Re: Any known issues with TPS71xxx regulators?

Joerg wrote:
Hello All,

Did anyone experience issues with the TPS71xxx series? These are micro power regulators from TI. Around 3uA quiescent which is nice but LDO which is not so nice because that architecture is known to be a bit fickle.

In one of my designs there is a TPS71550, the 5V version. 24V alkaline at the input but a 5.1V zener in front to lop off a few volts there. The zener is guaranteed to drop 2V at the quiescent current of the regulator so it never sees voltages above it's rated max.

0.1uF up front, 1uF ceramic on the output or about twice of what they recommend to maintain stability. When the battery is connected everything is fine, a nicely regulated 5V at the output. The output is switched via a FET (FDV304P) to a circuit that totals 0.1uF in decoupling caps and that's when it happens: Kablouie. TPS71550 shorts out and dies.
(snip)
I recommend you add a 10 or 15 ohm resistor in series with the 1 uF output capacitor. This will make the output load change from capacitive to resistive just about at the frequency where the output impedance peaks. I would also raise the input capacitor to be a couple times larger than the total capacitance that is switched at the output. This will increase the current spike, but lessen the input voltage collapse.
.

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