DC-to-DC Converter Combats EMI Application Circuit

Unwanted electromagnetic radiation referred to as EMI is emitted by all electronic systems, including switching regulators. Adopting spread-spectrum pulse-width modulation (SSPWM) as a control scheme enhances the suppression of EMI. Driving the external clock input pin of the MAX1703 DC-DC converter with a pseudo-random noise (PN) provides the regulator with a spread spectrum clock that reduces EMI. Spreading the interference frequencies over a wide range lowers the EMI power density that is otherwise concentrated at a single clock frequency