2.4.2
Summary Description
The NEXSYS Time Delay (TD1, TD2) 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. The NEXSYS Time Delay can be specified to start the delay timer when either IN (PIN 3) detects a state change (see Figure Figure 2.4.2.0-D for signal level definitions) or upon power-up, 28V (PIN 2). OUT (PIN 1) can generate either a delayed Low (Ground) or High-Z (Open) that is initiated by a defined trigger event at IN (PIN 3). OUT (PIN 1) will remain active until the trigger condition is reversed, see Figure 2.4.2.0-A.
The NEXSYS Time Delay features fault-tolerant circuitry and architecture, making it ideal for applications that require stable operation, reliability, and precision. The Time Delay features an extensive range of timing options that afford design versatility; the choices range from 125 ms to 4 hrs.
The NEXSYS Time Delay (TD1, TD2) 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 TD 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 Time Delay inputs are Power (28V), Ground (GND), and Input (IN). The inputs include the following characteristics for custom timed-output control. Time Delay 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.
IN (PIN 3): Detects trigger event, not used for Time Delay on Power-Up applications.
Output Characteristics
The NEXSYS Time Delay features a conditioned Output (OUT) that is open-drain, High-Z (Open) when not energized, and surge-protected against transients and overload conditions. The output load capacity is 0.5 A, see Figure 2.4.2.1-A (Operating Parameters) for electrical load rating types.
OUT (PIN 1): Specified as Active Low (Ground) or High-Z (Open) when delay timing has elapsed.
Configuration Options
The NEXSYS Time Delay features two trigger event configurations to initiate the delay timer, Time Delay on Trigger and Time Delay on Power-Up. The device also features four input level configurations, two output level configurations, and a wide range of Timing (Delay) configurations, which require constant power for operation. If power is removed or the trigger event is reversed, the timing is reset. Input and Output I/O signal level definitions are provided in the Parametric Table, see Figure 2.4.2.1-A.
Time Delay on Trigger: IN (PIN 3) detects the specified trigger event level. There are three operating states: Standby (Reset), Delay, and Active, see Figure 2.4.2.0-B.
Standby (Reset): IN (PIN 3) is at the Standby (Reset) level, and OUT (PIN 1) is opposite of the specified Active level.
Delay: IN (PIN 3), the detected input level is the trigger event that initiates the timer to start. OUT (PIN 1) remains at the Delay level until the specified timing has elapsed.The delay timer will reset if the trigger event is reversed and OUT (PIN 1) will return to the Standby (Reset) level.
Active: OUT (PIN 1), specified as Low (Ground) or High-Z (Open), is Active when the specified timing has elapsed. The Active state will reset if the trigger event is reversed, and OUT (PIN 1) will return to the Standby (Reset) level.
Time Delay on Power-Up: 28V (PIN 2), operating voltage is applied, and the timer is triggered. There are two operating states: Delay and Active. IN (PIN 3) is not used for the Time Delay on Power-Up configuration, see Figure 2.4.2.0-C. The Time Delay on Power-Up option is in the Off condition when not energized.
Delay: 28V (PIN 2), unit power-up is the trigger event that initiates the timer to start. OUT (PIN 1) remains at the Delay level until the specified timing has elapsed. The delay timer will reset if the trigger event is reversed, and OUT (PIN 1) will return to the Off condition.
Active: OUT (PIN 1), specified as Low (Ground) or High-Z (Open), is Active when the specified timing has elapsed. The Active state will remain until power is removed.
Off: Unit power is not applied, 28V (PIN 2) and OUT (PIN 1) is High-Z (Open).
Input Levels: IN (PIN 3) is used for the Time Delay on Trigger configuration option only, and will detect a signal level state change once the unit is energized. IN (PIN 3) features four input level configurations that transition the Standby (Reset) state to Delay/Active, see Figure 2.4.2.0-D. IN (PIN 3) detects a state-level change upon power-up. The following input level configurations do not apply to the Time Delay on Power-Up configuration.
| Code | STANDBY (RESET) | DELAY / 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 (Reset) to Low (Ground) in Delay/Active.
P Configuration Code*: IN (PIN 3) transitions from +28 VDC in Standby (Reset) to Low (Ground) or High-Z (Open) in Delay/Active.
D Configuration Code*: IN (PIN 3) transitions from Low (Ground) or High-Z (Open) in Standby (Reset) to +28 VDC in Delay/Active.
G Configuration Code: IN (PIN 3) transitions from Low (Ground) in Standby (Reset) to +28 VDC or High-Z (Open) in Delay/Active.
*Must be the same +28 VDC source as PIN 2 (28V).
Output Levels: OUT (PIN 1) features two output level configurations that transition Standby (Reset) or Delay to the Active state, see Figure 2.4.2.0-E.
TD1: OUT (PIN 1), Low (Ground) when Active, and High-Z (Open) when in Standby or Delay.
TD2: OUT (PIN 1), High-Z (Open) when Active, and Low (Ground) when in Standby or Delay.
| Code | STANDBY (RESET) or DELAY | ACTIVE |
| TD1 | High-Z (Open) | Low (Ground) |
| TD2 | Low (Ground) |
High-Z (Open) |
Timing (Delay): Delay timing configurations range from 125 ms to 4 hrs and are available in four delay timing increments.
Milliseconds: 125*, 250*, 500
Seconds: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, 20, 30
Minutes: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, 20, 30
Hours: 1, 2, 4
*Not available in the Time Delay on Power-up configuration.
2.4.2.1
| 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 | 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 |
| ** Delay 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. ** Delay time tolerance at EMC and environmental extremes is +/- 10%. |
|
For Qualification Summary, see Appendix A