Dear expert,
My customer is using LM3406HV in lighting. Now they found two problems as below, and made some tests. Could you help to check will their solution have other problems?
- Device parameters:
Inductance: 47uH * 2 (series connection)
Output capacitance: 4.7uF + 1uF
VCC capacitance: 0.1uF
COMP capacitor: 0.22uF
Ron: 510K
- Problem 1. Flashing at power off: Paralleling a 4.7uF ceramic capacitor at the output can eliminate this phenomenon. Will the paralleled capacitor category and larger capacitance cause problems ? For example, using 22uF / 63V aluminum electrolysis in parallel.
Cyan: Vin
Blue: COMP
Purple: VCC
Yellow: SW
- Problem 2. Abnormal start-up after continuous power-on: the front end 36-45V is a switching power supply. After the power is turned off, it takes time to reduce the voltage. The problem will occur if the voltage hasn't been reduced to 6V. After the power supply terminal voltage drops below 6V, then power on will be no problem. They plan to connect two 15K resistors in parallel at the input as discharge resistors, will it cause problems?
Thanks for your suggestions.