ZSSC3122 Datasheet

© 2018 Integrated Device Technology, Inc.

24

June 8, 2018

Table 10.3 Time Periods between Capacitance Measurements and Temperature Measurements for

Different Resolution and Update Rates

Total Time between

Capacitance Measurements (ms)

Total Time between

Temperature Measurements (ms)

CDC Resolution

(Bits)

Update Rate

00BIN

Update

Rate 01BIN

Update

Rate 10BIN

Update

Rate 11BIN

Update Rate

00BIN

Update Rate

01BIN

Update Rate

10BIN

Update Rate

11BIN

8

0.70

5.70

25.70

125.70

4.75

34.75

154.75

754.75

10

1.55

6.55

26.55

126.55

10.70

40.70

160.70

760.70

12

4.90

9.90

29.90

129.90

34.15

64.15

184.15

784.15

14

18.40

23.40

43.40

143.40

128.65

158.65

278.65

878.65

10.3.1.1 Data Fetch in Update Mode

In Update Mode, I2C and SPI are used to fetch data from the digital output register using a Data Fetch (DF) command (see section 10.6.3).

Detecting when data is ready to be fetched can be handled either by polling or by monitoring the Ready pin (see section 10.6.6 for details on

the Ready pin). The status bits of a DF tell whether or not the data is valid or stale (see section 10.4 regarding the status bits). As shown in

Figure 10.5 after a measurement cycle is complete, valid data can be fetched. If the next data fetch is performed too early, the data will be the

same as the previous fetch with stale status bits. As shown in Figure 10.5, a rise on the Ready pin can also be used to tell when valid data is

ready to be fetched.

Figure 10.5

I2C and SPI Data Fetching in Update Mode

Note: See section 10.2 for timing of measurements.

Ready Pin

Power down period

depends on selected

update rate

I2C/SPI

Data

Fetch

Write new corrected

signal measurement

to output register

(I2C or SPI)

Power Down

Power Down

Power Down

Cap

Conv

ZSSC3122

Core Activity

Cap

Calc

Temp

Calc

Temp

Conv

Cap

Calc

Cap

Conv

Cap

Calc

Cap

Conv

Write new corrected

signal measurement

to output register

(I2C or SPI)

Write new corrected

signal measurement

to output register

(I2C or SPI)

Serial Interface

Activity

I2C/SPI

Data

Fetch

I2C/SPI

Data

Fetch

I2C/SPI

Data

Fetch

I2C/SPI

Data

Fetch

Stale values

Valid read occurs

Stale values

Valid read occurs

Valid read occurs