UC3842B, UC3843B, UC2842B, UC2843B, NCV3843BV

http://onsemi.com

11

Figure 20. Continuous Current Waveforms

2(3)

EA

Bias

+

Osc

R

R

R

2R

5(9)

1(1)

4(7)

8(14)

0.01

The diode clamp is required if the Sync amplitude is large enough to cause the bottom

External

Sync

Input

47

+

R

R

R

2R

Bias

Osc

EA

5(9)

1(1)

2(3)

4(7)

8(14)

To Additional

UCX84XBs

R

S

Q

8

4

6

5

2

1

C

3

7

5.0k

5.0k

5.0k

MC1455

f +

1.44

(RA ) 2RB)C

D(max) +

RB

RA ) 2RB

+

-

5.0V Ref

+

-

S

R

Q

Bias

+

Osc

R

R

R

2R

EA

1.0V

5(9)

7(11)

6(10)

5(8)

3(5)

Q1

1(1)

2(3)

4(7)

8(14)

7(12)

Comp/Latch

1.0 mA

Ipk(max) [

VClamp

RS

1.67

R2

R1

) 1

R1R2

R1 ) R2

Control Voltage

Inductor

Current

Oscillator Period

Control Voltage

Inductor

Current

Oscillator Period

(A)

(B)

∆I

∆I

Dl ) Dl m2

m1

Dl ) Dl m2

m1

m2

m1

Figure 21. External Clock Synchronization

Figure 22. External Duty Cycle Clamp and

Multi–Unit Synchronization

Figure 23. Adjustable Reduction of Clamp Level