TC654/TC655

DS20001734C-page 20

 2002-2014 Microchip Technology Inc.

6.4

STATUS REGISTER (STATUS)

The Status register provides all the information about

what is going on within the TC654/TC655 devices. Fan

and over-temperature indication are all available in the

Status register. The Status register is an 8-bit Read-

Only register with bits 6 and 7 unused. See Register 6-

4 below for the bit descriptions.

REGISTER 6-4:

STATUS REGISTER (STATUS)

U-0

U-0

R-X

R-0

R-0

R-X

R-0

R-0

—

—

OTF

R2CO

R1CO

VSTAT

F2F

F1F

bit 7

bit 0

bit 7-6

Unimplemented: Read as ‘0’

bit 5

OTF: Over-Temperature Fault Condition

For the TC654/TC655 device, this bit is set to the proper state immediately at start-up and is therefore

(2.6V typical), then the bit will be set to a ‘1’. If it is less than the threshold, the bit will be set to ‘0’. This

is determined at power-up.

1

= Over-Temperature condition has occurred.

0

bit 4

R2CO: RPM2 Counter Overflow

1

= Fault condition. The maximum RPM reading of 12775 RPM in register RPM2 has been exceeded.

This bit will automatically reset to zero when the RPM reading comes back into range.

0

= Normal operation. RPM reading is within limits (default).

bit 3

R1CO: RPM1 Counter Overflow

1

= Fault condition. The maximum RPM reading of 12775 RPM in register RPM1 has been exceeded.

This bit will automatically reset to zero when the RPM reading comes back into range.

0

= Normal operation. RPM reading is within limits (default).

bit 2

1

0

bit 1

F2F: Fan 2 Fault

1

= Fault Condition. The value for fan RPM in the RPM2 Register has fallen below the value set in the

FAN_FAULT2 Threshold Register. The speed of Fan 2 is too low and a fault condition is being indi-

cated. 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 Register.

0

= Normal Operation (default).

bit 0

F1F: Fan 1 Fault

1

= Fault Condition. The value for fan RPM in the RPM1 Register has fallen below the value set in the

FAN_FAULT1 Threshold Register. The speed of Fan 1 is too low and a fault condition is being indi-

cated. 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 Register.

0

= Normal Operation (default).

Legend:

R = Readable bit

W = Writable bit

U = Unimplemented bit, read as ‘0’

-n = Value at POR

’1’ = Bit is set

’0’ = Bit is cleared

x = Bit is unknown