EMC2300-AZC-TR SMSC, EMC2300-AZC-TR Datasheet - Page 43

• Manufacturer Part Number: EMC2300-AZC-TR
• Description: Industrial Temperature Sensors Auto Fan Contrllr Up to 4 Fans
• Manufacturer: SMSC

Specifications of EMC2300-AZC-TR

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

Fan Control Device with High Frequency PWM and Temperature Monitors
Datasheet
SMSC EMC2300
7.1.4.9
7.1.4.10
FREQUENCY
PWM
(HZ)
87.7
58.6
35.2
29.3
21.9
14.6
44
11
Note 7.4
Note 7.5
Note 7.6
Note 7.7
Detection of a Stalled Fan
There is a fan failure bit (TACHx) in the interrupt status register used to indicate that a slow or stalled
fan event has occurred. If the tach reading value exceeds the value programmed in the tach limit
register the interrupt status bit is set. See Interrupt Status register 2 at offset 42h.
Notes:
Fan Interrupt Status Bits
The status bits for the fan events are in Interrupt Status Register 2 (42h). These bits are set when the
reading register is above the tachometer minimum and the Interrupt Enable 2 (Fan Tachs) register bits
are configured to enable Fan Tach events. No interrupt status bits are set for fan events (even if the
fan is stalled) if the associated tachometer minimum is set to FFFFh (registers 54h-5Bh).
The reading register will be forced to FFFFh if a stalled event occurs (i.e., stalled event =no edges
detected.)
The reading register will be forced to either FFFFh or FFFEh if a slow fan event occurs. (i.e., slow
event: 0 < #edges < programmed #edges). If the control bit, SLOW, located in the TACHx Options
registers at offsets 90h - 93h, is set then FFFEh will be forced into the corresponding Tach Reading
Register to indicate that the fan is spinning slowly.
The fan tachometer reading register stays at FFFFh in the event of a stalled fan. If the fan begins
to spin again, the tachometer logic will reset and latch the next valid reading into the tachometer
reading register.
(MSEC)
17.12
22.73
11.42
25%
2.85
4.27
5.68
8.53
PULSE WIDTH AT DUTY CYCLE
7.1
100% duty cycle is 255/256.
RPM=60/T
(PWM ”ON” Time – Guard Time). Minimum RPM values shown use minimum guard time
(88.88usec).
100% duty cycle is 255/256
RPM=60/T
2*(PWM ”ON” Time-Guard Time). Minimum RPM values shown use minimum guard time
(88.88usec).
(PWM ”ON” TIME)
Table 7.3 Minimum RPM Detectable Using 2 Edges
(MSEC)
Revolution
Revolution
17.06
22.83
34.25
45.45
11.36
50%
8.53
14.2
5.7
, T
, T
TachPulse
TachPulse
DATASHEET
(Note
(MSEC)
100%
11.36
22.64
45.48
68.23
90.55
28.3
17
34
= T
= T
43
7.6)
Revolution
Revolution
MINIMUM RPM AT DUTY CYCLE
/2. Using 3 edges for detection, T
/2. Using 2 edges for detection, T
5433
3588
2683
2139
1777
1324
25%
881
663
(30/T
2673
1777
1331
1063
50%
TachPulse
884
660
439
331
Revision 0.32 (06-23-08)
)
(Note
100%
1331
TachPulse
887
665
532
442
330
220
166
TachPulse
7.7)
=
=