User Manual

Functional Description (Continued)

2.1 Internal Registers of the LM81

TABLE 1. The internal registers and their corresponding internal LM81 addresses are as follows:

Address

Power on

Value

Notes

Configuration Register 40h 0000 1000

Interrupt Status Register 1 41h 0000 0000

Interrupt Status Register 2 42h 0000 0000

Interrupt Mask Register 1 43h 0000 0000

Interrupt Mask Register 2 44h 0000 0000

CI Clear Register 46h 0000 0000

VID/Fan Divisor Register 47h 0101 XXXX The upper four bits set the divisor for Fan Counters 1

and 2. The lower four bits reflect the state of the

VID0-VID3 inputs.

Serial Bus Address Register 48h 0010 11XX The lower 2 bits reflect the state of A1 and A0, the

Serial Bus address input pins.

VID4 Register 49h 1000 000X The lower bit reflects the state of VID4 input.

Temperature Configuration

4Bh 0000 0001

Extended Mode Register 1 4Ch 0100 0100

Extended Mode Register 2 4Dh 0000 0000

Value RAM DAC Data

19h 1111 1111

Value RAM 20h-3Fh Contains: monitoring results (temperature, voltages,

fan counts), WATCHDOG limits, and

Company/Stepping IDs

LM81