INFICON Spot CDS550D - Manual (Page 4)

Research & Development
SPOT CDS500D & CDS550D OEM Sensor SPI-Interface Specification_V1.1 Page 4 of 14
Christian Berg, T based on Felix Mullis, TL Created 11/10/2014 2:36:00 PM
2.2 Interface Connector and Cable
Connector Type: JST 1mm 10 pol.
pin Signal Description
Direction
(SPOT CDS5xxD-side)
1 +5V Power Supply input
2 GND Supply Common input
3 Clk SPI Clock input
4 SS/ SPI Slave Select (low true) input (low true)
5 MISO SPI Master Input Slave Output output (tristate)
6 MOSI SPI Master Output Slave Input input
7 RDY/ Ready Signal (new measurement value available) output (low true)
8 C1/C0 Internal use only, must be left open output
9 R0/Rref Internal use only, must be left open output
10 Vpp_OTP Internal use only, must be left open input
Table 1: pin assignment SPI connector
Cable length: max. 15 cm
2.3 Grounding Concept
The metallic sensor housing (flange) acts as a shielding for the very sensitive electronic measurement
frontend. In order to achieve the specified noise specifications, the sensor flange must be connected
to GND (Supply Common). The impedance of such a connection should be as low as possible. There-
fore it is realized directly on the PCB at the frontend of the electronics. This solution guarantees lowest
noise and simultaneously maximizes EMC robustness.
2.4 Timing Specifications
The SPI Timing is described in detail in chapter 5.2 (SPI Timing) in the Appendix.
Signal Description MIN TYP MAX UNIT
T_tot_cycle Total Measurement Cycle Time = Data Cycle Time 900 1000 1100 µs
T_sgl_cycle Single Measurement Cycle Time 800 900 1000 µs
T_rd_out Readout Time - - 100 µs
Table 2: SPI Readout Timing
For a description of the above used expressions refer to chapter 5.2 (SPI Timing) in the Appendix.