+

–

+

–

5.0V Ref

36V

S

R

Q

Bias

+

1.0mA

Osc

R

R

R

2R

EA

1.0V

7(12)

7(11)

6(10)

5(8)

3(5)

RS

VCC

Vin

1(1)

2(3)

4(7)

8(14)

RT

CT

The buffered oscillator ramp can be resistively summed with either the voltage

feedback or current sense inputs to provide slope compensation.

Figure 32. Slope Compensation

m

– 3.0m

–m

Rf

Cf

Ri

Rd

From VO

RSlope

MPS3904

Figure 33. 27 W Off–Line Flyback Regulator

5(9)

Comp/Latch

MUR110

+

–

+

–

S

R

+

R

R

5.0V Ref

Q

Bias

EA

5(9)

7(11)

6(10)

5(8)

3(5)

0.5

MTP

4N50

1(1)

2(3)

4(7)

8(14)

10k

4700pF

470pF

150k

100

pF

18k

4.7k

0.01

100

+

1.0k

115 Vac

4.7

Ω

MDA

202

250

56k

4.7k

3300

pF

1N4935

1N4935

++

68

47

1N4937

1N4937

680pF

2.7k

L3

L2

L1

++

++

++

1000

1000

2200

10

10

1000

5.0V/4.0A

5.0V RTN

12V/0.3A

–12V/0.3A

Primary: 45 Turns #26 AWG

Secondary

±12 V: 9 Turns #30 AWG (2 Strands) Bifiliar

Wound

Secondary 5.0 V: 4 Turns (six strands) #26 Hexfiliar Wound

Secondary Feedback: 10 Turns #30 AWG (2 strands)

Bifiliar Wound

Core: Ferroxcube EC35–3C8

Bobbin: Ferroxcube EC35PCB1

Gap:

≈ 0.10” for a primary inductance of 1.0 mH

MUR110

MBR1635

T1

22

Osc

T1 –

7(12)

Comp/Latch

L1

L2, L3

– 15

µH at 5.0 A, Coilcraft Z7156

– 25

µH at 5.0 A, Coilcraft Z7157

1N5819

UC3842B, 43B UC2842B, 43B

14

MOTOROLA ANALOG IC DEVICE DATA

Test

Conditions

Results

Line Regulation: 5.0 V

±12 V

Vin = 95 to 130 Vac

∆ = 50 mV or ± 0.5%

∆ = 24 mV or ± 0.1%

Load Regulation: 5.0 V

±12 V

Vin = 115 Vac,

Iout = 1.0 A to 4.0 A

Vin = 115 Vac,

Iout = 100 mA to 300 mA

∆ = 300 mV or ± 3.0%

∆ = 60 mV or ± 0.25%

Output Ripple:

5.0 V

±12 V

Vin = 115 Vac

40 mVpp

80 mVpp

Efficiency

Vin = 115 Vac

70%

All outputs are at nominal load currents, unless otherwise noted