ADT7460ARQZ-RL7 ONSEMI [ON Semiconductor], ADT7460ARQZ-RL7 Datasheet - Page 32

• Manufacturer Part Number: ADT7460ARQZ-RL7
• Description: dBCOOL Remote Thermal Monitor and Fan Controller
• Manufacturer: ONSEMI [ON Semiconductor]

1. The Fan Tachometer Reading registers count the number of 11.11 ms periods (based on an internal 90 kHz clock) that occur between a
1. These registers reflect the PWM duty cycle driving each fan at any given time. When in automatic fan speed control mode, the ADT7460
1. These registers become read−only when the Configuration Register 1 lock bit is set to 1. Any subsequent attempts to write to these registers
Table 41. Fan Tachometer Reading Registers (Power−On Default = 0x00)
Table 42. Current PWM Duty Cycle Registers (Power−On Default = 0xFF)
Table 43. Operating Point Registers (Power−On Default = 0x64)
Register Address
Register Address
Register Address
number of consecutive fan TACH pulses (default = 2). The number of TACH pulses used to count can be changed using the fan pulses per
revolution register (Reg. 0x7B). This allows the fan speed to be accurately measured. Since a valid fan tachometer reading requires that
two bytes are read, the low byte MUST be read first. Both the low and high bytes are then frozen until read. At power−on, these registers
contain 0x0000 until such time as the first valid fan TACH measurement is read in to these registers. This prevents false interrupts from
occurring while the fans are spinning up.
A count of 0xFFFF indicates that a fan is:
reports the PWM duty cycles back through these registers. The PWM duty cycle values vary according to temperature in automatic fan speed
control mode. During fan startup, these registers report back 0x00. In software mode, the PWM duty cycle outputs can be set to any duty
cycle value by writing to these registers.
will fail. These registers set the target operating point for each temperature channel when the dynamic T
fans being controlled are adjusted to maintain temperature about an operating point.
• Stalled or blocked (object jamming the fan).
• Failed (internal circuitry destroyed).
• Not populated. (The ADT7460 expects to see a fan connected to each TACH. If a fan is not connected to that TACH, its TACH minimum
• Alternate function, for example, TACH4 reconfigured as a THERM pin.
• 2−Wire Instead of 3−Wire Fan
high and low byte should be set to 0xFFFF.)
0x2C
0x2D
0x2A
0x2B
0x2E
0x2F
0x28
0x29
0x30
0x31
0x32
0x33
0x34
0x35
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
R/W
TACH1 low byte.
TACH1 high byte.
TACH2 low byte.
TACH2 high byte.
TACH3 low byte.
TACH3 high byte.
TACH4 low byte.
TACH4 high byte.
PWM1 current duty cycle (0% to 100% duty cycle = 0x00 to 0xFF).
PWM2 current duty cycle (0% to 100% duty cycle = 0x00 to 0xFF).
PWM3 current duty cycle (0% to 100% duty cycle = 0x00 to 0xFF).
Remote 1 Operating Point Register (Default = 100°C)
Local Temp Operating Point Register (Default = 100°C)
Remote 2 Operating Point Register (Default = 100°C)
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ADT7460
32
(Note 1)
Description
Description
Description
(Note 1)
(Note 1)
MIN
control feature is enabled. The