AN3109

Sensors

2

Freescale Semiconductor

SLEEP MODE FUNCTION

The g-Select series accelerometers feature a sleep mode

function, activated by a sleep mode option on the device’s

pinout. The sleep mode pin is an active high pin, enabling the

device “on” when VDD is applied to that pin (pin 12).

This is selectable on the evaluation board using either the

INPUT/OUTPUT sleep mode Pad or the dip switch that is

provided. When the dip switch is activated, the device is

enabled. The same occurs with the Sleep Mode Pad. When

the user attaches a 3.3 V or VDD voltage to this, the device will

be enabled. A VCC connection to this pin will place the device

in standby mode. If the device is enabled, the LED labeled

sleep mode will be lit.

The sleep mode allows the accelerometer to operate on

standby at 3 µA supply current. Regular operation uses

500 µA of supply current.

NOTE

Power Consumption is 3 µA during Sleep mode operation,

and 500 µA during normal operation. Note that when verifying

this information during prototyping, it is necessary to remove

the LEDs from the Evaluation Board. These have been

designed in to provide a clear indication of the part’s states,

but draw additional current as all items share the common

input voltage terminal.

QUICK STARTUP GUIDE

Figure 1. Evaluation Board Components for KIT3109

1. Connect the external power source to the Evaluation

board. The 3.3 V input is connected to the POWER

(VDD) and Ground (VSS) using the solder pads.

2. Note that the Main Power LED will turn on when the

Main Board Switch is thrown.

3. Next use a pointed object to turn the Sleep Mode

Dipswitch to the ‘ON’ position.

• You will notice that the Sleep Mode LED will light up

once the Sleep Mode Dip Switch is turned to the

“ON” position. This means that the device will have

X, Y, and Z outputs on the output pads. Sleep mode

will actually be disabled and the device is now

active.

• When “OFF”, no output voltages should be seen,

and the LED will be off. This will mean the board is

in Sleep Mode, in low power consumption.

4. Start to measure the voltages on the X, Y, and Z axes.

Solder these pads to your microcontroller A/D terminals

or other measuring devices.

The evaluation board has pads for interfacing to a 3.3 V

power source or battery. The pads on the side of the board

also provide a means for connecting to the accelerometer

analog output by soldering a wire from the evaluation board to

another breadboard or system. The ON/OFF switch provides

power to the accelerometer and helps preserve battery life if a

battery is being used as the power source. S1 must be set

towards the ON position for the accelerometer to function. The

green LED labeled PWR is lit when power is supplied to the

accelerometer.

Main Board Switch

Main Power LED

Sleep Mode LED

Sleep Mode

Dipswitch

ON/OFF

X,Y, ZOutput

pads

POWER

Ground

Accelerometer

Output Signals