UCC27423, UCC27424, UCC27425

SLUS545B − NOVEMBER 2002 − REVISED NOVEMBER 2004

8

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APPLICATION INFORMATION

Source/Sink Capabilities During Miller Plateau

Large power MOSFETs present a large load to the control circuitry. Proper drive is required for efficient, reliable

operation. The UCC27423/4/5 drivers have been optimized to provide maximum drive to a power MOSFET

during the Miller plateau region of the switching transition. This interval occurs while the drain voltage is swinging

between the voltage levels dictated by the power topology, requiring the charging/discharging of the drain-gate

Two circuits are used to test the current capabilities of the UCC27423 driver. In each case external circuitry is

added to clamp the output near 5 V while the IC is sinking or sourcing current. An input pulse of 250 ns is applied

at a frequency of 1 kHz in the proper polarity for the respective test. In each test there is a transient period where

the current peaked up and then settled down to a steady-state value. The noted current measurements are

made at a time of 200 ns after the input pulse is applied, after the initial transient.

The first circuit in Figure 2 is used to verify the current sink capability when the output of the driver is clamped

around 5 V, a typical value of gate-source voltage during the Miller plateau region. The UCC27423 is found to

UDG−01065

UCC27423

GND

1

2

3

4

INB

INA

7

6

5

8

OUTA

VDD

OUTB

INPUT

1

µF

CER

100

µF

AL EL

DSCHOTTKY

VDD

C2

1

µF

VSNS

RSNS

0.1

Ω

C3

100

µF

10

Ω

+

VSUPPLY

5.5 V

ENBB

ENBA

Figure 3.