Wig-Wag Controller & High Side Driver (WWX-1A)

The WWX-1A device drives a pair of automotive relays to provide wig-wag (alternate flashing capability) for aircraft landing and taxi lights. Compared with existing wig-wag controllers, it has the ability of providing on-off switching functions for the lights as well as the wig-wag function from a pair of low-cost 3-position single-pole switches.

An adjunct circuit in the WWX-1 device provides the ability to convert any low side drive (switched to ground) to a high-side drive (switched to 12 Volts). One example of its use would be to take the output of a lamp dimmer and combine it with a control switch to facilitate day or night brightness switching for annunciator lamps. The WWX-1A wig-wag section consists of a 2 Hz oscillator with a pair of out-of-phase drive signals on L1 and L2 outputs. Each of these driver signals can be shut off without stopping the oscillator by grounding the L1DIS/ or L2DIS/ signals. This capability allows a simple 3-position switch to provide OFF-FLASH-ON functionality for each of the outputs.

The high side driver has two inputs. The A input is non-inverting: a low on A will turn off the driver output on the DRV output, whereas a high on A will turn the DRV output on (high). The A/ input works in the opposite fashion, as long as the A input is high or disconnected. The D1 diode is used as a relay clamp by connecting the CLAMP input to ground. All of the electronics are contained in a 15-pin D-subminiature connector backshell, making the device compact, light and easy to install.

Technical Summary

• Wig-Wag driver for automotive relays, provides logical switching of landing and taxi lights On, Off and Flash.
• Switch sequence is in keeping with best-practice human factors engineering.
• High side driver for miscellaneous functions that require signal inversion.
• Can drive up to 500 mA, including lamps and relays.
• Useful for converting logical PWM signals into a high-side dimmer bus for cockpit lighting.