UCC27323, UCC27324, UCC27325
UCC37323, UCC37324, UCC37325
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SLUS492H –JUNE 2001–REVISED MAY 2013
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 UCC37323/4/5 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 and discharging of the drain-
gate capacitance with current supplied or removed by the driver IC. (see References)
Two circuits are used to test the current capabilities of the UCC37323 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 UCC37323 is found to
sink 4.5 A at VDD = 15 V and 4.28 A at VDD = 12 V.
VDD
UCC27323
ENBA
ENBB
1
2
3
4
8
7
6
5
DSCHOTTKY
10 ꢀ
OUTA
INA
C2
1 µF
C3
100 µF
DADJ
5.5 V
+
GND
INB
VDD
OUTB
Signal generator
producing 250 ns
wide pulse
VSNS
RSNS
0.1 ꢀ
1 µF
CER
100 µF
AL EL
Figure 2.
The circuit shown in Figure 3 is used to test the current source capability with the output clamped to around 5 V
with a string of Zener diodes. The UCC37323 is found to source 4.8 A at VDD = 15 V and 3.7 A at VDD = 12 V.
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