EMC1813 datasheet(24/102 Pages) MICROCHIP

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5.15

Programmable External Diode Ideality Factor

The EMC1812/13/14/15/33 device family is designed for external diodes with an ideality factor of 1.008.

Not all external diodes, processor or discrete, will have this exact value. This variation of the ideality

factor introduces errors in the temperature measurement which must be corrected for. This correction is

typically done using programmable offset registers. Since an ideality factor mismatch introduces an error

that is a function of temperature, this correction is only accurate within a small range of temperatures. To

provide maximum flexibility to the user, the EMC1812/13/14/15/33 devices provides a 6-bit register for

each external diode where the ideality factor of the diode used is programmed to eliminate errors across

all temperatures.

When monitoring a substrate transistor or CPU diode and beta compensation is enabled, the ideality

factor should not be adjusted. Beta compensation automatically corrects for most ideality errors.

When measuring a 65 nm Intel

® CPU, the Ideality Setting should be the default 12h. When measuring a

45 nm Intel CPU, the Ideality Setting should be 15h.

These registers store the ideality factors that are applied to the external diodes. The following table

defines each setting and the corresponding ideality factor. Since beta compensation and Resistance Error

Correction automatically correct for most diode ideality errors, it is not recommended that these settings

be updated without consulting Microchip.

Table 5-7. Ideality Factor Look-Up Table (Diode Model)

Setting

Factor

Setting

Factor

Setting

Factor

08h

0.9949

18h

1.0159

28h

1.0371

09h

0.9962

19h

1.0172

29h

1.0384

0Ah

0.9975

1Ah

1.0185

2Ah

1.0397

0Bh

0.9988

1Bh

1.0200

2Bh

1.0410

0Ch

1.0001

1Ch

1.0212

2Ch

1.0423

0Dh

1.0014

1Dh

1.0226

2Dh

1.0436

0Eh

1.0027

1Eh

1.0239

2Eh

1.0449

0Fh

1.0040

1Fh

1.0253

2Fh

1.0462

10h

1.0053

20h

1.0267

30h

1.0475

11h

1.0066

21h

1.0280

31h

1.0488

12h

1.0080

22h

1.0293

32h

1.0501

13h

1.0093

23h

1.0306

33h

1.0514

14h

1.0106

24h

1.0319

34h

1.0527

15h

1.0119

25h

1.0332

35h

1.0540

16h

1.0133

26h

1.0345

36h

1.0553

17h

1.0146

27h

1.0358

37h

1.0566

Multi-Channel Low-Voltage Remote Di...

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Datasheet

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