EMC1822 datasheet(32/103 Pages) MICROCHIP

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Read ROC Status register: For the third conversion, the ROC Status register (3Fh) reads F0h. The

initial slope of the sample period is positive, going from +25°C to +35°C. A change in temperature

from 35°C to 30°C causes a slope change, the number of slope changes is now 1 (odd). See ROC

Status register (3Fh) bit descriptions for more clarification.

10. Stabilize ambient temperature of device to 45°C.

11. Initiate One-Shot conversion: Write a value of FFh in register 0Fh.

12. Read ROC Status register: For the fourth conversion the ROC Status register (3Fh) should read

C0h. The previous slope was negative, going from +35°C to +30°C. A change in temperature from

+30°C to +45°C causes a slope change, the number of slope changes is now two (even).

13. Stabilize ambient temperature of device to +35°C.

14. Initiate One-Shot conversion: Write a value of FFh in register 0Fh.

15. Read ROC Status register: For the fifth conversion the ROC Status register (3Fh) should read FCh.

The previous slope was positive, going from +30°C to +45°C. A change in temperature from +45°C

to +35°C causes a slope change, the number of slope changes is now three (odd). Once the final

conversion of the sample period is completed, the ROC result is calculated using the equation

below and compared to the ROC HB/LB Limit registers. In this scenario, the ROC limit was

exceeded and the appropriate bits were set in the ROC Status register.

16. Read ROC Result HB/LB ROC Result register: Once the final conversion of the sample period is

completed, the ROC result is calculated using the following equation. This value is loaded into the

ROC HB/LB result register. Based on the equation, the result is 5:

ROCResults= 35−25��2

4 =5:

The ROCx high byte and low byte are in 9-bit signed two's complement format. The MSB of the low

byte is the LSB of the corresponding high byte. For this example the ROC HB and LB would be as

follows:

Table 7-11. ROC1,2/3 High-Byte (40h, 44h)

Sign

Table 7-12. ROC Low-Byte (45h)

LSB

HB2

—

HB1

—

0 (Note)

Note: Fractional value.

17. Read Global Max register (4Dh): The Global Max value is 2Dh or 45°C. The Global Max register

contains a history of the highest temperature value. This value is reset only at POR and it is

updated at the end of each ROC sample period.

18. Read Sample Period Max Register (49h): The Sample Period Max value should be 2Dh or 45°C.

This register contains the highest temperature value for a given sample period and is updated after

each temperature conversion.

Multi-Channel Low Voltage Temp Sens...

System Block Diagram

Datasheet

DS20006048A-page 32

EMC1822 Datasheet(PDF) 32 Page - Microchip Technology

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