Vccp Limit Registers; Additional Adc Functions For Voltage Measurements - Analog Devices ADT7473 Manual

V LIMIT REGISTERS
CCP
Associated with the V measurement channel is a high and
CCP
low limit register. Exceeding the programmed high or low limit
causes the appropriate status bit to be set. Exceeding either limit
can also generate SMBALERT interrupts.
Reg. 0x46 V Low Limit = 0x00 default
CCP
Reg. 0x47 V High Limit = 0xFF default
CCP
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 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 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 (Reg. 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 (Reg. 0x73) removes
the attenuation circuitry from the V
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 (Reg. 0x73) places the
ADT7473 into single-channel ADC conversion mode. In this
mode, the ADT7473 can be made to read a single voltage
channel only. If the internal ADT7473 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).
Bits <7:5> Reg. 0x55
001
010
101
110
111
Configuration Register 2 (Reg. 0x73)
<4> = 1, averaging off.
<5> = 1, bypass input attenuators.
<6> = 1, single-channel convert mode.
TACH1 Minimum High Byte (Reg. 0x55)
<7:5> selects ADC channel for single-channel convert mode.
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ADT7473
input. This allows the
CCP
Channel Selected
V
CCP
V
CC
Remote 1 temperature
Local temperature
Remote 2 temperature