MCU to ADC hardware connection

Thread Starter

tigerk2001

Joined Jan 7, 2010
8
Hi,
I have a MCU working on 3.3volts and I want to communicate with a ADC that work on 0-5volts range. Can someone give to me the best way to configure my hardware for CS, SDO, SDI, SCK?
thanks for your help
 

rjenkins

Joined Nov 6, 2005
1,013
It may work directly.

Many 5V circuits only need 2V for the logic High level ('TTL' Levels) - check the datasheet for the ADC and use pullups to the 3.3V supply to ensure the best possible High level.
 

Thread Starter

tigerk2001

Joined Jan 7, 2010
8
You're right,
I use a LTC2414 from linear as ADC and his high level is 2.5v and low level is 0.8v.
However, since my ADC VCC and ref is 5V, the problem will come from the SDO of the ADC. If it goes to 5v to the MCU GPIO, it may damage the MCU.
It is why I'm wondering if it is necessary to use a voltage level translator like ST2378 or equivalent.
Also, in the case I go directly, is there any buffer to install or I can go directly from the MCU to the ADC?
Thanks
 

Markd77

Joined Sep 7, 2009
2,806
You could put a few diodes in the path. Each silicon diode will drop 0.6V.
The logic high from the ADC will most likely be less than 5V anyway, check the datasheet. It's probably 4-4.5V.
 
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