GX4002 Datasheet, PDF (38/74 Pages) Gennum Corporation – Dynamic on-chip power management control

3.7 Digital Diagnostics
The GX4002 has an on-chip ADC to provide diagnostic information through the digital
interface. Temperature and voltage can be monitored.
3.7.1 Analog to Digital Converter (ADC)
The ADC converts several analog quantities including temperature, supply, vertical and
horizontal eye monitor outputs, and peak detector outputs.
The ADC is a sigma-delta converter with programmable resolution allowing trade-off
between conversion time and accuracy. The full scale dynamic range of the ADC is 0 to
1.8V. The various sources can be selected into the ADC for conversion and read-out.
Offset calibration signals are provided to zero-out the selected sources to facilitate the
calibration. Calibrated offsets can be programmed-in, such that the data read-out has
corrected offsets.
Furthermore, a user-defined offset can be programmed-in to account for external
systemic shifts. For example: if the temperature at the case is desired instead of the
device temperature, the temperature delta between device and case can be
programmed-in. Subsequent temperature read-outs will account for the temperature
delta, and provide the case temperature.
3.7.1.1 Usage Model
Two usage models are possible, manual conversion and auto conversion.
3.7.1.1.1 MANUAL CONVERSION MODE
For manual conversion mode, register controls provide a conversion-on-demand
interface. Polling or timing is required at the master end to read out the converted values
in manual mode.
The user is expected to select the desired source and to write a 1 to the
ADCSTARTCONV bit to initiate the conversion. The user can poll the ADCDONECONV
bit or time the conversion based on the requested resolution before reading out the data.
To read out the data in the timed mode, a block read transfer can be performed on the
ADCDONECONV, ADCOUTLO and ADCOUTHI registers. If the ADCDONECONV bit
is HIGH, then the data is valid.
The ADCSTARTCONV bit does not have to be reset before initiating another conversion.
Similarly, the ADCDONECONV bit does not have to be reset before initiating another
conversion. This minimizes the host interface transaction overhead while using the
ADC.
3.7.1.1.2 AUTO CONVERSION MODE
The user selects the desired source, and enables the auto conversion mode by setting
ADCAUTOCONVEN HIGH. The ADC will continuously convert the selected source and
update the ADCOUTHI/LO registers.
GX4002 2x2 14.025Gb/s Crosspoint Switch with Trace
Equalization and Output De-Emphasis
Data Sheet
55972 - 0
March 2012
38 of 74
Proprietary & Confidential