UC3845BD1 Просмотр технического описания (PDF) - Motorola => Freescale

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Компоненты Описание

производитель

UC3845BD1

High Performance Current Mode Controllers

Motorola => Freescale 

UC3844B, 45B UC2844B, 45B

Figure 26. Isolated MOSFET Drive

VCC

Vin

7(12)

Isolation

Boundary

5.0V Ref

+

–

+

–

T

S

Q

R

Comp/Latch

7(11)

6(10)

5(8)

3(5)

R

VGS Waveforms

Q1

+

+

0

0

–

–

50% DC

25% DC

V(Pin 1) – 1.4

Ipk =

3 RS

ǒNSǓ

Np

C

RS NS

NP

Figure 27. Latched Shutdown

8(14)

R

Bias

R

Osc

4(7)

+

1.0 mA 2R

2(3)

EA

R

1(1)

MCR

2N

101

3905

5(9)

2N

3903

The MCR101 SCR must be selected for a holding of < 0.5 mA @ TA(min). The

simple two transistor circuit can be used in place of the SCR as shown. All

resistors are 10 k.

Figure 28. Error Amplifier Compensation

From VO

Ri

2(3)

Rd Cf

Rf

1(1)

Rf ≥ 8.8k

2.5V

+

1.0mA 2R

EA

R

5(9)

Error Amp compensation circuit for stabilizing any current mode topology except

for boost and flyback converters operating with continuous inductor current.

From VO

Rp Ri

Cp

Rd Cf

2.5V

2(3)

+

1.0mA 2R

Rf

EA

R

1(1)

5(9)

Error Amp compensation circuit for stabilizing current mode boost

and flyback topologies operating with continuous inductor current.

12

MOTOROLA ANALOG IC DEVICE DATA

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