BH1621FVC-TR Rohm Semiconductor, BH1621FVC-TR Datasheet - Page 5

• Manufacturer Part Number: BH1621FVC-TR
• Description: IC AMBIENT LIGHT SENSOR 5WSOF
• Manufacturer: Rohm Semiconductor

Specifications of BH1621FVC-TR

• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

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BH1621FVC
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External parts Setting
1) Gain setting of BH1621FVC
2) Approximate formula of IOUT output voltage in each Gain Mode
3) C1
Please select the best gain controlled by 3 and 4pin based on the required illuminance range.
The reference is as follows.
This device will be mounted under the optical window in actual designing. Therefore, there is a possibility that the
illuminace to ALS ( Ambient Light Sensor ) will be less than the illuminance on the final product surface.
Please consider the attenuation of light through the optical window.
It is possible to detect illuminance up to about 5000 lx even in the H-Gain mode. However, the maximum output current
is about 3mA in this case. If you want to minimize consumption current, please use the L-Gain mode as much as possible.
Please set output resistance value ( R1 ) within the range of 1 kΩ ~ 1MΩ which needs to be smaller than the input
impedance of the next circuit.
(1) H-Gain mode
The output voltage is calculated as below.
Viout= 0.60 x 10
(2) L-Gain mode
Viout= 0.063 x 10
(1) To reject the flicker light..
(2) To control backlight smoothly by using illuminance value.
Please note that the rise time becomes slow at power-on and recovery from shutdown mode to operation mode.
Viout is IOUT output voltage [V]. Ev is an illuminance of the ALS surface [lx].
( For example ) In case you want to convert the illuminance value up to 500 lx by ADC.
If the maximum voltage of ADC input is 2V, output resistor value will be as below.
In case IOUT output is R1 only and an ALS receives the artificial lights such as fluorescent lamps and incandescent
lamps synchronized with 50/60 Hz of AC power supplies, the output current has a ripple. If you want to reject this ripple,
please add C1 to R1 in parallel. Please set it to C1 x R1 = about 0.1 as a time constant.
C1 is effective to control backlight smoothly for a rapid changing of the illuminance. In this case, please set it to C1 x R1
= about 1 ~ 10 as a time constant. It is not necessary if you average illuminance value with software to change backlight
smoothly.
R1 is IOUT output resistor[Ω].
R1 = Viout/(0.60 x 10
Illuminance detection range [lx]
= 2 /(0.60 x 10
-6
~50,000
-6
~1000
x Ev x R1
x Ev x R1
-6
x 500) = 6667[Ω]
-6
x Ev)
⇒6.8[kΩ]
H-Gain Mode
L-Gain Mode
Gain Mode
5/9
Technical Note
2009.04- Rev.B