In a switching power supply chip used LM2674 of company National Semiconducor. Instead LM2674 can apply a chip LM2671 IN these chips used key MOS transistors, made by technology LMDMOS, residual resistance in the on state is not more than 0.12 Ohm, allows to obtain high efficiency (in normal conditions is about 90%). The relatively large value of the operating frequency (up to 260 kHz) allows to reduce the size and weight of the parts of the filter energy storage.
Chip LM2674/71 are protected against overcurrent and overheating. The coefficients of volatility voltage and current do not exceed 1,5...2%, operating temperature range is -40 to +125°C. Available in packages of to-220, TO-263 and LLP.
IC this series available in fixed output voltages of 3.3, 5.0 and 12, as well as in adjustable version (from 1.2 to 37 In). The scheme provides an output 5 V and has a current up to 500 mA. Schottky diode VD1 should to withstand a reverse voltage of at least 45 and a maximum forward current of 3 A.
In LM2671 provides additional opportunities, particularly "soft" start and the external generator. The latter allows you to synchronize multiple converters that they create significantly reduces interference and provides compliance with the stringent requirements of electromagnetic compatibility (EMC).
Switching to standby by feeding the output ON/OFF high voltage level (maximum +5). In this case, the current consumption of the IC is 50 the ICA.
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