Looking for a microcontroller with ADC recommendation

[craigeasdale]

I'm looking for a microcontroller to interface with a few strain gauges and cut out the intermediate amplifier and ADC. I know that a lot more is being integrated into the microcontrollers these days and SoCs are pretty common for every application.

So if I wanted to remove the amp/ADC external compontents, I need to find a microcontroller that can provide a decent ADC with PGA. Does anyone know of any?

My requirements:

• Low power microcontroller (<5uA standby)
• 3ch. differential ADC with good noise filtering(16-bit or higher)
• on-board Programmable Gain Amplifier (x64 gain or higher)
• Not too expensive (<$3.50 @1k)
• SPI, I2C, UART

[xiangjun_rong]

Hi, Craig,

Regarding your question, I recommend you use Kinetis KM family or KL family.

Because you test the strain gauges signal  which is differential signals, and you do not want to use AMP to convert the differential signals to single-end signal, so the required ADC must support differential input.

At the time being, the Kinetis has two ADC module SAR ADC and AFE(Analog Front End), the SAR ADC supports 4 channels differential signal inputs(ADC0_DP0/ADC0_DM0, ADC0_DP1/ADC0_DM1, ADC0_DP2/ADC0_DM2,ADC0_DP3/ ADC0_DM3), but the SAR ADC does not support programmable gain feature.

The AFE module support differential analog input with programmable gain, the maximum gain is *32.

The KL family is a low cost and low power processor with SAR ADC and the required serial port(SPI,IIC,Uart), but the sar ADC does not support programmable gain, for example you can refer to KL43.

The KM family has AFE module, but it needs more power than Kl family.

This is KM family link:

ARM Cortex-M0+|Kinetis KM3x 50-75 MHz 32-bit MCUs|NXP 

This is KL family link:

Kinetis L Series Microcontrollers - Arm® Cortex™-M0+ Core|NXP 

Hope it can help you

BR

Xiangjun Rong