ADM1033

Rev. 0 | Page 11 of 40

Table 4. Internal Register Descriptions

Register

Description

Configuration

Provides control and configuration of various functions on the device.

Conversion Rate

Determines the number of measurements per second completed by the ADM1033.

Address Pointer

Contains the address that selects one of the other internal registers. When writing to the ADM1033, the first byte

of data is always a register address, which is written to the address pointer register.

Status

Provides the status of each limit comparison.

Interrupt Mask

Allows the option to mask ALERTs due to particular out-of-limit conditions.

Value and Limit

Stores the results of temperature and fan speed measurements, along with their limit values.

Offset

Allows the local and remote temperature channel readings to be offset by a twos complement value written to

them. These values are automatically added to the temperature values (or subtracted from them if negative). This

allows the systems designer to optimize the system, if required, by adding or subtracting up to 15.875°C from a

temperature reading.

THERM Limit and

Hysteresis

Contains the temperature value at which THERM is asserted and determines the level of hysteresis.

Look-Up Table

Used to program the look-up table for the fan-speed-to-temperature profile.

THERM % Ontime and

THERM % Limit

Reflects the state of the THERM input and monitors the duration of the assertion time of the signal as a

percentage of a time window. The user can program the length of the time window.

Table 5. Resistor Ratios for Setting LOCATION Bits

Ideal Ratio R2/(R1 + R2)

R1 (kΩ)

R2 (kΩ)

Actual R2/(R1 + R2)

Error (%)

SMBus Mode

SMBus Address

UDID LLL

N/A

0

O/C

1

0

ARP1

N/A

111

0.8125

18

82

0.82

+0.75

N/A

110

0.6875

22

47

0.6812

−0.63

N/A

101

0.5625

12

15

0.5556

−0.69

N/A

100

0.4375

15

12

0.4444

+0.69

0x53

N/A

0.3125

47

22

0.3188

+0.63

0x52

N/A

0.1875

82

18

0.18

−0.75

0x51

N/A

N/A

O/C

0

0

0

0x50

N/A

Table 6. UDID Values

Bit No.

Name

Function

Value

<127:120>

Device Capabilities

Describes the ADM1033’s capabilities (for instance, that it supports PEC

and uses a random number address device)

11000001

<1119:112>

Version/Revision:

UDID version number (Version 1) and silicon revision identification

00001010

<111:96>

Vendor ID

Vendor ID number, assigned by the SBS Implementer’s Forum or the

PCI SIG

00010001

11010100

<95:80>

Device ID

Device ID

00010000

00110011

<79:64>

Interface

Identifies the protocol layer interfaces supported by the ADM1033. This

represents SMBus 2.0 as the Interface version.

00000000

00000100

<63:48>

Subsystem Vendor ID

Subsystem Vendor ID = 0 (subsystem fields are unsupported)

00000000

00000000

<47:32>

Subsystem Device ID

Subsystem Device ID = 0 (subsystem fields are unsupported)

00000000

00000000

<31:0>

Vendor-Specific ID

A unique number per device. Contains the LOCATION Information (LLL)

and a 16-bit random number (x). See Table 5 for information on setting

the LLL bits.

00000000

00000LLL

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