www.sensirion.com

Version 1 – March 2022

5/21

2.3 Interface Specifications

The SCD42 comes in an LGA package (Table 6). The package outline is schematically displayed in chapter 4.1. The landing

pattern of the SCD42 can be found in chapter 4.2.

Name

Comments

VDD

Supply voltage

VDDH

Supply voltage IR source, must

be connected to VDD on

customer PCB

GND

Ground contact

SDA

SCL

DNC

Do not connect, pads must be

soldered to a floating pad on

the customer PCB

Table 6 Pin assignment (top view). The notched corner of the protection membrane serves as a

polarity mark to indicate pin 1 location.

VDD and VDDH are used to supply the sensor and must always be kept at the same voltage, i.e. should both be connected to

the same power supply. The combined maximum current drawn on VDD and VDDH is indicated in Table 4. Care should be

taken to choose a low noise power supply, which is adequately dimensioned for the relatively large peak currents. The power

supply should be designed such that voltage variations caused by external influences remain below 5 mV. Consequently, no

other components causing larger load variations should be supplied by the same voltage regulator. Sensirion recommends

integrating a low-dropout regulator, LDO, such as the Toshiba TCR2EF33,LM(CT.

avoid signal contention, the microcontroller must only drive SDA and SCL low. For dimensioning resistor sizes please take bus

should be noted that pull-up resistors may be included in I/O circuits of microcontrollers.

Figure 1: Typical application circuit (for better clarity in the image, the positioning

of the pins does not reflect the positions on the real sensor). VDD and VDDH must

be connected to each other close to the sensor on the customer PCB.

14

NXP’s I2C-bus specification and user manual UM10204, Rev.6, 4 April 2014