GX3202 Datasheet, PDF (32/49 Pages) Semtech Corporation – Crosspoint Switch with Trace Equalization and Output De-emphasis

Table 4-10: Junction Temperature Registers
Thermometer ADC
0
1
2
3
Sensor Location Select
Register
ADC_IN_0
ADC_IN_1
ADC_IN_2
ADC_IN_3
Result Register
JNCTN_TEMP_0
JNCTN_TEMP_1
JNCTN_TEMP_2
JNCTN_TEMP_3
Digitized 10-bit temperature values can be read through the host interface from
registers JNCTN_TEMP_0 (register 0xA08h[9:0]) through JNCTN_TEMP_3 (register
0xA0Bh[9:0]). The temperature word in each register will be updated every 2¹³ clock
cycles, provided the value of the respective COUNT_PD_[3:0] bit remains LOW. When
a COUNT_PD_[3:0] bit goes HIGH, the ADC is reset and the corresponding
JNCTN_TEMP_[3:0] register retains its last updated value. The clock rate can be
selected between 211kHz or 844kHz through the corresponding
ADC_CTRL_CLK_SEL_[3:0] bits (registers 0xA04h, 0xA05h, 0xA06h and 0xA07h).
The junction temperature at each temperature sensor in terms of the ADC output code
is given by:
T_j = 0.5489 × JNCTN_TEMP_[3:0] – 263 + δ₃
Where δ₃ is the temperature uncertainty. The accuracy of the temperature sensors can
be improved by calibrating the GX3202 at a known junction temperature. Without
calibration, the temperature uncertainty, due to process variations and component
mismatch, can be as high as ±27°C. After calibration, the uncertainty can be reduced to
about ±2°C.
See Using the Monitoring Features of the GX3290 Application Note for more
information.
GX3202 202 x 202 3.5Gb/s Crosspoint
Data Sheet
56077 - 1
October 2012
32 of 49
Proprietary & Confidential