 2002 Microchip Technology Inc.

DS21737A-page 19

TC664/TC665

6.3

CONFIGURATION REGISTER

(CONFIG)

The Configuration Register is an 8-bit, read/writable,

multi-function control register. This register allows the

user to clear fan faults, select RPM resolution, select

fan current pulses per rotation for the fan (for fan RPM

calculation) and put the TC664/TC665 device into a

shutdown mode to reduce power consumption. See

Register 6-3 below for the Configuration Register bit

descriptions.

REGISTER 6-3:

CONFIGURATION REGISTER (CONFIG)

R/W-0

R/W-0

R/W-0

U-0

U-1

R/W-0

R/W-1

R/W-0

FFCLR

RES

DUTYC

—

—

FPPR

FPPR

SDM

bit 7

bit 0

bit 7

FFCLR: Fan Fault Clear

1

= Clear Fan Fault, this will reset the Fan Fault bit in the Status Register and the FAULT out-

put.

0

= Normal Operation (default)

bit 6

RES: Resolution Selection for RPM Output Register

1

= RPM Output Register (RPM) will be set for 25 RPM (9-bit) resolution.

0

= RPM Output Register (RPM) will be set for 50 RPM (8-bit) resolution. (default)

bit 5

DUTYC: Duty-Cycle Control Method

1

duty-cycle will be taken from the duty-cycle register (DUTY_CYCLE).

0

(default)

bit 4

Unimplemented: Read as '0'

bit 3

Unimplemented: Read as '1'

bit 2-1

FPPR: Fan Pulses Per Rotation

The TC664/TC665 device uses this setting to understand how many current pulses per revolu-

tion the fan should have. It then uses this as part of the calculation for the fan RPM value for

the RPM Register. See Section 7.7 for application information on determining your fan’s

number of current pulses per revolution.

00

=1

01

= 2 (default)

10

=4

11

=8

bit 0

SDM: Shutdown Mode

1

= Shutdown Mode. See Section 4.9 for more information on low power shutdown mode.

0

= Normal Operation. (default)

Legend:

R = Readable bit

W = Writable bit

U = Unimplemented bit

-n = Value at POR

’1’ = Bit is set

’0’ = Bit is cleared

x = Bit is unknown