BMA253 current consumption when using Low-power Mode 2 to detect free-fall

[Coleman]

Hello

I am reading two Sensor data (Acceleration data and Temperature sensor) on BMA253.

And using Orientation recognition and Low-g interrupt.

I am using Low-power Mode 2 (please see my previous post.)

The bandwidth = 1kHz, and the sleep duration = 25ms.

Today I measured the current consumption of my board using a Digital Multi Meter.

I realized that the current comsumption of BMA253 in Low-power Mode 2 wasn't as low as the current consumption that is mentioned in the datasheet.

The current consumption was almost close to what was mentioned for the Normal Mode, which is 130 uA.

I measured the current consumption with only the orientation interrupt enabled, then the current consumption was about 66 uA.

But when I measured the current consumption with the low-g interrupt enabled, then the current consumption was about 130 uA, even though the power mode was in Low power Mode 2.

I assumed the current consumption was going to be around 66 uA, but the result was different.

Am I misunderstanding something?

Why does the current consume more than 66 uA (close to 130 uA) in Low power Mode 2?

Thank you in advance.

[FAE_CA1 · Accepted solution]

Hi,

Thanks for your inquiry.

BMA253 low power mode 2 is automatically switching between normal mode (130uA) and standby mode (62uA) according to the selected sleep time. When the sleep time is set to 25ms and the bandwidth is set to 1KHz, then the typical average current consumption becomes 66uA as shown in the datasheet.

However, when you enable low-g interrupt in low power mode 2 with the low-g threshold and duration parameters that you set, BMA253 will spend more time which is the low-g duration in normal mode to take measurements to see if low-g interrupt condition is met or not. If the condition is not met, then BMA253 will enter standby mode and wait for another 25ms sleep time to expire so that it can enter normal mode again. If the condition is met, then BMA253 will generate low-g interrupt. For example, if the sleep time is still 25ms and the low-g duration is set to 200ms for about 20cm height freefall detection, then BMA253 will consume close to 130uA. This is because 25ms sleep time @62uA plus 200ms normal mode (130uA) will result in about 122uA average current which is close to 130uA.

Thanks.

Thanks.

[Coleman]

Hello,

Thank you for the reply.

I understand that when I enable low-g interrupt in Low-power mode 2, BMA253 will spend more time in normal mode to take measurements to see if low-g interrupt condition is met or not.