______________________________________________________________________________________ 3
1.207
1.206
1.205
1.204
1.203
1.202
1.201
TRIP THRESHOLD VOLTAGE
vs. TEMPERATURE
MAX836/7 01
TEMPERATURE (°C)
TRIP THRESHOLD VOLTAGE (V)
200-20-40-60 100806040
0
5.0
4.0
3.0
2.0
1.0
24 8
SUPPLY CURRENT vs. SUPPLY VOLTAGE
MAX836/7 02
VCC (V)
SUPPLY CURRENT (µA)
61035 971112
VIN = 1.22V 0
16
14
12
10
8
6
4
2
02 6
SUPPLY CURRENT vs. IN VOLTAGE
MAX836
/
7 03
VIN (V)
SUPPLY CURRENT (µA)
4813 75 9 10 11 12
VCC = 11V
VCC = 3.6V
0
80
70
60
50
40
30
20
10
02 6
IN LEAKAGE CURRENT vs. IN VOLTAGE
MAX836/7 04
VIN (V)
IN LEAKAGE CURRENT (nA)
4813 75 9 10 11
VCC = 11V
TA = +85°C
TA = -40°C
TA = +25°C
10,000
1,000
1
0.1
0.01 10.1 10 100
OUTPUT VOLTAGE
vs. OUTPUT SINK CURRENT
MAX836/7-06B
OUTPUT SINK CURRENT (mA)
OUTPUT VOLTAGE (mV)
100
10
TA = +85°C
TA = -40°C
TA = +25°C
2.0
2.4
2.8
3.2
3.6
4.0
4.4
4.8
24 8
IN LEAKAGE CURRENT
vs. SUPPLY VOLTAGE
MAX836/7 05
VCC (V)
IN LEAKAGE CURRENT (nA)
61035 971112
TA = -40°C
TA = +85°C
TA = +25°C
VIN = 1.2V
5.5
5.0
1.5
0
0.5
1.0
0.01 10.1 10 100
MAX837 OUTPUT VOLTAGE
vs. OUTPUT SOURCE CURRENT
MAX836/7-06A
OUTPUT SOURCE CURRENT (mA)
OUTPUT VOLTAGE (V)
4.5
2.0
2.5
3.0
3.5
4.0
TA = +25°C
TA = -40°C
TA = +85°C
20
130
120
110
100
90
80
70
60
50
40
30
24 8
OUTPUT LOW VOLTAGE
vs. SUPPLY VOLTAGE
MAX836/7 07
VCC (V)
OUTPUT LOW VOLTAGE (mV)
635 97 101112
ISINK = 500µA
0
10
20
30
40
50
60
70
24 8
SHORT-CIRCUIT SINK CURRENT vs.
SUPPLY VOLTAGE
MAX836/7 08
VCC (V)
SHORT-CIRCUIT SINK CURRENT (mA)
61035 971112
TA = +85°C
TA = -40°C
TA = +25°C
__________________________________________Typical Operating Characteristics
(VCC = +5V, RLOAD = 1MΩ, RPULLUP = 10kΩ(MAX836 only), TA = +25°C, unless otherwise noted.)
Detailed Description
The MAX836/MAX837 micropower voltage monitors
contain a 1.204V precision bandgap reference and a
comparator (see the Typical Operating Circuit). The
only difference between the two parts is the structure of
the comparator output driver. The MAX836 has an
open-drain n-channel output driver that can be pulled
up to a voltage higher than VCC, but under 11V. The
MAX837’s output is push-pull, and can both source
and sink current.
Programming the Trip Voltage
Two external resistors set the trip voltage, VTRIP (Figure 1).
VTRIP is the point at which the applied voltage (typically
VCC) toggles OUT. The MAX836/MAX837’s high input
impedance allows large-value resistors without compro-
mising trip-voltage accuracy. To minimize current con-
sumption, select a value for R2 between 500kΩand
1MΩ, then calculate R1 as follows:
where VTRIP = desired trip voltage (in volts), VTH =
threshold trip voltage (1.204V).
__________Applications Information
Adding Hysteresis
Hysteresis adds noise immunity to the MAX836/MAX837
and prevents repeated triggering when VIN is near the
threshold trip voltage. Figure 2 shows how to add hys-
teresis to the comparator. The technique is similar for
R1 = R2 V
V-1
TRIP
TH
⎛
⎝
⎜⎞
⎠
⎟
MAX836/MAX837
4-Pin Micropower Voltage Monitors
4 ______________________________________________________________________________________
_____________________________Typical Operating Characteristics (continued)
(VCC = +5V, RLOAD = 1MΩ, RPULLUP = 10kΩ(MAX836 only), TA = +25°C, unless otherwise noted.)
_____________________Pin Description
NAME FUNCTION
1GND System Ground
2 VCC System Supply Input
PIN
3IN
Noninverting Input to the Comparator.
The inverting input connects to the
internal 1.204V bandgap reference.
4OUT Open-Drain (MAX836) or
Push-Pull (MAX837) Output
GND
RPULLUP
OUT
IN
MAX836
VCC
VCC
VCC
R2
R1
R1 + R2
R2
VTRIP = (1.204)
NOTE: UNITS ARE OHMS AND VOLTS
0.1µF
Figure 1. Programming the Trip Voltage, VTRIP
0
200
400
600
800
1000
1200
1400
1600
1800
24 8
OUT RISE/FALL-TIME
vs. SUPPLY VOLTAGE
MAX836/7 10
VCC (V)
TIME (ns)
61035 971112
FALL TIME
RISE TIME
MAX837 ONLY
40
160
140
120
100
80
60
-60 -20 60
VCC FALLING PROPAGATION DELAY
vs. TEMPERATURE
MAX836/7 09
TEMPERATURE (°C)
PROPAGATION DELAY (µs)
20-40 0 8040 100
1mV/µs
10mV/µs
VTRIP = 3.0V
VTRIP = 3.0V
VTRIP = 4.63V
VTRIP = 4.63V
both parts. For the MAX836, select the ratio of resistors
R1 and R2 so that IN sees 1.204V when the monitor
voltage falls to or rises above the desired trip point
(VTRIP). R3 adds hysteresis and is typically an order of
magnitude larger than R1 or R2. The current through R1
and R2 should be at least 500nA to ensure that the
12nA maximum input current does not shift the trip
point significantly. Capacitor C1 adds additional noise
rejection.
Monitoring Voltages Other than VCC
The MAX836/MAX837 can monitor voltages other than
VCC (Figure 3). Calculate VTRIP as shown in the
Programming the Trip Voltage section. The monitored
voltage (VMON) is independent of VCC. VIN must be 1V
less than VCC.
Heater Temperature Control
Figure 4 shows a basic heater temperature-control cir-
cuit. Upon power-up, OUT is high and the n-channel
MOSFET turns on. Current flows through the heating
element (R4), warming the surrounding area. R2 is a
negative-temperature-coefficient thermistor and as tem-
perature increases, its resistance decreases. As the
thermistor heats up and its resistance decreases, the
MAX837’s voltage at IN decreases until it reaches the
1.204V threshold voltage. At this point, OUT goes low,
turning off the heating element. The thermistor cools
and the voltage at IN rises until it overcomes the
MAX837’s hysteresis (6mV). OUT returns high when this
point is reached, turning on the heating element again.
This cycle repeats as long as power is applied.
Determine the thermistor’s resistance (R2) at the
desired temperature. Then, using R2’s resistance and
half the resistance of R3, calculate R1’s value with the
following formula:
Chip Information
TRANSISTOR COUNT: 54
R1 = (R2 + R3) V
1.204 -1
CC
⎛
⎝
⎜⎞
⎠
⎟
MAX836/MAX837
4-Pin Micropower Voltage Monitors
_______________________________________________________________________________________ 5
GND
NOTE: C1 ADDS ADDITIONAL NOISE IMMUNITY
OUT OUT
IN
VCC
VCC
C1
R1
R3
R2
0.1µF
MAX837
Figure 2. Adding Hysteresis to the Comparator
GND OUT
IN
VCC
VMON
VCC
R2
R1
0.1µF
MAX837
Figure 3. Monitoring Voltages Other than VCC
IN
THERMISTOR
WITH
NEGATIVE
COEFFICIENT
HEATING
ELEMENT
R4
OUT
GND
VCC
VCC
VCC
R2
T
R3
R1
0.1µF
R1 = (R2 + R3) (- 1 Ω
)
1.204
MAX837
Figure 4. Heater Temperature Control
SOT-143 4L.EPS
E
1
1
21-0052
PACKAGE OUTLINE, SOT-143, 4L
MAX836/MAX837
4-Pin Micropower Voltage Monitors
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.
6_____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600
© 2005 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products, Inc.
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.)
