MAX835 View Datasheet(PDF) - Maxim Integrated
Part Name
Description
Manufacturer
MAX835 Datasheet PDF : 9 Pages
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Micropower, Latching Voltage Monitors
in SOT23-5
CLEAR
LATCH
CLEAR
OUT
VCC
VMON
RL*
R1
OUT
GND
IN
VCC
VCC
R2
MAX834
0.1μF
MAX835
*MAX834 ONLY
VTRIP
=
(1.204)
R1 + R2
R2
(UNITS ARE OHMS AND VOLTS)
Figure 4. Monitoring Voltages Other than VCC
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 Programming the Trip Voltage (VTRIP) section.
When monitoring voltages other than VCC, ensure that
the maximum value for VMON is not exceeded:
VMON(MAX) = (VCC - 1) (R1 + R2) / R2
Load-Disconnect Switch
The circuit in Figure 5 is designed to prevent a lead-
acid 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 dis-
connects. 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.
VBATT
CLEAR
LATCH
R1
CLEAR OUT
GND
VCC
IN
MAX835
P
Q1
1MΩ
Q2
N
RLOAD
R2
VCC
0.1μF
Figure 5. Load-Disconnect Switch
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