AP2007 データシートの表示（PDF） - Anachip Corporation

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AP2007

Synchronous PWM Controller

Anachip Corporation 

Synchronous PWM Controller

AP2007

„ Typical Application Circuit

R1

12Ω

C1

470u/16V

C2

0.1u

C3

330n

1 VCC

2 DRVP

3 GND

VREF 8

PHASE 7

FB 6

4 DRVN SS/SHDN 5

AP2007

C4

330n

C5

10n

1Ω Option

1Ω Option

C6

47n

R2 R3

Q1

1K 3K*

L1

AF9435

(4835)

10uH

Q2

AF9410

(4412) D1

Option

C7

C8

C9

0.1u 470u/16V 470u/16V

* Vout = 0.8 x (1+R3/R2)

R2 ≅1K ~ 10K

+

Vin

-

+

Vout=3.2V*

-

„ Virtual Frequency Control

Virtual Frequency Control combines the

advantages of constant frequency and constant

off-time control in a single mode of operation. This

allows fix frequency, precision switching voltage

regulator control with fast transient response and

the smallest solution size. Switch duty cycle can be

adjusted from 0% to 100% on a pulse by pulse basis

when responding to transient conditions. Both 0%

and 100% duty cycle operation can be maintained

for extended periods of time in response to load or

line transients. Figure 1 depicts a simplified

operation of the Virtual Frequency Control

technique: The VFC oscillator generates a pulse of

a known duration (VFC_Pulse). The regulator loop

responds by returning a complementary feedback

pulse (FB_Pulse). The FB_Pulse duration is a result

of external conditions such as inductor size, the

voltage across the inductor and the duration of the

VFC_Pulse. A VFC control loop is then formed

whereby the duration of the VFC_Pulse is modified

as a result of the FB_Pulse duration. The VFC loop

arrives at a state of equilibrium, where the operating

frequency remains inherently constant.

VIN

Anachip Corp

www.anachip.com.tw

ERROR

COMP

Vref

+

GATE

CONTROL

-

LOGIC

VFC Pulse

VIRTUAL FREQ

OSCILLATOR

FB Pulse

Lout

Cout

Vout

Rfb1

Rfb2

Figure 1: Virtual Frequency Control Loop-

Synchronous single supply application.

Rev. 1.0 Apr 1, 2005

4/7

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