LM5088: LM5088

trond inge wang

Part Number: LM5088

Hi TI,

we are using LM5088-1 to create +5.3VDC. Input voltage is 24V and it draws 0.2A with the load we have. The design is based on the component values from webbench. Our problem is that some of the powers will not start at -20C. In this case it draws 30mA. There are pulses on the gate of the MOSFET in this case.

Do you have any proposals how we should proceed to find the reason? The problem is that we cannot search for the reason on the labbench in an easy way.

Are there any component changes we should try out (connected to ramp, soft start, boot etc.) ?

Capacitance on input is 3x100uF. On 5VDC side it is 2x330uF. Load is mainly resistive-capacitive

Regards Trond Inge WAng

over 6 years ago

0 Arief Hernadi over 6 years ago

TI__Mastermind 23845 points

Hi is the design ok at room temperature?
You can try to use some ceramic capacitor maybe with lower tolerance on ESR. Maybe your input or output capacitor ESR goes up at cold and affected your stability

Thanks
-Arief

0 trond inge wang over 6 years ago in reply to Arief Hernadi

Intellectual 385 points

Hi Arief,
at the input we have 2 x 100nF ceramics in parallel with electrolytics and on the output is a 1uF ceramic in parallell.
We never saw any startproblems at room temperature (10 units tested)

The load is an MPU which is powered through a PMIC and 3 other switching supplies. It is also a 0.5F supercap connected (for backup), but it is charged through a 100 ohm resistor. So the charge current is small.
regards Trond Inge Wang

0 Arief Hernadi over 6 years ago in reply to trond inge wang

TI__Mastermind 23845 points

Hi,

Do you have schematic for your design? Also does the ESR on the input and output capacitor similar to webench value?

Thanks
-Arief

0 Arief Hernadi over 6 years ago in reply to Arief Hernadi

TI__Mastermind 23845 points

Hi,

Since we are discussing this through email, i will close the thread for now

Thanks
-Arief

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LM5088: LM5088