Hello,
I am having trouble with a LM3409 driver design. I made a PCB but the buck regulator is not working. It's just passing the input voltage to the output. In other words I think pgate is always keeping the p-fet on despite if the enable pin on or off. I have 3 copies of the assembled board, all with the same behavior. I believe it is the design and not a short or something in the hardware.
This isn't exactly my area of expertise so I might be missing something obvious.
Any ideas on how to troubleshoot this would be very helpful.
Thank you
| Desired specs | |
| Vo | 3.5V |
| Vin | 8.4V |
| Current | 3A |
| Part | Value | PN | Manufacturer |
| L1 | 3.6uH | SRN8040-3R6Y | Bourns |
| D1 | CD214A-B320 | Bourns | |
| Pfet | FDT434P | Fairchild | |
| R_uv2 | 49.9K | ||
| R_uv1 | 16.5K | ||
| R_off | 4.99K | ||
| C_off | 470pF | ||
| R_sence | .075 ohm | ||
| CF | 1uF | ||
| C_in | 10uf |
