ZXGD3104EV2

Issue 1 – October, 2011

www.diodes.com

© Diodes Incorporated 2011

5

Board schematic

Figure 6 shows the circuit schematic of ZXGD3104EV2. Power for the controller is applied to the

terminal block P1. A three way header, P2 is located at the other end of the board. The header allows

the board to be soldered directly across a synchronous MOSFET in a TO220 package. The board can

also be used with an SMD MOSFET by connecting the pin-outs accordingly.

The evaluation board is designed to accept a supply voltage of 19V, which is the typical output

voltage of a laptop power adaptor. If the power supply’s output voltage is required to be greater than

25V, a voltage regulator should be used to step down the high voltage to 19V before connecting to the

evaluation board. The values of the threshold setting resistors, Rref and Rbias, are chosen for

Vcc=19V. Please refer to the ZXGD3105N8 datasheet for more information.

DZ is an optional Zener diode connected to the BIAS pin of the controller to limit the maximum gate

voltage to 12V. DZ is recommended when the controller is used to drive a high-gate-charge

synchronous MOSFET or/and at high switching frequency. This configuration reduces the gate-charge

switching loss.

Figure 6: Circuit diagram

Please note that the component part numbers are given as a guide only. Due to continual component

development, all parts quoted should be checked for suitability and availability with their respective

manufacturers.

Table 1: Part list

Ref.

Value

Package

Part number

Manufacturer

Notes

U1

25V VCC max

synchronous controller

SO8

ZXGD3104N8

Diodes Inc.

DZ

12V Zener

SOT23

BZX84C12

Diodes Inc.

C1

1uF 50V capacitor

1206

C1206X105K5R

Kemet

X7R

P1

2-way terminal

generic

P2

3-way header

generic

Rbias

6k2 resistor

1206

Generic

1%, 200ppm/ºC

Rgate

0R resistor

1206

Generic

5%, 200ppm/ºC

Rref

8k2 resistor

1206

Generic

1%, 200ppm/ºC