EMC2113 datasheet(48/88 Pages) MICROCHIP

48 / 88 page

RPM-Based Fan Controller with Multiple Temperature Zones & Hardware Thermal Shutdown

Datasheet

DS20005251A-page 48

 2013 Microchip Technology Inc.

7.8

Beta Configuration Register

The Beta Configuration Register controls advanced temperature measurement features of the External

Diode channels.

If External Diode 1 is selected as the hardware shutdown measurement channel (see Section 6.1,

"Critical/Thermal Shutdown") then the External Diode 1 Beta register will be read only. If the internal

diode is selected, then this register can be written normally. Likewise, if the External Diode 2 channel

is selected then this register can be written normally. Finally, if External Diode 2 is selected as the

hardware shutdown measurement channel, then the External Diode 2 Beta Configuration Register will

be read only.

The External Diode 3 channel beta configuration will always be set at 07h (disabled / diode mode).

Writing to a read only register will have no affect. The data will be ignored.

Bit 4 - AUTOx - Enables the Automatic Beta detection algorithm for the External Diode X channel.



‘0’ - The Automatic Beta detection algorithm is disabled. The BETAx[2:0] bit settings will be used

to control the beta compensation circuitry.



‘1’ (default) - The Automatic Beta detection algorithm is enabled. The circuitry will automatically

detect the transistor type and beta values and configure the BETAx[2:0] bits for optimal

performance.

Bits 2 - 0 - BETAx[2:0] - hold a value that corresponds to a range of betas that the Beta Compensation

circuitry can compensate for. These three bits will always show the current beta setting used by the

circuitry. If the AUTO bit is set (default), then these bits may be overwritten with every temperature

conversion. If the AUTO bit is not set, then the value of these bits is used to drive the beta

compensation circuitry. In this case, these bits should be set with a value corresponding to the lowest

expected value of beta for the PNP transistor being used as a temperature sensing device.

See Table 7.13, "Beta Compensation Look Up Table" for supported beta ranges. A value of 111b

indicates that the beta compensation circuitry is disabled. In this condition, the diode channels will

function with default current levels and will not automatically adjust for beta variation. This mode is

used when measuring a discrete 2N3904 transistor or AMD thermal diode.

The Beta Configuration Registers are Software Locked.

Table 7.12 Beta Configuration Register

ADDR

R/W

DEFAULT

14h

R/W

External Diode 1

Beta

Configuration

AUT

BETA1[2:0]

10h

15h

R/W

External Diode 2

Beta

Configuration

AUT

BETA2[2:0]

10h

Table 7.13 Beta Compensation Look Up Table

BETAX[2:0]

MINIMUM BETA

210

000

< 0.08

001

< 0.111

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