ADT7476AARQZ-R ON Semiconductor, ADT7476AARQZ-R Datasheet - Page 59

• Manufacturer Part Number: ADT7476AARQZ-R
• Description: IC REMOTE THERMAL CTLR 24-QSOP
• Manufacturer: ON Semiconductor
• Series: dBCool®r

Specifications of ADT7476AARQZ-R

• Function: Fan Control, Temp Monitor
• Topology: ADC, Comparator, Fan Speed Counter, Multiplexer, Register Bank
• Sensor Type: External & Internal
• Sensing Temperature: -40°C ~ 125°C, External Sensor
• Output Type: SMBus™
• Output Alarm: No
• Output Fan: Yes
• Voltage - Supply: 3 V ~ 3.6 V
• Operating Temperature: -40°C ~ 125°C
• Mounting Type: Surface Mount
• Package / Case: 24-QSOP
• Full Temp Accuracy: +/- 0.5 C
• Digital Output - Bus Interface: Serial (3-Wire, 4-Wire)
• Maximum Operating Temperature: + 125 C
• Minimum Operating Temperature: - 40 C
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

1. These registers become read-only when the ADT7476A is in automatic fan control mode.
1. These are the T
2. These registers become read-only when the Configuration Register 1lock bit is set. Any further attempts to write to these registers have no effect.
1. If any temperature measured exceeds its THERM limit, all PWM outputs drive their fans at 100% duty cycle. This is a fail-safe mechanism
2. These registers become read-only when the Configuration Register 1 lock bit is set to 1. Any further attempts to write to these registers have
1. Each 4-bit value controls the amount of temperature hysteresis applied to a particular temperature channel. Once the temperature for that
2. These registers become read-only when the Configuration Register 1 lock bit is set to 1. Any further attempts to write to these registers have
Table 34. PWM Minimum Duty Cycle Registers
Table 35. T
Table 36. THERM Limit Registers
Table 37. Temperature/T
Bit No.
[7:0]
minimum speed and increases with temperature according to T
incorporated to cool the system in the event of a critical overtemperature. It also ensures some level of cooling in the event that software
or hardware locks up. If set to 0x80, this feature is disabled. The PWM output remains at 100% until the temperature drops below THERM
limit − hysteresis. If the THERM pin is programmed as an output, exceeding these limits by 0.25°C can cause the THERM pin to assert low
as an output.
no effect.
channel falls below its T
hysteresis can be assigned to any temperature channel. The hysteresis value chosen also applies to that temperature channel if its THERM
limit is exceeded. The PWM output being controlled goes to 100% if the THERM limit is exceeded and remains at 100% until the temperature
drops below THERM – hysteresis. For acoustic reasons, it is recommended that the hysteresis value not be programmed less than 4°C.
Setting the hysteresis value lower than 4°C causes the fan to switch on and off regularly when the temperature is close to T
no effect.
Register Address
Register Address
Register Address
Register Address
0x67
0x68
0x69
0x6A
0x6B
0x6C
0x6D
0x6E
0x6E
0x64
0x65
0x66
[3:0]
[7:4]
PWM duty
MIN
Name
cycle
Registers
MIN
registers for each temperature channel. When the temperature measured exceeds T
MIN
R/W (Note 1)
R/W (Note 2)
R/W (Note 2)
R/W (Note 2)
MIN
(Note 1)
HYSR1
HYSR2
value, the fan remains running at PWM
HYSL
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Hysteresis Registers
(Note 1)
PWM1 minimum duty cycle.
PWM2 minimum duty cycle.
PWM3 minimum duty cycle.
These bits define the PWM
0x00 = 0% duty cycle (fan off).
0x40 = 25% duty cycle.
0x80 = 50% duty cycle.
0xFF = 100% duty cycle (fan full speed).
Remote 1 temperature T
Local temperature T
Remote 2 temperature T
Remote 1 THERM temperature limit.
Local THERM temperature limit.
Remote 2 THERM temperature limit.
Remote 1 and local temperature hysteresis.
Local temperature hysteresis. 0°C to 15°C of hysteresis
can be applied to the local temperature AFC control
loops.
Remote 1 temperature hysteresis. 0°C to 15°C of hyster-
esis can be applied to the Remote 1 temperature AFC
control loops.
Remote 2 temperature hysteresis.
Local temperature hysteresis. 0°C to 15°C of hysteresis
can be applied to the local temperature AFC control
loops.
http://onsemi.com
(Note 1)
Description
MIN
RANGE
Description
Description
Description
.
59
MIN
MIN
MIN
MIN
.
.
.
duty cycle until the temperature = T
duty cycle for PWMx.
Description
0x80 (50% duty cycle)
0x80 (50% duty cycle)
0x80 (50% duty cycle)
Power−On Default
MIN
MIN
Power−On Default
, the appropriate fan runs at
Power−On Default
Power−On Default
– hysteresis. Up to 15°C of
0x64 (100°C)
0x64 (100°C)
0x64 (100°C)
0x5A (90°C)
0x5A (90°C)
0x5A (90°C)
0x44
0x40
MIN
.