UCC39571, UCC39572, UCC39573, UCC39574

SLUS236B – JANUARY 1999 – REVISED SEPTEMBER 2002

6

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APPLICATION INFORMATION

overview (continued)

Figure 2 shows a four-cell protector with optional components to protect the charge FET from excessive

gate-to-source transients. In this application, the Zener diode VR1 and the resistor R2 are optional. They protect

the MOSFET Q1 from excessive open-circuit charger voltage. Diode D1 protects MOSFET Q2 from inductive

kick during turn-off.

UDG–98017

1

3

2

4

DVDD

VDD

CLCNT

WU

AN1

AN2

AN3

AN4

BATLO

CHGEN

AN4

CHG

CDLY2

AVDD

CDLY1

5

7

6

8

16

14

15

13

12

10

11

9

C3

OPTIONAL

+

+

+

PACK (–)

PACK (+)

Q1

IFR7416

CHARGE

Q2

IFR7416

DISCHARGE

Q3

2N7002

LI–ION

BATTERY

STACK

+

VR1 18 V

D1

1 A, 50 V

R1 1 M

Ω

R2

10 k

Ω

C1

0.1

µF

C2

0.1

µF

C5

4.7

µF

25 V

C4

0.022

µF

RSENSE

0.025

Ω

DCHG

Figure 2. Four-Cell Lithium-Ion Protector Application Diagram

connecting the cell stack

When connecting the cell stack to the circuit, it is important to do so in the proper order. First, the bottom of the

stack should be connected to AN4 . Next, the top of the stack should be connected to VDD. The cell taps can

then be connected to AN1, AN2, and AN3 in any order.

choosing three or four cells

For three-cell packs, the cell-count pin (CLCNT) should be connected to the DVDD pin, and the AN3 pin should

be tied to the AN4 pin. For four-cell applications, the CLCNT pin should be grounded (to AN4) and the AN3 pin

is connected to the positive terminal of the bottom cell in the stack.

Not Recommended for New Designs