ADT7467ARQZ-R7 datasheet(9/77 Pages) ONSEMI

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ADT7467

Rev. 3 | Page 9 of 77 | www.onsemi.com

PRODUCT DESCRIPTION

The ADT7467 is a complete thermal monitor and multiple fan

controller for systems requiring thermal monitoring and

cooling. The device communicates with the system via a serial

system management bus. The serial bus controller has a serial

data line for reading and writing addresses and data (Pin 16)

and an input line for the serial clock (Pin 1). All control and

programming functions for the ADT7467 are performed over

the serial bus. In addition, one of two pins can be reconfigured

as an SMBALERT output to signal out-of-limit conditions.

COMPARISON BETWEEN ADT7460 AND ADT7467

The ADT7467 is an upgrade from the ADT7460. The ADT7467

and ADT7460 are almost pin and register map compatible. The

ADT7467 and ADT7460 have the following differences:

On the ADT7467, the PWM drive signals can be config-

ured as either high frequency or low frequency drives. The

low frequency option is programmable between 10 Hz and

100 Hz. The high frequency option is 22.5 kHz. On the

ADT7460, only the low frequency option is available.

Once VCC and VCCP are powered up, monitoring of

temperature and fan speeds is enabled on the ADT7467. If

VCCP is never powered up, monitoring is enabled when the

first SMBus transaction with the ADT7467 is complete. On

the ADT7460, the STRT bit in Configuration Register 1

must be set to enable monitoring.

The fans are switched off by default upon power-up of the

ADT7467. On the ADT7460, the fans run at full speed

upon power-up.

Fail-safe cooling is provided on the ADT7467. If the

measured temperature exceeds the THERM limit

(100°C), the fans run at full speed.

Fail-safe cooling is also provided 4.6 sec after VCCP is powered

up. The fans operate at full speed if the ADT7467 has not

been addressed via the SMBus within 4.6 sec of when the

VCCP is powered up. This protects the system in the event

that the SMBus fails. The ADT7467 can be programmed at

any time, and it behaves as programmed. If VCCP is never

powered up, fail-safe cooling is effectively disabled. If VCCP

is disabled, writing to the ADT7467 at any time causes the

ADT7467 to operate normally.

Series resistance cancellation (SRC) is provided on the

remote temperature channels on the ADT7467, but not on

the ADT7460. SRC automatically cancels linear offset

introduced by a series resistance between the thermal

diode and the sensor.

The ADT7467 has an extended temperature measurement

range. The measurement range goes from −64°C to

+191°C. On the ADT7460, the measurement range is from

−127°C to +127°C. This means that the ADT7467 can

measure higher temperatures. The ADT7467 also includes

the ADT7460 temperature range; the temperature measure-

ment range can be switched by setting Bit 0 of Configuration

The ADT7467 maximum fan speed (% duty cycle) in the

automatic fan speed control loop can be programmed. The

maximum fan speed is 100% duty cycle on the ADT7460

and is not programmable.

The offset register in the ADT7467 is programmable up to

±64°C with 0.50°C resolution. The offset register of the

ADT7460 is programmable up to ±32°C with 0.25°C

resolution.

VCCP is monitored on Pin 14 of the ADT7467 and can be

used to set the threshold for THERM (PROCHOT) (2/3 of

VCCP). 2.5 V is monitored on Pin 14 of the ADT7460. The

threshold for THERM (PROCHOT) is set at VIH = 1.7 V

and VIL = 0.8 V on the ADT7460.

On the ADT7460, Pin 14 could be reconfigured as

SMBALERT. This is not available on the ADT7467.

SMBALERT can be enabled instead on Pin 9.

10. A GPIO can also be made available on Pin 9 on the

ADT7467. This is not available on the ADT7460. Set the

GPIO polarity and direction in Configuration Register 5.

The GPIO status bit is Bit 5 of Status Register 2 (it is shared

with TACH4 and THERM because only one can be enabled

at a time).

11. The ADT7460 has three possible SMBus addresses, which

are selectable using the address select and address enable

pins. The ADT7467 has one SMBus address available at

Address 0x2E.

Due to the inclusion of extra functionality, the register map has

changed, including an additional configuration register,

Configuration Register 5 at Address 0x7C.

ADT7467ARQZ-R7 Datasheet(PDF) 9 Page - ON Semiconductor

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