SHT40

Part: SHT4x (Sensirion)

Type: 16-bit Relative Humidity and Temperature Sensor

Description: 4th Generation, High-Accuracy, Ultra-Low-Power, 16-bit Relative Humidity and Temperature Sensor Platform with up to ±1.5 %RH and ±0.1 °C accuracy, operating from 1.08 V to 3.6 V and featuring I2C communication.

Operating Conditions:

• Supply voltage: 1.08 V – 3.6 V
• Operating temperature: -40 to 125 °C
• Operating RH range: 0 to 100 %RH

Absolute Maximum Ratings:

• Max supply voltage: 3.6 V (based on operating range, no explicit VDD max in AMR table)
• Max junction/storage temperature: 150 °C

Key Specs:

• SHT45 RH accuracy (typ.): ±1.5 %RH
• SHT45 T Accuracy (typ.): ±0.1 °C
• Supply voltage: 1.08 V to 3.6 V
• Average supply current (low repeatability, 1 meas/s): 0.4 μA
• Idle supply current: 0.08 μA
• RH Resolution: 0.01 %RH
• Temperature Resolution: 0.01 °C
• Measurement duration (low repeatability): 1.3 ms (typ.)

Features:

• Relative humidity accuracy: up to ±1.5 %RH
• Temperature accuracy: up to ±0.1 °C
• Supply voltage: 1.08 V … 3.6 V
• Average current: 0.4 μA (at meas. rate 1 Hz)
• Idle current: 80 nA
• I2C fast mode plus, CRC checksum
• Fully functional in condensing environment
• Variable power heater

Package:

• four-pin dual-flat-no-leads package

• Relative humidity accuracy: up to ±1.5 %RH
• Temperature accuracy: up to ±0.1 °C
• Supply voltage: 1.08 V … 3.6 V
• Average current: 0.4 μA (at meas. rate 1 Hz)
• Idle current: 80 nA
• I2C fast mode plus, CRC checksum

Figure 11 Pin assignment (transparent top view). Dashed lines are only visible if sensor is viewed from below. The die pad is not directly connected to any pin.

Figure 11 Pin assignment (transparent top view). Dashed lines are only visible if sensor is viewed from below. The die pad is not directly connected to any pin.

The laser marking consists of two lines, indicated in Figure 11 . In the first line a filled circle serves as pin-1 indicator and is followed by 'SH4'. The last character will indicate the accuracy class of this product (here 'x' serves as place holder). In the second line, the first three characters specify the product characteristics according to positions 7,8 and 9 of Table 9 . The second three characters serve as internal batch tracking code.

Valid for all electrical specifications: Typical values correspond to V DD = 3.3 V and T = 25 °C. Min. and max. values are valid in the full temperature range -40 °C … 125 °C and at declared V DD levels.

Figure 7: SHT41 typical and maximal temperature accuracy.

Stress levels beyond those listed in Table 5 may cause permanent damage or affect the reliability of the device. These are stress ratings only and functional operation of the device at these conditions is not guaranteed. Ratings are only tested each at a time.

Table 5: Absolute maximum ratings.

The sensor shows best performance when operated within the recommended normal temperature and humidity range of 5 °C … 60 °C and 20 %RH … 80 %RH, respectively. Long term exposure to conditions outside recommended normal range, especially at high relative humidity, may temporarily offset the RH signal (e.g. +3 %RH after 60 h at > 80 %RH). After returning into the recommended normal temperature and humidity range the sensor will recover to within specifications by itself. Prolonged exposure to extreme conditions may accelerate ageing.

To ensure stable operation of the humidity sensor, the conditions described in the document (Sensirion, 2020) regarding exposure to volatile organic compounds have to be met. Please note as well that this does apply not only to transportation and manufacturing, but also to operation of the SHT4x.

Table 8 Typical values for thermal metrics. In the 'heater on' columns a heater power of 200 mW was assumed. Soldering of the die pad is not recommended, therefore the two right hand side columns are bold. Values are based on simulation.

Figure 9 Dimensional drawing of SHT4x including package tolerances (units mm).