ADT7460 Analog Devices, Inc., ADT7460 Datasheet - Page 41

• Manufacturer Part Number: ADT7460
• Description: Dbcool? Remote Thermal Controller And Fan Controller
• Manufacturer: Analog Devices, Inc.

Table 54. Fan Tachometer Limit Registers (Power-On Default = 0xFF)
Register Address
0x54
0x55
0x56
0x57
0x58
0x59
0x5A
0x5B
Exceeding
in Inter
Table
RegisterAddr
0x5C
0x5D
0x5E
These registers become read-only when
registers will fail.
Table
Bit
<2:0>
<3>
<4>
<7:5>
55. PWM Configuration Registe
56. PWM Con iguration Registe
rup
Name
SPIN
SLOW
INV
BHVR
any of t
t Statu
ess
s R
he
R/W
Read/Write
Read
Read/Write
Read/Write
egister 2 to in
TACH
f
/Write
limit registe
R/W
Read/Write
Read/Write
Read/Write
Read/Write
Read/Write
Read/Write
Read/Write
Read/Write
dicate
R/W
Read/
Read/Write
Read/Write
Description
These bits control the start-up timeout for PWMx. The PWM output stays high until two valid TACH rising
edges
after the fan start-up timeout period, the TACH measurement reads 0xFFFF and Status Register 2 reflects
the fan fault. If the TACH minimum high and low byte contains 0xFFFF or 0x0000, the Status Register 2
bit is not set, even if the fan has not started.
000
001
010
011
100
101 = 1 s
110 = 2 s
111 = 4 s
SLOW
This bit inverts the PWM output. The default is 0, which corresponds to a logic high output for 100% duty
cycle. Setting this bit to 1 inverts the PWM output, so 100% duty cycle corresponds to a logic low output.
These bits assign each fan to a particular temperature sensor for localized cooling.
000 = Remote 1 temperature controls PWMx (automatic fan control mode).
001 = Local temperature controls PWMx (automatic fan control mode).
010 = Remote 2 temperature controls PWMx (automatic fan control mode).
011 = PWMx runs full speed (default).
100 = PWMx is disabled.
101 = Fastest speed calculated by Local and Remote 2 Temperature Control PWMx.
110 = Fastest speed calculated by all three Temperature Channels Control PWMx.
111 = Manual mode. PWM duty cycle registers (Reg. 0x30–0x32) become writable.
Write
rs (P we On Defa
the Configuration Register 1 Lock bit is set to 1. Any subsequent attempts to write to these
r Bits
= no tar up tim
= 10 ms
= 25 ms defaul
= 40 ms
= 66 ms
rs by 1 indica
the fan failure. Setting the Configuration
= 1 m kes the ramp ra
are se n fr
o
a
e
0
0
0
7
s
r-
t-
om the fan. If there is not a valid TACH signal during the fan TACH measurement directly
(
tes that the fan is running too slowly or has stalled. The approp ate statu
t)
eout
ult = 0x62)
Rev. C | Page 41 of 52
tes for acoustic enhancement four times longer.
Descripti
PWM1 Configuration
PWM2 Configuration
PWM3 Configuration
Description
TACH1 Minimum Low Byte
TACH1 Minimum High Byte
TACH2 Minimum Low Byte
TACH2 Minimum High Byte
TACH3 Minimum Low Byte
TACH3 Minimum High Byte
TACH4 Minimum Low Byte
TACH4 Minimum High Byte
Register 1 lock bit has no effect on
on
ri
th
ese regis
ADT7460
s b
ters.
it is set