Datasheet

V
DDQ
(50 mV / div)
I
LOAD
(5 A / div)
I
L1
(5 V / div)
V
OUT
= 1.8 V
D-CAP Mode
V
DDQ
(50 mV / div)
I
LOAD
(5 A / div)
I
L1
(5 V / div)
V
OUT
= 1.8 V
D-CAP Mode
www.ti.com Performance Data and Characteristic Curves
Figure 5. TPS51116EVM 0-A to 8-A Load Figure 6. TPS51116EVM - 8-A to 0-A Load
Transient Response Transient Response
Figure 5 shows the switching output ripple voltage, the inductor current and the output load current. The
advantage of the semi-hysteretic D-CAP mode is clearly visible. Here an 8-A load transient of 5 A/s
causes less than 30 mV of voltage drop and nominal operation is recovered in less than 2 s, that’s a
single switching cycle at the normal 400 kHz switching frequency.
Figure 6 , with the same channel designations of Figure 5 shows the falling transient. As soon as the first
main switching pulse is terminated normally, the TPS51116EVM turns on the lowside FET and
immediately begins dropping the inductor current as fast as possible by shorting the switch node to
ground. The low-side MOSFET is then turned OFF when the inductor current reaches zero and the
high-side MOSFET is held off until the output voltage drops below the valley comparator and nominal
operation is immediately restored.
SLUU202A – SEPTEMBER 2004 – Revised November 2008 Using the TPS51116EVM 13
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