HIP6301V, HIP6302V

FN9034 Rev 3.00

Page 18 of 20

May 5, 2008

However, large gate-charge increases the switching time,

Ensure that both MOSFETs are within their maximum

junction temperature at high ambient temperature by

calculating the temperature rise according to package

thermal-resistance specifications. A separate heatsink may

be necessary depending upon MOSFET power, package

type, ambient temperature and air flow.

of Figure 1. These diodes function as a clamp that catches

the negative inductor swing during the dead time between

the turn off of the lower MOSFETs and the turn on of the

upper MOSFETs. The diodes must be a Schottky type to

prevent the lossy parasitic MOSFET body diode from

conducting. It is usually acceptable to omit the diodes and let

the body diodes of the lower MOSFETs clamp the negative

inductor swing, but efficiency could drop one or two percent

as a result. The diode's rated reverse breakdown voltage

must be greater than the maximum input voltage.

2







------------------------------------------------------------







2

----------------------------------------------------------

+

=

2





–





---------------------------------------------------------------------------------

=

(EQ. 9)