Environmental Monitoring and Control Device
Datasheet
Chapter 7 Fan Control
The following sections describe the various fan control and monitoring modes in the part.
7.1
General Description
The EMC6D100/EMC6D101 device is capable of driving three DC fans and monitoring up to four fans with
tachometer outputs in either Manual Fan Control mode or in Auto Fan Control mode.
The fan outputs (PWMx pins) are controlled by a Pulse Width Modulation (PWM) scheme.
The four pins dedicated to monitoring the operation of each fan are the TACH[1:4] pins. Fans equipped
with Fan Tachometer outputs may be connected to these pins to monitor the speed of the fan.
7.2
Limit and Configuration Registers
At power up, all the registers are reset to their default values and PWM[1:3] are set to “Fan always on Full”
mode. Before initiating the monitoring cycle for either manual or auto mode, the values in the limit and
configuration registers should be set.
The limit and configuration registers are:
Registers 4Eh – 53h:
Zone x Temperature Low/High Limit registers
Registers 54h – 5Bh: TACHx Minimum
Registers 5Fh – 61h: Zone x Range/FANx Frequency
Registers 5Ch – 5Eh:FANx Configuration
Registers 62h − 63h: Min/Off, Zone x Spike Smoothing
Registers 64h – 66h: FANx PWM Minimum
Registers 67h – 69h: Zone x Fan Temp LIMIT
Registers 6Ah – 6Ch:Zone x Temp Absolute Limit – all fans to full
Registers 6Dh – 6Eh:Zone x Hysteresis
The limit and configuration registers are defined in section Chapter 8 Register Set on page 37.
Notes:
1) The START bit in Register 40h Ready/Lock/Start Register must be set to ‘1’ to start
temperature monitoring functions.
2) Setting the Fan Configuration register to Auto Mode will not take effect until after the START
bit is set.
SMSC EMC6D100/EMC6D101
Page 29
Rev. 09-09-04
DATASHEET
SMSC [ SMSC CORPORATION ]
