SI7021-A20

Part: Si7021-A20-GM1 — Silicon Labs

Type: I²C Humidity and Temperature Sensor

Description: Factory-calibrated digital relative humidity and temperature sensor with ±3% RH (max, 0–80% RH) and ±0.4 °C (max, -10 to 85 °C) accuracy, 1.9–3.6 V supply, and 150 μA active current in a 3x3 mm DFN-6 package.

Operating Conditions:

• Supply voltage: 1.9–3.6 V
• Operating temperature: -40 to +85 °C (G grade); -40 to +125 °C (I and Y grades)
• I²C clock: up to 400 kHz
• Humidity operating range: 0–100% RH, non-condensing

Absolute Maximum Ratings:

• Max supply voltage (VDD with respect to GND): 4.2 V
• Voltage on I/O pins: -0.3 V to VDD + 0.3 V
• Ambient temperature under bias: -55 to 125 °C
• Storage temperature: -65 to 150 °C
• ESD tolerance: 2 kV HBM, 1.25 kV CDM, 250 V MM

Key Specs:

• RH accuracy: ±2% typ, ±3% max (0–80% RH, 30 °C)
• Temperature accuracy: ±0.3 °C typ, ±0.4 °C max (-10 to 85 °C)
• Active current: 150 μA typ, 180 μA max (RH conversion); 90 μA typ, 120 μA max (temperature conversion)
• Standby current: 0.06 μA typ; 0.62 μA max (-40 to +85 °C), 3.8 μA max (-40 to +125 °C)
• Conversion time: 10 ms typ, 12 ms max (12-bit RH); 7 ms typ, 10.8 ms max (14-bit temperature)
• Powerup time: 18 ms typ, 25 ms max (25 °C); 80 ms max over full temperature range
• RH repeatability: 0.025 %RH RMS (12-bit); temperature repeatability: 0.01 °C RMS (14-bit)
• Long-term stability: <0.25 %RH/yr (RH); 0.01 °C/yr (temperature)
• Heater current: 3.1 to 94.2 mA (when enabled)
• Thermal resistance, junction to air: 256 °C/W (DFN-6, JEDEC 2-layer, no airflow)

Features:

• Precision relative humidity and temperature sensing
• Factory-calibrated, with calibration data stored in on-chip non-volatile memory
• I²C interface
• Integrated on-chip heater
• Excellent long-term stability
• Optional factory-installed protective cover
• Hardware- and software-compatible drop-in upgrade for 3x3 mm DFN-6 RH/temperature sensors

Applications:

• HVAC/R
• Thermostats/humidistats
• Respiratory therapy
• White goods
• Indoor weather stations
• Micro-environments/data centers
• Automotive climate control and defogging
• Asset and goods tracking
• Mobile phones and tablets

Package:

• 3x3 mm 6-pin DFN
• 3x3 mm 6-pin DFN with protective cover (optional)

• Precision Relative Humidity Sensor
• ± 3% RH (max), 0-80% RH
• High Accuracy Temperature Sensor
• ±0.4 °C (max), -10 to 85 °C
• 0 to 100% RH operating range
• Up to -40 to +125 °C operating range
• Wide operating voltage (1.9 to 3.6 V)
• Low Power Consumption
• 150 μA active current
• 60 nA standby current

• HVAC/R
• Thermostats/humidistats
• Respiratory therapy
• White goods
• Indoor weather stations

Unless otherwise specified, all min/max specifications apply over the recommended operating conditions.

Table 1. Recommended Operating Conditions

1. Absolute maximum ratings are stress ratings only, operation at or beyond these conditions is not implied and may shorten the life of the device or alter its performance.

2. Special handling considerations apply; see application note, 'AN607: Si70xx Humidity Sensor Designer's Guide'.

The primary function of the Si7021 is to measure relative humidity and temperature. Figure 4 demonstrates the typical application circuit to achieve these functions.

Figure 4. Typical Application Circuit for Relative Humidity and Temperature Measurement

Figure 10. 3x3 6-pin DFN

Table 16. 3x3 6-pin DFN Package Diagram Dimensions

1. All dimensions shown are in millimeters (mm).
2. Dimensioning and Tolerancing per ANSI Y14.5M-1994.