J-Tech Engineering - Hardware Design Expertise

Hardware Design Expertise

One of the hallmarks of J-Tech is to research and develop new techniques for accomplishing design goals and solving problems. Our customers can, and do, expect us to produce cutting edge designs that push the available technology to its limits. This consistently yields highly competitive products.

Some illustrations of hardware designs are shown below. Each example depicts a different type of design expertise typically employed in our design process.

Switching supply example. A design for producing both a regulated + and - 12V out of an unregulated 12V input.

A switching power supply for producing +/-12V from an unregulated input.

The above switching supply was one of six regulators used in one design. The design is very compact, and uses off-the-shelf switching magnetics to produce an affordable supply. Why so many supplies? In this case, the product had several analogue input stages requiring multiple heavily filtered supply voltages, plus digital interfaces operating at additional incompatible levels. One subtle problem that had to be overcome with this design is a bug that can appear when switching supplies are placed in close proximity. Each supply typically operates at its own switching frequency, and if they (the frequencies) are close together, will tend to produce a 'beat' frequency similar to old AM radio receiver input stages. The beat frequency could (would) be coupled into the analogue input stages and ruin an otherwise fine design. The solution to the problem was to synchronise all switching supplies to a universal 650KHz clock.

Telephony example, a shunt current regulator for a POTS interface

A shunt-current regulator typically found in fax/modem interfaces.

The above circuit is typically found in a Direct Access Arrangement (DAA) employed in telephone sets and fax/modem cards. This is actually found in virtually any piece of equipment that connects to the telephone system at the customer premises. These types of interfaces draw a consistent amount of current, indicating to the Central Office (CO) that the telephone set (or fax machine, or modem) is off-hook and requires a line. Though a fixed amount of DC current is drawn, the circuit presents a virtually infinite impedance to AC, which means when analogue or voice data is transmitted through the telephone system, none of that signal energy is lost to the above regulator.

A section of a FLASH SIMM interface as designed on the Cirrus Logic CL-PS7500FE evaluation Board.

Section of
FLASH SIMM.

At left is shown a portion of an 80-pin FLASH SIMM as designed into the Cirrus Logic CL-PS7500FE evaluation board. The FLASH SIMM was chosen as a means of permitting developers to employ as much or as little FLASH memory as required during development. An additional advantage of the FLASH SIMM is that, at the time of design, a ROM emulator could be purchased and plugged into the socket. This permitted development without having to do any burning of application code into memory.

J-Tech currently uses OrCAD Capture for its design needs. Capture is able to produce output suitable for import into most layout editors. For example:

Pads
Cadstar
Zuken Redac

OrCAD Layout (goes without saying)
Eagle Layout Editor

Importing designs from competing schematic capture packages such as Protel is possible, however this tends to be nearly as much work as starting over. The limiting problem is generally the library components don't have the same names from one CAD package to another.

Inquiries regarding designing with OrCAD (or any other schematic editor) should be directed to J-Tech Engineering. Please see the company information page for contact information.

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