ADS1148-Q1: Ads1148-q1design requirements

Zhonghui Xu

Part Number: ADS1148-Q1
Other Parts Discussed in Thread: ADS1148, ADS114S06, ADS114S08

Hi team,

We need a 16 bit high-precision ADC to collect the output signal of Hall sensor to achieve high-precision sampling requirements. Ads1148-q1 is a 16 bit ADC. The chip channel is differential or single channel signal compatible mode, but if using single signal acquisition, single power supply, how to design the specific circuit?

If I use the ADC to collect 6-channel Hall sensor voltage signals, and the signal input range is 0 ~ 5V, where should I connect the common input? How to design? Please help to see, or please recommend a more suitable ADC, thank you.

Best regards,

over 3 years ago

0 Bryan Lizon86 over 3 years ago

TI__Mastermind 34971 points

Hi Zhonghui,

Do you need an automotive (-Q1) ADC for your application? Or will a standard ADC be okay? Not all of our ADCs are -Q1 qualified so we will have more limited options if this is a requirement.

The ADS1148-Q1 is not the best choice for single-ended measurements as the PGA has common-mode range limitations as shown below in equation 3 (this is taken from the ADS1148 datasheet). You can see that if AVDD = 5V, AVSS = 0V, PGA = 1, and your input range is 0-5V, then VIN(MAX) = 5 and equation 3 results in:

0V + 0.1V + (5*1) / 2 ≤ VCM ≤ 5V - 0.1V - (5*1) / 2

2.6V ≤ VCM ≤ 2.4V --> this result does not make any sense

This means the configuration you need is not supported by the ADS1148.

If you do not need a -Q1 qualified ADC, I would suggest the ADS114S06. This device has 6 analog inputs with a common connection point (AINCOM) that can be used for your sensors. The ADS114S08 has a PGA, but the PGA can be bypassed so that the ADC can measure signals from AVSS to AVDD. To use the ADC's total code range, I would suggest biasing the AINCOM pin to 2.5V.