Datasheet

Voltage
Current
t − Time − ns
LGATE Falling, V or A
LGATE Falling, V or A
LGATE Current, A
Voltage
Current
t − Time − ns
UGATE Falling, V
UGATE Falling, V
UGATE Current, A
TPS28225
TPS28226
SLUS710C –MAY 2006–REVISED APRIL 2010 www.ti.com
The I
SOURCE
current charges the gate capacitor and the I
SINK
current discharges it. The rise and fall time of
voltage across the gate defines how quickly the MOSFET can be switched. The timing parameters specified in
datasheet for both upper and lower driver are shown in Figure 15 and Figure 16 where 3-nF load capacitor has
been used for the characterization data. Based on these actual measurements, the analytical curves in Figure 25
and Figure 26 show the output voltage and current of upper and low side drivers during the discharging of load
capacitor. The left waveforms show the voltage and current as a function of time, while the right waveforms show
the relation between the voltage and current during fast switching. These waveforms show the actual switching
process and its limitations because of parasitic inductances. The static V
OUT
/ I
OUT
curves shown in many
datasheets and specifications for the MOSFET drivers do not replicate actual switching condition and provide
limited information for the user.
Figure 25. LGATE Turning Off Voltage and Sink Current vs Time (Related Switching Diagram (right))
Figure 26. UGATE Turning Off Voltage and Sink Current vs Time (Related Switching Diagram (right))
22 Submit Documentation Feedback Copyright © 2006–2010, Texas Instruments Incorporated
Product Folder Link(s): TPS28225 TPS28226