BMA253
Data sheet
Page 13
4. Functional description
Note: Default values for registers can be found in chapter 6.
4.1 Supply voltage and power management
The BMA253 has two distinct power supply pins:
• VDD is the main power supply for the internal blocks
• VDDIO is a separate power supply pin used for supplying power for the interface
There are no limitations on the voltage levels of both pins relative to each other, as long as
each of them lies within its operating range. Furthermore, the device can be completely
switched off (VDD = 0V) while keeping the VDDIO supply on (VDDIO > 0V) or vice versa.
When the VDDIO supply is switched off, all interface pins (CSB, SDI, SCK, PS) must be kept
close to GNDIO potential.
The device contains a power-on reset (POR) generator. It resets the logic part and the register
values after powering-on VDD and VDDIO. Please note, that all application specific settings which
are not equal to the default settings (refer to 6.2 register map), must be re-set to its designated
values after POR.
There are no constraints on the switching sequence of both supply voltages. In case the I²C
interface shall be used, a direct electrical connection between VDDIO supply and the PS pin is
needed in order to ensure reliable protocol selection. For SPI interface mode the PS pin must
be directly connected to GNDIO.
BST-BMA253-DS000-01 | Revision 1.0 | August 2015
Bosch Sensortec
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Note: Specifications within this document are subject to change without notice.
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