Paragraph 7.3.2 of the TPS7A16 data sheet indicates the LDO has a soft start feature, but there is no additional details as to how this works or its timing.The start-up waveforms in the data sheet and EVM User Guide look like there is soft start control.
Can you provide more information?
Hi Mark,
Yes TPS7A16 has an internal soft-start. The purpose is to provide a controlled startup for the output voltage and current by controlling the slew rate of the internal reference. The output of a linear regulator is a gained version of the internal reference. As such, the output slew rate will be equal to the slew rate of the internal reference. This holds true unless current limit is triggered or the slew rate of Vin is slower than the slew rate of the reference and the regulator enters dropout. Unlike some linear regulators, the soft-start is not adjustable for TPS7A16. This means that the slew rate of the internal reference will be constant. Therefore the output will be constant unless limited by the slew rate of Vin or current limit.
Figure 16 shows the normal startup of TPS7A16. The slew rate of Vout is controlled by the internal softstart. Figure 17 shows the change in slew rate when Vout is limited by the slow ramp of Vin (Vin is equal to Ven).
Very Respectfully,
Ryan
