EMC6D103S-CZC-TR SMSC, EMC6D103S-CZC-TR Datasheet - Page 37

• Manufacturer Part Number: EMC6D103S-CZC-TR
• Description: Industrial Temperature Sensors Auto Fan Contrllr Up to 4 Fans
• Manufacturer: SMSC

Specifications of EMC6D103S-CZC-TR

• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

Fan Control Device with High Frequency PWM Support and Hardware Monitoring Features
Datasheet
SMSC EMC6D103
7.1.3.3
Temp
PWM
Duty
Cycle
Spin Up
When a fan is being started from a stationary state (PWM duty cycle =00h), the part will cause the fan
to “spin up” by going to 100% duty cycle for a programmable amount of time to overcome the inertia
of the fan (i.e., to get the fan turning). Following this spin up time, the fan will go to the duty cycle
computed by the auto fan algorithm.
During spin-up, the PWM duty cycle is reported as 0%.
To limit the spin-up time and thereby reduce fan noise, the part uses feedback from the tachometers
to determine when each fan has started spinning properly. The following tachometer feedback is
included into the auto fan algorithm during spin-up.
Auto Fan operation during Spin Up:
The PWM goes to 100% duty cycle until the tachometer reading register is below the minimum limit
(see
until the tachometer enters the valid count range, unless the spin up time expires. If the spin up expires
before the tachometer enters the valid range, an interrupt status bit will be set once spin-up expires.
Note that more than one tachometer may be associated with a PWM, in which case all tachometers
associated with a PWM must be in the valid range for spin-up to end.
Tmax
=Tmin
+Trange
Tmin
Notes:
1. When exiting spin-up, the PWM is set to the current calculated PWM
2. The PWM is set to OFF when the current temperature is less than
Max
=FFh
min
(Tmin-Hysteresis Temp)
(Fan off when temperature is below minimum)
Figure
Spin-Up
Time
7.3), or the spin-up time expires, whichever comes first. This causes spin-up to continue
MIN/OFF bit = 0
Figure 7.2 Automatic Fan Control
Hysteresis
Temperature
DATASHEET
Hysteresis
Time
Time
37
Temp
PWM
Duty
Cycle
Tmax
=Tmin
+Trange
Tmin
Max
=FFh
min
(Fan stays on when temperature is below minimum)
MIN/OFF bit = 1
Revision 0.3 (03-01-07)
Time
Time