EMC2113 datasheet(69/88 Pages) MICROCHIP

69 / 88 page

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

Datasheet

 2013 Microchip Technology Inc.

DS20005251A-page 69

The Look Up Table Registers hold the 40 entries of the Look Up Table that control the drive of the

PWM. As the temperature channels are updated, the measured value for each channel is compared

against the respective entries in the Look Up Table and the associated drive setting is loaded into an

internal shadow register and stored.

The bit weighting for temperature inputs represents °C and is compared against the measured data.

Note that the LUT entry does not include a sign bit. The Look Up Table does not support negative

temperature values and the MSBit should not be set for a temperature input.

APPLICATION NOTE: When the PWM Input Duty cycle values are used, then the bit weighting represents a unit-

less threshold that does not corresponded to specific temperature values. It is used to drive

the fan speed based on external temperatures known to a separate microcontroller driving

the PWM_IN pin.

Each temperature channel threshold for a single “column” shares the same hysteresis value; however,

each temperature input has a different hysteresis value. When the measured temperature for any of

the channels meets or exceeds the programmed threshold, the drive setting associated with that

threshold is used. The temperature must drop below the threshold minus the hysteresis value before

the drive setting will be set to the previous value.

52h

R/W

LUT Temp 1

Setting 1

7Fh

(127°C)

53h

R/W

LUT Temp 2

Setting 1

7Fh

(127°C)

54h

R/W

LUT Temp 3

Setting 1

7Fh

(127°C)

55h

R/W

LUT Temp 4

Setting 1

7Fh

(127°C)

. . .

74h

R/W

LUT Drive

Setting 8

‘0’

4096

2048

1024

512

256

128

92h

‘1’

128

75h

R/W

LUT Temp

1Setting 8

7Fh

(127°C)

76h

R/W

LUT Temp 2

Setting 8

7Fh

(127°C)

77h

R/W

LUT Temp 3

Setting 8

7Fh

(127°C)

78h

R/W

LUT Temp 4

Setting 8

7Fh

(127°C)

79h

R/W

LUT Temp 1

Hysteresis

8421

0Ah

(10°C)

7Ah

R/W

LUT Temp 2

Hysteresis

8421

0Ah

(10°C)

7Bh

R/W

LUT Temp 3

Hysteresis

8421

0Ah

(10°C)

7Ch

R/W

LUT Temp 4

Hysteresis

8421

0Ah

(10°C)

Table 7.52 Look Up Table Registers (continued)

ADDR

R/W

RPM /

PWM

DEFAULT

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