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Maithil Pachchigar

Let's Compare SAR & Δ-Σ Converters for a Mux'd DAS: Part 3

Maithil Pachchigar
Victor Lorenzo
Victor Lorenzo
12/17/2013 6:07:04 AM
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Re: Simple SAR
Yes, it was randomly producing artifacts (spurius) and the digital filter used by the Δ-Σ ADC had a very long setting time (40+ samples), the ENOB was 9 bits (12 bits ADC) even in the demostration kit. The device was supposed to remain in low power mode 98% of the time and wake-up once every second to make some checks and take some temperature samples but we needed to implement strategies for detecting and correcting those errors. It seems it was caused by something related to internal power and clock control logic, probably correlated with the temperature variations the device was standing. The errors were detected when the device was already deployed and operating in field.

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Vishal Prajapati
Vishal Prajapati
12/16/2013 11:42:19 PM
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Master
Re: Simple SAR
Why? Was there any accuracy problem with internal ADC?

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Victor Lorenzo
Victor Lorenzo
12/16/2013 10:30:00 AM
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Re: Simple SAR
"I am big fan of integrated ADCs with the microcontorller". Me too. It's a feature that in many situations greatly simplifies the external hardware. But I was very disappointed a few years ago with one SoC (based on one ARM7TDMI@50MHz core) when using the internal ADC for measuring ambient temperature.

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Vishal Prajapati
Vishal Prajapati
12/16/2013 2:39:07 AM
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Master
Simple SAR
I like the simplicity of SAR ADCs. I am big fan of integrated ADCs with the microcontorller. I used to provide simple RC LPF in front of MCU ADC pin. In some cases I provide unity gain amp along with RC LPF to provide low impedence output.

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More Blogs from Maithil Pachchigar
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Multiplexing allows the use of fewer ADCs per system, offering significant savings in power, size, and cost.
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