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Contributor I

We are using TDA8035 as a replacement for TDA8002 as it is getting obsolete.

We have few queries on the working of TDA8035 and those are given below.


  1.       TDA8002 datasheet clearly mentioned that it will support both Synchronous and asynchronous cards (memory and smart cards). But TDA8035 datasheet didn’t mention anything about the synchronous cards. Please let us know whether TDA8035 can support both Synchronous and asynchronous cards or not.
  2.       Second point is regarding the clock selection. As per the datasheet, clock selection will happen when CMDVCCN goes from High (1) to low (0). If already there is a clock on the XTAL1 pin during CMDVCCN transition from 1 to 0, then the chip will consider it as an external clock and the crystal will not be activated. And if there is no clock on the XTAL1 pin during CMDVCCN transition from 1 to 0, then the chip will wait for 3mSec and start the crystal oscillator. But in our development boards, we are observing that, when the CMDVCCN is continuously low (there is no transition from 1 to 0) and if there is no external clock to the XTAL1 pin, then the crystal oscillator is getting activated. Please let us know why this is happening.
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NXP TechSupport
NXP TechSupport

Hi Anoop Abraham,

Actually TDA8035 is an interface chip which provide  level switch function with protect circuits inside, so it doesn't care about synchronous/asynchronous cards , so it supports synchronous cards as well.

For the second question, I don't understand how you made CMDVCCN pin continuously low, connecting it to GND out of POR? Please kindly help to clarify.

Thanks for your patience!

Have a great day,

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