Register

[HEX]

Register Name

Read/Write

POR Default

[HEX]

CONVERSION AND ONE-SHOT REGISTERS

04 (0A)

Conversion Rate

R/W

08

0F

One-Shot

Write Only

N/A

ALERT STATUS AND MASK REGISTERS

02

ALERT Status

Read Only

N/A

16

ALERT Mask

R/W

A4

ID REGISTERS

FE

Manufacturer’s ID

Read Only

01

FF

Stepping/Die Rev. ID

Read Only

51

GENERAL PURPOSE REGISTERS

1A

General Purpose Input

Read Only

(Note 15)

1B

General Purpose Output

R/W

(Note 16)

[RESERVED] REGISTERS — NOT USED

06

Not Used

N/A

N/A

0C

Not Used

N/A

N/A

15

Not Used

N/A

N/A

17

Not Used

N/A

N/A

18

Not Used

N/A

N/A

1C–1F

Not Used

N/A

N/A

20

Not Used

N/A

N/A

22–2F

Not Used

N/A

N/A

30–3F

Not Used

N/A

N/A

40–45

Not Used

N/A

N/A

4E

Not Used

N/A

N/A

60–BE

Not Used

N/A

N/A

C0–FD

Not Used

N/A

N/A

Note 15: For Register 0x1A the Power-On-Reset for the five LSB’s are the logic states present on the 5 GPIOx pins.

Note 16: For Register 0x1B the Power-On-Reset for the five LSB’s are the logic states present on the 5 GPDx pins.

2.3 LM64 INITIAL REGISTER SEQUENCE AND REGISTER DESCRIPTIONS IN FUNCTIONAL ORDER

The following is a Register Map grouped in functional and sequence order. Some address locations have been left blank to

maintain compatibility with LM86. Addresses in parenthesis are mirrors of named address for backwards compatibility with some

older software. Reading or writing either address will access the same 8-bit register.

2.3.1 LM64 Required Initial Fan Control Register Sequence

Important! The BIOS must follow the sequence below to configure the following Fan Registers for the LM64 before using any of

the Fan or Tachometer or PWM registers:

Step

[Register]

1

[4A] Write bits 0 and 1; 3 and 4. This includes tach settings if used, PWM internal clock select (1.4 kHz or

360 kHz) and PWM Output Polarity.

2

[4B] Write bits 0 through 5 to program the spin-up settings.

3

[4D] Write bits 0 through 4 to set the frequency settings. This works with the PWM internal clock select.

4

Choose, then write, only one of the following:

A. [4F–5F] the Lookup Table, or

B. [4C] the PWM value bits 0 through 5.

5

If Step 4A, Lookup Table, was chosen and written then write [4A] bit 5 = 0.

All other registers can be written at any time after the above sequence.

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