Analog Devices dBCool ADT7476, Руководство пользователя

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ADT7476
Rev. B | Page 18 of 72
Table 6. Conversion Time with Averaging Disabled
Channel Measurement Time (ms)
Voltage Channels 0.7
Remote Temperature 1 7
Remote Temperature 2 7
Local Temperature 1.3
When Bit 7 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 V, V
CCP
, V
CC
, 5 V, and 12 V
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 attenua-
tors 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 7. Bypassing Individual Voltage Input Attenuators
Using Configuration Register 4 (0x7D)
Bit Channel Attenuated
4 Bypass 2.5 V attenuator
5 Bypass V
CCP
attenuator
6 Bypass 5 V attenuator
7 Bypass 12 V attenuator
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.
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
ADT7476 into single-channel ADC conversion mode. In this
mode, the ADT7476 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 [7:5] of the TACH1
minimum high byte register (0x55).
Table 8. Programming Single-Channel ADC Mode
Register 0x55, Bits [7:5] Channel Selected
1
000 2.5 V
001 V
CCP
010 V
CC
011 5 V
100 12 V
101 Remote 1 temperature
110 Local temperature
111 Remote 2 temperature
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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