A brief summary of the use of MAX9611/9612 current detection chips

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A brief summary of the use of MAX9611/9612 current detection chips [Copy link]

 

Attach the manual first

MAX9611AUB High-Side, Current-Sense Amplifiers with 12-B.pdf (2.41 MB, downloads: 144)

2021-6-29 17:58 上传

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Recently, due to project requirements, we need to use the MAX9611 chip to detect charging current.

The detection range is not very large, 0-4A, but I encountered a lot of problems when debugging the MAX9611 driver.

Attached is the internal structure diagram of the chip

First, the problem is the measurement range of the ADC inside the MAX9611. Although the same 12-bit ADC is used for sampling,

However, when calculating the measurement data, each channel corresponds to a different range, and it is fixed. Each ADC channel is different .

For example, when reading the bus voltage from the RS+ pin, the maximum measurement range is 65V, so the bus voltage is calculated as (ADC/4096*65000)mV;

The same is true for the OUT pin, the maximum value measured is also 65V;

The voltage value of the SET pin must also be measured. The manual states that the maximum measurement value of the pin is 1.126V, so the calculated pin voltage is (ADC/4096*1126)mV;

Then there is temperature. The measured value is only a 9-bit ADC value, which is 512. The measurement range is (-125-125)℃, and the actual effective value can only be (-40-125)℃. When calculating, it is (ADC*(125+125)/512)℃, and the accuracy is only 0.5℃.

The most complicated part is the current measurement. By connecting a sampling resistor Res in series between the RS+ and RS- pins of the chip, the voltage difference is obtained and input into the ADC after internal amplification. The input value amplification factor 1x, 4x or 8x can be configured here.

The corresponding measurement value Ranges are also different, namely 440mV, 110mV and 55mV. The calculation is ((ADC/4096)*Range/Res*1000)mV;

freebsder

Thanks for sharing.

dcexpert

TI's current measurement chip is also good, you can try it

zpf185961

Thanks