UPDATE (2021-Jan-16) - All working as expected - Project link for anyone to build or do as they please.

PAM2804, I've been trying to use this chip for a single Li-ion cell flashlight project, but it does not work for me. I've designed 2 PCBs so far, but both failed.

I'm driving a Cree X-Lamp XML @ 1A.

I can see voltage on the output, but the LED does not light.

1st PCB was a 2 layer; 2nd PCB was a 4 layer with 2 inner ground layers.

Anyone kindly point out what I might be doing wrong please?

Components used;

enter image description here

My schematics: **

  • For testing I have only solder the PAM2804 side. For now ignore reset of the circuitry please.
  • Direct power injected from a charged Li-ion battery at C1.
  • Sorry I have no oscilloscope at the moment. It's on it's way. **

enter image description here

My 2nd PCB:

enter image description here

Voltages at;

enter image description here

U1 Pin 1 - 4.092v

U1 Pin 2 - 3.258v strange this is GND

U1 Pin 3 - Starts at 3.3v and goes down to 3.089v and stables.

U1 Pin 4 - 4.092v (same as C1 voltage)

U1 Pin 5 - Starts at 3.475v and goes down to 3.369v and stables.

C1 - 4.092v

C7 - Starts at 3.3v and goes down to 3.085v and stables.

  • \$\begingroup\$ What is the DC voltage on pin 4 of the PAM2804? Is it perhaps too low to get the required 2.98 volts needed for the LED at 1000 mA? \$\endgroup\$
    – Andy aka
    Jan 14, 2021 at 18:07
  • \$\begingroup\$ No component specs. No measurements. No answers. You need to offer clues of failures. \$\endgroup\$ Jan 14, 2021 at 18:18
  • 2
    \$\begingroup\$ "i see voltage" ... voltage is a little vague ... any particular voltage, and how does in compare with the forward voltage of your LED? \$\endgroup\$
    – user16324
    Jan 14, 2021 at 18:39
  • 2
    \$\begingroup\$ You perhaps have a solder short over small gaps. Record voltage on every pin on schematic \$\endgroup\$ Jan 15, 2021 at 1:15
  • 2
    \$\begingroup\$ "U1 Pin 2 - 3.258v strange this is GND" - Dry joint on pin 2? Measuring between wrong points? Don't just leave it at that - find out why your 'GND' is not ground! \$\endgroup\$ Jan 15, 2021 at 6:49

1 Answer 1


I had a pretty similar circuit 2 months ago, using TP4056 with PAM. Since, you are getting the output voltage, only other fault could be coming from lack of current. I would check if

  • Amperage and ESR of Inductor L1, are within specified tolerances (0.1 value of R1 will require atleast 1.5amp rated inductor, and LED you are driving requires a minimum of 700mA)
  • C1 is MLCC
  • C2, C7 could be Tantalum

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