ADT7476AARQZ-RL7 ON Semiconductor, ADT7476AARQZ-RL7 Datasheet - Page 52

• Manufacturer Part Number: ADT7476AARQZ-RL7
• Description: IC REMOTE THERMAL CTLR 24-QSOP
• Manufacturer: ON Semiconductor
• Series: dBCool®r

Specifications of ADT7476AARQZ-RL7

• 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. Bit 0 (STRT) of Configuration Register 1 (0x40) remains writable after lock bit is set.
2. When monitoring (STRT) is disabled, PWM outputs always go to 100% for thermal protection.
Table 22. Register 0x40 — Configuration Register 1 (Power−On Default = 0x04)
Table 23. Register 0x41 — Interrupt Status Register 1 (Power−On Default = 0x00)
Bit No.
Bit No.
[0]
[1]
[2]
[3]
[4]
[5]
[6]
[7]
[0]
[1]
[2]
[3]
[4]
[5]
[6]
[7]
(Notes 1, 2)
Mnemonic
Mnemonic
Reserved
FSPDIS
THERM
TODIS
LOCK
STRT
FSPD
2.5 V/
V
5.0 V
RDY
OOL
V
R1T
R2T
Vx1
LT
CCP
CC
Read/Write
Write once
Read-only
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
N/A
Logic 1 enables monitoring and PWM control outputs based on the limit settings
programmed.
Logic 0 disables monitoring and PWM control is based on the default powerup limit settings.
Note that the limit values programmed are preserved even if a Logic 0 is written to this bit
and the default settings are enabled. This bit does not become locked once Bit 1 (LOCK bit)
has been set.
Logic 1 locks all limit values to their current settings. Once this bit is set, all lockable registers
become read-only and cannot be modified until the ADT7476A is powered down and
powered up again. This prevents rogue programs such as viruses from modifying critical
system limit settings. (Lockable.)
This bit is set to 1 by the ADT7476A to indicate that the device is fully powered-up and ready
to begin system monitoring.
When set to 1, this bit runs all fans at max speed as programmed in the max PWM current
duty cycle registers (0x30 to 0x32). Power-on default = 0. This bit is not locked at any time.
BIOS should set this bit to a 1 when the ADT7476A is configured to measure current from an
ADOPT
software to display CPU watts usage. (Lockable.)
Logic 1 disables fan spin-up for two TACH pulses. Instead, the PWM outputs go high for the
entire fan spin-up timeout selected.
When this bit is set to 1, the SMBus timeout feature is enabled.
In this state, if at any point during an SMBus transaction involving the ADT7476A activity
ceases for more than 35 ms, the ADT7476A assumes the bus is locked and releases the
bus. This allows the ADT7476A to be used with SMBus controllers that cannot handle
SMBus timeouts. (Lockable.)
Reserved. Do not write to this bit.
2.5 V = 1 indicates that the 2.5 V high or low limit has been exceeded. This bit is cleared on a
read of the status register only if the error condition has subsided. If Pin 22 is configured as
THERM, this bit is asserted when the timer limit has been exceeded.
V
a read of the status register only if the error condition has subsided.
V
read of the status register only if the error condition has subsided.
A 1 indicates that the 5.0 V high or low limit has been exceeded. This bit is cleared on a read
of the status register only if the error condition has subsided.
R1T = 1 indicates that the Remote 1 low or high temperature has been exceeded. This bit is
cleared on a read of the status register only if the error condition has subsided.
LT = 1 indicates that the local low or high temperature has been exceeded. This bit is cleared
on a read of the status register only if the error condition has subsided.
R2T = 1 indicates that the Remote 2 low or high temperature has been exceeded. This bit is
cleared on a read of the status register only if the error condition has subsided.
OOL = 1 indicates that an out-of-limit event has been latched in Interrupt Status Register 2.
This bit is a logical OR of all status bits in Interrupt Status Register 2. Software can test this
bit in isolation to determine whether any of the voltage, temperature, or fan speed readings
represented by Interrupt Status Register 2 are out-of-limit, which eliminates the need to read
Interrupt Status Register 2 during every interrupt or polling cycle.
CCP
CC
= 1 indicates that the V
= 1 indicates that the V
®
VRM controller and to measure the CPU’s core voltage. This bit allows monitoring
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CC
CCP
high or low limit has been exceeded. This bit is cleared on a
high or low limit has been exceeded. This bit is cleared on
Description
Description