Datasheet

Designing the VEML6070 UV Light Sensor
Into Applications
Application Note
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Vishay Semiconductors
APPLICATION NOTE
Revision: 26-Mar-18
2
Document Number: 84310
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Fig. 2 - Application Circuit
The value for the pull-up resistors should be 2.2 kΩ.
The supply current of this device is also dependent on the R
SET
value. When activated for measuring it is typically 100 μA; in
shut-down mode (SD = 1) it is typically just 1 μA.
The resistor R
SET
value at pin 4 of the VEML6070 needs to be selected depending on the application and required sensitivity.
The table below shows how this value also affects the integration time that is programmed within the command register with
bits 2 and 3 (IT0 and IT1).
The VEML6070 shows its peak sensitivity at 355 nm. Bandwidth (λ
0.5
) is achieved for a range of about 335 nm to 375 nm.
Fig. 3 - Relative Responsivity vs. Wavelength
EXAMPLE OF RELATION BETWEEN INTEGRATION TIME AND R
SET
VALUE
REGISTER SETTING
REFRESH TIME
R
SET
= 300 kΩ R
SET
= 600 kΩ R
SET
= 1.2 MΩ
(IT1 : IT0)
(0 : 0) = 1/2T 62.5 ms 125 ms 250 ms
(0 : 1) = 1T 125 ms 250 ms 500 ms
(1 : 0) = 2T 250 ms 500 ms 1000 ms
(1 : 1) = 4T 500 ms 1000 ms 2000 ms
I
2
C bus data SDA
I
2
C bus clock SCL
GPIO (INT)
SDA (3)
SCL (5)
ACK (2)
GND (1)
V
DD
(6)
C1
100 nF
2.7 V to 5.5 V
1.7 V to 5.5 V
R2R1
R
SET
(4)
R3
R5
270 kΩ
Host
Micro Controller
VEML6070
10
100
1000
10000
0
10
20
30
40
50
60
70
80
90
100
300 350 400 450 500 550 600
Axis Title
1st line
2nd line
2nd line
Normalized Output (%)
λ - Wavelength (nm)
2nd line