ADM1034ARQZ-REEL 查看數據表（PDF） - ON Semiconductor

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ADM1034ARQZ-REEL

Thermal Monitor and Fan Speed (RPM) Controller

ON Semiconductor 

ADM1034

Table 6. Temperature Measurement Registers

Register

Description

Default

0x40

Local Temperature, LSBs

0x00

0x41

Local Temperature, MSBs

0x00

0x42

Remote 1 Temperature, LSBs

0x00

0x43

0x44

0x45

Remote 1 Temperature, MSBs

Remote 2 Temperature, LSBs

Remote 2 Temperature, MSBs

0x00

0x00

0x00

High and low temperature limit registers are associated

with each temperature measurement channel. Exceeding the

programmed high and low limits sets the appropriate status

bit. Exceeding either limit can cause an SMBusALERT

interrupt.

I

N2 ×I N1 ×I IBIAS

Table 7. Temperature Measurement Limit Registers

Register

Description

Default

0x0B

0x0C

0x0D

0x0E

0x0F

0x10

0x11

0x12

0x13

Local High Limit

Local Low Limit

Local THERM Limit

Remote 1 High Limit

Remote 1 Low Limit

Remote 1 THERM Limit

Remote 2 High Limit

Remote 2 Low Limit

Remote 2 THERM Limit

0x8B (75°C)

0x54 (20°C)

0x95 (85°C)

0x8B (75°C)

0x54 (20°C)

0x95 (85°C)

0x8B (75°C)

0x54 (20°C)

0x95 (85°C)

VDD

D+

REMOTE

SENSING

TRANSISTOR

D–

LOW−PASS FILTER

fC = 65kHz

VOUT+

TO ADC

VOUT–

Figure 27. ADM1034 Signal Conditioning

Additional Functions

Several other temperature measurement functions

available on the ADM1034 offer the systems designer added

flexibility.

Turn−off Averaging

The ADM1034 performs averaging at conversion rates of

less than or equal to 8 conversions per second. This means

that the value in the measurement register is the average of 16

measurements. For faster measurements, set the conversion

rate to 16 conversions per second or greater. (Averaging is not

carried out at these conversion rates.) Alternatively, switch

off averaging at the slower conversion rates by setting Bit 1

(AVG) of Configuration 1 Register (Address 0x01).

Single−Channel ADC Conversions

In normal operating mode, the ADM1034 converts on

three temperature channels: the local temperature channel,

and the remote 1 and remote 2 channels. However, the user

has the option to set up the ADM1034 to convert on one

channel only. To enable single−channel mode, the user sets

the round−robin bit (Bit 7) in Configuration Register 2

(Address 0x02) to 0. When the round−robin bit equals 1, the

ADM1034 converts on all three temperature channels. In

single−channel mode, it converts on one channel only, to be

determined by the state of the channel selector bits (Bits 5

and 4) of the Configuration Register 2 (Address 0x02).

Table 8. Channel Selector

Bits 5:4

Channel Selector (Configuration 2)

00

Local Channel = Default

01

Remote 1 Channel

10

Remote 2 Channel

11

Reserved

Removing Temperature Errors

As CPUs run faster and faster, it gets more difficult to

avoid high frequency clocks when routing the D+ and D−

traces around a system board. Even when the recommended

layout guidelines are followed, temperature errors attributed

to noise coupled onto the D+ and D− lines remain. High

frequency noise generally gives temperature measurements

that are consistently too high. The ADM1034 has Local,

Remote 1, and Remote 2 temperature offset registers at

0x16, 0x17, and 0x18; one for each channel. By completing

a one−time calibration, the user can determine the offset

caused by the system board noise and remove it using the

offset registers. The registers automatically add a twos

compliment word to the remote temperature measurements,

ensuring correct readings in the value registers.

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