AMC6821 Datasheet, PDF (36/47 Pages) Burr-Brown (TI) – Analog Monitor and Control Circuit

AMC6821
SBAS386A – MAY 2006 – REVISED MAY 2006
www.ti.com
Fan Characteristics Register (Address 0x20, Value After Power-On or Reset = 0x1D)
BIT
NAME DEFAULT DESCRIPTION
7
FSPD
0
Fast Spin Disable Bit
When FSPD = 1, the fan spin-up process is disabled.
When FSPD = 0, the fan spin-up process is enabled.
6
0
0
Reserved
5
PWM2
0
PWM Frequency Bits
4
PWM1
1
PWM2
PWM1
PWM0
PWM Frequency
3
PWM0
1
When PWM-MODE pin is floating or tied to V_DD
0
0
0
10Hz
0
0
1
15Hz
0
1
0
23Hz
0
1
1
30Hz (Default)
1
0
0
38Hz
1
0
1
47Hz
1
1
0
62Hz
1
1
1
94Hz
When PWM-MODE pin is tied to GND
0
0
0
1kHz
0
0
1
10kHz
0
1
0
20kHz
0
1
1
25kHz (Default)
1
0
0
30kHz
1
0
1
40kHz
1
1
0
40kHz
1
1
1
40kHz
2
STIME2
1
Spin-Up Time Bit
1
STIME1
0
STIME2
STIME1
STIME0
Spin-Up Time
(in Seconds)
0
STIME0
1
0
0
0
0.2
0
0
1
0.4
0
1
0
0.6
0
1
1
0.8
1
0
0
1
1
0
1
2 (Default)
1
1
0
4
1
1
1
8
This register specifies the PWM frequency and the fan spin-up functions.
Fan Spin Disable Bit: FSPD
This bit enables or disables the spin-up function.
PWM Frequency Bits: [PWM2:PWM0]
These bits specify the PWM frequency; the high range (1kHz–40kHz) has a default value of 25kHz, and the low
range (10Hz–94Hz) has a default value of 30Hz. The clock frequency is 12.8MHz. The PWM-MODE pin
determines which range is selected. When the PWM mode is tied to ground, the high range is selected;
otherwise, the low range is selected.
Spin-Up Time Bits: [STIME2:STIME0]
These bits specify a predetermined time period, or spin-up time, during which the 100% duty cycle is applied to
start the fan spinning. These bits are ignored when FSPD = 1.
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