2.4.3
Summary Description
The NEXSYS Square Wave Oscillator (CT1, CT2) is a Series A (4 Pin) device that can be specified to detect a signal level state change (trigger event) to activate the output once the unit is energized. OUT (PIN 1) can be specified to begin oscillating when IN (PIN 3) detects a state change, see Figure 2.4.3.0-C for signal level definitions. OUT (PIN 1) can generate an oscillating High-Z (Open) to Low (Ground) or Low (Ground) to High-Z (Open) at a specified frequency initiated by a defined trigger event at IN (PIN 3). OUT (PIN 1) will remain active until the trigger condition is reversed, see Figure 2.4.3.0-A.
The NEXSYS Square Wave Oscillator features fault-tolerant circuitry and architecture, making it ideal for applications that require stable operation, reliability, and precision. The Square Wave Oscillator offers a range of frequency/cycle options from 0.25 Hz to 500 Hz.
The NEXSYS Square Wave Oscillator (CT1, CT2) 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 CT 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 Square Wave Oscillator inputs are Power (28V), Ground (GND), and Input (IN). The inputs include the following characteristics for custom oscillating-output control. Square Wave Oscillator input circuity is diode isolated, buffered, and debounced for reliable operation. See additional sections for specific details concerning the Input/Output (I/O) interface.
28V (PIN 2): Operating Voltage (Nom.), Current Draw 4 mA (Max).
GND (PIN 4): Continuous Ground required, otherwise, inadvertent operation could occur.
SENSE (PIN 3): Detects trigger event.
Output Characteristics
The NEXSYS Square Wave Oscillator features a conditioned Output (OUT) that is open-drain High-Z (Open) when not active and surge-protected against transients and overload conditions. When Active, OUT Oscillates between Ground and Open. The output load capacity is 0.5 A, see Figure 2.4.3.1-A (Operating Parameters) for electrical load rating types.
OUT (PIN 1): Oscillates Low (Ground)/High-Z (Open) when triggered.
Configuration Options
The NEXSYS Square Wave Oscillator features two trigger event configurations to initiate oscillation, Oscillate on Trigger and Oscillate on Power-Up. The device also features four input level configurations, two output level configurations, and a wide range of oscillation configurations, which require constant power for operation. Input and output I/O signal level definitions are provided in the Parametric Table, see Figure 2.4.3.1-A.
Oscillate on Trigger: IN (PIN 3) detects the specified trigger event level. There are two operating states: Standby and Active, see Figure 2.4.3.0-B.
Standby: IN (PIN 3) is at the Standby level, and OUT (PIN 1) is specified as either steady-state Low (Ground) or High-Z (Open).
Active: OUT (PIN 1) oscillates between Low (Ground) and High-Z (Open) at the specified oscillation frequency. Oscillation will terminate if the trigger event is reversed, and OUT (PIN 1) will return to the Standby level.
Input Levels: IN (PIN 3) features four input level configurations that transition Standby state to Active, see Figure 2.4.3.0-C. IN (PIN 3) detects a state-level change upon power-up.
| Code | Oscillation STANDBY | Oscillation ACTIVE |
| W | +28 VDC or High-Z (Open) | Low (Ground) |
| P | +28 VDC Must be same power source as PIN 2 |
Low (Ground) or High-Z (Open) |
| D | Low (Ground) or High-Z (Open) | +28 VDC Must be same power source as PIN 2 |
| G | Low (Ground) | +28 VDC or High-Z (Open) |
W Configuration Code: IN (PIN 3) transitions from +28 VDC or High-Z (Open) in Standby to Low (Ground) in Active.
P Configuration Code*: IN (PIN 3) transitions from +28 VDC in Standby to Low (Ground) or High-Z (Open) in Active.
D Configuration Code*: IN (PIN 3) transitions from Low (Ground) or High-Z (Open) in Standby to +28 VDC in Active.
G Configuration Code: IN (PIN 3) transitions from Low (Ground) in Standby to +28 VDC or High-Z (Open) in Active.
*Must be the same +28 VDC source as +28 VDC (PIN 2).
Output Levels: OUT (PIN 1) features two output level configurations that transition Standby to the Active state.
CT1: OUT (PIN 1) is Low (Ground) in Standby and Oscillates Low (Ground)/High-Z (Open) when Active.
CT2: OUT (PIN 1), High-Z (Open) in Standby, and Oscillates Low (Ground)/High-Z (Open) when Active.
| Code | Oscillation STANDBY | Oscillation ACTIVE |
| CT1 | Low (Ground) | Oscillating, Low (Ground) to High-Z (Open) |
| CT2 | High-Z (Open) |
Oscillating, Low (Ground) to High-Z (Open) |
Oscillation Frequency: Oscillation configurations range from 0.25 Hz to 500 Hz and are available in eight increments, see Figure 2.4.3.0-E.
| Frequency
(Cycles / Sec) |
Period
(Sec / Cycle) |
| 0.25 Hz | 4 |
| 0.5 Hz | 2 |
| 1 Hz | 1 |
| 2 Hz | 0.5 |
| 4 Hz | 0.25 |
| 10 Hz | 0.1 |
| 100 Hz | 0.01 |
| 500 Hz | 0.002 |
2.4.3.1 Square Wave Oscillator, Operating Parameters
| 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 | 200 ms (Minimum) |
| Input Parameters | |
| Input Timing at 25°C | 10 ms (Maximum) |
| * High Level Input Voltage ( VIH ) at 25°C | 1 mA (Maximum) |
| * Low Level Input Voltage ( VIL ) at 25°C | < +1.5 VDC |
| Low Level Input Current ( IIL ) at 25°C | > +8 VDC |
| All Pulled-up inputs are diode isolated | |
| Output Parameters | |
| Output Load Capacity | IntelliFET® 0.5 A (Resistive/Motor/Inductive/Lamp) |
| On-State Resistance at 25°C | Typical 0.4 ohms / Maximum 0.6 ohms |
| Off-State Resistance at 25°C | Open Drain (High-Z), Self-Protected IntelliFET®, +32 VDC Maximum |
| Cycle Time Tolerance at 25°C | +/- 5% |
| Temperature | |
| Operating | -55°C to +85°C |
| Non-operating | -55°C to +125°C |
| Reliability MIL-HDBK-217F, Notice 2 |
|
| Airborne Inhabited Cargo (AIC) at +40°C Continuous Operation |
MTBF = 321,986 hrs |
| * VIL and VIH specifications are in reference to unit Ground. | |
For Qualification Summary see Appendix A