Top Banner

Click here to load reader

Electronic Latch - Applied Avionics · PDF fileTable 2: Electronic Latch Signal Description Table 4: Electronic Latch Truth Table Table 3: Electronic Latch (8-pin Component) Table

Feb 01, 2018




  • The Electronic Latch is an 8-pin electronic switching component developed as a part of the LOGIC Series by VIVISUN. The Electronic Latch replaces traditional magnetic or solenoid latching switches and can be integrated in a traditional 4-pole switch housing, creating a LOGIC Body (LB), or can be included in a stand-alone LOGIC Module (LM) for use behind the panel. The Electronic Latch can also be combined with electromechanical switches and other LOGIC Series components to create a custom configuration that uniquely addresses the designers specific functional requirements. The Electronic Latch is designed and tested in accordance with MIL-PRF-22885 and DO-160.

    Electronic Latch

    Set, Reset, and Toggle Capabilities Local, Remote, and Lockout Control Simplifies Complex Circuit Designs Replaces Magnetic or Solenoid Switches Built-in Blink Circuitry Powers up in either RESET (EL1) or SET with BLINK active (EL2) Resets to known or safe position with loss of power cycle Approved, witnessed and conformed to RTCA/DO-160

    High Capacity LOGIC Body as shown contains

    Electronic Latch, single switch pole and 4-pin

    LOGIC component

    LOGIC Module as shown contains

    Electronic Latch and 4-pin LOGIC components

    Data Sheet: DS-EL1-12

    LO G I C C o m p o n e n t Te c h n o l o g y

    E L E C T R O N I C L AT C HE L E C T R O N I C S W I T C H I N G

  • Electronic Latch Figure 1: Block Diagram

    Table 1: Operating Parameters

    The LOGIC Series Electronic Latch performs in a similar fashion to traditional magnetic or solenoid latching switches but does not contain failure-prone electro-mechanical components, is significantly smaller, lighter and requires a fraction of the power. The Electronic Latch can eliminate the need for a physical action by an operator. The switch may now be controlled from a remote location allowing a set, reset or toggle from multiple locations outside the physical reach of the operator. The same switch may also function as a momentary or alternate action depending on conditional inputs. It also has the ability to power up in a known or safe position.

    Benefits: The LOGIC Series Electronic Latch functionality allows, within the existing switch envelope, the ability to:

    Replace Magnetic or Solenoid Switches, Set, Reset, and Toggle Capabilities, Power up in either RESET (EL1) or SET with BLINK active (EL2), Resets to a known or safe position with loss of power cycle, Local, Remote, and Lockout Control, Blink via internal circuitry, and Simplify circuit designs by eliminating external relays.

    How it works: The Electronic Latch contains an integrated electrical circuit that accepts two different operating modes by activating Set, Reset or Toggle. The switch then responds with conditioned outputs that may be used to perform various system functions. Inputs may originate through external sensors, other switches, or even through physical activation of the internal switch poles. Refer to Figure 1 and Table 1 for Block Diagram and Operating Parameters. A Signal Description and Truth Table can be found in Table 2 and Table 4.

    Applications: In addition to the technical and qualification information on the following pages, typical applications for the Electronic Latch are shown in Application Examples. The local and remote control features as well as blink are highlighted in Example 1. It also demonstrates a remote lockout that can override the function of a switch. Example 2 details a simple safe mode function assuring the system automatically turns off when power is cycled. Example 3 is a traditional Speaker Mute control.

    Compatibility: The LOGIC Series Electronic Latch is compatible with a wide range of proven VIVISUN products, including:

    Indicators, switches and modules, 3/4" LED caps and 1" x 1.2" LR3 LED caps, 95 Series incandescent caps, and the Quik-Connect solderless termination system (see Table 5).

    VIVISUN LOGIC Series Overview: The Electronic Latch is one of VIVISUNs LOGIC Series electronic components designed to enhance avionics design flexibility. The Electronic Latch can be inserted into either a) a High-Capacity LOGIC Body (LB), based on a standard 4-pole switch body with an illuminated lens cap, or b) a stand-alone behind-the-panel electronic LOGIC Module (LM). The innovative LOGIC Series was developed to simplify operator interface and circuit complexity by providing the ability to internally integrate multiple combinations of LOGIC Series components into a single envelope, including functionality such as:

    Switch poles (LOGIC Body only), Electronic switching, Electronic sensing and detecting, and Logic/interface devices.

    A single 8-pin LOGIC Series component like the Electronic Latch can be combined with up to two additional 4-pin LOGIC Series components (LOGIC Module or LOGIC Body) or can be combined with an additional 8-pin component (LOGIC Module only) to bring a customized solution to your application. See Table 6 and How to Order for a complete description of the various configurations.

    Logic Input Circuitry: Provides a reliable diode isolated, buffered, and debounced input interface. The inputs are internally pulled up to approximately 18 VDC. This provides simple reliable operation with either external switches or open drain drivers.

    Latch Circuitry: Proven reliable latch circuitry that holds the current state and provides the set, reset and toggle features.

    Blink Circuitry: Free running 1 hertz square wave generator. This signal is then gated to provide a selectable blink output.

    Logic Output Circuitry: Provides ground switched open drain output drivers that are both fused and surge protected against transients and overload conditions.

    Power Supply: Efficient internal regulated supply that allows the unit to operate reliably on less than 4 mA.

    Description Parameters

    Operating Parameters

    Maximum Operating Voltage +32 VDC

    Nominal Operating Voltage +28 VDC

    Minimum Operating Voltage +18 VDC

    Power Supply Input Current 4 mA maximum

    Reset From Power Loss 5 second maximum @ +25C

    Input Parameters at 25C

    EL1: /RESET, EL2: /SET 120 ms

    /TOGGLE 45 ms

    EL1: /SET, EL2: /RESET 45 ms

    High Level Input Voltage ( VIH ) 10 VDC minimum

    Low Level Input Voltage ( VIL ) 0.4 VDC maximum

    Low Level Input Current ( IIL ) 1 mA maximum

    Note: All signal inputs are diode isolated

    Output Load Capacity

    Resistive 2.0 A

    Motor 1.0 A

    Lamp 0.8 A

    lnductive 0.8 A

    Operational Life 500,000 cycles at rated loads


    Operating -55C to +85C

    Non-Operating -55C to +85C

    O V E R V I E WE L E C T R O N I C L AT C H


  • Table 2: Electronic Latch Signal Description Table 4: Electronic Latch Truth Table

    Table 3: Electronic Latch (8-pin Component) Table 5: Connector Plug

    Inputs Outputs/Set /Reset /Toggle Q Output

    Q Output Blink

    High (Open) Low (Ground) XHigh (Open) Low (Ground) Steady ON

    See Note 1

    Low (Ground) High (Open) XLow (Ground) High (Open) 1Hz Blink

    See Note 1

    High (Open) High (Open) Opposite StateOpposite

    StateChange State

    See Note 2

    Low (Ground) Low (Ground) X Low (Ground) See Note 3Low (Ground)

    See Note 3 Steady ON



    Signal Name

    Quik-Connect Pin* Number Function

    Active State Description

    /RESET J1 Input Low (Ground)

    Forces Q OUTPUT to OFF (Open). Forces /Q OUTPUT to ON (Ground).

    Forces BLINK to Steady ON (Ground). See Note 1.

    /TOGGLE J2 Input Toggles Q OUTPUT and /Q OUTPUT. Toggles blink mode. See Note 2.

    /SET J3 Input Low (Ground)

    Forces Q OUTPUT to ON (Ground). Forces /Q OUTPUT to OFF (Open).

    Initiates the 1Hz blink mode to BLINK Output.

    +28 VDC J4 Power Power (+18 VDC to +32 VDC)

    GROUND K1 Common Continuous Ground Required.

    Q Output K2 Output Low (Ground)

    Open Drain Output. Forced OFF (Open) by /RESET Input. Forced ON (Ground) by /SET Input. Toggled by

    Falling Edge of /TOGGLE Input.

    Q Output K3 Output Low (Ground)

    Open Drain Output. Forced ON (Ground) by /RESET Input. Forced OFF (Open) by /SET Input. Toggled by Falling Edge of /TOGGLE Input.

    BLINK K4 Output Low (Ground)

    Open Drain Output. Forced ON (Ground) while /RESET is held

    Low (Ground).

    * Pin-out will change if two 8-pin components are configured in a LOGIC Module.

    Note 1: BLINK Output is held Steady ON (Ground) while /RESET is held low. BLINK Output goes OFF (Open) when /RESET returns to the inactive high level. This feature provides essentially three states to the BLINK Output: OFF, ON and BLINK.

    Note 2: /TOGGLE input causes BLINK Output to switch between 1 Hz Blink state and OFF (Open). /TOGGLE disabled if /RESET or/SET are active.

    Note 3: Unstable state. If both /SET and /RESET are released at the same time the unit will return to the default power-up state, otherwise unit will follow defined logic input settings.



    Powers up in Reset Powers up in Set

    Pins* High Capacity LOGIC Body LOGIC ModuleConnector

    PlugA, B, C, D, F, G Lamp Circuits N/A

    P/N 18-440

    H1-H4, L1-L4Switch Contacts

    4-Pin LOGIC Series Contacts

    J1-J4, K1-K4 Electronic Latch Contacts (assuming a single 8-pin component)

    * Pin-out will change if two 8-pin components are configured in a LOGIC Module.

    Table 6: LOGIC Series Overview

    The Electronic Latch may be used in the following packaging options:

    The LOGIC Body (LB) expands the capabilities of a standard pushbutton switch or indicator by utilizing the 8-pin Electronic Latch internally in 6 distinct combinations of elec