The SAMA5D2-ICP board embeds one PAC1934. The PAC1934 is a four-channel DC power/energy monitor with accumulator. A 16-bit ADC is used to measure voltages across a current sense resistor, connected by a differential multiplexer to (+) and (-) inputs for each channel.
Four current sense resistors (10 mΩ) are populated on-board for measuring voltage on power rails:
- 3.3V VDDIOP group (SENSE1_P and SENSE1_N)
- 3.3V VDDOSC, VDDUTMII, VDDANA, VDDAUDIOPLL, VDDSDHC (SENSE2_P and SENSE2_N)
- 1.35V VDDIODDR (SENSE4_P and SENSE4_N)
- 1.25V VDDCORE (SENSE3_P and SENSE3_N)
The PAC1934 communicates with the MPU via a TWI bus.
The figure below shows the current measurement.
Figure 1. PAC1934 Current Measurement
| PIO | Mnemonic | Shared PIO | Signal Description |
|---|---|---|---|
| PC28 | PC28_PAC1934 | POWER TWI | TWI data |
| PC29 | PC29_PAC1934 | POWER TWI | TWI clock |
| PB17 | INT_PAC1934 | – | Interrupt |