2.3.1
Summary Description
The NEXSYS Electronic Latch (EL1, EL2) is a Series C (8 Pin) electronic component with multiple trigger modes that activate orthogonal switching (flip-flop) between two known states, see Figure 2.3.1.0-A. The device can perform similar functions of traditional electromagnetic or solenoid switches but at a fraction of the size, weight, and power requirements due to its solid-state design.
The NEXSYS Electronic Latch (EL1, EL2) 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 EL 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 Latch inputs are Power (28V), Ground (GND), Toggle (/TGL), Set (/SET), and Reset (/RST). The Signal Definition Table and Truth Table provide specific details concerning the Input/Output (I/O) interface, see Figure 2.3.1.0-B and Figure 2.3.1.0-C. The inputs include the following characteristics for custom switching and output control. Electronic Latch input circuity is diode isolated, buffered, and debounced for reliable operation.
28V (PIN 4): Operating Voltage (Nom.), Current Draw 4 mA (Max).
GND (PIN 5): Continuous Ground required, otherwise, inadvertent operation could occur.
/TGL (PIN 2): Detects High to Low signal transitions, which function as the control interface to drive outputs.
/SET (PIN 3): Immediate activation to the Set state.
/RST (PIN 1): Immediate activation to the Reset state.
Output Characteristics
The NEXSYS Electronic Latch features conditioned outputs Q, Q and Blink (BLK) 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 2.3.1.1-A (Operating Parameters) for electrical load rating types.
Q (PIN 6), Q (PIN 7): Active = Low (Ground), Not Active = High-Z (Open) and Q is the complement of Q.
BLK (PIN 8): 1 Hz square wave (50% duty cycle) oscillation frequency (Blink), alternating High-Z (Open) to Low (Ground).
Configuration Options
The NEXSYS Electronic Latch is available in two configurations for custom solid-state switching control. The device powers-up in a specified, known state. Upon power-up, High to Low (
)signal transitions to the /SET, /TGL, and /RST input functions to control the Q, Q and BLK outputs.
Electronic Latch 1 (EL1), Default Power-Up State: Q = High-Z (Open), Q = Low (Ground) and BLK = High-Z (Open).
Electronic Latch 2 (EL2), Default Power-Up State: Q = Low (Ground), Q = High-Z (Open) and BLK = 1 Hz oscillation frequency.
Signal Description
For a description of the input and output functions of the Electronic Latch component, see Figure 2.3.1.0-B.
| Pin Reference | Pin Identification | Function | Input Trigger | Description |
|---|---|---|---|---|
| 1 | /RST | Input | Low (Ground) | Forces Q OUT to OFF High-Z (Open). Forces Q OUT to ON Low (Ground). Forces BLK to Steady ON Low (Ground). See Note 1. |
| 2 | /TGL | Input |
See Note 4 |
Toggles Q OUT and Q OUT. Toggles blink mode. See Note 2. |
| 3 | /SET | Input | Low (Ground) | Forces Q OUT to ON Low (Ground). Forces Q OUT to OFF High-Z (Open). Initiates the 1Hz blink mode to BLK Output. |
| 4 | 28V | Power | – | Power (+18 VDC to +32 VDC) |
| 5 | GND | Common | – | Continuous Ground Required. |
| Pin Reference | Pin Identification | Function | Output Active State | Description |
| 6 | Q OUT | Output | Low (Ground) | Open Drain Output. Forced OFF High-Z (Open) by /RST Input. Forced ON Low (Ground) by /SET Input. Toggled by Falling Edge of /TGL Input. |
| 7 | Q OUT | Output | Low (Ground) | Open Drain Output. Forced ON Low (Ground) by /RST Input. Forced OFF High-Z (Open) by /SET Input. Toggled by Falling Edge of /TGL Input. |
| 8 | BLK | Output | Low (Ground) | Open Drain Output. Forced ON Low (Ground) while /RST is held Low (Ground). BLK Active (1 Hz) in /SET and Not Active in /RST. |
Truth Table
For a description of the operational states of the Electronic Latch component, see Figure 2.3.1.0-C.
| Inputs | Outputs | Comments | ||||
| /SET | /RST | /TGL | Q OUT | Q OUT | Blink | |
| High-Z (Open) | Low (Ground) | X | High-Z (Open) | Low (Ground) | Steady ON See Note 1 |
Represents EL1 Power-Up State |
| Low (Ground) | High-Z (Open) | X | Low (Ground) | High-Z (Open) | 1 Hz Blink See Note 1 |
Represents EL2 Power-Up State |
| High-Z (Open) | High-Z (Open) | See Note 4 |
Opposite State | Opposite State | Change State See Note 2 |
|
| Low (Ground) | Low (Ground) | X | Low (Ground) See Note 3 |
Low (Ground) See Note 3 |
Steady ON See Note 1 |
|
Notes
- BLK is steady-state Low (Ground) while /RST is held Low (Ground). BLK Active (1 Hz) in /SET and Not Active in /RST. Upon EL1 Power-Up, /RST is internally held Low (Ground) momentarily, causing BLK to flash.
- /TGL controls BLK, ON = 1 Hz oscillation (50% duty cycle) and OFF = High-Z (Open). /TGL is overridden when /RST or /SET is held Low (Ground).
- If /SET and /RST release simultaneously, the device returns to the default power-up state. Otherwise, it functions according to the defined input levels.
- Transition from High-Z (Open) to Low (Ground) toggles Q and Q. Input signal level definitions are provided in the Parametric Table, see Figure 2.3.1.1-A.
2.3.1.1
| Description | Parameters |
| Operating Parameters | |
| Operating Voltage (Max. / Nom. / Min.) | +32 VDC / +28 VDC / +18 VDC |
| Power Supply Input Current | 4 mA (Maximum) |
| Reset From Power Loss at 25°C | 5 sec (Minimum) at +25° C |
| Hold Up On Power Loss at 25°C | 50 ms (Minimum) |
| Input Parameters | |
| EL1: /RST, EL2: /SET at 25°C | 120 ms (Minimum) |
| /TGL at 25°C | 45 ms (Minimum) |
| EL1: /SET, EL2: /RST at 25°C | 45 ms (Minimum) |
| * High Level Input Voltage ( VIH ) at 25°C | +3 VDC (Minimum) |
| * Low Level Input Voltage ( VIL ) at 25°C | +0.4 VDC (Maximum) |
| Low Level Input Current ( IIL ) at 25°C | 1 mA (Maximum) |
| Note: All signal inputs are diode isolated | |
| Output Parameters | |
| 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 = 274,801 hrs |
| * VIL and VIH specifications are in reference to unit Ground. | |
For Qualification Summary, see Appendix A