MAX32550 Current Measurement Breakdown of Peripherals
Usually the power consumption numbers in the datasheet of a chip are not a good representation of real-life application. This application note tries to explain the setup and typical conditions under which the measurements are taken for the MAX32550 EV kit. At the end, the results are presented in graphical form.
To measure the current on the single power supply of the board, jumper JP17 of the MAX32550 EV kit is removed and based on the test of a digital ammeter inserted between the jumper heads or a current probe clamped to a small jumper wire connected across JP17.
Let the MAX32550 power up normally. As it goes through different sequences such as secure boot, loading code, and running freeRTOS, the current is measured during each operation. This data is presented in Figure 1. The different operations are clearly marked on this figure.
Figure 1. Current profile during power-up and running freeRTOS.
The breakdown of average power consumption for each operation per supply rail is presented in Table 1.
Table 1. Breakdown of Average Power and Current Consumption Per Operations
|Current Consumption on 3.3V (mA)||Total Power for Each Operation (mW)|
|Running code (freeRTOS)||64||212|
|Magnetic Card Transaction||1||3.3|
Table 2. Breakdown of Average Power Consumption Per Peripherals
|VDD = 3.3V (µA) (typ)||Total Power for Each Block (mW)|
|Smart Card Controller||390||1.3|
The breakdown of the current per peripheral is shown graphically in Figure 2.
Figure 2. Breakdown of average current consumption per peripherals.
Conclusion and Observations
- Turning off the PLL reduces the current from 64mA to 13mA
- The highest contributions to total current are the MSR, color TFT, DMA controller, and the cryptography engine.
- Smart card operation and magnetic card reading have very little effect on the power rails.
- The 3.3V rail is mainly plateaued at 64mA.
- STOP mode power consumption is around 230mW