TLK2501EVM: Capacitor really required on RREF pin ?

phil chabot

Part Number: TLK2501EVM
Other Parts Discussed in Thread: TLK2501

Hi,

The TLK2501 evaluation board has a 0.01uF capacitor directly connected to RREF pin and ground. It seems to cause some oscillation on the supply lines. Can anybody confirm the capacitor is needed ?

The datasheet for the tlk2501 makes no mention of a capacitor on that pin.

thanks

Phil

over 8 years ago

0 Luis Omar Moran over 8 years ago

TI__Genius 16150 points

Hi Phil,

If at all possible, each supply pin needs to have a decoupling capacitor placed directly at the pin. Additional bulk capacitances can be placed near the device.
This cap is suggested for EMI and attenuation concerns, even in the figure 13 of datasheet (Application Information) is placed. This is the reason why in the EVM is connected.

Best Regards,
Luis Omar Moran
High Speed Interface
SWAT Team

0 phil chabot over 8 years ago in reply to Luis Omar Moran

Prodigy 110 points

thanks for you quick reply Luis. Actually there is no cap on pin 56/RREF in the datasheet (fig 13) - please look again. It appears on the EVM schematics, and I can see oscillations when it is placed, but it seems fine without it. can you confirm there is a mistake on the EVM ?
thanks
Phil

0 phil chabot over 8 years ago in reply to Luis Omar Moran

Prodigy 110 points

not sure if you got my reply, i cant see it - but if you look carefully the cap on the EVM is directly on the RREF pin, not VDDA? it seems to cause oscillations.

0 Luis Omar Moran over 8 years ago in reply to phil chabot

TI__Genius 16150 points

Hi Phil,

You are right, the cap is not placed directly to te pin in datasheet, it seems an error in the EVM design, I need to verify with the design team.

Regards,

Luis

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TLK2501EVM: Capacitor really required on RREF pin ?