BMA145 Bosch Sensortec, BMA145 Datasheet - Page 10

• Manufacturer Part Number: BMA145
• Description: 3-AXIS ACCELEROMETER ANALOG I/F
• Manufacturer: Bosch Sensortec

Specifications of BMA145

• Axis: X, Y, Z
• Acceleration Range: ±4g
• Sensitivity: 300mV/g
• Voltage - Supply: 1.8 V ~ 3.5 V
• Output Type: Analog
• Bandwidth: 1.5kHz
• Interface: Parallel
• Mounting Type: Surface Mount
• Package / Case: 16-LGA
• For Use With: 828-1011 - BMA145 DAUGHTERCARD FOR DEV KIT
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: 828-1002-2

4
4.1
An internal power-on reset (POR) is implemented to ensure proper reset during power-up. The
POR is active during 100µs (typical value). For this application the power on sequence only
occurs when a battery or an external supply is connected to VDD. Normally GND is connected
first. There should be a coupling capacitor connected between VDD and GND as shown in
chapter 4.8. Low resistance connections are required between decoupling capacitor and sensor
pads (< 100Ohms).
4.2
Two operation modes can be selected: NORMAL and STAND-BY mode. The operation modes
are selected by setting SEL1 and SEL0 according to the table given below.
SEL.1
When stand-by mode is activated, all sensor electrodes are connected to Vss. No electrostatic
forces are generated to the electrodes. Power consumption is drastically reduced in this mode.
All blocks are disabled except some bias generation and power-on reset generation. This
feature enables ultra low power mode operation if the sensor module is turned into Standby
mode e.g. between each acceleration measurement.
4.3
Using the Channel Multiplexer, it is possible to choose specific axis output signals on the AMUX
pin. This allows the user to connect the triaxial BMA145 to an economical single channel AD
converter without loss of axis information. The channel selection on AMUX is performed by
setting SEL.0 and SEL.1 according to the following table. By setting both, SEL.0 and SEL.1 to
1, the sensor module is set to stand-by Mode.
Rev. 1.1
© Bosch Sensortec GmbH reserves all rights even in the event of industrial property rights. We reserve all rights of disposal such
as copying and passing on to third parties. BOSCH and the symbol are registered trademarks of Robert Bosch GmbH, Germany.
Note: Specifications within this document are subject to change without notice.
SEL.1
0
0
1
1
1
1
0
0
Operation
Power-on-reset and power-up sequence
Operation mode selection
Channel multiplexer output selection
SEL.0
SEL.0
0
1
0
1
0
1
0
1
Operation
NORMAL
STAND-
STAND-BY
Operation
NORMAL
NORMAL
NORMAL
Mode
BY
Mode
performance
Operation
Triaxial, analog acceleration sensor
Output Signal on Channel Multiplexer Serial Output Pin (AMUX)
Sensor module set to Standby Mode, no Signal on X, Y, Z and AMUX
Ax, Ay, Az plus AMUX = Ax
Ax, Ay, Az plus AMUX = Ay
Ax, Ay, Az plus AMUX = Az
feature
current
saving
full
Data sheet
Consumption
Page 10
BMA145
Current
(typical)
(typical)
200 µA
0,7 µA
Description
Acceleration measurements of all axes
(Ax, Ay, Az plus AMUX) are performed.
All sensor features are enabled.
Acceleration measurements are stopped,
Ax, Ay, Az and AMUX signals are driven
to GND through 110kΩ resistors.
Bosch Sensortec
02 April 2008