Parth Electronics Corporation

Product Highlights Lowest Cost, Low Power Switcher Solution • Lower cost than RCC, discrete PWM and other integrated/hybrid solutions • Cost effective replacement for bulky linear adapters • Lowest component count • Simple ON/OFF control – no loop compensation devices • No bias winding – simpler, lower cost transformer • Allows simple RC type EMI filter for up to 2 W from universal input or 4 W from 115 VAC input Extremely Energy Efficient • Consumes only 30/60 mW at 115/230 VAC with no load • Meets Blue Angel, Energy Star, Energy 2000 and 200 mW European cell phone requirements for standby • Saves $1 to $4 per year in energy costs (at $0.12/kWHr) compared to bulky linear adapters • Ideal for cellular phone chargers, standby power supplies for PC, TV and VCR, utility meters, and cordless phones. High Performance at Low Cost • High-voltage powered – ideal for charger applications • Very high loop bandwidth provides excellent transient response and fast turn on with practically no overshoot • Current limit operation rejects line frequency ripple • Glitch free output when input is removed • Built-in current limit and thermal protection • 44 kHz operation (TNY253/4) with snubber clamp reduces EMI and video noise in TVs and VCRs • Operates with optocoupler or bias winding feedback Description The TinySwitch family uses a breakthrough design to provide the lowest cost, high efficiency, off-line switcher solution in the 0 to 10 W range. These devices integrate a 700 V power MOSFET, oscillator, high-voltage switched current source, current limit and thermal shutdown circuitry. They start-up and run on power derived from the DRAIN voltage, eliminating the need for a transformer bias winding and the associated circuitry. And yet, they consume only about 80 mW at no load, from 265 VAC input. A simple ON/OFF control scheme also eliminates the need for loop compensation.

Unique Dual-Mode Operation

 

The TL499A's core functionality is its seamless transition between two modes of operation, often used to power static RAM or microprocessors that need constant, reliable power:

1. Series Regulator Mode: When the main supply voltage  is present and high enough, the IC uses a linear series pass transistor to regulate the output. This is highly efficient when the input voltage is close to the output voltage.

2. Step-Up (Boost) Mode: If the main supply fails and the input voltage drops below a threshold battery level), the IC automatically switches to its internal boost switching regulator to maintain the regulated output voltage. This allows a small, low-voltage battery to back up a higher-voltage circuit.