UCC39571, UCC39572, UCC39573, UCC39574

SLUS236B – JANUARY 1999 – REVISED SEPTEMBER 2002

10

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APPLICATION INFORMATION

controlling discharge FET turn-on and turn-off times

Figure 3 shows a four-cell protector with slew-rate limiting the discharge FET. In this application, VR1 and R2

are optional, They protect Q1 from excessive open-circuit charger voltage. R3 and C6 are chosen based on

capacitive load that must be driven. R4 minimizes inductive kick at turn-off.

UDG–98018

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

LI–ION

BATTERY

STACK

+

VR1 18 V

D1

1 A, 50 V

Q3

2N7002

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

R1 1 M

Ω

R3 1 k

Ω

C6

0.22

µF

R4

100

Ω

DCHG

Figure 3. Four-Cell Lithium-Ion Protector Application Diagram

Not Recommended for New Designs