Preliminary Datasheet

LP28011

LP28011 – 01 Ver. 1.1 Datasheet

Nov.-2007

Page 2 of 10

Functional Pin Description

P a ckag e Ty pe

Pin Con f igurat i o ns

TDFN- 10

47

10

VSS

VIN

1

BATT

8

VIN

ISET

STAT

BATT

STAT

5

VSS

VSS

9

2

3

6

11

Pi n Desc ript io n

PIN

PIN

Number

DESCRIPTION

VIN

1,2

VIN is the input power source. Connect to a wall adapter.

STAT

3

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.

NC

4

No connector.

VSS

5,7,8,11

VSS is the connection to system ground.

ISET

6

Charge Current Program, Charge Current Monitor and Shutdown Pin. The charge current is pro-

grammed by connecting a 1% resistor(R

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

BAT

= (V

PROG

/R

PROG

) • 830

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

charger to normal operation.

VBAT

9,10

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.