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LTC3114 devices failing in application according to datasheet

Question asked by joachimbaumm on Jan 15, 2018
Latest reply on Feb 20, 2018 by Tones

LTC3114 devices failing in application taken from datasheet


Customer Kuhnt has an issue with LTC3114EFE.

About 30 devices of 40 in total were damaged.

They use an application like the lead acid battery charger on page 29 of the data

sheet, with the optional diode.

The deviations from the datasheet schematics is

- they have a 24V battery instead of 12V

- hence the output voltage is set to 27,5V

- with a prog-resistor of 100k they set a current limit of 250mA,

- they have a regulated input voltage of 24V

- they use a 10uH inductor (Bourns SRR0745A-100M).

The layout of the four layer PCB is based on the recommendation on page

 18 of the data sheet. There is a shottky diode between the regulator

 output and the battery to prevent reverse current.

 -> Damaged parts have a shortcut either from SW1 to ground or from SW2 to ground.

 The application has also been simulated with LTspice and did not show any fault.