Name: Flora UV Index Sensor - Si1145 Light Sensor
Brand: Adafruit
SKU: 1981

Logical pinout · physical placement not verified

Vin
Input to the onboard regulator; Adafruit says power with 3-5VDC and notes reverse-polarity protection.
Type · PowerVoltage · 3-5VDC input
GND
Signal and power ground; connect to microcontroller ground.
Type · GroundVoltage · 0V
3Vo
3.3V output from the onboard regulator; Adafruit says up to 100mA can be drawn.
Type · PowerVoltage · 3.3V output, up to 100mA
INT
Interrupt output from the SI1145 with a 10K pullup to 3.3V; indicates when conversions are done.
Type · SignalVoltage · pulled up to 3.3V
LED
Open-collector IR LED drive pin for proximity use; Adafruit says connect IR LED cathode to this pin and anode to 3-5VDC, with sink spikes up to 300mA.
Type · SignalVoltage · open collector, LED anode to 3-5VDC
SCL
I2C clock pin for the SI1145; connect to the microcontroller I2C clock master pin.
Type · I2CVoltage · 3V or 5V logic safe, level shifted
SDA
I2C data pin for the SI1145; connect to the microcontroller I2C data master pin.
Type · I2CVoltage · 3V or 5V logic safe, level shifted

Pin	Type	Function	Voltage
Vin	Power	Input to the onboard regulator; Adafruit says power with 3-5VDC and notes reverse-polarity protection.	3-5VDC input
GND	Ground	Signal and power ground; connect to microcontroller ground.	0V
3Vo	Power	3.3V output from the onboard regulator; Adafruit says up to 100mA can be drawn.	3.3V output, up to 100mA
INT	Signal	Interrupt output from the SI1145 with a 10K pullup to 3.3V; indicates when conversions are done.	pulled up to 3.3V
LED	Signal	Open-collector IR LED drive pin for proximity use; Adafruit says connect IR LED cathode to this pin and anode to 3-5VDC, with sink spikes up to 300mA.	open collector, LED anode to 3-5VDC
SCL	I2C	I2C clock pin for the SI1145; connect to the microcontroller I2C clock master pin.	3V or 5V logic safe, level shifted
SDA	I2C	I2C data pin for the SI1145; connect to the microcontroller I2C data master pin.	3V or 5V logic safe, level shifted

Logical pinout · physical placement not verified

Pin details

7 connections

Vin
Input to the onboard regulator; Adafruit says power with 3-5VDC and notes reverse-polarity protection.
PowerVoltage · 3-5VDC input
GND
Signal and power ground; connect to microcontroller ground.
GroundVoltage · 0V
3Vo
3.3V output from the onboard regulator; Adafruit says up to 100mA can be drawn.
PowerVoltage · 3.3V output, up to 100mA
INT
Interrupt output from the SI1145 with a 10K pullup to 3.3V; indicates when conversions are done.
SignalVoltage · pulled up to 3.3V
LED
Open-collector IR LED drive pin for proximity use; Adafruit says connect IR LED cathode to this pin and anode to 3-5VDC, with sink spikes up to 300mA.
SignalVoltage · open collector, LED anode to 3-5VDC
SCL
I2C clock pin for the SI1145; connect to the microcontroller I2C clock master pin.
I2CVoltage · 3V or 5V logic safe, level shifted
SDA
I2C data pin for the SI1145; connect to the microcontroller I2C data master pin.
I2CVoltage · 3V or 5V logic safe, level shifted

Start wiring

I2C · Analog · 3.3 – 5 V · Breakout

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Module pins: Vin, 3Vo, GND, INT, LED, SCL, SDA. Schematik maps them to your board in the app.

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