Datasheet

MCP73841/2/3/4
DS21823D-page 14  2003-2013 Microchip Technology Inc.
5.1.6 BATTERY VOLTAGE SENSE (V
BAT
)
The MCP7384X monitors the battery voltage at the
V
BAT
pin. This input is tied directly to the positive
terminal of the battery. The MCP7384X is offered in
four fixed-voltage versions for single or dual series cell
battery packs, with either coke or graphite anodes:
- 4.1V (MCP73841-4.1, MCP73843-4.1)
- 4.2V (MCP73841-4.2, MCP73843-4.2)
- 8.2V (MCP73842-8.2, MCP73844-8.2)
- 8.4V (MCP73842-8.4, MCP73844-8.4)
5.1.7 DRIVE OUTPUT (DRV)
The MCP7384X controls the gate drive to an external
P-channel MOSFET. The P-channel MOSFET is
controlled in the linear region regulating current and
voltage supplied to the cell. The drive output is
automatically turned off when the voltage on the V
DD
input falls below the undervoltage lockout voltage
(V
STOP
).
5.2 Digital Circuitry
5.2.1 CHARGE STATUS OUTPUT (STAT1)
A status output provides information on the state-of-
charge. The current-limited, open-drain output can be
used to illuminate an external LED. Optionally, a pull-up
resistor can be used on the output for communication
with a host microcontroller. Table 5-1 summarizes the
state of the status output during a charge cycle.
TABLE 5-1: STATUS OUTPUTS
The flashing rate (1 Hz) is based off a timer capacitor
(C
TIMER
) of 0.1 µF. The rate will vary based on the
value of the timer capacitor.
5.2.2 LOGIC ENABLE (EN)
The logic-enable input pin (EN) can be used to
terminate a charge anytime during the charge cycle,
initiate a charge cycle or initiate a recharge cycle.
Applying a logic-high input signal to the EN pin, or tying
it to the input source, enables the device. Applying a
logic-low input signal disables the device and
terminates a charge cycle. When disabled, the device’s
supply current is reduced to 0.25 µA, typically.
Charge Cycle State Stat1
Qualification OFF
Preconditioning ON
Constant-Current Fast
Charge
ON
Constant-Voltage ON
Charge Complete OFF
Safety Timer Fault Flashing
(1 Hz, 50% duty cycle)
Cell Temperature Invalid Flashing
(1 Hz, 50% duty cycle)
Disabled - Sleep mode OFF
Battery Disconnected OFF