LT1027 output drop abnormally & recover

Q1: yep, C642 may cause the dip as the capacitor shunts the internal reference diode directly, it is the most sensitive pin of the LT1027

Q2: you have to use a high quality capacitor there, with a very low leakage (and low dielectric absorption), best a Mylar type one as the DS suggests, doublecheck the pcb layout around the capacitor as well (potential leakage/EMI/grounding problems)

Q3: doublecheck the VIN, the voltage drop at the R630 (1k) may limit the VIN at the pin 2 - as it will flow at least 2mA through it.

Q1: yep, C642 may cause the dip as the capacitor shunts the internal reference diode directly, it is the most sensitive pin of the LT1027

Q2: you have to use a high quality capacitor there, with a very low leakage (and low dielectric absorption), best a Mylar type one as the DS suggests, doublecheck the pcb layout around the capacitor as well (potential leakage/EMI/grounding problems)

Q3: doublecheck the VIN, the voltage drop at the R630 (1k) may limit the VIN at the pin 2 - as it will flow at least 2mA through it.

Thanks for the reply.

VIN supply is 13.5V to R630, voltage drop at R630 is 3.1V meaning current drawn is 3.1mA.

From spec the max supply current is 3.5mA. what will happen if over the max supply current.

Pls advise. Thanks.