QCH28515T

The QCH28515T/RCH28515T series of DC-DC converters provides the ruggedness, reliability and features required to meet the advanced challenges of today's hi-rel market. This family of converters uses all surface-mounted hybrid components including magnetics, all ceramic capacitors and ultrasonic wirebonds to give long life in full temperature range and high acceleration environments. There is no power derating anywhere in the 55°C to 125°C operating range.

This product family is tolerant of many types of faults including load short, load overload, loss of voltage feedback, large forward and reverse voltages applied to the synchronization pin and input overvoltage. This converter family will operate during input transients to 80 volts. The output voltages have little overshoot during the input voltage transient such that typical logic and linear parts on the outputs will stay well within data sheet absolute maximums.

Other operational features include low duty factor current limit and dynamic current limit threshold. The current limit operates in a cyclic on-off mode with an on time of about 2 milliseconds and an off time of 20 milliseconds for a duty factor of about 10 percent. This limits the converter dissipation to about 1 watt, so there is no danger of overheating during an output fault at 125° C. The dynamic current limit threshold allows over 50 percent more current to flow for a short time after power application, release from shutdown or recovery from previous current limit allowing large load capacitances to be charged during turn-on.

This converter family is a push-pull 400 kHz forward converter with full isolation between the input side, output side and case. This isolation is achieved without optocouplers for an even greater margin of reliability. The converter is housed in a power DIP package and is hermetically sealed. The RCH28515T has tabs for bolting the device down.