AP3595

Document number: DS36749 Rev. 1 - 2

11 of 23

www.diodes.com

January 2014

© Diodes Incorporated

AP3595

A Product Line of

Diodes Incorporated

capacitor connected to the SS pin. This reduces inrush current to charge/discharge the large output capacitors during soft start and VID changing,

and prevents OCP, OVP/UVP false trigger. The SS buffer sinking/sourcing capability is limited to 22

A during soft start and 200A after soft start

end. Therefore, the slew rate of voltage ramping up/down at SS, EAP and FB pin during soft start or VID changing is calculated as:

During Soft Start

After Soft Start

4. Pre-Bias Function

place.

5. Chip Oscillator Frequency Programming

)

(

)

(

10000

kHz

k

R

f

FS

OSC





When released, the RT/EN pin voltage is regulated at 1V. Pulling the RT/EN pin to ground shuts down the IC.

6. Current Balance

AP3595 extracts phase currents for current balance by parasitic on-resistance of the lower switches when turned on as shown in Figure 3.

The GM amplifier senses the voltage drop across the lower switch and converts it into current signal when it turns on. The sampled and held

current is expressed as:

A

12

10

R

I

I

3

)

ON

(

DS

LX

CSX













SS

FB

EAP

SS

C

A

dt

dV

dt

dV

dt

dV



22







SS

FB

EAP

SS

C

A

dt

dV

dt

dV

dt

dV



200







Sample

&Hold

Current

Balance

_

+

Reference

Voltage

+

_

PHASE