TPS75003 Spartan-3(E) Voltage Regulator
The TPS75003 is a triple voltage regulator for Xilinx Spartan-3(E) FPGAs. Farnell are now supplying these in low quantities.
The device has some quite specific external component requirements. As most of the components listed on the datasheet and application notes seem to be only available in the US, this page lists suitable components available in the UK, via Farnell.
This board has been built and tested, it works OK so far. I've powered 16 Spartan-3E 500s using one of these boards (although not under heavy load).
Note: One aspect of Buck controllers is the audible noise generated by the inductors. The switching frequencies used by the TPS75003 are well within the audible range. Depending on the load and components used, using this device can result in quite a (audibly) noisy regulator.
Circuit & PCB
The photo below shows a simple regulator board that uses a TPS75003.
TPS75003 Board
The schematic for the board is shown below. A PDF version can be downloaded using the link below.
TPS75003 Schematic
The two images below show the top (red) and bottom (blue) layers of the PCB. The board also include two current sensors (not shown in the schematic above) these are not required for the TPS75003 to operate.
PCB Top Layer
PCB Bottom Layer
The PCB and Schematic in Eagle format can downloaded using the link below.
Component List
Below is a list of the parts required to build a triple regulator for a Spartan-3 FPGA. All the parts are available from Farnell.
| ICs | ||||
| PCB Number | Value | Farnell Code | Spec | Notes |
|---|---|---|---|---|
| U1 | - | 9969187 | TPS75003 Regulator | |
| Capacitors | ||||
| PCB Number | Value | Farnell Code | Spec | Notes |
| C1, C3, C7 | 10uF | 940-2136 | Ceramic Multilayer, 10V, ±10% | Buck input cap, LDO output cap |
| C2, C4, C6 | 100uF | 975-1858 | Polymer Tantalum, 6.3V, ±20%, 45mΩ | Buck output cap, LDO input cap |
| C5 | 1uF | 880-5628 | Multilayer Ceramic, 16V, ±10% | LDO input cap |
| C8, C9, C10 | 1.5nF | 722-182 | Multilayer Ceramic, 0603, 50V, ±10% | Soft start cap |
| C11 | 10pF | 975-3559 | Multilayer Ceramic, 0805, 50V, ±5% | Feedback cap |
| Resistors | ||||
| PCB Number | Value | Farnell Code | Spec | Notes |
| R1, R2 | 33mΩ | 806-7554 | Thick Film, 0.5W, ±1% | Buck current limit resistor |
| R10 | 100K | 933-3738 | Thick Film, 0805, 0.1W, ±5% | LDO feedback resistor |
| R11 | 22K | 933-4157 | Thick Film, 0805, 0.1, ±5% | LDO feedback resistor |
| R12 | 47K | 933-4599 | Thick Film, 0805, 0.1, ±5% | Buck feedback resistor |
| R13 | 27K | 933-4270 | Thick Film, 0805, 0.1, ±5% | Buck feedback resistor |
| R4, R7 | 10K | 122-7539 | Trimmer | Buck & LDO trimmer |
| R9 | 330Ω | 933-4351 | Thick Film, 0805, 0.1W, ±5% | LED series resistor |
| Inductors | ||||
| PCB Number | Value | Farnell Code | Spec | Notes |
| L1, L2 | 22uH | 743-0388 | 3.6A, 0.038Ω, ±20% | Buck Inductor |
| Discrete | ||||
| PCB Number | Value | Farnell Code | Spec | Notes |
| D1, D2 | SSB43L | 133-6556 | Schottky, 4A, Vrrm: 30V, Vf: 0.45 |
Buck Diode |
| U2, U3 | Si5475DC | 955-0674 | MOSFET, Id:7.6A, Vds:12V, Rds on:0.054Ω |
Buck MOSFET |
| LED1 | KP-3216YC | 853-0041 | KINGBRIGHT,1206, YELLOW | 3.3V Power LED |
| Connectors & Switches | ||||
| PCB Number | Value | Farnell Code | Spec | Notes |
| SW1 | SPDT | 947-3017 | 0.4VA, 20mΩ | Enable Switch |
| J6 | 1x2 | 949-2038 | 7A, 3.96mm pitch | Input Connector |
| J8 | 1x4 | 949-2054 | 7A, 3.96mm pitch | Output Connector |
| J9 | 1x2 | 512-035 | 0.1" pitch | GND scope probe connector |
