ADM1034ARQZ datasheet(8/39 Pages) ONSEMI

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ADM1034

http://onsemi.com

TYPICAL CHARACTERISTICS

Figure 13. Supply Current vs. Conversion Rate

Figure 14. Supply Current vs.

ADM1034 Temperature

CONVERSION RATE (Hz)

1200

1000

800

600

400

200

0.01

0.1

100

DEV 33

DEV 32

DEV 31

TEMPERATURE (°C)

1.55

1.50

1.45

1.40

1.35

1.30

1.25

–60

–40

–20

100

Functional Description

The ADM1034 is a local− and remote−temperature

monitor and fan controller for use in a variety of

applications, including microprocessor−based systems. The

device accurately monitors remote and ambient temperature

and uses that information to quietly control the speed of a

cooling fan. Whenever one of the fans stalls, the device

asserts a FAN_FAULT output.

The ADM1034 features a THERM I/O. As an input, this

measures assertions on the THERM pin. As an output, it

asserts a low signal to indicate when the measured

temperature

exceeds

the

programmed

THERM

temperature. The ADM1034 communicates over an SMBus

2.0 interface. Its LOCATION input determines which

version of SMBus to use, as well as the SMBus address (in

fixed and discoverable mode) and the LOCATION bits in

the UDID (in ARP−capable mode).

Internal Registers

Table 1 gives a brief description of the ADM1034’s

principal internal registers. For more detailed information

on the function of each register, refer to Table 31.

Serial Bus Interface

The ADM1034 communicates with the master via the

2−wire SMBus 2.0 interface. It supports two versions of

SMBus 2.0, determined by the value of the LOCATION

input’s resistors.

The first version is fully ARP−capable. This means that it

supports address resolution protocol (ARP), allowing the

master to dynamically address the device on powerup. It

responds to ARP commands such as “Prepare to ARP.”

The second SMBus version, fixed and discoverable, is

backwards compatible with SMBus 1.0 and 1.1. In this mode,

the ADM1034 powers up with a fixed address, which is

determined by the state of the LOCATION pin on powerup.

NOTE: When using the ADM1034, Addresses 0xC2 and

0xCA should not be used by any other device on the bus.

Location Input

The LOCATION input is a resistor divider input. It has

multiple functions and can specify the SMBus version (in

fixed and discoverable or ARP−capable modes); the SMBus

address (in fixed and discoverable mode); and the LLL bits

(in UDID in ARP−capable mode).

The voltage of this 8−level input is set by a potential

divider. The voltage on LOCATION is sampled on powerup

and digitized by the on−chip ADC to determine the

LOCATION input value. Because the LOCATION input is

sampled only at powerup, changes made while power is

applied have no effect.

Figure 15. Bootstrapping the LOCATION Input

VCC

GND

ADM1034

LOCATION

PIN 13

SMBus 2.0 ARP−Capable Mode

In ARP−capable mode, the ADM1034 supports features

such as address resolution protocol (ARP) and unique

device identifier (UDID). The UDID is a 128−bit message

that describes the ADM1034’s capabilities to the master.

The UDID also includes a vendor specific ID for

functionally equivalent devices.

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