ADS8509: Tantalum vs Ceramic Decouple Caps

Jewel Holt

Part Number: ADS8509

Tool/software:

Datasheet says to use tantalum caps for 2.2uf and 10 uf decouple caps on Vref and Vana pins. Is there a reason why we cannot use ceramic for those decouple caps

1 month ago

0 Tom Hendrick 1 month ago

TI__Guru**** 180931 points

Hi Jewel,

There is an equivalent series resistor (ESR) need with the bypass caps associated with the ADS8509 (see Figure 23 and pg. 18, 3rd paragraph). You may be able to use a ceramic cap if you inclued a smal series R to ground.

0 Jewel Holt 1 month ago in reply to Tom Hendrick

Prodigy 60 points

Hi Tom,

So if I understand figure 23 and page 18 para 3 correctly, if my ceramic cap has esr less than 3 ohms (@~250kHz) we should maintain our signal integrity?

0 Tom Hendrick 1 month ago in reply to Jewel Holt

TI__Guru**** 180931 points

Hi Jewel,

Yes, that is my understanding as well. The esr of tantalum caps can help damp oscillations and reduce noise, which is important especially on the reference node.

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ADS8509: Tantalum vs Ceramic Decouple Caps