Setting Of Automatic Luminance Control - Epson S1F76680 Technical Manual

7.3.2 Setting of automatic luminance control

[1] Connection of a sensor
For enabling automatic luminance control, a luminance sensor and resistor have to be connected externally.
Connect the sensor between V
shown below.
When current flowing to the sensor is assumed IPD, VPD=IPD×RPD is established. S1F76680 uses this
VPD to evaluate brightness on the scale of 1 to 16.
The voltage at PDOUT and PD pins is 0V in the standby state.
Measures, such as shorter wiring between the sensor and sense resistor and S1F76680, stable V
supply, etc, are required to avoid noise influence as much as possible.
It is recommended that CPD, a capacitor in the range from 0.1 to 1µF, be connected between VPD and
PDOUT pin as shown below as a measure.
[2] Selection of brightness evaluation sampling cycle
The S1F76680 sensor evaluates brightness in the brightness evaluation sampling cycle (TSAMPL).
The following values can be selected for the sampling cycle by setting SAMPL pin.
When using default sampling cycle (655msec), set SAMPL pin to "OPEN."
* This pin is pulled up to V
S1F76680 Technical Manual (Rev.1.22)
Downloaded from Elcodis.com electronic components distributor
SS2
CPD
VPD
IPD
Sensor
Brightness
Sensor
evaluation
SAMPL pin setting
H (pulled up)
L
=V
DD1
7. OPERATIONAL AND FUNCTIONAL DESCRIPTION
and PD pin, and sense resistor RPD between PDOUT and PD pin as
PDOUT
RPD
PD
V
SS2
LED current
setting table
Sampling cycle (TSAMPL)
level in the IC.
DD2
EPSON
S1F76680
LED driver
Brightness evaluation
Sampling cycle TSAMPL
655msec
1310msec
level
SS2
9