UCC3911 Datasheet, PDF (1/12 Pages) Texas Instruments – Lithium-Ion Battery Protector

UCC3911-1, UCC3911-2
UCC3911-3, UCC3911-4
SLUS429B– FEBRUARY 2000 – REVISED NOVEMBER 2002
LITHIUMĆION AND LITHIUMĆPOLYMER
BATTERY PROTECTOR
FEATURES
D Protects Sensitive Lithium-Ion and
Lithium-Polymer Cells from Overcharging
and Overdischarging
D Used for Two-Cell Battery Packs
D No External FETs Required
D Provides Protection Against Battery Pack
Output Short Circuit
D Extremely Low Power Drain on Batteries of
About 20 µA
D Low Internal FET Switch Voltage Drop
D User Controllable Delay for Tripping Short
Circuit Current Protector
D 3-A Current Capacity
APPLICATIONS
D PDA, Camcorder, Digital Camera, Private
Mobile Radio
SIMPLIFIED APPLICATION DIAGRAM
UCC3911
B2 16
1 NC
2 _OV CDLY 15
ISOLATED
COPPER
PAD
3 _UV
B1 14
4 SUBS SUBS 13 ISOLATED
COPPER
5 SUBS SUBS 12
PAD
6 GND
B0 11
7 GND
B0 10
8 LPWARN CE 9
+
+
UDG–01075
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
achieve the lowest possible R_DS(on). In this state
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.
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Copyright  2000–2003, Texas Instruments Incorporated
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