2.3.2
Summary Description
The NEXSYS Electronic Rotary (ER1) is a Series C (8 Pin) component designed to provide incremental switching through a loop of up to four latched output states (/Q1-/Q4), see Figure 2.3.2.0-A. The product offers a solid-state replacement for applications that traditionally utilize up to a four position rotary device. The NEXSYS Electronic Rotary component provides the ability to use a single illuminated pushbutton switch or indicator to cycle through multiple latched states either from successive switch closures or from a remote source.
The NEXSYS Electronic Rotary (ER1) is a commercial-off-the-shelf (COTS) item. This standard catalog hardware includes features to allow for flexible interface design solutions while also meeting aircraft performance standards. The ER is designed, tested, and qualified to MIL-PRF-22885/116, MIL-PRF-22885/117, DO-160 and MIL-STD-461 requirements. Specifications are available in our MIL-PRF and DO-160 Documents page, and the qualification table is available in Appendix A.
Input Characteristics
The NEXSYS Electronic Rotary inputs are Power (28V), Ground (GND), Increment (/INC) and Reset (/RST). Electronic Rotary input circuity is diode isolated, buffered, and debounced for reliable operation. The Signal Description Table and Truth Table provide specific details concerning the Input/Output (I/O) interface, see Figure 2.3.2.0-B and Figure 2.3.2.0-C. The inputs include the following characteristics for custom multi-state switching and output control.
28V (PIN 4): Operating Voltage (Nom.), Current Draw 4 mA (Max).
GND (PIN 5): Continuous Ground required, otherwise, inadvertent operation could occur.
/INC (PIN 3): Detects signal transitions, which function as the control interface to loop through four outputs. /INC is disabled when /RST is held Low (Ground).
/RST (PIN 1): Immediate activation to the /RST state.
Output Characteristics
The NEXSYS Electronic Rotary features conditioned outputs /Q1-/Q4 to perform functions that may originate from remote inputs or switch closures. All outputs are open-drain High-Z (Open) when not active, fused, and surge-protected against transients and overload conditions. The output load capacity is 2.0 A, see Figure 2.3.2.1-A (Operating Parameters) for electrical load rating types.
/Q1 (PIN 6), /Q2 (PIN 7), /Q3 (PIN 8), /Q4 (PIN 2): Active = Low (Ground), Not Active = High-Z (Open).
Configuration Options
The NEXSYS Electronic Rotary standard configuration powers-up in a known state, which is /Q1 = Active Low (Ground) and /Q2-/Q4 = High-Z (Open). Following power-up, /INC will detect a High to Low (
) signal transition, and successive transitions will activate the next of four latched outputs in the loop sequence. The ER1 latching circuitry holds the current state until /INC or /RST inputs are toggled, High to Low. Configuring an ER1 circuit to reduce the number of states, advance (skip) a state, hold a state, customize the state sequence or a shift register is performed by a simple input-pin interface.
Reduce State: is performed by wiring the next output state back to /RST. For example, wiring /Q4 to /RST configures a three-state rotary (/Q1-/Q3) circuit.
Advance State: is performed by NOT wiring an output. For example, NOT wiring /Q1 configures an “OFF” or “STBY” state in /Q1. States /Q2-/Q4 will advance with each successive High to Low transition to /INC, following the NOT /Q1 state.
Hold State: is performed by wiring the next output state back to /INC. For example, wiring /Q4 back to /INC configures a hold circuit, until power is cycled.
Custom State: is performed by wiring outputs in a custom sequence. For example, wiring /Q1-/Q4 in a defined sequence configures custom indicator illumination circuit activation (i.e., loop or zigzag).
Shift Register: is performed by wiring ER1 I/O to additional NEXSYS timing and Boolean logic gate components. For example, wiring can be configured with additional NEXSYS components to produce parallel, serial and bidirectional shift register circuits.
Signal Description
For a description of the input and output functions of the Electronic Rotary component, see Figure 2.3.2.0-B.
| Pin Reference | Pin Identification | Function | Input Trigger |
| 1 | /RST | Low (Ground) Resets to State 1 with /Q1 latched Low (Ground) and remains in Reset until Low (Ground) is released. | Low (Ground) |
| 3 | /INC | High to Low transition (  ) advances the unit to the next state. Input signal level definitions are provided in the Parametric Table, see Figure 2.3.2.1-A. |
Increment input at state 4 will return the unit to state 1 |
| 4 | 28V | Power | +28 VDC |
| 5 | GND | Ground | Continuous Ground req’d |
| Pin Reference | Pin Identification | Function | Active State |
| 6 | /Q1 | Default upon power-up or Reset is Active Low (Ground). | Active Low (Ground) |
| 7 | /Q2 | Default upon power-up or Reset is High-Z (Open) and transitions to Active Low (Ground) upon /INC. | Active Low (Ground) |
| 8 | /Q3 | Default upon power-up or Reset is High-Z (Open) and transitions to Active Low (Ground) upon /INC. | Active Low (Ground) |
| 2 | /Q4 | Default upon power-up or Reset is High-Z (Open) and transitions to Active Low (Ground) upon /INC. | Active Low (Ground) |
Truth Table
For a description of the operational states of the Electronic Rotary component, see Figure 2.3.2.0-C.
| Inputs | Outputs | ||||
| /RST | /INC | /Q1 | /Q2 | /Q3 | /Q4 |
| High | High to Low | Next output, transistions from High-Z (Open) (Open Drain) to Active Low (Ground) | |||
| Low | X | Active Low (Ground) | High-Z (Open) (Open Drain) |
High-Z (Open) (Open Drain) |
High-Z (Open) (Open Drain) |
| X = Input has no effect on output, it is a logic don't-care (DC) condition. Note: Only one output is active at any one time. | |||||
2.3.2.1
| Description | Parameters |
| Operating Parameters | |
| Operating Voltage (Max. / Nom. / Min.) | +32 VDC / +28 VDC / +18 VDC |
| Power Supply Input Current | 5 mA (Maximum) |
| Reset From Power Loss at 25°C | 5 sec (Minimum) at +25° C |
| Hold Up On Power Loss at 25°C | 200 ms (Minimum) |
| Input Parameters | |
| /INC at 25°C | 50 ms (Minimum) |
| /RST at 25°C | 80 ms (Minimum) |
| Timing /INC to output at 25°C | 100 ms (Maximum) |
| * High Level Input Voltage ( VIH ) at 25°C | +3 VDC (Minimum) |
| * Low Level Input Voltage ( VIL ) at 25°C | +1.2 VDC (Maximum) |
| Low Level Input Current ( IIL ) at 25°C | 1 mA (Maximum) |
| Note: All signal inputs are diode isolated | |
| Output Load Capacity | |
| Output Load Capacity | 2.0 A (Resistive) / 1.0 A (Motor) / 0.8 A (Inductive/Lamp) |
| On-State Resistance at 25°C | Typical 0.07 ohms / Maximum 0.09 ohms |
| Off-State Resistance at 25°C | Open Drain (High-Z), Fuse-Protected MOSFET, +32 VDC Maximum |
| Temperature | |
| Operating | -55° C to +85° C |
| Non-Operating | -55° C to +85° C |
| Reliability MIL-HDBK-217F, Notice 2 |
|
| Airborne Inhabited Cargo (AIC) at +40°C Continuous Operation |
MTBF = 202,483 hrs |
| * VIL and VIH specifications are in reference to unit Ground. | |
For Qualification Summary, see Appendix A