|
GX3246 Datasheet, PDF (31/47 Pages) Semtech Corporation – Crosspoint Switch with Trace Equalization and Output De-emphasis | |||
|
◁ |
In addition to the diode temperature sensors, four ADCs, each with two selectable
temperature sensors, are also provided. Digitized temperatures can be read through the
deviceâs host interface.
thermo
ADC 1 Even Outputs 0 to 288
thermo
ADC 2
Crosspoint Core
Legend:
ADC and âlocalâ temperature sensors
âremoteâ temperature sensors
thermo
ADC 3
Odd Outputs 1 to 289
thermo
ADC 0
Package Top-view of Die
Figure 4-4: Map of Thermometer ADC Positions on Die
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:
Tj = 0.5489 à JNCTN_TEMP_[3:0] â 263 + δ3
Where δ3 is the temperature uncertainty. The accuracy of the temperature sensors can
be improved by calibrating the GX3246 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.
GX3246 290 x 146 3.5Gb/s Crosspoint
Final Data Sheet Rev. 2
GENDOC-056078 March 2013
www.semtech.com
31 of 47
Proprietary & Confidential
|
▷ |