The In-System Programmers on the market employ two ways for obtaining high impedance on their ISP lines:
- Driving them to tri-state (using a solid-state semiconductor like a line buffer);
- Using relays to disconnect them from the target system.
- Driving ISP lines to tri-state is easier and cheaper to design than the relay approach. On the other hand, the high impedance obtained this way may not be enough to isolate it from the UUT.
- Using relays helps keeping a higher Zeq impedance; in particular, the parasitic capacitance is lower than in the above approach (1-5pf), while the leakage current is 0.
The multi-site WriteNow! models have a dedicated line and software instructions for driving an external relay barrier or a demultiplexer module.
Algocraft supplies a series of accessories that have been designed to ease the integration to customers as well as saving on engineering time and costs. These accessories were designed to be integrated with WriteNow! Programming series easily with a full hardware and software compatibility. These modules have been used by our customers since many years.
The Relay Barrier
ModuleWith WriteNow! models (WN-PRG02A, WN-PRG04A and WN-PRG08A) is possible to connect externally a dedicated relay barrier module to ensures true galvanic isolation and reliability. During the execution of the programming project, the programmer pilots automatically the connected module through a dedicated line.
The demultiplexer module is designed to increase the number of ISP lines to be managed. A stack of up to 4 boards could be mounted to each ISP connector. It is built as a tower in order to save space. The Reed relay technology ensures true galvanic isolation and reliability. No external lines are needed in order to control the multiplexer.
Discover more at:http://www.algocraft.com/en/products/writenow-programmers