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Part Number: TMCS1101
Other Parts Discussed in Thread: TMCS1100,

TMCS1101A1BQDR Vout drops Down as We Switch ON the load 

Without Load 2.42VDC

WIth AC Load  2.2VDC

  • VCC Given 5VDC.

    Load Given 220W.

    I am not getting any ADC Change at the Vout Side of MCU.

  • new mono switch.pdf

    Please find the Schematic in the attachment, We have used TMCS1101A1BQDR and also TMCS1101A2BQDR at the Place of U$1 pinout are the same. 

  • Rahul,

    I'll need some additional information to help diagnose the issue here. 

    1. The TMCS1101B us designed such that the output in a no load condition should be 2.5V. Do you know why your no load condition is 2.4V, or about 100 mV lower than this value. This seems odd, and makes me wonder if there is something off on the output node. Can you share what else is being interfaced to ground here? You mention you are digitizing this information, but I don't see any ADC connections off the load. Can I assume you are feeding this line into an ADC directly in a single ended configuration?

    2. Can you share the ADC information (resolution, sampling rate, device, etc.) here?

  • The TMCS1101B pin 7 (Vout) is connected to the P$23(ADC0) of the microcontroller. The adc information is as follows:

    Resolution: 10-bit

    device : N79E715

    Sampling rate:  150 ksps

  • Rahul,

    Is it possible to decouple the ADC from the TMCS1100 and see if this alleviates the offset and settling issue (cut trace on a board, desolder the MCU, etc.)? I am unfamiliar with this MCU, but I hypothesize what may be happening is due to loading effects and the inability to settle at a sampling rate this high. The BW of the TMCS1101 is only 80kHz, and to successfully drive an ADC at 150ksps, typically a buffer may need to be considered to ensure proper drive to within 1/2LSB. The period here is 6.67us, and the conversion period is going to eat a portion of this. What is your ADC clock speed, as the conversion time will be 35* this number. Subtracting the resulting time value should give you the acquisition time of the device. 

    Also, have you examined the TMCS1101 on a scope as the ADC is sampling to examine droop effects and resettling per sample?