Datasheet
© 2007-2011 Microchip Technology Inc. DS22071B-page 19
MCP73837/8
5.2.2 USB-PORT CURRENT
REGULATION SELECT (PROG2)
For the MCP73837/8, driving the PROG2 input to a
logic Low selects the low charge current setting
(maximum 100 mA). Driving the PROG2 input to a logic
High selects the high charge current setting (maximum
500 mA).
The Precondition current and Termination current are
percentages of the charge current selected by the
PROG2 level. The percentage is based upon the
selected part number of the device.
TABLE 5-1: STATUS OUTPUTS
5.2.3 POWER GOOD (PG
) OPTION
The power good (PG) option is a pseudo open-drain
output. The PG
output can sink current, but not source
current. However, there is a diode path back to the
input, and as such, the output should be pulled up only
to the input. The PG
output is low whenever the input
to the MCP73837 is above the UVLO threshold and
greater than the battery voltage. If the supply voltage is
above the UVLO, but below V
REG
(typical)+0.3V, the
MCP73837 will pulse the PG
output as the device
determines if a battery is present. The PG
option is
available only on MCP73837.
5.2.4 TIMER ENABLE (TE) OPTION
The timer enable (TE) input option is used to enable or
disable the internal timer. A low signal on this pin
enables the internal timer and a high signal disables
the internal timer. The TE
input can be used to disable
the timer when the charger is supplying current to
charge the battery and power the system load. The TE
input is compatible with 1.8V logic. The TE option is
available only on MCP73838.
5.2.5 DEVICE DISABLE (PROG1/2)
The current regulation set input pin (PROG1/2) can be
used to terminate a charge at any time during the
charge cycle, as well as to initiate a charge cycle or to
initiate a recharge cycle. Placing a programming
resistor from the PROG1/2 input to V
SS
enables the
device. Allowing the PROG1/2 input to float or applying
a logic-high input signal to PROG1 disables the device
and terminates a charge cycle. When disabled, the
device’s supply current is reduced to 75 µA, typically.
CHARGE CYCLE STATE STAT1 STAT2 PG
Shutdown Hi-Z Hi-Z Hi-Z
Standby Hi-Z Hi-Z L
Preconditioning L Hi-Z L
Constant Current L Hi-Z L
Constant Voltage L Hi-Z L
Charge Complete - Standby Hi-Z L L
Temperature Fault Hi-Z Hi-Z L
Timer Fault Hi-Z Hi-Z L
System Test Mode L L L