TC665 Microchip Technology Inc., TC665 Datasheet - Page 20

• Manufacturer Part Number: TC665
• Description: Smbus Pwm Fan Speed Controllers With Fan Fault Detection
• Manufacturer: Microchip Technology Inc.

TC664/TC665
6.4
The Status Register provides all the information about
what is going on within the TC664/TC665 devices. Fan
fault information, V
REGISTER 6-4:
DS21737A-page 20
STATUS REGISTER (STATUS)
bit 7-6
bit 5
bit 4
bit 3
bit 2
bit 1
bit 0
IN
status, RPM counter overflow
bit 7
Unimplemented: Read as ‘0’
OTF: Over Temperature Fault Condition
For the TC664/TC665 device, this bit is set to the proper state immediately at startup and is
therefore treated as an unknown (X). If V
cycle on V
bit will be set to ‘0’. This is determined at power-up.
1 = Over temperature condition has occurred.
0 = Normal operation, V
Unimplemented: Read as ‘0’
RCO: RPM Counter Overflow
1 = Fault condition. The maximum RPM reading of 12775 RPM in register RPM has been
0 = Normal operation. RPM reading is within limits (default).
VSTAT: V
For the TC664/TC665 devices, the V
external thermistor or voltage output network is connected (V
If an external network is detected, this bit is set to ‘0’. If the V
has not been selected in the Configuration Register, the V
1 = V
0 = Normal operation. Voltage present at V
Unimplemented: Read as ‘unknown’
FF: Fan Fault
1 = Fault Condition. The value for fan RPM in the RPM Register has fallen below the value set
0 = Normal Operation (default).
Legend:
R = Readable bit
-n = Value at POR
STATUS REGISTER (STATUS)
U-0
—
exceeded. This bit will automatically reset to zero when the RPM reading comes back into
range.
in the FAN_FAULT Threshold Register. The speed of the fan is too low and a fault condi-
tion is being indicated. The FAULT output will be pulled low at the same time. This fault bit
can be cleared using the Fan Fault Clear bit (FFCLR (bit 7<0>)) in the Configuration Reg-
ister.
IN
is open.
IN
OUT
Input Status
(2.6 V typical), then the bit will be set to a ‘1’. If it is less than the threshold, the
U-0
—
IN
OTF
R-X
is less than 2.6 V.
W = Writable bit
’1’ = Bit is set
IN
U-0
—
and over temperature indication are all available in the
Status Register. The Status Register is an 8-bit Read
only register with bits 1, 4, 6 and 7 unused. See
Register 6-4 below for the bit descriptions.
IN
pin status is checked immediately at power-up. If no
is greater than the threshold required for 100% duty
IN
.
U = Unimplemented bit
’0’ = Bit is cleared
RCO
R-0
OUT
IN
VSTAT
pin is open and SMBus operation
IN
duty cycle will default to 39.33%.
R-X
is open), this bit is set to a ‘1’.
2002 Microchip Technology Inc.
x = Bit is unknown
U-X
—
R-0
FF
bit 0