Designing Ideas

A Hopfield network can convert analog signals into digital format and can perform associative recalling, signal estimation, and combinatorial optimization similar to the way a human retina performs first-level signal processing. "Flexible Hopfield neural-network ADCs quash noise" explores the Hopfield-neural-network paradigm for ADCs.

Listing 1, available with "8-bit microcontroller implements digital lowpass filter," shows a simple engineering method to design singlepole, lowpass-digital-filter firmware for 8-bit microcontrollers. The low-end Freescale MC69HC908QT2 is the target of the assembler program, but you can apply this Design Idea to any type of microcontroller because it uses only standard assembler instructions.

Engineers often face difficult trade-offs when voltage regulators can encounter high-voltage transients that are well above normal input supply operating ranges. This situation is common in automotive applications in which high-voltage transients from an alternator load dump can produce transients of 36 to 75V for typical durations of less than 400 msec. The simple circuit in "Automotive switching regulators get input-transient-voltage protection" provides a highly cost-effective method for clamping an input voltage from a battery input with transients as high as 50V to take advantage of a 20V, 3-MHz regulator.