ZXGD3101N8
Document Number DS31945 Rev. 1 - 2
9 of 14
www.diodes.com
June 2010
© Diodes Incorporated
ZXGD3101N8
Product Line o
Diodes Incorporated
SYNCHRONOUS RECTIFIER CONTROLLER
-0.10 -0.08 -0.06 -0.04 -0.02 0.00
0
2
4
6
8
10
-0.10 -0.08 -0.06 -0.04 -0.02 0.00
0
2
4
6
8
10
Transfer Characteristic
V
G
Gate Voltage (V)
V
D
Drain Voltage (V)
I
REF
= 2mA
I
REF
=2.5mA
I
REF
= 3mA
I
REF
=3.5mA
I
REF
= 4mA
V
CC
= 10V
I
BIAS
= 5mA
R
LOAD
=1kΩ
I
BIAS
= 6mA
I
BIAS
=5.5mA
I
BIAS
= 5mA
I
BIAS
=4.5mA
I
BIAS
= 4mA
Transfer Characteristic
V
G
Gate Voltage (V)
V
D
Drain Voltage (V)
V
CC
= 10V
I
REF
= 3mA
R
LOAD
=1kΩ
Component Selection
It is advisable to decouple the ZXGD3101 closely to V
CC
and ground due to the possibility of high peak gate currents with C1 in Figure 2.
The proper selection of external resistors R
REF
and R
BIAS
is important to the optimum device operation. Select a value for resistor R
REF
to give a
reference current, I
REF
, of ~3mA. The value of R
BIAS
must then be 0.6 times the value of R
REF
giving a bias current, I
BIAS
, of ~1.6 times I
REF
. This
provides a recommended typical offset voltage of ~20mV.
External gate resistors are optional. They can be inserted to control the rise times which may help with EMI issues, power supply consumption
issues or dissipation within the part.
R
REF
= (V
CC
-0.7V) / 0.003
R
BIAS
= (V
CC
-0.3V) / 0.005
Layout considerations
The Gate pins should be as close to the MOSFET Gate as possible. Also the ground return loop should be as short as possible. The decoupling
capacitor should be close to the V
CC
and Ground pin, and should be a X7R type.
For more detailed information refer to application note AN54..
