CS5157H データシートの表示（PDF） - ON Semiconductor

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CS5157H

CPU 5−Bit Synchronous Buck Controller

ON Semiconductor 

CS5157H

VCC1

SS

VID0

VID1

VID2

VID3

VID4

VFB

COMP

VFFB

LGnd

VCC1 Monitor

− Comparator

+

3.90 V

3.85V

5.0 V

60 mA

2.0 mA

5 BIT

DAC

Error

Amplifier

+

−

Slow Feedback

PWM

Comparator

−

+

2.5 V

Fast Feedback

1.0 V

−

+

VFFB Low

Comparator

−

+

0.7 V

+

−

SS Low

Comparator

SS High

Comparator

Maximum

On−Time

Timeout

Normal

Off−Time

Timeout

Extended

Off−Time

Timeout

FAULT

RQ

S Q FAULT

FAULT

Latch

VCC2

VGATE(H)

PGnd

VCC1

VGATE(L)

PGnd

RQ

SQ

PMW

Latch

Off−Time

Timeout

GATE(H) = ON

GATE(H) = OFF

COFF

One Shot

R

SQ

COFF

PWM COMP

Time−Out

Timer

(30 ms)

Edge Triggered

Figure 2. Block Diagram

APPLICATIONS INFORMATION

THEORY OF OPERATION

V2 Control Method

The V2 method of control uses a ramp signal that is

generated by the ESR of the output capacitors. This ramp is

proportional to the AC current through the main inductor

and is offset by the value of the DC output voltage. This

control scheme inherently compensates for variation in

either line or load conditions, since the ramp signal is

generated from the output voltage itself. This control

scheme inherently compensates for variation in either line or

load conditions, since the ramp signal is generated from the

output voltage itself. This control scheme differs from

traditional techniques such as voltage mode, which

generates an artificial ramp, and current mode, which

generates a ramp from inductor current.

COMP

PWM

Comparator

+

VGATE(H)

C

−

VGATE(L)

Ramp

Signal

VFFB

Error

Signal

Error

Amplifier −

E

+

Output

Voltage

Feedback

VFB

Reference

Voltage

Figure 3. V2 Control Diagram

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