RD3172MMA7455L Freescale Semiconductor, RD3172MMA7455L Datasheet - Page 25

• Manufacturer Part Number: RD3172MMA7455L
• Description: EVAL BOARD FOR MMA7455L
• Manufacturer: Freescale Semiconductor
• Series: ZSTAR3r

Specifications of RD3172MMA7455L

• Design Resources: ZSTAR3 Schematic
• Sensor Type: Accelerometer, 3 Axis
• Sensing Range: ±2g, 4g, 8g
• Interface: RF
• Sensitivity: 16, 32, 64 LSB/g
• Voltage - Supply: 3V
• Embedded: Yes, MCU, 16-Bit
• Utilized Ic / Part: MMA7455
• Acceleration: 5000 g
• Sensing Axis: Triple Axis
• Output Type: Digital
• Interface Type: I2C, SPI
• Operating Voltage: 3.6 L
• Operating Current: 490 uA
• Maximum Operating Temperature: + 85 C
• Minimum Operating Temperature: - 40 C
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• For Use With/related Products: MMA7455L

3.2.5
A CR2032 Lithium battery provides a fairly limited charge for such a real-time-like demo that demands
frequent transmissions. Some sort of power management has to be implemented in order to keep the
current consumption at a reasonable level.
Typically, current consumptions of the Sensor Board components are as follows:
It is obvious that in a battery operated application care must be taken to ensure the lowest possible current
consumption, especially when the maximum current (provided by the battery) is somehow limited. A
CR2032 Lithium battery cannot provide current in the range of 40 mA for long periods of time. To alleviate
high current surges, an additional large capacitor has been designed.
For transmission and reception using the MC13213, a specific scheme has been used to ensure the battery
is not depleted or overloaded, targeting a 30 samples per second (33 ms period) transmission rate. For
better power management, the software uses a system of skipping transmission if sensor output data is the
same or very similar to the last transmitted sample. The maximum count of skip transmissions is 10, then
sensor data is always transmitted. Every received transmission from the sensor board clears the time-out
counter in the USB stick. The ZSTAR3 sensor board typically opens a receive window every 10th period
(~333 ms) to maintain synchronization with the USB stick (Communication Master) and to receive
possible control data from the master.
1. The MMA7660FC is supported by new PCB with revision code 00288_04.
Freescale Semiconductor
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SiP - System in Pack MC13213
— 2.4GHz transceiver of the MC13213
— 8-bit microcontroller of the MC13213
Tri-axial accelerometers
— low-g tri-axial analog sensor MMA7361L
— low-g tri-axial digital sensor MMA7455L
— low-g tri-axial digital sensor MMA7660FC
– in Off mode, 200 nA
– in Hibernate mode, 2.3 μA
– in Doze mode, 35 μA
– in Idle mode, 500 μA
– in Transmit mode, 30 mA
– in Receive mode, 37 mA
– in Stop3 mode, 700 nA
– in Wait mode, 560 μA
– in Run mode, 6.5 mA
– in Sleep mode, 3 μA
– in Normal mode, 400 μA
– in Sleep mode, 5 μA
– in Normal mode, 400 μA
– in Sleep mode, 2 μA
– in Normal mode, Configurable down to 47 μA
Power Management
DRM103, Rev. 2
1
ZSTAR3 Sensor Board Description
25