PRODUCT SPECIFICATION

FAN5037

REV. 1.0.3 9/26/01

9

Power and Ground Connections

The connection of VCCA to the 5V power supply plane

should be short and bypassed with a 0.1µF directly at the

VCCA pin of the FAN5037. The ideal connection would be a

via down to the 5V power plane. A similar arrangement

should be made for the VCCP pin that connects to +12V.

Each ground should have a separate via connection to the

ground plane below.

A 12V power supply is used to bias the VCCP. A 47

Ω resis-

tor is used to limit the transient current into VCCP. A 1uF

capacitor filter is used to filter the VCCP supply and source

the transient current required to charge the MOSFET gate

capacitance. This method provides sufficiently high gate bias

Figure 4 provides about 5V of gate bias which works well

when using typical logic-level MOSFETs. Non-logic-level

MOSFETs should not be used because of their higher

MOSFET Gate Bias

Figure 4. 12V Gate Bias Configuration

+5V

VCCP

47

Ω

Q1

L2

D1

1

µF

GNDP

+12V