BCM20732S Electrical Spec - Interfacing to Higher Voltages

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Anonymous
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1. What is the recommended maximum voltage that can be applied to any pin relative to VDDIO?  Or is it just the absolute range of 0V to 3.63V?  How is power consumption affected?

2. Same question, but relative to the ADC reference voltage.

I will give an example:

The BCM20732S has VDDIO=1.8V:

a. It is interfacing to a digital circuit that operates at 3.3V.  A 3.3V signal is coming into the BCM20732S through a GPIO input.  Does this voltage need to be clamped at 1.8V?  Ignore Vih and Vil issues.

b. It has the ADC reference voltage set at 1.2V.  It is interfacing to an analog circuit that operates at 3.3V.  A 3.3V signal is coming into the BCM20732S through an ADC channel.  Does this voltage need to be clamped at 1.8V?  At 1.2V?  If not, does the ADC value obtained from adc_readVoltage() just rail at 1.2V?

Thank you.

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1 Solution
Anonymous
Not applicable


Hello jpwerre,

GPIO and ADC Voltage Range Questions:

1. What is the recommended maximum voltage that can be applied to any pin relative to VDDIO?
      a. [JT] – 3.63V
2. What is the Absolute Range of voltage that can be applied to the ADC?
      a. [JT] – Absolute Range of voltage that can be applied is 0V to 3.63V
3. What is the ADC Reference Voltage?
      a. [JT] – The ADC Reference voltage is the Core Voltage which is always 1.2V
4. How is power consumption affected by the input voltage range to the ADC?
      a. [JT] – The voltage is clamped at the low end by the Core Voltage and at the high end by the VDDIO Voltage.

Use Case 1: BCM20732S has VDDIO=1.8V

1. A 3.3V input signal is applied to the GPIO Pin:
2. Does the 3.3V need to be clamped at 1.8V?
      a. [JT] – Yes, since the VDDIO=1.8V

Use Case 2: BCM20732S has ADC reference voltage =1.2V

1. A 3.3V analog signal is applied to the ADC
2. Does this 3.3V ADC signal need to be clamped at 1.8V?
      a. [JT] – The ADC signal should be clamped to the 1.2V voltage reference.
3. Is the ADC value obtained from adc_readVoltage() rail at 1.2V?
      a. [JT] – Yes.

Let me know if this answers your questions.

JT

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1 Reply
Anonymous
Not applicable


Hello jpwerre,

GPIO and ADC Voltage Range Questions:

1. What is the recommended maximum voltage that can be applied to any pin relative to VDDIO?
      a. [JT] – 3.63V
2. What is the Absolute Range of voltage that can be applied to the ADC?
      a. [JT] – Absolute Range of voltage that can be applied is 0V to 3.63V
3. What is the ADC Reference Voltage?
      a. [JT] – The ADC Reference voltage is the Core Voltage which is always 1.2V
4. How is power consumption affected by the input voltage range to the ADC?
      a. [JT] – The voltage is clamped at the low end by the Core Voltage and at the high end by the VDDIO Voltage.

Use Case 1: BCM20732S has VDDIO=1.8V

1. A 3.3V input signal is applied to the GPIO Pin:
2. Does the 3.3V need to be clamped at 1.8V?
      a. [JT] – Yes, since the VDDIO=1.8V

Use Case 2: BCM20732S has ADC reference voltage =1.2V

1. A 3.3V analog signal is applied to the ADC
2. Does this 3.3V ADC signal need to be clamped at 1.8V?
      a. [JT] – The ADC signal should be clamped to the 1.2V voltage reference.
3. Is the ADC value obtained from adc_readVoltage() rail at 1.2V?
      a. [JT] – Yes.

Let me know if this answers your questions.

JT