CS2841B

http://onsemi.com

7

tc + RTCT ln

VREF * Vlower

VREF * Vupper

td + RTCT ln

VREF * IdRT * Vupper

VREF * IdRT * Vlower

Substituting in typical values for the parameters in the

above formulas:

VREF + 5.0 V

Vupper + 2.7 V

Vlower + 1.0 V

Id + 8.3 mA

tc [ 0.5534RTCT

td + RTCT ln

2.3

* 0.0083RT

4.0

* 0.0083RT

The frequency and maximum duty cycle can be

determined from the Typical Performance Characteristic

graphs.

Grounding

High peak currents associated with capacitive loads

necessitate careful grounding techniques. Timing and

bypass capacitors should be connected close to GND pin in

a single point ground.

The transistor and 5.0 k

W potentiometer are used to

sample the oscillator waveform and apply an adjustable

ramp to Sense.

C8

VC

C10

0.1

mF

10

mF

0.1

mF

C9

C13

4.7 nF

OSC

SENSE

COMP

GND

PGND

R8

4.99 k

1.0 %

C14

47 pF

R7

22.1 k

C11

0.33

mF

R6

1.0 k

R4

10

C12

10 nF

R3

4.99 k

1.0 %

MTDISN06VTL4

R9

0.2

1.0 %

Q2

VPR

GND

Q1

2n4401

DZ1

13 V

1N5243B

R1

4.7 k

C1

68

mF

68

mF

C2

C3

4.7 pF

100 V

MURS120T3

D1

R2

47

0.1

mF

C7

1000

mF

C5

1000

mF

C6

C4

0.1

mF

D2 MBR360

L1 2.2

mH

9T

R5

2.0 k

CS2841B

20T

Figure 8. Flyback Application