AS1163 datasheet(27/91 Pages) AMSOSRAM

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AS1163

Functional description

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The 9 drivers are addressable with the command payload with numbering from 1 to 9 in the

following order: R0, R1, R2, B0, B1, B2, G0, G1, G2.

From now on, the device alternates a forward voltage measurement with a temperature

measurement, until the command READADCDAT is received. This command returns the last

forward voltage measurement and causes the device to resume the measurement routine

across all active drivers

After a SETADC command a READADCDAT must follow. Changing PWM value or issuing a

new SETADC command requesting a measurement on a different driver is not permitted until

the previous result has been read.

6.4.1.1

DRVx Vf measurement routine

DRVx Vf measurements are triggered by the respective PWM signal and are valid only for

PWM duty cycles above the minimum conversion time or sampling time.

This sequence allows a temperature measurement nominally every 5.7 ms when PWM at

500Hz is selected with all PWM drivers on.

The adjusted temperature sensor reading is stored in the temperature register (8 bits right

aligned out of the 10 bits of the ADC), while the DRVx OUT voltage readings are constantly

updating the VFMAX register (only for drivers that are not used for addressing, synch pin or I²C

bridge) and is stored in the READADCDAT register.

If the ADC_VLED_MUX_CTRL field in the SETADCSET register specifies a particular driver to

be measured, the ADC will cycle between the specified voltage to be measured and the

temperature, and the READADCDAT register is filled with the selected measurement.

DRVx measurements are triggered only if the respective driver is active, because all DRVx

voltage measurements are synchronized with the PWM start signal. If a particular driver is not

active or PWM setting is 0x00, the measurement is skipped, unless the bit

ADC_VLED_DISABLE_SYNC is selected in the SETADCSET register (this is also valid when

a measurement is triggered with the ADC_VLED_MUX_CTRL). In this case, the driver output

remains high-Z. To be noted: Driver output measurements are always referred to VDD.

Moreover, to ensure a correct measurement, the PWM output must be still active during the

ADC sampling time , otherwise the voltage measurement is not saved.

This poses a limitation to the minimum PWM setting in combination with Vforward

measurements.

AS1163 Datasheet(PDF) 27 Page - ams-OSRAM AG