ADT7473 Analog Devices, Inc., ADT7473 Datasheet - Page 61

• Manufacturer Part Number: ADT7473
• Description: Dbcool Remote Thermal Monitor And Fan Controller
• Manufacturer: Analog Devices, Inc.

Table 19. Temperature Reading Registers (Power-On Default = 0x01)
Reg
0x25
0x26
0x27
1
2
3
4
Table 20. Fan Tachometer R
Register Address
0x28
0x29
0x2A
0x2B
0x2C
0x2D
0x2E
0x2F
1
Table 21. Curr nt PWM Duty Cycle Re
Register Addre
0x30
0x31
0x32
1
Table 22. Operating Point Registers (Power-On Default = 0xA4)
Regist
0x33
0x34
0x35
1
2
3
These temperatur
If the extended re
resolution registe
In twos compleme
In Offset 64 mode,
These registers co
The number of TA
measured. Becaus
read. At power-on, these re
while the fans are
•
•
•
•
These registers re
back through the
report back 0x00. I
These registers set the target op
The fa
These
ist
Stalled or bl
Failed (inter
Not populated.
be set to 0xF
Alternate function, fo
ns being controlled are ad
registers become read-only
er Addr ss
er Address
e
e
flect th
se regist
solution bits of these readings a
rs have
ocked bject jamming the fan).
nal circ try destroyed).
e readi
unt the
ss
CH pu
e a vali
spinni
n soft
nt mo
FFF.)
a tem
(Th
lse
wa
ng
(o
de
pe
e
ng
ui
e ADT7473 e
d f
b
n
e
PWM duty cycle driving e
een read, all associated
umber of 11.11 µs pe
s used to count can be ch
rs. The PWM duty cycle va
re mode, the PWM duty
, a temperature readi
rature reading of −64
gisters contain 0x0000 u
r example, TACH4 reconfigured as THERM pin.
s can be in twos com
an tachometer reading
up. A count of 0xFFFF in
erating
R/W
Read only
Read only
Read only
R/W
Read only
Read only
Read only
Read only
Read only
Read only
Read only
Read only
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
justed
whe
eading Registers (Power-On De
xpects to see a fan connected to each TACH. If a fan is not connected to that TACH, its TACH minimum high and low byt
3
n the Configuration
to maintain tem
point for each
plement or Offset 64 format; this interpretation is
ng of −128°C (0x80) indicates a diode fault (open o
riods (based on an internal 90 kHz clock) that occu
gisters (Power-On Default = 0x00)
°C (0x00) indicates a diode fault (open or short) on
re also being read, the extended resolution regist
MSB reading registers are frozen until read. Both
requires that two bytes are read, the low byte m
cycle outputs can be set to any duty cycle value
ntil the first valid fan TACH measurement is rea
dicates a fan is one of the following:
ach fan at any given time. When in automatic fa
anged using the TACH pulses per revolution r
lues vary according to temperature in automa
temperature channel when the dynamic T
perature about an operating point.
Description
Remote 1 temperature reading
Local temperature reading (8 MSB of reading).
Remote 2 temperature reading (8 MSB of reading).
Description
TACH1 low byte.
TACH1 high byte.
TACH2 low byte.
TACH2 high byte.
TACH3 low byte.
TACH3 high byte.
TACH4 low byte.
TACH4 high byte.
Description
PWM1 current duty cycle (0% to 100
PWM2 current duty cycle (0% to 100
PWM3 current duty cycle (0% to 100
Description
Remote 1 operating point register (default = 100°C).
Local temperature operating point register (default = 100°C).
Remote 2 operating point register (default = 100°C).
Register 1 lock bit is set to 1. Any subsequent attempts to write to these registers fail.
Rev. A | Page 61 of 76
fault = 0x00)
1, 2, 3
1, 2
1
1
3, 4
(8 MSB of reading).
MIN
determined by Bit 0 o
egister (Register 0x7B). T
r between a number of con
d into these registers. Th
tic fan speed control mo
ers (Reg. 0x76, 0x77)
r short) on that chann
that channel.
ust be read first. Both th
% duty cycle = 0x
% duty cycle = 0x
% duty cycle = 0x00
the extended resolu
n speed control mode, t
by writing to these register
control feature is enabled.
tion registers and the MSB registers are frozen.
f Configuration Register 5 (0x7C).
must be read first. Once the extended
00 to 0xFF).
00 to 0xFF).
el.
his allows the fan speed to be accurately
e low and high bytes are then frozen until
is prevents false interrupts from occurring
he ADT7473 reports the PWM duty cycles
de. During fan start up, these registers
to 0xFF).
secutive fan TACH pulses (default = 2).
s.
ADT7473
es should