
Here is the schematic. I inherited this circuit, and my analysis has not turned up a culprit or a fix. Any input would be helpful.
KCC Quizzes AQQ303 about the radius of a circle
1. Quote of the month: "When I die, I want to die like my grandfather who died peacefully in his sleep. Not screaming like all the passengers in his car" - Will Rogers
2. Quiz AQQ304 about finding the radius of a circle
Good luck, and try to be
View All
August Monthly Blog Quiz! Read the blog, take the quiz, and you could win a gift card
Important: Read the blog first . The quiz questions are all based on the content of the blog:
Stay in the loop and win! Read the blog Current Output Driving Industrial Loops , then take our quick five-question quiz for a chance to win a gift card
View All
LTC7001
Recommended for New Designs
The LTC7001 is a fast high side N-channel MOSFET gate driver that operates from input voltages up to 135V. It contains an internal charge pump that fully...
Datasheet
LTC7001 on Analog.com

Here is the schematic. I inherited this circuit, and my analysis has not turned up a culprit or a fix. Any input would be helpful.
Hi William23 ,
Probably in the field you have long supply wires? If there is no shunt capacitor near Vcc pin, rapid load changes may cause huge swing in the supply line (due to wire inductance). Repeat your lab test with supply wiring identical to the field.
Add a shunt capacitor (say 10uF) across the Vcc and GND (optionally with 1 ohm series resistor to lower the Q value) to see if the failures in the field go away.
Cheers, heke
The 5V comes from an onboard 12-5V switching supply. I used a fast oscilloscope (1Ghz) and checked the VCC. I did not see a voltage drop. or any transients.
I instrumented BST, INP, FAULT, TGUP. I saw BST go to 9V, and as soon as 3.3V appeared on INP, FAULT went high. 25us later FAULT went low. I did not see any change on TGUP.
I thought the only two failure modes where VCCUV and Current Sense. Are there any others? These both seem okay. Also, after the first symptom, I saw the regular pattern of FAULT going high, then low, every 26ms, around the timer interval.