The Lab Book Pages

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Dr. Andrew Greensted
Last modified: 27th September 2010

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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

TPS75003 Board

The schematic for the board is shown below. A PDF version can be downloaded using the link below.

Board Schematic

TPS75003 Schematic

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 Top Layer

PCB Bottom Layer

PCB Bottom Layer

The PCB and Schematic in Eagle format can downloaded using the link below.

Eagle Files (Board and Schematic)

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.

PCB Number Value Farnell Code Spec Notes
U1 - 9969187 TPS75003 Regulator
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
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
PCB Number Value Farnell Code Spec Notes
L1, L2 22uH 743-0388 3.6A, 0.038Ω, ±20% Buck Inductor
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

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