TMS320F28377S: Power supply design for tms320f28377s

Hi Aniruddh,

Download C2000ware and check the designs for the C2000 launchpad and/or ControlCards to see how the power supply could work.

Physically you are probably going to want to build a base-board that has some single higher voltage input (e.g. 5V) that gets reduced to 3.3V and 1.2V by LDOs or Switching supplies. You then distribute the 3.3V rail to all VDDIO, VDDA, and VDDSFL pins and 1.2V to all VDD pins. You also need to add decoupling capacitors at each pin to help the power-distribution network cope with fast transient currents that are drawn by the device.

Hi Devin,

Thanks for the reply. I have gone through the schematics and the datasheet. Designing the power supply system for a microcontroller is not an issue. The problem is, there is an already existing PCB around the microcontroller die and the only way to get access to different pins is through some of the pads on the PCB. How do I connect power supply board to these pads? Are there any methods? Or should I solder wires to these pads and connect these wires manually on a bread board and see if it works? Also, the pads are in such a way that, they are shorted to multiple pins. For example, the VDD pins are all connected internally and through a pad. Do I pull a wire from the pad and then connect the required capacitors between the wire and ground? If you require the PCB files, please let me know. I will be willing to send them.

HI Aniruddh,

The same-voltage pins being shorted together is probably a good thing.  Does the MCU daughter-card also have decoupling capacitors and ground planes on the board? That would be ideal.

If the decoupling capacitors are not on the MCU board, you will want to add one near each power connection pad when you build the mother-board. 

Best-case would be to build a mother-board PCB with nice ground and power planes and with decoupling capacitors at each daughter-card power connection point.  You can do something similar with just traces on a proto-board if that is what you have to work with.  Note that making good ground connections to the MCU board are just as important as the power connections. 

As far as connecting daughter board to mother board, I think you want to get the mating connectors.  e.g. if the daughter board has 3x20 .100 male headers, find the matching 3x20 .100 female headers to put on the mother PCB or protoboard.  I really would not recommend just using wires.     

Hi Devin,

Thank you, I'll give this a try and get back to you as soon as possible. And also, if I want to power let us say the VDDIO pins and all the 9 pins are shorted to a pad. And each pin requires, let us say 2.2uF capacitor. Do I connect all the 9, 2.2uF capacitors in parallel and connect one end to the pad that is shorted to all the pins and the other end to the ground plane? Or only one 2.2uF is required?

Hi Devin,

Thanks a lot for the suggestion. Designing the daughter board helped. Although the design is a little shoddy, I got the microprocessor to respond. Now I will be given a new die to work on, and I can design everything from the bottom up. Thank you very much.