LTC2344-16

Embedded Development Boards, Kits, Programmers
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1

Hi all,

I would like to configure the reference pins (REFIN (pin 10) and REFBUF (pin 12)) as an external reference un-buffered to achieve the continuous 5V on the VREFBUF pin as a reference voltage to the LTC2344 output.

Please correct me if I understand is wrong.

From page 8 (Note 14): From this, I understand that the REFIN pin must connect to GND (0V) when Overdriving the REFBUF. That’s fine.
From page 16: From this, I understand that REFIN connect to GND/0V (as mentioned in note 14 in page 8), and I need to set the 101 SoftSpan code in SW and also I need to apply the 0V to 5V to the analog input, to achieve continuous 5V on the VREFBUF. If I understand is correct that’s fine. Otherwise, please correct me.

If I understand correct, then can you go to page 26 (In the section: External Reference with Disabled Internal Buffer), there it’s said that the reference voltage between 2.5V and 5V. So, Im confusing that, in page 16 said that 5V and page 26 said that between 2.5V to 5V.

If I connect the pins as stated in page 8 and page 16, Do I get the continuous 5V on the VREFBUF and Do I get the corresponding digital outputs when I vary the the analog inputs from 0V to 5V?.

When configuring as an External Reference Unbuffered, Do I need to add 47uf between the REFBUF and GND?

Please, can you guide me how to achieve the continuous 5V on the VREFBUF pin to drive the ADC for 5V, because my input is vary from 0V to 5V.

2

The intended meaning of this phrase is not clear. Connecting REFIN to GND disables the internal buffer amplifier, allowing REFBUF to be driven to a value of your choosing, within allowed limits. It will not assume a potential of 5V by itself.

When using an external reference, it is permissible to set REFBUF to any value between 2.5 and 5V, with the understanding that the analog input range changes accordingly. Because you want to use a 0~5V input signal, you would want to use a 5V external reference and set the softspan code to 101, as suggested.

That depends on where you’re getting the 5V reference signal from. It is suggested to help filter the incoming reference signal, which is an input to the converter just as much as the analog input pins are. If the reference source is noise-free and well-buffered, the 47u may not be necessary. If it comes from a noisy 5v power supply rail, additional filtering may be needed to obtain a satisfactory result.