AMC6821 Datasheet, PDF (36/54 Pages) Burr-Brown (TI) – Analog Monitor and Control Circuit

AMC6821
SBAS386C – MAY 2006 – REVISED JULY 2007
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REGISTER DESCRIPTION
In this section, all interrupts are the interrupt signal through the SMBALERT pin, unless otherwise noted.
DEVICE CONFIGURATION REGISTERS
Configuration Register 1 (Address 0x00, Value After Power-On Reset = 0xD4)
BIT
NAME
R/W
7 THERMOVIE R/W
6
FDRC1
R/W
5
FDRC0
R/W
4 FAN-Fault-EN R/W
3
PWMINV
R/W
2
FANIE
R/W
1
INT-EN
R/W
0
START
R/W
DEFAULT
1
1
0
1
0
1
0
0
DESCRIPTION
THERM interrupt enable. When this bit is set, the THERM interrupt is enabled.
L-THERM = 1 or R-THERM = 1 causes an interrupt. When this bit is cleared ('0'), the
THERM interrupt is disabled. When disabled, L-THERM = 1 or R-THERM = 1 does not
assert the SMBALERT pin, but forces the THERM pin low. Power-on default = 1.
Fan driver control bit 1. Power-on default = 1. Refer to Table 15.
Fan driver control bit 0. Power-on default = 0. Refer to Table 15.
Setting this pin to '1' enables the FAN-FAULT pin. Clearing this pin ('0') disables the
FAN-FAULT pin (always in Hi-Z). Power-on default = 1.
PWM invert bit. When PWMINV = 0 (default), the PWM-Out pin goes low for 100% duty
cycle (suitable for driving the fan using a PMOS device). Setting PWMINV to '1' makes
the PWM-Out pin go high (with an external pull-up resistor) for 100% duty cycle (suitable
for driving the fan using a NMOS device). Power-on default = 0.
Fan RPM interrupt enable bit. Power-on default = 1. When FANIE = 1, the FAN-RPM
interrupt is enabled. FANS = 1 or RPM-ALARM = 1 generates a FANORN interrupt,
making the SMBALERT pin go low. When FANIE = 0, a FAN-RPM interrupt is disabled.
Fan out-of-range = 1 does not generate an interrupt.
Setting this bit to '1' enables the interrupt from the SMBALERT pin. Clearing this bit ('0')
disables the interrupt. Power-on default = 0.
Temperature monitoring and fan speed monitoring. When START = 0 , only
software-DCY control mode works; software-RPM and auto temperature control modes
do not work.
FDRC1
1
1
0
0
FDRC0
1
0
0
1
Table 15. Fan Driver Control Bits
FUNCTION
Maximum speed calculated control. The required duty cycle for remote temperature and
local temperature is calculated respectively. The larger value is used to control the fan.
Auto remote-temperature-fan control. The PWM duty cycle is controlled by the remote
temperature. Power-on default mode.
Software DCY control. Host writes DCY register to set the PWM duty cycle directly.
Software RPM control. Host writes the TACH setting register with the value corresponding
to the desired RPM. The device measures the actual RPM and adjusts the PWM duty cycle
to maintain the fan speed to the target value.
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