ZMOD4450 Datasheet

© 2021 Renesas Electronics Corporation

11

June 30, 2021

Table 7.

Typical ZMOD4450 Sensor Module Accuracy Achievable with Calibration

Parameter

Conditions

Minimum

Typical

Maximum

Unit

Accuracy

With additional calibration

±15

%

Consistency

Part-to-Part Variation

±25

%

Durability to Siloxanes

Change in sensitivity

±5

%

7.4 Sensor Module Algorithm and Firmware

To operate the ZMOD4450, the software and libraries provided by Renesas should be used. The algorithm for the user’s microprocessor always

uses the raw output signals from the ZMOD4450, which are resistances, to determine the change of RAQ gases. Depending on the

microprocessor and compiler used, the firmware and its algorithms require 10 to 20 kB flash size. All algorithms feature an automated baseline

correction function, ensuring that the module can learn from its environment and distinguish elevated levels of gases under all conditions. The

proprietary metal oxide (MOx) used in the sensor ensures that the sensor module can respond effectively to changing RAQ gases during long-

term operation. Therefore, the user focus should always be on the relevant output parameter: The Air Quality Change Rate.

For implementing the sensor module in a customer-specific application, detailed information on the programming is available. More information

and guidance on the firmware integration, architecture, and supported platforms are available in the ZMOD4450 Programming Manual – Read

Me. Code Examples in C and additional firmware descriptions for API, HAL, libraries, etc., are included at no cost in the downloadable firmware

package from the ZMOD4450 product page.

8. Assembly Restrictions, Operation, Integration Notes, and Storage

When implementing the ZMOD4450 in electrical circuit boards, a gas sensor module may react to chemicals during the assembly process and

to outgassing components, such as resins from the printed circuit board (PCB) assembly. A standard soldering profile can be used to assemble

the ZMOD4450 on the user’s PCB and should fulfill the IPC/JEDEC J-STD-020C Standard (“Moisture/Reflow Sensitivity Classification for Non-

hermetic Solid State Surface Mount Devices”). A typical lead-free reflow solder profile is shown in Figure 4. After assembly, an outgassing of

the PCB and electronic components must be considered, especially when operating the sensor module at elevated temperatures. This will

ultimately influence the sensor module signal and may dominate the air quality reading. A PCB heat treatment before assembling the ZMOD4450

is recommended. After the gas sensor module assembly, no coating, cleaning, or ultrasonic bath should be applied to the PCB. Also, in case

the sensor module’s parts are contaminated during assembly or storage, the device can be cleaned after assembly by using the cleaning library

provided with the firmware to remove any contamination of solder vapor from the MOx surface. In case the sensor module does not show full

performance after a cleaning cycle, a change to the protection sticker package is recommended (see Ordering Information). Store the sensor

module in an antistatic metallic bag with a low TVOC background after the sensor module is removed from its original packaging or the

assembled PCB is populated. The optimal storage conditions are < 1 ppm TVOC, < 100 ppb O3, < 100 ppb NO2, 10°C to 50°C, and humidity

levels within 20% to 80%RH. If the sensor module is stored outside of these conditions for extended periods of time, the sensor module readings

can exhibit a temporary offset. The sensor module can be reconditioned and brought back to its calibration state by operation for 24 to 48 hours

in clean air.

To receive the Renesas Gas Sensor Guidelines with detailed information and on assembly, material outgassing, test and validation procedures,

contact Renesas via the contact information on the last page.