Coaxial switching products

Transcription

1 Coaxial switching products Technical training B BARBE RADIALL IDA April 2010 Updated February 2011

2 Summary Coaxial line Switching sequence on basic product : SPDT - Break Before Make / Make Before Break Main RF Contact s arrangements Actuator : Failsafe / Latching TTL driver Binary Coded Decimal Latching reset or Automatic reset Manual Reset Indicator Power breaker, Cut-off, Self Cut-Off Suppression diodes Feb-11 2

3 Coaxial line To switch a signal, transmission line must be : OPEN / OFF : No transmission CLOSE / ON : Full transmission OPEN LINE / OFF : Isolation CLOSE LINE / ON : Insertion Loss Closing plate RF Blade RF body Waveguide mode Rectangular coaxial mode Feb-11 3

4 Switching sequence on basic product : SPDT TIME (ms) COIL / ACTUATOR VOLTAGE VCC = 12 or 28VDC Polarity / 0 or Common : + or - VCC 0 BREAK ON INSERTION LOSS OFF ISOLATION Break Before Make ON INSERTION LOSS MAKE OFF ISOLATION Switching time (ms) Feb-11 4

5 Switching sequence Break Before Make / Make Before Break TIME (ms) TIME (ms) VCC 0 BREAK BREAK INSERTION LOSS ISOLATION Break Before Make Make Before Break INSERTION LOSS ISOLATION MAKE MAKE Impedance 50 Ω 25 Ω 0 Ω Switching time (ms) Switching time (ms) Feb-11 5

6 RF Contact s arrangements Based on OPEN / CLOSED line, RF arrangements have been defined regarding applications. Main ones are SPDT / DPDT / SPnT, these switches are called : NON terminated " SPDT Single Pole Double Throw SPnT Single Pole n Throw n = 3 to 12 ways DPDT Double Pole Double Throw Or SPnT with n = 2 ways Feb-11 6

7 RF Contact s arrangements Main products can be also Terminated, all non used ways are impedance terminated SPDT Single Pole Double Throw SPnT Single Pole n Throw n = 3 to 12 ways 1 C 2 1 C 2 Non terminated Terminated Non terminated Terminated Feb-11 7

8 Different switching configurations based on a same RF arrangement RF Contact s arrangements 2 SPDT linked together = DP3T + = Double pole Three throw DP3T with 1 load = BYPASS DP3T with 2 loads = SPDT terminated Feb-11 8

9 Switching by operator ON OFF Actuator Failsafe / Latching FAILSAFE LATCHING + TIME (ms) +1 TIME (ms) - -C + 2 -C ON ON C-NC C-2 OFF OFF ON C-NO Break Before Make ON C-1 Break Before Make OFF OFF Switching time (ms) Switching time (ms) Switching time (ms) Switching time (ms) Feb-11 9

10 Actuator Failsafe / Latching The Latching or Pulse Latching. Actuation requires a pulse length equal to or greater than the switching time. Main use is when the switch must be kept in a same position for a long time as for satellite. Indicator is often requested to remember the last position. The Fail-Safe Actuator is used where system requirements dictate the switch return to the normally closed or fail-safe position when actuator power is removed. Main use is linked with its name it s to say even without voltage, switch must be always kept in a same safe position as for redundancy in telecommunication market or military aircraft The Normally open Actuator is used where system requirements require all output ports of the switch to be disconnected from the input port until a voltage is applied to a selected position. Normally open actuator is used mainly on multithrow switches. No specific use Feb-11 10

11 TTL driver TTL driver option (Transistor Transistor Logic) is an electronic circuit enables the status of the switch to be controlled by the level of the TTL Logic input, TTL option can be compared to : VCC : +12VDC or +28VDC E : 0 /+5VDC 0 / GND +VCC +5VDC 0VDC TIME (ms) ON C-NC VCC OFF TTL E 0 / GND ON C NO RF Ways VOLTAGE TTL input ON position VCC / GND E / GND LEVEL C - NC +12 or +28VDC 0 to +0,8VDC 0 C - NO +12 or +28VDC +2,2 to +5VDC 1 OFF Feb-11 11

12 TTL driver One TTL input per RF position. Diodes option is always included Note : Memory means to keep the last position Feb-11 12

13 TTL driver For SPnT with TTL driver, one TTL input per RF way : 6 RF ways means 6 Inputs 12 RF ways means 12 Inputs Example for Input E1: RF Ways VOLTAGE TTL input E1 ON position VCC / GND E / GND LEVEL Open ways +12 or +28VDC 0 to +0,8VDC 0 IN or +28VDC +2,2 to +5VDC 1 Normally open : Logic Input RF continuity E6 E5 E4 E3 E2 E1 IN - 1 IN - 2 IN - 3 IN - 4 IN - 5 IN ON OFF OFF OFF OFF OFF OFF ON OFF OFF OFF OFF OFF OFF ON OFF OFF OFF OFF OFF OFF ON OFF OFF OFF OFF OFF OFF ON OFF OFF OFF OFF OFF OFF ON Latching : all RF ways RESET input Logic Input RF continuity Reset E6 E5 E4 E3 E2 E1 IN - 1 IN - 2 IN - 3 IN - 4 IN - 5 IN ON OFF OFF OFF OFF OFF OFF ON OFF OFF OFF OFF OFF OFF ON OFF OFF OFF OFF OFF OFF ON OFF OFF OFF OFF OFF OFF ON OFF OFF OFF OFF OFF OFF ON OFF OFF OFF OFF OFF OFF Feb-11 13

14 Binary Coded Decimal In order to reduce the numbers of inputs, TTL inputs can be coded : All manufacturers use BCD code ( Binary Coded Decimal ) according to the following conversion/thruth table between Inputs and Outputs: Weight of E1 input is factor 1 E2 is factor 2 E3 is factor 4 E4 is factor 8 Inputs : E1,2,3,4 are TTL level : 0 or 1 E4=X8 E3=X4 E2 = X2 E1=X1 Output TTL level 0 or 1 (0V / 5VDC) is applicable on each BCD Input For example for Input E1: RF Ways VOLTAGE TTL input E1 ON position VCC / GND E / GND LEVEL Open ways +12 or +28VDC 0 to +0,8VDC 0 IN or +28VDC +2,2 to +5VDC 1 Feb-11 14

15 Binary Coded Decimal For example, SP8T need 8 inputs with TTL driver and only 4 Inputs with BCD Logic Decoder option : Feb-11 15

16 Indicator It s an open/short electrical contact, mechanically linked to the actuator and synchronised with switched RF path, to ensure the recopy of positions of RF transmission paths : Feb-11 16

17 Applicable on latching switches only. Self Cut-Off This option disables the actuator current on completion of actuation. An integrated circuit provides the current cut-off to minimize power consumption by the RF switch. Suppression diodes are already included with this option TIME (ms) 40ms<T<120ms 40ms <T< 120ms 40ms<T<120ms Feb-11 17

18 Self Cut-Off This applies to latching switches only. This option disables the actuator current on completion of actuation. An integrated circuit provides the current cut-off to minimize power consumption by the RF switch. Suppression diodes are already included with this option Feb-11 18

19 Suppression Diodes This option offers fast-recovery diodes connected in parallel with the coils of the switch to suppress any transient voltage generated by the coils. Another diode is connected to protect the switch against wrong voltage polarity. Without diode With diode Suppression Diodes are always included in electronic options such as TTL driver, Cut-off Feb-11 19

20 Manual reset / Latching reset Applicable only on SPnT latching When a RF path is closed, it remains in its closed position after the voltage is removed (latching actuator) or interrupted (Cut-Off). To switch another path, all closed paths must be opened via a reset terminal, followed by the closing of second path. This reset mode then permits random selection of any desired switch position and garantees clean break-before-make switching. Feb-11 20

21 Swtching sequence for SP3T: Manual reset Pins driver 15ms min Need 125mA 28vdc Pin 1 0Vdc time 15ms min Need 125mA x 3 = 375mA 28vdc Reset Pin (manual) 0Vdc time Pin 2 Etc RF ways 15ms min Need 125mA 28vdc 0vdc time open voie RF 1 close open time open voie RF 2 close time Reset Pin current: I = n x I current per position with n : number of ways Due to heating during RESET: Pulse Reset time < 1s and Reset duty cycle > 10% Feb-11 21

22 Automatic reset Applicable only on SPnT latching To simplify the use of latching product, an automatic reset is recommanded. The auto-reset function is accomplished by an electronic circuit which brings the automatic opening of a previously closed path during changes of position of the switch. Cut-off and diode options are always included Feb-11 22

23 Automatic reset In order to optimize the reset mode, all coils are reseted per group of 2,3 or 4 coils with a cut-off reset/set time of 10ms according to below sequence. Switching time : Up to 6 positions <40ms and for 7 to 12p <52ms Actuator Current value (ma) ma Reset 9 Reset 5 Reset 2 Reset 1 28VDC RESET coils Reset 10 Reset 6 Reset 4 Reset 3 Reset 11 Reset 12 Reset 8 Reset 7 Set n 3 n ms Time (ms) SET coil Feb-11 23

24 Combined Options Some options can be combined in a same product : SP6T Terminated Latching Suppression diodes Indicators Cut-off Automatic reset TTL with BCD decoder Some options are non-compatible : Failsafe with Cut-off BCD for SP3 to 6T Feb-11 24

25 Combined Options Some options are included in others: Suppression diodes in electronic options (cut-off, TTL,Autoreset, ) TTL driver in BCD option Feb-11 25