Datasheet
2008-2013 Microchip Technology Inc. DS20002090C-page 29
MCP73871
For example, by utilizing a 10 k at 25°C NTC
thermistor with a sensitivity index, , of 3892, the
charge temperature range can be set to 0-50°C by
placing a 1.54 k resistor in series (R
T1
), and a
69.8 k resistor in parallel (R
T2
) with the thermistor.
6.1.1.6 Charge Status Interface
A status output provides information on the state of
charge. The output can be used to illuminate external
LEDs or interface to a host microcontroller. Refer to
Table 5-1 for a summary of the state of the status
output during a charge cycle.
6.1.1.7 System Load Current
The preferred discharge current for Lithium-Ion cells
should always follow references and guidance from
battery manufacturers. The recommended system
load should be the lesser of 1.0 amperes or the
maximum discharge rate of the selected Lithium-Ion
cell. This limits the safety concerns of power
dissipation and exceeding the manufacturer’s
maximum discharge rate of the cell.
The ideal diode between V
BAT
and OUT is designed to
drive a maximum current up to 2A. The built-in thermal
shutdown protection may turn the MCP73871 device
off with high current.
6.2 PCB Layout Issues
For optimum voltage regulation, it is recommended to
place the battery pack closest to the device’s V
BAT
and
V
SS
pins to minimize voltage drops along the high
current-carrying PCB traces.
If the PCB layout is used as a heatsink, adding many
vias in the heatsink pad can help conduct more heat to
the PCB backplane, thus reducing the maximum junc-
tion temperature.