UCC3911-1, UCC3911-2

UCC3911-3, UCC3911-4

SLUS429B– FEBRUARY 2000 – REVISED NOVEMBER 2002

LITHIUMION AND LITHIUMPOLYMER

BATTERY PROTECTOR

1

www.ti.com

FEATURES

Lithium-Polymer Cells from Overcharging

and Overdischarging

Output Short Circuit

About 20

µA

Circuit Current Protector

APPLICATIONS

Mobile Radio

SIMPLIFIED APPLICATION DIAGRAM

DESCRIPTION

The UCC3911 is a two-cell lithium-ion (Li-Ion) and

lithium-polymer (Li-Pol) battery pack protector

device that incorporates an on-chip series FET

switch thus reducing manufacturing costs and

increasing

reliability.

The

device’s

primary

function is to protect both Li-Ion and Li-Pol cells in

a two-cell battery pack from being either

overcharged (overvoltage) or overdischarged

(undervoltage). It employs a precision bandgap

voltage reference that is used to detect when

either cell is approaching an overvoltage or

undervoltage state. When on-board logic detects

either condition, the series FET switch opens to

protect the cells.

A negative feedback loop controls the FET switch

when the battery pack is in either the overvoltage

or undervoltage state. In the overvoltage state the

action of the feedback loop is to allow only

discharge current to pass through the FET switch.

In the undervoltage state, only charging current is

allowed to flow. The operational amplifier that

drives the loop is powered only when in one of

these two states. In the undervoltage state the

chip enters sleep mode until it senses that the

pack is being charged.

The FET switch is driven by a charge pump when

the battery pack is in a normally charged state to

the negative feedback loop’s operational amplifier

is powered down to conserve battery power. Short

circuit protection for the battery pack is provided

and has a nominal delay of 100

µs before tripping.

An external capacitor may be connected between

CDLY and B0 to increase this delay time to allow

longer overcurrent transients.

A chip enable (CE) pin is provided that when held

low, inhibits normal operation of the device to

facilitate assembly of the battery pack.

PRODUCTION DATA information is current as of publication date.

Products conform to specifications per the terms of Texas Instruments

standard warranty. Production processing does not necessarily include

testing of all parameters.

Copyright

 2000–2003, Texas Instruments Incorporated

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16

14

15

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10

11

9

NC

SUBS

SUBS

GND

LPWARN

GND

B2

CDLY

B1

SUBS

SUBS

B0

CE

B0

UCC3911

+

+

ISOLATED

COPPER

PAD

ISOLATED

COPPER

PAD

OV

UV

UDG–01075