LP28011 Datasheet, PDF (2/10 Pages) Lowpower Semiconductor inc – 1A Single-chip Li-ion and Li-POL Charge with OVP

Preliminary Datasheet
Functional Pin Description
Package Type
Pin Configurations
LP28011
TDFN- 10
VIN
1
VIN
2
STAT 3
STAT 4
VSS
5
10
9
11
8
7
6
BATT
BATT
VSS
VSS
ISET
Pin Description
PIN
VIN
STAT
NC
VSS
ISET
VBAT
PIN
Number
1,2
3
4
5,7,8,11
6
9,10
DESCRIPTION
VIN is the input power source. Connect to a wall adapter.
Open-Drain Charge Status Output. When the battery is charging, the STAT pin is pulled low by an
internal N-channel MOSFET. When the charge cycle is completed, a weak pull-down of
approximately 20µA is connected to the STAT pin, indicating an “AC present” condition. When the
LP28011 detects an under voltage lockout condition, STAT is forced high impedance.
No connector.
VSS is the connection to system ground.
Charge Current Program, Charge Current Monitor and Shutdown Pin. The charge current is pro-
grammed by connecting a 1% resistor(R_PROG)to ground. When charging in constant-current mode, this
pin servos to 1V. In all modes, the voltage on this pin can be used to measure the charge current using
the following formula:
I = (V /R ) • 830
BAT
PROG PROG
The PROG pin can also be used to shut down the charger. Disconnecting the program resistor from
ground allows a 3µA current to pull the PROG pin high. When it reaches the 1.21V shutdown
threshold voltage, the charger enters shutdown mode, charging stops and the input supply current
drops to 25µA. This pin is also clamped to approximately 2.4V. Driving this pin to voltages beyond
the clamp voltage will draw currents as high as 1.5mA. Reconnecting R_PROG to ground will return the
charger to normal operation.
VBAT is the connection to the battery. Typically a 1µF Tantalum capacitor is needed for stability
when there is no battery attached. When a battery is attached, only a 0.1µF ceramic capacitor is
required.
LP28011 – 01 Ver. 1.1 Datasheet
Nov.-2007
Page 2 of 10