I'm building a LED driver using Diodes AL8871Q IC to power a XHP70 LED powered from a 4 series protected Lithium battery pack, integrated on the board it has an Attiny85.
I plan to use the Attiny85 to control the PWM pin on the AL8871Q, read voltage from an NTC thermistor. I am using a Diodes AP7370 SOT23 regulator to power the Attiny85 from the incoming 14v VIN.
Using a bench top power supply to emulate a battery pack, I set to 14V 1A and hook everything up including LED load. Powering on the PSU, all works, I can control the PWM of the Attiny85 which in turns control LED brightness.
Problem I have is when I tried with a battery the LDO regulator burns out. So I tried with a new LDO regulator, turning on the PSU before connecting to my circuit, it burns the LDO regulator.
I figured that the PSU has a soft start that stops the in rush of current vs battery or connect an already on PSU.
Is this what is happening? How can I prevent it from happening with adding the least amount of components.
PSU set to 14v 10A
Works Circuit is connected to powered down PSU, LED/load is connected. Power on PSU, Attiny boots up fine, triggers PWM that controls AL8871Q IC that powers the LED. All this happens almost instantaneously. Scopes shows PWM duty cycle at 40% as programmed on Attiny85. PSU displays shows 25W power drawn, voltage reads 14v and 1.8A+-.
Burns PSU powered on NOT connected to circuit. LED is connected to circuit. PSU is then connected to circuit. AP7370 burns up and breaks.
Burns 14.8V battery pack is connect to circuit, AP7370 burns up
Works Circuit is connected to powered down PSU, NO LED/load connected. Power on PSU, Attiny boots up. Scopes shows PWM.
Works Attiny85 & AP7370 removed from circuit, PSU powered ON then connected to circuit with LED connected. PSU displays shows 50W power drawn, voltage displays 6+V and about 8+A.