NOA1305

http://onsemi.com

10

POWER_CONTROL Register (0x00)

The POWER_CONTROL register is used to power the

device up and down via software control. By default this

device powers up in the power ON mode. To reduce power

consumption, the NOA1305 can be powered down at any

time by writing 0x00 to this register.

To power up the device, use the following write command

sequence:

1. Issue Start command

0x39 followed by write−bit 0)

3. Issue 0x00 for the POWER_CONTROL register

address

4. Issue 0x08 to put the device in the power on state

5. Issue Stop command

After applying power to the device or after issuing a

power−on command, stable ALS_DATA and INT signal

may not be available for the first three integration times. For

master should wait at least 600 ms before accessing this

device.

To power down the device, use the following write

command sequence:

1. Issue Start command

0x39 followed by write−bit 0)

3. Issue 0x00 for the POWER_CONTROL register

address

4. Issue 0x00 to put the device in the power down

state

5. Issue Stop command

should wait at least 1.5 ms before accessing this device.

The data registers are set to their default values when

power is first applied to the device. However the

power−down and power−on commands do not affect the

values of the data registers.

The test modes provide a useful debugging mode as they

cause the device to output known values in place of the

ALS_DATA values.

RESET Register (0x01)

Software reset is controlled by this register. Setting this

register followed by an I2C_STOP sequence will

immediately reset the NOA1305 to the startup standby state

and clear the ALS_DATA register. However the values of

the other data registers are not affected.

To reset the device, use the following write command

sequence:

1. Issue Start command

0x39 followed by write−bit 0)

3. Issue 0x01 for the RESET register address

4. Issue 0x10 to reset the device

5. Issue Stop command

After issuing a reset command, the device will reset the

RESET register to 0x00.

INTEGRATION_TIME Register (0x02)

The INTEGRATION_TIME register controls the

integration time of the ambient light sensor which directly

affects the sensitivity.

To set the integration time, use the following write

command sequence:

1. Issue Start command

0x39 followed by write−bit 0)

3. Issue 0x02 for the INTEGRATION_TIME register

address

4. Issue 0x02 to set the integration time to 200 ms

(for example)

5. Issue Stop command

INT_SELECT Register (0x03)

The INT_SELECT register controls the polarity of the

interrupt pin INT and enables or disables interrupts on that

pin.

To specify low to high transitions on INT to signal an

interrupt, use the following write command sequence:

1. Issue Start command

0x39 followed by write−bit 0)

3. Issue 0x03 for the INT_SELECT register address

4. Issue 0x01 to specify low to high signaling on INT

5. Issue Stop command

To specify low to high transitions on INT to signal an

interrupt, use the following write command sequence:

1. Issue Start command

0x39 followed by write−bit 0)

3. Issue 0x03 for the INT_SELECT register address

4. Issue 0x02 to specify high to low signaling on INT

5. Issue Stop command

Disabling interrupts causes the INT pin to be held in the

open−drain or high state. To disable interrupts completely on

the INT pin, use the following write command sequence:

1. Issue Start command

0x39 followed by write−bit 0)

3. Issue 0x03 for the INT_SELECT register address

4. Issue 0x03 to disable interrupts on INT

5. Issue Stop command

INT_THRESH_LSB and INT_THRES_MSB Registers

(0x04, 0x05)

The INT_THRESH register specifies an ambient light

threshold value for signaling interrupts on the INT pin. The

INT_THRESH register is 16−bits wide to match the 16−bit

8−bit registers for the least and most significant bits (LSB

and MSB). On any measurement cycle where the

ALS_DATA intensity count exceeds the INT_THRESH

value, the INT pin will become active and will remain active

until a measurement cycle where the count is less than or