1.3 Supply Current Measurement
The current consumption of the TA100 device can be measured by using the EV39Y17A
24-Pad VQFN socket board. The only devices on the board that will
consume power are the TA100 socketed device, the Power LED and the I2C
pull-up resistors. Follow these steps to measure the current:
- Modify the board to remove the resistor, R1, which is in series with the LED. This will remove the current through the LED from the total measured current.(1)
- Install the TA100 device into the socket.
- Install the socket board into the host system with the appropriate power settings.
- Select either 3.3V or 5V power for the measurement.(2)
- Connect the high side of the ammeter to the 3.3V or 5V supply.
- Connect the low side of the ammeter to the common PWR signal of the header.
- Current measurements can now be taken by running various TA100 commands and measuring the current. (3)
Note:
- For lower accuracy current measurements, this resistor may be kept in the circuit. It is recommended that a separate measurement of the current through just the LED path be made prior to measuring the TA100 device currents. This value can, then, be subtracted from the total current measured.
- The host board provides power to the mikroBUS extension board, so whichever supply is selected must match the capabilities and setting used on the host board.
- When measuring the current of I2C devices, the measurement will include the I2C pull-up currents used to pull up the bus. For SPI signals, the pull-ups are internal to the device and will also factor into the total current consumed.