Phaedrus2129
- Jan 13, 2013
- 5
- Joined
- Jan 13, 2013
- Messages
- 5
High-current SMPS LED driver (32mm diameter PCB)
So I'm designing a circuit board with some very unusual characteristics. I have somewhat limited circuit design experience, so I was somewhat wary of tackling a project like this, but I gave it a shot. I think it's come out well, but I want to double check.
The specifications were as such:
Turns out this was bloody hard, with the tiny circular PCB. This was probably the hardest layout I've ever done and I had to sort of edge up to the, ah, very limits of Good Layout Practice, just a little bit.
I elected to use a Texas Instruments TPS53319, which I can obtain a free sample of.
IC PDF: http://www.ti.com/lit/ds/symlink/tps53319.pdf
After a great deal of searching, headscratching, and frustration I found an inductor that would work for me: HCTR-441
http://www.digikey.com/product-deta...=PLA_1553305&gclid=CIvapaDs47QCFSmCQgod_HYA4Q
I'm using a 300kHz switching frequency. I selected 150uF .22ohm ESR Tantalum caps for the output filtering, 0603 ceramic caps for input filtering and signal, and 0402 1% resistors.
Now I would have built this on a 3-layer board, but ExpressPCB only offers 4-layer boards and I'm going to go with them for simplicity's sake. So I'm treating both internal layers as ground planes, to help filter noise before it reaches the back of the PCB, and they're cross-linked with vias.
A final note, the "+in", "GND", and "SW" wires will enter from the back of the PCB, while "+out" and "GND" wires will exit from the front of the PCB to go to the LEDs.
My main concern is the close proximity of traces, vias, and components, and I'm worried that there may be cross-talk or mechanical incompatibilities in places. I'd appreciate any help or advice.
Schematics updated, below.
So I'm designing a circuit board with some very unusual characteristics. I have somewhat limited circuit design experience, so I was somewhat wary of tackling a project like this, but I gave it a shot. I think it's come out well, but I want to double check.
The specifications were as such:
- SMPS for driving high-current LEDs, with battery input
- Input voltage: 10.8V +/-0.5V
- Output voltage: 4.2V +/-0.1V
- Output current: 9A +/- 0.2A
- Efficiency: >80%
- Temperature: -20C to 80C
- Must fit on circular PCB with diameter of 32mm
- Budget: <$200 including board
Turns out this was bloody hard, with the tiny circular PCB. This was probably the hardest layout I've ever done and I had to sort of edge up to the, ah, very limits of Good Layout Practice, just a little bit.
I elected to use a Texas Instruments TPS53319, which I can obtain a free sample of.
IC PDF: http://www.ti.com/lit/ds/symlink/tps53319.pdf
After a great deal of searching, headscratching, and frustration I found an inductor that would work for me: HCTR-441
http://www.digikey.com/product-deta...=PLA_1553305&gclid=CIvapaDs47QCFSmCQgod_HYA4Q
I'm using a 300kHz switching frequency. I selected 150uF .22ohm ESR Tantalum caps for the output filtering, 0603 ceramic caps for input filtering and signal, and 0402 1% resistors.
Now I would have built this on a 3-layer board, but ExpressPCB only offers 4-layer boards and I'm going to go with them for simplicity's sake. So I'm treating both internal layers as ground planes, to help filter noise before it reaches the back of the PCB, and they're cross-linked with vias.
A final note, the "+in", "GND", and "SW" wires will enter from the back of the PCB, while "+out" and "GND" wires will exit from the front of the PCB to go to the LEDs.
My main concern is the close proximity of traces, vias, and components, and I'm worried that there may be cross-talk or mechanical incompatibilities in places. I'd appreciate any help or advice.
Schematics updated, below.
Last edited:
