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19-1157; Rev 0; 12/96
Micropower, Latching Voltage Monitors in SOT23-5
_______________General Description
The MAX834/MAX835 micropower voltage monitors contain a 1.204V precision bandgap reference, comparator, and latched output in a 5-pin SOT23 package. Using the latched output prevents deep discharge of batteries. The MAX834 has an open-drain, N-channel output driver, while the MAX835 has a push/pull output driver. Two external resistors set the trip-threshold voltage. The MAX834/MAX835 feature a level-sensitive latch, eliminating the need to add hysteresis to prevent oscillations in battery-load-disconnect applications.
____________________________Features
o Prevents Deep Discharge of Batteries o Precision 1.25% Voltage Threshold o Latched Output (once low, stays low until cleared) o SOT23-5 Package o Low Cost o Wide Operating Voltage Range, +2.5V to +11V o <2A Typical Supply Current o Open-Drain Output (MAX834) Push/Pull Output (MAX835)
MAX834/MAX835
________________________Applications
Precision Battery Monitor Load Switching Battery-Powered Systems Threshold Detectors
______________Ordering Information
PART MAX834EUK-T MAX835EUK-T TEMP. RANGE -40C to +85C -40C to +85C PINPACKAGE 5 SOT23-5 5 SOT23-5 SOT TOP MARK AAAX AAAY
__________Typical Operating Circuit
VCC (MAX834 ONLY)
CLEAR LATCH CLEAR OUT
RL
__________________Pin Configuration
TOP VIEW
OUT
MAX834 MAX835
GND CLEAR 1 5 OUT
VCC
VCC
IN
GND 2
MAX834 MAX835
4 IN
VCC 3 R1 0.1F R2
SOT23-5
________________________________________________________________ Maxim Integrated Products
1
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Micropower, Latching Voltage Monitors in SOT23-5 MAX834/MAX835
ABSOLUTE MAXIMUM RATINGS
VCC, OUT (MAX834), CLEAR to GND ......................-0.3V to 12V IN, OUT (MAX835), to GND........................-0.3V to (VCC + 0.3V) INPUT Current VCC .................................................................................20mA IN.....................................................................................10mA OUT Current.......................................................................-20mA VCC Rate of Rise .............................................................100V/s Continuous Power Dissipation SOT23-5 (derate 7.1mW/C above +70C)..................571mW Operating Temperature Range ...........................-40C to +85C Storage Temperature Range .............................-65C to +150C Lead Temperature (soldering, 10sec) .............................+300C
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
(VCC = +2.5V to +11V, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25C.) PARAMETER Operating Voltage Range (Note 1) SYMBOL VCC VIN = 1.16V, OUT = low, VCLEAR VCC - 0.25V or VCLEAR 0.25V VIN = 1.25V, OUT = high, VCLEAR VCC - 0.25V or VCLEAR 0.25V VIN falling TA = +25C TA = TMIN to TMAX CONDITIONS MIN 2.5 2.4 TYP MAX 11 5 10 15 A 1.1 4 8 13 1.185 1.169 1.204 1.204 6 0 VIN = VTH VCC = 5V, 50mV overdrive VCC = 5V, 100mV overdrive tRT tFT ILOUT VOH VOL VCC = 5V, no load (MAX835 only) VCC = 5V, no load (MAX834 pull-up = 10k) VIN > VTH(MAX) (MAX834 only) VIN > VTH(MAX), ISOURCE = 500A (MAX835 only) VIN < VTH(MIN), ISINK = 500A VCC - 0.5 0.4 3 80 35 200 480 1 VCC - 1 12 1.215 1.231 V mV V nA s s s s A V V UNITS V
VCC = 3.6V
Supply Current (Note 2)
ICC
VCC = full operating range VCC = 3.6V TA = +25C TA = TMIN to TMAX
VCC = full operating range TA = +25C TA = 0C to +70C
Threshold Voltage Threshold Voltage Hysteresis IN Operating Voltage Range (Note 1) IN Leakage Current (Note 3) Propagation Delay Glitch Immunity OUT Rise Time OUT Fall Time Output Leakage Current (Note 4) Output Voltage High Output Voltage Low
VTH VHYST VIN IIN tPL
VCC = 5V, IN = low to high
2
_______________________________________________________________________________________
Micropower, Latching Voltage Monitors in SOT23-5
ELECTRICAL CHARACTERISTICS (continued)
(VCC = +2.5V to +11V, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25C.) PARAMETER CLEAR Input High Voltage CLEAR Input Low Voltage CLEAR Input Leakage Current CLEAR Input Pulse Width Note 1: Note 2: Note 3: Note 4: SYMBOL VCIH VCIL ICLEAR tCLR 1 1 CONDITIONS MIN 2 0.4 100 TYP MAX UNITS V V nA s
MAX834/MAX835
The voltage-detector output remains in the correct state for VCC down to 1.2V when VIN VCC / 2. Supply current has a monotonic dependence on VCC (see Typical Operating Characteristics). IN leakage current has a monotonic dependence on VCC (see Typical Operating Characteristics). The MAX834 open-drain output can be pulled up to a voltage greater than VCC, but may not exceed 11V.
__________________________________________Typical Operating Characteristics
(VCC = +5V, Typical Operating Circuit, TA = +25C, unless otherwise noted.)
INPUT LEAKAGE CURRENT vs. TEMPERATURE
MAXMAX834/835-07
INPUT LEAKAGE CURRENT vs. INPUT VOLTAGE
80 70 60 50 40 30 20 10 0 TA = +85C 0 12 3 45 6 7 8 9 10 11 12 TA = -40C TA = +25C VCC = 11.0V
MAXMAX834/835-08
SUPPLY CURRENT vs. SUPPLY VOLTAGE
4.0 SUPPLY CURRENT (A) 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0 0 12 3 45 6 7 8 9 10 11 12 TA = +25C TA = -40C TA = +85C VIN = 1.25V
MAXMAX834/835-10
5.0 INPUT LEAKAGE CURRENT (nA) 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 -60 -40 -20 0 20 40 60 VCC = 5.0V VIN = 1.2V
90 INPUT LEAKAGE CURRENT (nA)
4.5
80 100
TEMPERATURE (C)
VIN (V)
VCC (V)
SUPPLY CURRENT vs. INPUT VOLTAGE
MAX834/835-11
SUPPLY CURRENT vs. INPUT VOLTAGE
MAXMAX834/835-12
PROGRAMMED TRIP VOLTAGE vs. TEMPERATURE
5.6 5.2 TRIP VOLTAGE (V) 4.8 4.4 4.0 3.6 3.2 2.8 2.4 2.0 VTRIP 3.3V (FIGURE 2, R1 = 180k, R2 = 100k) VTRIP 4.5V (FIGURE 2, R1 = 270k, R2 = 100k)
MAXMAX834/835-13
6 VCC = 3.6V SUPPLY CURRENT (A) 5
12 11 10 SUPPLY CURRENT (A) 9 8 7 6 5 4 3 2 1 0 VCC = 11.0V
6.0
4
2
1
0 0 0.4 0.8 1.2 1.6 2.0 2.4 2.8 3.2 3.6 VIN (V)
0
12
3
45
6
7
8
9 10 11 12
-60 -40 -20
0
20
40
60
80
100
VIN (V)
TEMPERATURE (C)
_______________________________________________________________________________________
3
Micropower, Latching Voltage Monitors in SOT23-5 MAX834/MAX835
_____________________________Typical Operating Characteristics (continued)
(VCC = +5V, Typical Operating Circuit, TA = +25C, unless otherwise noted.)
OUTPUT LOW VOLTAGE vs. SUPPLY VOLTAGE
MAXMAX834/835-14
MAX835 OUTPUT HIGH VOLTAGE vs. SUPPLY VOLTAGE
MAXMAX834/835-15
OUTPUT SHORT-CIRCUIT SINK CURRENT vs. SUPPLY VOLTAGE
VIN = 1.1V SHORT-CIRCUIT CURRENT (mA) 15 TA = -40C TA = +25C TA = +85C 5
MAXMAX834/835-17
250 ISINK = 500A 200 TA = +85C VOL (mV) 150
500 450 400 VCC - VOH (mV) 350 300 250 200 150 100 TA = -40C TA = +25C TA = +85C ISOURCE = 500A
20
10
100
TA = +25C
50 TA = -40C 0 0 12 345 6 7 8 9 10 11 12 VCC (V)
50 0 0
0 12 3 45 6 7 8 9 10 11 12 0 12 3 45 6 7 8 9 10 11 12 VCC (V) VCC (V)
MAX835 OUTPUT SHORT-CIRCUIT SOURCE CURRENT vs. SUPPLY VOLTAGE
VIN = 1.3V SHORT-CIRCUIT CURRENT (mA) 20 TA = -40C TA = +25C 10
MAXMAX834/835-18
SUPPLY VOLTAGE FALLING TO OUT PROPAGATION DELAY vs. TEMPERATURE
MAXMAX834/835-19
MAX835 OUTPUT RISE TIME vs. SUPPLY VOLTAGE
900 800 RISE TIME (ns) 700 600 500 400 300 TA = +25C TA = +85C
MAXMAX834/835-20
25
160 150 PROPAGATION DELAY (s) 140 130 120 110 100 90 80 70 60 50 40 10mV/s 1mV/s
1000
15
5
TA = +85C
200 100 0 TA = -40C 0 12 3 45 6 7 8 9 10 11 12
0 0 12 345 6 7 8 9 10 11 12 VCC (V)
-60 -40 -20
0
20
40
60
80 100
TEMPERATURE (C)
VCC (V)
OUTPUT FALL TIME vs. SUPPLY VOLTAGE
MAXMAX834/835-21
OUTPUT LOW VOLTAGE vs. OUTPUT SINK CURRENT
MAXMAX834/835-23
MAX835 OUTPUT HIGH VOLTAGE vs. OUTPUT SOURCE CURRENT
VCC = 11V 10k VCC - VOH (mV) TA = +25C
MAXMAX834/835-25
2.5
100k VCC = 11V 10k TA = +25C VOL (mV) 1k TA = +85C 100
100k
2.0 FALL TIME (s) TA = +85C
1.5
1k
TA = +85C
1.0 TA = +25C 0.5 TA = -40C 0 0 12 3 45 6 7 8 9 10 11 12 VCC (V)
100
TA = -40C
10 1 0.1 1
TA = -40C
10 1 10 100 0.1 1 10 100
OUTPUT SINK CURRENT (mA)
OUTPUT SOURCE CURRENT (mA)
4
_______________________________________________________________________________________
Micropower, Latching Voltage Monitors in SOT23-5
_____________________________Typical Operating Characteristics (continued)
(VCC = +5V, Typical Operating Circuit, TA = +25C, unless otherwise noted.)
OUTPUT LOW VOLTAGE vs. OUTPUT SINK CURRENT
MAXMAX834/835-27
MAX834/MAX835
MAX835 OUTPUT HIGH VOLTAGE vs. OUTPUT SOURCE CURRENT
VCC = 3.6V 1k VCC - VOH (mV) TA = +85C
MAXMAX834/835-29
CLEAR TO OUT PROPAGATION DELAY vs. TEMPERATURE
VIN > VTH
MAXMAX834/835-30
10k VCC = 3.6V 1k VOL (mV) TA = +85C
10k
1.5 1.3 PROPAGATION DELAY (s) 1.1 0.9 0.7 0.5 0.3 VCC = 11.0V VCC = 5.0V
VCC = 3.6V
100 TA = +25C 10
TA = -40C
100 TA = +25C 10
TA = -40C
1 0.1 1 10 OUTPUT SINK CURRENT (mA) 100
1 0.1 1 OUTPUT SOURCE CURRENT (mA) 10
0.1 -60 -40 -20 0 20 40 60 80 100 TEMPERATURE (C)
______________________________________________________________Pin Description
PIN NAME CLEAR GND VCC IN OUT FUNCTION Clear Input resets the latched output. With VIN > VTH, pulse CLEAR high for a minimum of 1s to reset the output latch. Connect to VCC to make the latch transparent. System Ground System Supply Input Noninverting Input to the Comparator. The inverting input connects to the internal 1.204V bandgap reference. Open-Drain (MAX834) or Push/Pull (MAX835) Latched Output. OUT is active low.
1
2
3
4
5
VCC CLEAR CLEAR LATCH CLEAR GND VCC VCC OUT IN RL (MAX834 ONLY) OUT
GND
MAX834 MAX835
LATCH
OUT
1.204V VCC
IN
MAX834 MAX835
0.1F VTRIP = (1.204)
R1 + ( R1R2R2 ) R2
(UNITS ARE OHMS AND VOLTS)
Figure 1. Functional Diagram
Figure 2. Programming the Trip Voltage (VTRIP)
5
_______________________________________________________________________________________
Micropower, Latching Voltage Monitors in SOT23-5 MAX834/MAX835
_______________Detailed Description
The MAX834/MAX835 micropower voltage monitors contain a 1.204V precision bandgap reference and a comparator with an output latch (Figure 1). The difference between the two parts is the structure of the comparator output driver. The MAX834 has an open-drain, N-channel output driver that can be pulled up to a voltage higher than VCC, but less than 11V. The MAX835's output is push/pull and can both source and sink current. where VTRIP is the desired trip voltage and VTH is the threshold voltage (1.204V). The voltage at IN must be at least 1V less than VCC.
Latched-Output Operation
The MAX834/MAX835 feature a level-sensitive latch input (CLEAR), designed to eliminate the need for hysteresis in battery undervoltage-detection applications. When the monitored voltage (VMON) is above the programmed trip voltage (VTRIP) (as when the system battery is recharged or a fresh battery is installed), pulse CLEAR low-high-low for at least 1s to reset the output latch (OUT goes high). When VMON falls below VTRIP, OUT goes low and remains low (even if VMON rises above VTRIP), until CLEAR is pulsed high again with VMON > VTRIP. Figure 3 shows the timing relationship between VMON, OUT, and CLEAR.
Programming the Trip Voltage (VTRIP)
Two external resistors set the trip voltage, VTRIP (Figure 2). VTRIP is the point at which the falling monitored voltage (typically VCC) causes OUT to go low. IN's high input impedance allows the use of large-value resistors without compromising trip voltage accuracy. To minimize current consumption, choose a value for R2 between 500k and 1M, then calculate R1 as follows: R1 = R2 [(VTRIP / VTH) - 1]
> VTRIP VMON < VTRIP > 1s VCC CLEAR 0V VCC OUT 0V > 1s > 1s
Figure 3a. Timing Diagram
> VTRIP VMON < VTRIP VCC OUT
0V
Figure 3b. Timing Diagram, CLEAR = VCC
6 _______________________________________________________________________________________
Micropower, Latching Voltage Monitors in SOT23-5
VCC CLEAR LATCH CLEAR OUT RL* R1 OUT VMON
Monitoring Voltages Other than VCC The typical operating circuit for the MAX834/MAX835 monitors VCC. Voltages other than VCC can easily be monitored, as shown in Figure 4. Calculate VTRIP as in the section Programming the Trip Voltage. When monitoring voltages other than VCC, ensure that the maximum value for VMON is not exceeded:
VMON(MAX) = (VCC - 1)(R1 + R2) / R2
MAX834/MAX835
GND VCC VCC
IN
Load-Disconnect Switch
MAX834 MAX835
R1 + R2 R2 (UNITS ARE OHMS AND VOLTS) R2
0.1F
*MAX834 ONLY
VTRIP = (1.204)
Figure 4. Monitoring Voltages Other than VCC
The circuit in Figure 5 is designed to prevent a leadacid battery or a secondary battery such as an NiCd, from sustaining damage through deep discharge. As the battery reaches critical undervoltage, OUT switches low. Q1 and Q2 turn off, disconnecting the battery from the load. The MAX835's latched output prevents Q1 and Q2 from turning on again as the battery voltage relaxes to its open-circuit voltage when the load disconnects. CLEAR can be connected to a pushbutton switch, an RC network, or a logic gate to reset the latch when the battery is recharged or replaced.
P Q1 CLEAR LATCH VBATT R1 Q2 CLEAR OUT N 1M
___________________Chip Information
TRANSISTOR COUNT: 74
RLOAD
GND VCC IN R2
MAX835
VCC 0.1F
Figure 5. Load-Disconnect Switch
_______________________________________________________________________________________
7
Micropower, Latching Voltage Monitors in SOT23-5 MAX834/MAX835
__________________________________________________Tape-and-Reel Information
E D P0 P2 W B0
F
D1
t
NOTE: DIMENSIONS ARE IN MM. AND FOLLOW EIA481-1 STANDARD.
P A0
K0
A0 B0 D D1
3.200 3.099 1.499 0.991
0.102 0.102 +0.102 +0.000 +0.254 +0.000
E F K0 P
1.753 3.505 1.397 3.988
0.102 0.051 0.102 0.102
P0 P010 P2 t
3.988
0.102
40.0050.203 2.0070.051 0.2540.127 +0.305 -0.102
5 SOT23-5
W 8.001
________________________________________________________________Package Information
b e
DIM A A1 A2 b C D E E1 L e e1 MILLIMETERS MIN MAX 0.90 1.45 0.00 0.15 0.90 1.30 0.35 0.50 0.08 0.20 2.80 3.00 2.60 3.00 1.50 1.75 0.35 0.55 0.95ref 1.90ref 0 10
21-0057B
E
e1 D
E1
A A2
C
L A1
5-PIN SOT23-5 SMALL-OUTLINE TRANSISTOR PACKAGE
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.
8 ___________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 (408) 737-7600 (c) 1996 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.

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