Hi,
I used the PTH08T230W to power motherboard with FPGA VIRTEX5.
I use 4 PTH08T230W modules. the modules set to 3.3v, 2.5v, 1.8v and 1.0v.
A daughter card is connected to the motherboard through board to board connectors.
The daughter card include HDMI Tx/Rx chip.
The PTH08T230W supply the power to the daughter card.
When we make FFT to the HDMI TMDS clock (output clock from the HDMI transmitter) we got the expected frequency (148.5MHz) but we have two spikes, 280KHz from the central frequency.
When I operate the daughter card as stand alone board (not connected to the motherboard, powered from external power supplies) these spikes are disappeared.
I suspect that the PTH08T230W cause these spikes (switching frequency Fs of 300KHz?).
I connected the PTH08T230W as followed:
Pin1: Short to GND
Pin2: Vin is 5v, connected 330uF, 22uF and 2.2uF (all in parallel) between pin 2 and GND
Pin3: connect to GND.
Pin4: connected 100uF and 4x 47uF (all in parallel) between pin 4 and GND.
Pin5: 82.5K resistor between pin 5 and pin 8.
Pin6: connect to GND. 2 pin header connect between pin 5 and pin 6.
Pin7: connected 1k resistor and 2k potentiometer (in serial) between pin 7 and pin 6.
Pin8: 82.5K resistor between pin 5 and pin 8.
Pin9: short to pin 2.
Pin10: 82.5K resistor between pin 10 and GND.
You can find below a list of all the capacitors i use around the PTH08T230W:
Cap ESR Voltage rating Tolerance Part number Note
330u 14mOhm 16V ±20% APS-160ELL331MJC5S
22u 1.6Ohm 16V ±10% T491C226K016AT
2.2u 16V ±10% EMK212B7225KG-T X7R
100u 16V ±20% CKG57NX5R1C107M X5R
47u 6.3V ±20% JMK325BJ476MM-T X5R
Please advice if you see any problem in my design or you have any recomendations
Best regards
Roni