Datasheet

SR 0.32 CT 13.7= ´ +
TPS22966
www.ti.com SLVSBH4C –JUNE 2012–REVISED JUNE 2013
ADJUSTABLE RISE TIME
A capacitor to GND on the CTx pins sets the slew rate for each channel. To ensure desired performance, a
capacitor with a minimum voltage rating of 25V should be used on the CTx pin. An approximate formula for the
relationship between CTx and slew rate is (the equation below accounts for 10% to 90% measurement on V
OUT
and does NOT apply for CTx = 0pF. Use table below to determine rise times for when CTx = 0pF):
(1)
Where,
SR = slew rate (in µs/V)
CT = the capacitance value on the CTx pin (in pF)
The units for the constant 13.7 is in µs/V.
Rise time can be calculated by multiplying the input voltage by the slew rate. The table below contains rise time
values measured on a typical device. Rise times shown below are only valid for the power-up sequence where
V
IN
and V
BIAS
are already in steady state condition, and the ON pin is asserted high.
RISE TIME (µs) 10% - 90%, C
L
= 0.1µF, C
IN
= 1µF, R
L
= 10Ω
TYPICAL VALUES at 25°C, V
BIAS
= 5V, 25V X7R 10% CERAMIC CAP
CTx (pF)
5V 3.3V 1.8V 1.5V 1.2V 1.05V 0.8V
0 124 88 63 60 53 49 42
220 481 323 193 166 143 133 109
470 855 603 348 299 251 228 175
1000 1724 1185 670 570 469 411 342
2200 3328 2240 1308 1088 893 808 650
4700 7459 4950 2820 2429 1920 1748 1411
10000 16059 10835 6040 5055 4230 3770 3033
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