APW7066 datasheet(21/35 Pages) ANPEC

21 / 35 page

Rev. A.8 - Aug., 2009

APW7066

www.anpec.com.tw

Function Description

Figure 1. Independent Mode Circuit

Figure 2.DDR Mode Circuit

Table1. Mode and Phase Selection

MODE

SS2/EN2 REFOUT REFIN

PHASE

SHIFT

CH1/CH2

DDR

VCC

VOUT1

0 deg

DDR

VCC

Open

VOUT1 90 deg

SS1/EN1

for CH1

and CH2

Independent SS2 cap

VCC

VREF

0 deg

Independent SS2 cap

Open

VREF 180 deg

SS1/EN1

for CH1

SS2/EN2

for CH2

The advantage of Phase shift is to avoid overlapping the

switching current spikes of the two channels, or interac-

tion between the channels; it also reduces the RMS cur-

rent of the input capacitors, allowing fewer caps to be

employed. However, the phase shift between the rising

edge of LGATE1 and LGATE2 (See figure 3.), depending

on the duty cycles, the falling edges of the two channels

might overlap; so the user should check it.

Figure 3. Phase of LG2 with respect to rising edge of LG1

Operational Modes

The APW7066 has two independent synchronous buck

converters, and it also has DDR mode operation to allow

VOUT2 to track VOUT1.

In independent mode operation, connect a capacitor from

each SS/EN pin to the ground to set each regulator’s soft-

start time. The 3.3V reference VREF can be used directly,

or divided by two resistors for REFIN, since the VREF is

controlled by the SS2/EN2.

DDR mode is chosen by connecting the SS2/EN2 pin to

VCC(5V). In this mode, SS2/EN2 function will be disabled,

SS1/EN1 is used to control soft start and enable both

VOUT1 and VOUT2. The VOUT1 is used as the REFIN for

the VOUT2, that makes VOUT2 to track VOUT1.

VREF

REFIN

SS3/EN3

SS2/EN2

SS1/EN1

GND

REFIN

SS3/EN3

SS2/EN2

SS1/EN1

GND

VOUT1

VCC

Phase Shift

The APW7066 has phase shift function, use the REFOUT

pin to select the phase shift between Independent mode

and DDR mode. Connect the REFOUT to VCC to get the 0

degre in either mode. In this case, the buffer of the

REFOUT is disabled. Leave the REFOUT open shifts the

phase 90 degrees in DDR mode, or 180 degrees in Inde-

pendent mode, REFOUT can be used in this case (see

Table 1.).

180

LG1

LG2

(0deg)

LG2

(90deg)

LG2

(180deg)

APW7066 Datasheet(PDF) 21 Page - Anpec Electronics Coropration

APW7066 Datasheet(HTML) 21 Page - Anpec Electronics Coropration

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35

Datasheet Download

Link URL