Table 3. register map (continued) – Rainbow Electronics MAX6640 User Manual
Page 12
MAX6640
2-Channel Temperature Monitor with Dual
Automatic PWM Fan-Speed Controller
12
______________________________________________________________________________________
READ/
WRITE
REGISTER
NO.
ADDRESS
POR
STATE
FUNCTION
D7
D6
D5
D4
D3
D2
D1
D 0
R/W
12h
0000
0000
Fan 1
configuration
2b
RPM step-
size B
(MSB)
RPM step-
size B
RPM step-
size B
RPM
step-size
B (LSB)
Start
step-size
B (MSB)
Start
step-size
B
Start step-
size B
S tar t step -
si ze B ( LS B)
R/W
13h
0100
0001
Fan 1
configuration
3
Spin-up
disable
THERM to
full-speed
enable
Pulse
stretching
disable
Reserved Reserved Reserved
Fan PWM
frequency
(MSB)
Fan P WM
fr eq uency
( LSB)
R/W
14h
1000
0010
Fan 2
configuration
1
PWM
mode
Step-size
delay
(MSB)
Step-size
delay
Step-size
delay
(LSB)
Fan 2
channel 1
control
Fan 2
channel 2
control
RPM
range
select
RP M r ang e
select
R/W
15h
0000
0000
Fan 2
configuration
2a
RPM step-
size A
(MSB)
RPM step-
size A
RPM step-
size A
RPM
step-size
A (LSB)
Temp
step-size
A (MSB)
Temp
step-size
A (LSB)
PWM
100%
duty
cycle
M i ni m um fan
sp eed
0 = 0%, 1=
value in 22h
R/W
16h
0000
0000
Fan 2
configuration
2b
RPM step-
size B
(MSB)
RPM step-
size B
RPM step-
size B
RPM
step-size
B (LSB)
Start
step-size
B (MSB)
Start
step-size
B
Start step-
size B
S tar t step -
si ze B ( LS B)
R/W
17h
0100
0001
Fan 2
configuration
3
Spin-up
disable
THERM to
full-speed
enable
Pulse
stretching
disable
Reserved Reserved Reserved
Fan PWM
frequency
(MSB)
Fan P WM
fr eq uency
( LSB)
R
20h
1111
1111
Fan 1
tachometer
count
MSB
—
—
—
—
—
—
LS B
R
21h
1111
1111
Fan 2
tachometer
count
MSB
—
—
—
—
—
—
LS B
R/W
22h
1111
1111
Fan 1 max
tach count/
target tach
count
MSB
—
—
—
—
—
—
LS B
R/W
23h
1111
1111
Fan 2 max
tach count/
target tach
count
MSB
—
—
—
—
—
—
LS B
R/W
24h
0100
0000
Pulses per
revolution/
fan 1
minimum
tach count
Pulse per
revolution
(MSB)
Pulse per
revolution
(LSB)
Fan 1 min
tach count
(MSB)
Fan 1 min
tach
count
Fan 1 min
tach
count
Fan 1 min
tach
count
Fan 1 min
tach
count
Fan 1 mi n
tach count
( LSB)
R/W
25h
0100
0000
Pulses per
revolution/
fan 2
minimum
tach count
Pulse per
revolution
(MSB)
Pulse per
revolution
(LSB)
Fan 2 min
tach count
(MSB)
Fan 2 min
tach
count
Fan 2 min
tach
count
Fan 2 min
tach
count
Fan 2 min
tach
count
Fan 2 mi n
tach count
( LSB)
R
26h
0000
0000
Fan 1 cur r ent
d uty cycl e
MSB
—
—
—
—
—
—
LS B
Table 3. Register Map (continued)