PT1109 Datasheet | PowTech

1.5A,24V,380KHz Step-Down Converter GENERAL DESCRIPTION The PT1109 is a monolithic step-down switch mode regulator with a built in internal power MOSFET. It achieves 1.5A continuous output current over a wide input supply range with excellent load and line regulation. Current mode operation provides fast transient response and eases loop stabilization. Fault condition protection includes cycle-by-cycle current limiting and thermal shutdown. In shutdown mode the regulator draws 23μA of supply current. The PT1109 requires a minimum number of readily available standard external ponents. APPLICATION z PC Monitors z Distributed Power Systems Features z 1.5A Output Current z 0.5Ω Internal Power MOSFET Switch z Stable with Low ESR Output Ceramic Capacitors z Up to 95% Efficiency z 23µA Shutdown Mode z Fixed 380KHz Frequency z Thermal Shutdown z Cycle-by-Cycle Over Current Protection z Wide 4.75V to 24V Operating Input Range z Output Adjustable from 1.13V to 18V z Programmable Under Voltage Lockout z Available in 8-Pin SOP8 Packages z Battery Charger z Pre-Regulator for Linear Regulators TYPICAL APPLICATION CIRCUIT PIN ASSIGNMENT Figure 1 PT1109_DSB Rev EN_0.3 SOP8 .micro-bridge. Page1 1.5A,24V,380KHz Step-Down Converter PIN DESCRIPTIONS SOP8 PIN No. 1 2 3 4 5 6 7 8 PIN NAMES BS IN SW GND FB P EN NC DESCRIPTION Bootstrap (C5) - This capacitor is needed to drive the power switch’s gate above the supply voltage. It is connected between SW and BS pins to forma floating supply across the power switch driver. The voltage across C5 is about 5V and is supplied by the internal +5V supply when the SW pin voltage is low. Supply Voltage - The PT1109 operates from a +4.75V to +24V unregulated input. C1 is needed to prevent large voltage spikes from appearing at the input. Switch - This connects the inductor to either IN through M1 or to GND through M2. Ground - This pin is the voltage reference for the regulated output voltage. For this reason...