MC33340, MC33342

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11

AAVID #

592502B03400

24.0

593002B03400

14.0

590302B03600

9.2

Figure 13. Printed Circuit Board and Component Layout

(Circuit of Figure 12)

MC33340

2.25

″

1.70

″

C2

(Top View)

(Bottom View)

Battery

Negative

Battery

Positive

Input

Return

Input

Positive

IC2

IC1

32 1

Charge Mode

R3

R2

R8

D2

R7

R4

D3

Input

C1

Output

D1

Figure 14. Line Isolated Switch Mode Charger

The MC33340/342 can be combined with any of the devices in the UC3842 family of current mode controllers to form a switch mode battery charger. In this

example, optocouplers OC1 and OC2 are used to provide isolated control signals to the UC3842. During battery voltage sensing, OC2 momentarily grounds

the Output/Compensation pin, effectively turning off the charger. When fast charge termination is reached, OC1 turns on, and grounds the lower side of R3.

This reduces the peak switch current threshold of the Current Sense Comparator to a programmed trickle current level. For additional converter design in-

formation, refer to the UC3842 and UC3844 device family data sheets.

Current Sense

Comparator

Error

Amplifier

Gate

Fast/

Trickle

Voltage

Feedback

Input

Gnd

5

3

2

1

Gate

F/T

2R

R2

R1

1.0 V

1.0 mA

UC3842 Series

Output/

Compensation

R

Primary Circuitry

Secondary Circuitry

Isolation Boundary

MC33340 or MC33342

Gnd

4

2

OC2

OC1

R3