ADT7490ARQZ-R7 データシートの表示（PDF） - ON Semiconductor

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ADT7490ARQZ-R7

dBCool Remote Thermal Monitor and Fan Controller with PECI Interface

ON Semiconductor 

ADT7490

Table 4. Conversion Time with Averaging Disabled

Channel

Voltage Channels

Remote Temperature 1

Remote Temperature 2

Local Temperature

Measurement Time (ms)

0.7

7

7

1.3

When Bit 7 (ExtraSlow) of Configuration Register 6

(0x10) is set, the default round−robin cycle time increases to

240 ms.

Bypass All Voltage Input Attenuators

Setting Bit 5 of Configuration Register 2 (0x73) removes

the attenuation circuitry from the 2.5 VIN, VCCP, VCC, 5 VIN,

and 12 VIN inputs. This allows the user to directly connect

external sensors or rescale the analog voltage measurement

inputs for other applications. The input range of the ADC

without the attenuators is 0 V to 2.25 V.

Bypass Individual Voltage Input Attenuators

Bits [7:4] of Configuration Register 4 (0x7D) can be used

to bypass individual voltage channel attenuators.

Table 5. Bypassing Individual Voltage Input

Attenuators

Configuration Register 4 (0x7D)

Bit No.

4

5

6

7

Channel Attenuated

Bypass +2.5 VIN attenuator

Bypass VCCP attenuator

Bypass +5 VIN attenuator

Bypass +12 VIN attenuator

Single−Channel ADC Conversion

While single−channel mode is intended as a test mode that

can be used to increase sampling times for a specific

channel, therefore helping to analyze that channel’s

performance in greater detail, it can also have other

applications.

Setting Bit 6 of Configuration Register 2 (0x73) places the

ADT7490 into single−channel ADC conversion mode. In

this mode, the ADT7490 can read a single voltage channel

only. The selected voltage input is read every 0.7 ms. The

appropriate ADC channel is selected by writing to Bits [7:4]

of the TACH1 minimum high byte register (0x55).

Table 6. Programming Single−Channel ADC Mode

Bits [7:4], Register 0x55

Channel Selected (Note 1)

0000

0001

0010

0011

0100

0101

+2.5 VIN

VCCP

VCC

+5 VIN

+12 VIN

Remote 1 temperature

0110

Local temperature

0111

Remote 2 temperature

1000

VTT

1001

IMON

1. In the process of configuring single-channel ADC conversion

mode, the TACH1 minimum high byte is also changed, possibly

trading off TACH1 minimum high byte functionality with

single-channel mode functionality.

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