AnsweredAssumed Answered

mma8451 power consumption

Question asked by Mark Ross-Smith on Sep 20, 2018
Latest reply on Oct 1, 2018 by Mark Ross-Smith


I have developed a remote monitoring device that uses an MMA8451 communicating with an MSP430 microprocessor.  During development I used the MMA8451 on a breakout board, the intention being to use the "raw" chip in the production version.


The power consumption through the MMA8451 is 29uA which is very different from the 6uA I was expecting from the settings I am using.  My settings are:


 // ******************* Start Transient Detection ***********************
Transmit(CTRL_REG1, 0x18);                   // Enable Standby mode
Transmit(TRANSIENT_CFG, 0x08);          // Enable Transient Detection Z axis only
Transmit(TRANSIENT_THS, 0x03);          // Set Threshold >0.2G
Transmit(TRANSIENT_COUNT, 0x01);    // Set Debounce counter 12.5Hz, 80ms (0x02 = 160ms)
Transmit(CTRL_REG3, 0x40);                  // Transient wake, push-pull, active Low interrupt
Transmit(CTRL_REG4, 0x20);                 // Set Interrupt function in System
Transmit(CTRL_REG5, 0x20);                // Set Interrupt to pin Int1
Transmit(ASLP_COUNT, 0x02);             // Set sleep count 2 x 320ms = 640ms
Transmit(CTRL_REG2, 0x1F);                // Set Sleep Mode = low power, Active mode = low power
Transmit(CTRL_REG1, 0x65);                // ODR = 12.5Hz, ODR = 50Hz, Active mode
} // **************** End Transient Detection ****************************


Is the excessive power consumption because I am using the break-out version, and can I expect something closer to 6uA in the production version?