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Monitoring Voltage and Current with PSoC 1 | Cypress Semiconductor

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Monitoring Voltage and Current with PSoC 1

Last Updated: September 21, 2014

Question How do you monitor voltage and current with PSoC 1? What are the requirements for the same?

Response The voltage and current measurements are done using the ADC user module block. The values are either displayed or used for other data processing. The requirements and the associated application notes are provided below:

1. Port Pins: Only Port 0 pins (P0[0] to P0[7] thus limiting to 8 inputs) can be used. Since the voltage and current measurements will be analog, these are the only pins available through AMUX. (There are 4 port 2 pins (P2[0] to P2[3]) available that can be connected to switched capacitor blocks but they cannot be multiplexed).

2. For basic voltage measurement, if the voltage is high, then it needs to be scaled down to the PSoC voltage range and well above the offset range (0.01V). For this, external resistors are required for scaling. For information about accuracy and noise cancellation then AN2226 is helpful.

Correlated Double Sampling for Thermocouple Measurement - AN2226

3. For current measurement, the current needs to be converted into voltage before measuring, since there is no inherent trans-impedance amplifier in PSoC 1. AN2267 and AN2267a are on battery charging which demonstrate both voltage and current monitoring. Both App notes have different method of current sensing methods. These will are a good reference.

Power Management - Single Cell Li-Ion Battery Charger - AN2267

Power Management - Single Cell Li-Ion Battery Charger using CY8C21xxx

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