High Performance at Affordable Prices
• Charger applications benefit from high voltage powered.
• Fast turn-on with little overshoot is made possible by high bandwidth.
• Line frequency ripple is rejected by current limit operation.
• Built-in thermal and current limit protection increases security
superior cost/performance than RCC and linear
• Less expensive than RCC, discrete PWM, and other hybrid and integrated systems.
• Affordable substitute for bulky regulated linears
• Simple control of ON/OFF - no loop compensation required
• Simpler and more affordable transformer with no bias winding
• Simple design virtually eliminates manufacturing rework
A monolithic device called TinySwitchTM-II incorporates a 700 V power MOSFET, oscillator, high voltage switched current source, current limit, and thermal shutdown circuitry. A bias coil and related circuitry are not required because the start-up and operational power is simply obtained from the voltage on the DRAIN pin. The TinySwitch-II devices also provide frequency jittering, auto-restart, and line undervoltage detection. When using a typical taped/varnished transformer construction, a unique design reduces audio frequency components in the straightforward ON/OFF control scheme to almost remove audible noise.
With fewer components and less expensive secondary feedback circuitry, the fully integrated auto-restart circuit reliably limits output power under fault circumstances like output short circuit or open loop. When a line under voltage threshold is externally programmed with an optional line sensing resistor, power down glitches brought on by the slow discharge of input storage capacitors prevalent in applications like standby supplies are eliminated. The quasi-peak and average EMI are greatly reduced by jittering the operating frequency of 132 kHz, lowering filtering costs.