Additional Adc Functions For Voltage Measurements - Analog Devices ADT7473 Manual

ADT7473/ADT7473-1
Table 9 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 μs 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 μs), but the reading may be noisier.
Bypass Voltage Input Attenuator
Setting Bit 5 of Configuration Register 2 (0x73) removes the
attenuation circuitry from the V
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.
input. This allows the user
CCP
Rev. C | Page 14 of 72
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 μs. The appropriate ADC channel is selected by writing to
Bits [7:5] of the TACH1 minimum high byte register (0x55).
Table 8. Programming Single-Channel ADC Mode
Bits [7:5] Register 0x55
001
010
101
110
111
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.
Channel Selected
V
CCP
V
CC
Remote 1 temperature
Local temperature
Remote 2 temperature