EMC6D103S datasheet(32/84 Pages) SMSC

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Fan Control Device with High Frequency PWM Support and Hardware Monitoring Features

Datasheet

Revision 0.2 (06-14-06)

SMSC EMC6D103S

DATASHEET

4. [5C-5Eh] Set the fan spin-up delays.

5. [5C-5Eh] Match each PWM output with a corresponding thermal zone.

6. [67-69h] Set the zone temperature low limits.

7. [6A-6Ch] Set the zone temperature absolute limits.

8. [64-66h] Set the PWM minimum duty cycle.

9. [81h] Associate a Tachometer input to a PWM output Register

10. [90-93h] Select the TACH Mode of operation (Mode 1 or Mode 2)

11. [90-93h] Set the number of edges per tach reading

12. [90-93h] Set the ignore first 3 edges of tach input bit

13. [90-93h] Set the SLOW bit to 0b if tach reading should indicated slow fan event as FFFEh and 1b

if stalled fan event as FFFFh.

14. [94-96h] Set the TACH Reading Update rate

15. [94-96h] Set the tach reading guard time (Mode 2 Only)

16. [94-96h] Set the TACH reading logic for Opportunistic Mode (Mode 2 Only)

17. [94-96h] Set the SZEN bit, which determines if the PWM output will ramp to Off or jump to Off.

18. [40h] Set bit 0 (Start) to start monitoring.

19. [40h] Set bit 1 (Lock) to lock the limit and parameter registers (optional)

7.1.3

PWM Fan Speed Control

Note: The following description applies to PWM1, PWM2, and PWM3.

When describing the operation of the PWMs, the terms “Full on” and “100% duty cycle” means that

the PWM output will be high for 255 clocks and low for 1 clock (INVERT bit = 0). The exception to this

is during fan spin-up when the PWM pin will be forced high for the duration of the spin-up time.

7.1.3.1

Manual Fan Control Operating Mode (Test Mode)

When operating in Manual Fan Control Operating Mode, software controls the speed of the fans by

directly programming the PWM duty cycle. The operation of the fans can be monitored based on

reading the temperature and tachometer reading registers and/or by polling the interrupt status

registers. The EMC6D103S offers the option of generating an interrupt indicated by the INT# signal

located on the PWM2 and TACH3 pins.

To control the PWM outputs in manual mode:

Write ‘111’ to bits[7:5] Zone/Mode, located in Registers 5Ch-5Eh: PWMx Configuration.

The speed of the fan is controlled by the duty cycle set for that PWM output. The duty cycle must

be programmed in Registers 30h-32h: Current PWM Duty

To monitor the fans:

Fans equipped with Tachometer outputs can be monitored via the TACHx input pins. See Section 7.1.4,

"Fan Speed Monitoring," on page 40.

If an out-of-limit condition occurs, the corresponding status bit will be set in the Interrupt Status

registers. Setting this status bit will generate an interrupt signal on the INT# pin (if enabled). Software

must handle the interrupt condition and modify the operation of the device accordingly. Software can

evaluate the operation of the Fan Control device through the Temperature and Fan Tachometer

Reading registers.

When in manual mode, the current PWM duty cycle registers can be written to adjust the speed of the

fans, when the start bit is set. These registers are not writable when the lock bit is set.

EMC6D103S Datasheet(PDF) 32 Page - SMSC Corporation

EMC6D103S Datasheet(HTML) 32 Page - SMSC Corporation

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