Network resistors are used in a wide range of applications from relatively simple pull up/pull- down resistors and terminating resistors to matched resistors. In some applications, resistors with a variety of resistance values may be incorporated on the same substrate.
The key advantages of a network resistor include reduced resistor drift due to temperature and power variations, reduced system board area and improved system reliability. However, there are resistor network application limitations the system designer should be aware of.
System Board Layout
One of the main advantages of network resistors is high component packaging density but this can complicate circuits board track routing. higher component density in one area of the system board may increase track lengths and therefore negatively affect signal integrity.
Thermal Considerations
Concentrating several resistors in a relatively small area increases the demand for heat dissipation in that area. it is therefore important to position the network resistor in an area with good airflow/cooling. An appropriate heatsink could be used or the network resistor could be designed with a vertical in line profile to maximise cooling. If it is not possible to manage thermal issues resistor derating may be required.
Isolation
With several resistors in close proximity on the same substrate, there is the potential for cross-talk between resistor devices. Specialist resistor manufacturers will be aware of the issue and take steps to minimise the impact but there are limits to what can be achieved.
Sourcing limitations & Cost
A wide variety of network resistor devices are available from several major resistor manufacturers. These devices will cover the majority of project requirements but for more specialist applications it may be necessary to identify a custom resistor network manufacturer.
When all factors are considered network resistors are generally cheaper than using several discrete resistors. If a custom device is required it may increase the cost.
With careful application management network resistors can offer several advantages over discrete devices. Where application issues are identified that prevent the use of a standard device it is possible a specialist resistor manufacturer may be able to offer a solution.