ADT7473 Ver la hoja de datos (PDF) - ON Semiconductor

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ADT7473

dBCOOL® Remote Thermal Monitor and Fan Control

ON Semiconductor 

ADT7473

Table 5 shows the input ranges of the analog inputs and

output codes of the 10−bit ADC.

When the ADC is running, it samples and converts a

voltage input in 711 ms and averages 16 conversions to

reduce noise; a measurement takes nominally 11.38 ms.

Additional ADC Functions for Voltage Measurements

A number of other functions are available on the

ADT7473/ADT7473−1 to offer the system designer

increased flexibility.

Turn−Off Averaging

For each voltage measurement read from a value register,

16 readings have actually been made internally and the

results averaged before being placed into the value register.

When faster conversions are needed, setting Bit 4 of

Configuration Register 2 (0x73) turns averaging off. This

effectively gives a reading 16 times faster (711 ms), but the

reading may be noisier.

Bypass Voltage Input Attenuator

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

the attenuation circuitry from the VCCP input. This allows

the user to directly connect external sensors or to 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.

Single−Channel ADC Conversion

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

ADT7473/ADT7473−1 into single−channel ADC

conversion mode. In this mode, the ADT7473/ADT7473−1

can be made to read a single voltage channel only. If the

internal ADT7473/ADT7473−1 clock is used, the selected

input is read every 711 ms. The appropriate ADC channel is

selected by writing to Bits [7:5] of the TACH1 minimum

high byte register (0x55).

Table 4. Programming Single−Channel ADC Mode

Bits [7:5], Register 0x55

Channel Selected

001

VCCP

010

VCC

101

Remote 1 temperature

110

Local temperature

111

Remote 2 temperature

Configuration Register 2 (0x73)

Bit 4 = 1; averaging off.

Bit 5 = 1; bypass input attenuators.

Bit 6 = 1; single−channel convert mode.

TACH1 Minimum High Byte Register (0x55)

Bits [7:5] select ADC channel for single−channel convert

mode.

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