MCP73861/2/3/4
The flashing rate (1 Hz) is based off a timer capacitor
(CTIMER) of 0.1 µF. The rate will vary based on the
value of the timer capacitor.
5.1.6
BATTERY VOLTAGE SENSE (VBAT3)
The MCP7386X monitors the battery voltage at the
VBAT3 pin. This input is tied directly to the positive
terminal of the battery pack.
During a fault condition, the STAT1 status output will be
off and the STAT2 status output will be on. To recover
from a fault condition, the input voltage must be
removed and then reapplied, or the enable input (EN)
must be de-asserted to a logic-low, then asserted to a
logic-high.
5.1.7
BATTERY CHARGE CONTROL
OUTPUT (VBAT1, VBAT2
)
The battery charge control output is the drain terminal
of an internal P-channel MOSFET. The MCP7386X
provides constant current and voltage regulation to the
battery pack by controlling this MOSFET in the linear
region. The battery charge control output should be
connected to the positive terminal of the battery pack.
When the voltage on the THERM input is outside the
preset window, the charge cycle will not start, or will be
suspended. The charge cycle is not terminated and
recovery is automatic. The charge cycle will resume (or
start) once the THERM input is valid and all other
qualification parameters are met. During an invalid
THERM condition, the STAT1 status output will be off
and the STAT2 status output will flash.
5.2
Digital Circuitry
5.2.1
CHARGE STATUS OUTPUTS
(STAT1,STAT2)
5.2.2
The VSET input selects the regulated output voltage of
the MCP7386X. With VSET tied to VSS the
MCP73861/3 and MCP73862/4 regulate to 4.1V and
8.2V, respectively. With VSET tied to VDD the
VSET INPUT
Two status outputs provide information on the state of
charge. The current-limited, open-drain outputs can be
used to illuminate external LEDs. 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 outputs during a charge cycle.
,
,
MCP73861/3 and MCP73862/4 regulate to 4.2V and
8.4V, respectively.
TABLE 5-1:
STATUS OUTPUTS (NOTE)
5.2.3
LOGIC ENABLE (EN)
CHARGE
CYCLE STAT1
STAT1
STAT2
The logic enable input pin (EN) can be used to
terminate a charge at any time during the charge cycle,
as well as to initiate a charge cycle or initiate a recharge
cycle.
Qualification
Off
On
On
Off
Off
Off
Preconditioning
Constant-
Current Fast
Charge
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 termi-
nates a charge cycle. When disabled, the device’s
supply current is reduced to 0.17 µA, typically.
Constant-
Voltage
On
Off
Charge
Complete
Flashing (1 Hz,
50% duty cycle)
(MCP73861/2)
Off
(All Devices)
Off
(MCP73863/4)
Fault
Off
Off
On
THERM Invalid
Flashing (1 Hz,
50% duty cycle)
Disabled –
Sleep mode
Off
Off
Off
Input Voltage
Disconnected
Off
Note:
Off state: Open-drain is high-impedance
On state: Open-drain can sink current
typically 7 mA
Flashing: Toggles between off state and
on state
DS21893C-page 16
© 2005 Microchip Technology Inc.
MICROCHIP [ MICROCHIP ]
