ZSSC3122 datasheet(13/64 Pages) IDT

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ZSSC3122 Datasheet

January 25, 2016

1.6

Temperature Sensor Nonlinearity

Temperature sensor nonlinearity can vary depending on the type of calibration and the selected calibration points.

It is highly recommended that a temperature calibration is done with calibration points at least 20°C apart from

each other. Figure 1.6 and Figure 1.7 show the resulting nonlinearity error for the full temperature range (-20°C to

125°C) using the optimal calibration points, 0°C and 100°C for a first-order fit and -20°C, 40°C, and 100°C for a

second-order fit.

Figure 1.6

First Order Fit (Typical Part)

Figure 1.7

Second Order Fit (Typical Part)

2 Circuit Description

2.1

Signal Flow and Block Diagram

As seen in Figure 2.1, the ZSSC3122 comprises three main blocks: the analog core, digital core, and output

communication. The capacitive input is first sampled by the analog core using a charge-balancing CDC and is

adjusted for the appropriate capacitance range using the CDC_Offset, and CDC_Reference. The digital core

corrects the digital sample with an on-chip digital signal processor (DSP), which uses coefficients stored in

EEPROM for precise conditioning. An internal temperature sensor can be used to compensate for temperature

effects of the capacitive input. A temperature value can also be calibrated and output as a 14-bit reading.

The corrected capacitance value can be read using four different output types, I

2C™, SPI, PDM, and alarms.

They can all be directly interfaced with a microcontroller, and optional filtering of the PDM output can provide a

ratiometric analog output. The alarm pins can also be used to control a variety of analog circuitry.

Temperature Error

-0.5

-0.4

-0.3

-0.2

-0.1

0.0

0.1

0.2

0.3

0.4

0.5

-50

100

150

Temperature (°C)

Temperature Error

-0.5

-0.4

-0.3

-0.2

-0.1

0.0

0.1

0.2

0.3

0.4

0.5

-50

100

150

Temperature (°C)

ZSSC3122 Datasheet(PDF) 13 Page - Integrated Device Technology

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