3.2.1.5 Current Measurement

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 3-6. PAC1934 Current Measurement
Table 3-5. PAC1934 Signal Descriptions
PIOMnemonicShared PIOSignal Description
PC28PC28_PAC1934POWER TWITWI data
PC29PC29_PAC1934POWER TWITWI clock
PB17INT_PAC1934–Interrupt