Sonoff Sensor Si7021

Overview

Sonoff Si7021 Temperature and Humidity Sensor is a digital temperature and humidity sensor with a calibrated digital signal output. It adopts dedicated digital module acquisition technology and temperature&humidity sensing technology to ensure that the sensor has a very high reliability and excellent long-term stability. The sensor includes an integrated single-chip temperature and humidity sensor chip, which connects to a high-performance 8-bit MCU. The Si7021 sensor has advantages such as excellent quality, ultra-fast response, anti-interference ability and cost-effective. The sensor has 2.5mm 4-pole stereo audio male plug connector, which works perfectly with Sonoff TH10/TH16.

Features

• Relative humidity and temperature measurement
• All calibrated, digital output
• Good long-term stability
• No additional parts required
• Ultra-low energy consumption
• The sensor is fully interchangeable

Electrical Characteristics

Rated Parameters

Parameter	Symbol	Min	Typ	Max	Unit
Voltage input	VCC	2.2	3.3	3.6	V
Operating temp.	Ta	-40	-	+85	℃
Storage temp.	Ta	-65	-	+150	℃

Performance parameters

Parameter	Condition	Min	Typ	Max	Unit
Humidity
Operating range		0	—	100	%RH
Accuracy	0-80	—	±2	±3	%RH
	80-100	See Figure 1
Temperture drift		—	0.05	—	%RH/℃
Stability		—	≤0.25	—	%RH/yr
Temperature
Operating range		-40	—	+85	℃
Accuracy	-10≤Ta≤85	—	±0.3	±0.4	℃
	-40≤Ta≤125	See Figure 2
Stability		—	≤0.01	—	℃/yr

Figure 1. RH Accuracy at 30℃

Figure 2. Temperature Accuracy

Hardware

Interface Description

It is recommended that the DATA pin use a 10K pull-up resistor and a 100nF capacitor can be added between the power supply pins (VCC, GND) for decoupling.

Audio Connector

Pins

Pin	Name	Description
1	VCC	Power supply 2.2~3.6VDC
2	GND	GND
3	NC	NC
4	DATA	Single bus, data port