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AS7211 − Detailed Description

Photopic Sensor

The photopic sensor, part of the AS7211 CLE, is a

next-generation digital light sensor device which approximates

the human eye response. The sensor contains an integrating

analog-to-digital converter (16-bit resolution ADC), which

integrates current from photodiodes. Upon completion of the

conversion cycle, the result is transferred to the corresponding

data registers. Transfers are double-buffered to ensure integrity

of the data is maintained.

The photopic response is accomplished via silicon interference

filters which are extremely stable over time and temperature.

To ensure accuracy, the AS7211 LGA package contains an

internal aperture that limits the sensor field of view (PFOV ) of

± 20.5°, as shown in the figure above. External optics can be

used as needed to expand or reduce this built in PFOV.

AS7211 Inputs

Figure 16:

VDDHV Based Settings for Inputs

Note(s):

1. For VDDHV <= 3.6V, VDDHV and VDD should be tied together.

2. With external dividers connected to 0-10V inputs, the max voltage to the device input is 2V.

For the AS7211, dimming can be accomplished from either the

input pin (0_10V_DIM) or network commanded dimming using

the AS7211 Smart Lighting Command set via the UART

interface.

The typical example of a hardware controlled input is a standard

0-10V dimmer. The 0-10V DIM analog input signal is downscaled

by the AS7211 with an internal voltage divider and converted

to a 10 bit digital value, 0V=full dimming, 10V=no dimming.

When using the internal voltage divider the voltage at the

VDDHV pin has to be higher than 10V.

If a second supply is not available, VDDHV and VDD are tied

together and the downscale has to be done using an external

resistor divider. The maximum range in the downscaled input

is limited to 2V. Hence to accept a full range 10V signal the input

resistor divider has to be 5:1 ratio. Dependent on the level at

pin VDDHV, the Smart Lighting Manager automatically selects

either the internal or the external voltage divider. Refer to the

Figures above and below. If the 0_10V_DIM pin is not used, an

external resister pull-up connecting it to VDDHV is

recommended.

VDDHV

Dimming

10.5-15V

Direct input for 0_10V_DIM, dimming input

2.97-10V (1)

External 5:1 resistor divider for 0-10V_DIM, dimming input (2)

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