ADM1021AARQZ View Datasheet(PDF) - Analog Devices

Part Name

Description

Manufacturer

ADM1021AARQZ

Low-Cost Microprocessor System Temperature Monitor

Analog Devices 

ADM1021A

7. For really long distances (up to 100 feet), use shielded twisted

pair such as Belden #8451 microphone cable. Connect the

twisted pair to D+ and D– and the shield to GND close to

the ADM1021A. Leave the remote end of the shield uncon-

nected to avoid ground loops.

Because the measurement technique uses switched current sources,

excessive cable and/or filter capacitance can affect the measure-

ment. When using long cables, the filter capacitor may be

reduced or removed.

Cable resistance can also introduce errors. 1 Ω series resistance

introduces about 1°C error.

APPLICATION CIRCUITS

Figure 8 shows a typical application circuit for the ADM1021A,

using a discrete sensor transistor connected via a shielded,

twisted pair cable. The pull-ups on SCLK, SDATA, and ALERT

are required only if they are not already provided elsewhere in

the system.

The SCLK and SDATA pins of the ADM1021A can be inter-

faced directly to the SMBus of an I/O chip. Figure 9 shows how

the ADM1021A might be integrated into a system using this

type of I/O controller.

C1*

2N3904 SHIELD

*C1 IS OPTIONAL

ADM1021A VDD

STBY

D+

SCLK

SDATA

D–

ALERT

ADD0

ADD1

GND

0.1␮F

3.3V

ALL 10k⍀

IN

I/O

OUT

TO CONTROL

CHIP

SET TO REQUIRED

ADDRESS

Figure 8. Typical Application Circuit

PROCESSOR

SYSTEM BUS

DISPLAY

DISPLAY

CACHE

HARD

CD ROM DISK

2 IDE PORTS

USB USB

2 USB PORTS

GMCH

SYSTEM

MEMORY

PCI SLOTS

ICH

I/O CONTROLLER

HUB

PCI BUS

SUPER

I/O

FWH

(FIRMWARE HUB)

D–

D+

ADM1021A

ALERT SDATA SCLK

SMBUS

Figure 9. Typical System Using ADM1021A

–12–

REV. D

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