Datasheet

 2002-2013 Microchip Technology Inc. DS21737B-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
V
OUT
duty cycle (fan speed) control method, select the
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 = The V
OUT
duty-cycle will be controlled via the SMBus interface. The value for the V
OUT
duty-cycle will be taken from the duty-cycle register (DUTY_CYCLE).
0 = The V
OUT
duty-cycle will be controlled via the V
IN
analog input pin. The V
OUT
duty-cycle
value will be between 30% and 100% for V
IN
values between 1.62 V and 2.6 V typical. If
the V
IN
pin is open when this mode is selected, the V
OUT
duty-cycle will default to 39.33%.
(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