Datasheet

© 2007-2011 Microchip Technology Inc. DS22071B-page 13
MCP73837/8
3.0 PIN DESCRIPTION
The descriptions of the pins are listed in Tab le 3-1.
TABLE 3-1: PIN FUNCTION TABLES
3.1 AC-Adapter Supply Input (V
AC
)
A supply voltage of V
REG
+ 0.3V to 6V from ac-dc wall-
adapter is recommended. When both the AC-adapter
and the USB-port supply voltages are present at the
same time, the AC-adapter dominates the regulated
charge current with the maximum value of 1A. Bypass
to V
SS,
with a minimum of 4.7 µF, is recommended.
3.2 USB-Port Supply Input (V
USB
)
A supply voltage of V
REG
+ 0.3V to 6V from the USB-
port is recommended. When no supply voltage from
V
AC
pin is available, the Li-Ion battery is charged
directly from USB-port. Bypass to V
SS,
with a minimum
of 1 µF, is recommended.
3.3 Charge Status Output 1 (STAT1)
STAT1 is an open-drain logic output for connection to a
LED for charge status indication. Alternatively, a pull-up
resistor can be applied for interfacing to a host micro-
controller.
3.4 Charge Status Output 2 (STAT2)
STAT2 is an open-drain logic output for connection to a
LED for charge status indication. Alternatively, a pull-up
resistor can be applied for interfacing to a host
microcontroller.
3.5 Battery Management 0V Reference
(V
SS
)
Connect to the negative terminal of battery and input
supply.
3.6 Battery Charge Control Output
(V
BAT
)
Connect to the positive terminal of Li-Ion / Li-Polymer
batteries. Bypass to V
SS,
with a minimum of 1 µF, to
ensure loop stability when the battery is disconnected.
3.7 AC-Adapter Current Regulation
Set (PROG1)
The AC-adapter constant charge current is set by
placing a resistor from PROG1 to V
SS
. PROG1 is the
set point of precondition and termination when the AC-
adapter is present.
PROG1 also functions as device charge control
enable. The MCP73837/8 is shut down when an
impedance value greater than 70 kΩ is applied to
PROG1. When PROG1 is floating, the MCP73837/8
enters Stand-by mode.
Pin Number
Symbol I/O Function
MSOP-10 DFN-10
11V
AC
I AC-adapter Supply Input
22V
USB
I USB-port Supply Input
3 3 STAT1 O Charge Status Output 1 (Open-Drain)
4 4 STAT2 O Charge Status Output 2 (Open-Drain)
55V
SS
— Battery Management 0V Reference
6 6 PROG1 I/O Current Regulation Setting With AC-adapter; Device Charge Control
Enable; Precondition Set Point for AC control
7 7 PROG2 I Current Regulation Setting With USB-port; Precondition Set Point
for USB control.
88PG
O Available on MCP73837: Power-Good Status Output (Open-Drain)
88TE
I Available on MCP73838: Timer Enable; Enables Safety Timer
(Active Low)
9 9 THERM I/O Thermistor Monitoring Input and Bias current; System Test (LDO)
Mode Input
10 10 V
BAT
I/O Battery Positive Input and Output Connection
—EPV
SS
— EP (Exposed Thermal Pad); There is an internal electrical
connection between the exposed thermal pad and V
SS
. The EP
must be connected to the same potential as the V
SS
pin on the
Printed Circuit Board (PCB).