LT1373CN8#PBF Integrated Circuits (ICs)

PMIC - Voltage Regulators - DC DC Switching Regulators

The LT1373CN8#PBF is a monolithic switching regulator designed to generate a regulated output voltage from an unregulated supply source. The device consists of a temperature-compensated bandgap reference, error amplifier, high-current operational amplifier, a P-channel power MOSFET, an N-channel synchronous MOSFET, and the necessary circuitry to implement a fixed frequency current-mode control topology. With low external component count and wide operating voltage range, the device requires only two external components to generate any output voltage between 0.8V and 3.3V.

Applications

• Notebook and Desktop PCs
• Set-top Boxes/Home Automation
• White Goods/Industrial Controllers
• Network Routers/High-End Network Servers

Working Principle

The device operates by connecting the unregulated DC input voltage directly to the LX pin. The supplied voltage is then regulated to the output voltage by an internal voltage controlled oscillator operating in current-mode. Current is sourced from the LX pin and then passes through an internal P-channel MOSFET to the output voltage. During each cycle, the inductor current ramps up to a peak and then returns to zero. The current loop is compensated with an external compensation capacitor at the OUT pin, allowing the user to tailor the control loop performance.

The output voltage is precisely regulated by the error amplifier, whose output is compared to the voltage reference. The error amplifier reference is enabled via an external capacitor that can reduce the turn on time and make output regulation faster. To improve efficiency and reduce system cost, the LT1373 automatically syncs to the input voltage, switching between Burst Mode® operation and Pulse Frequency Mode. The limitation of theMHz operating limit imposed by the input voltage is automatically detected and corrected.