US3034 Datasheet | UNISEM

FEATURES 8 pin SOIC Switching Controller with HICCUP Current Limiting Reduces Diode Power Dissipation to Less than 1% of Normal Operation Soft Start Capacitor allows for smooth Output Voltage ramp up On board MOSFET driver Fastest transient response of any controller method. ( 0 to 100% Duty Cycle in 100 n S ) 1% internal voltage reference Internal Under Voltage Lockout protects MOSFET during start-up PRELIMINARY DATASHEET DESCRIPTION The US3034 IC provides an 8 pin low cost switching controller with true short circuit protection all in a pact 8 pin surface mount package, providing a low cost switching solution for dual supply processor applications that require switching regulator for the 3.3V supply such as the applications with AGP on board. Typically in these applications a dual supply regulator converts 5V to 3.3V for I/O supply and a jumper programmable supply of 1.25V to 3.5V for CORE supply . The IC uses an internal regulator generated from the 12V supply to power the controller as well as the 12V supply to drive the power MOSFET, allowing a low cost N channel MOSFET to be used. The IC also includes an error parator for fast transient response, a precise voltage reference for setting the output voltage as well as a direct drive of the MOSFET for the minimum part count. APPLICATIONS Dual supply low voltage processor applications, such as: P55C™,CYRIX M2™, POWER PC™ and AMD K6™ Simple 5V to 3.3V switcher for Pentium with AGP or Pentium II™ applications TYPICAL APPLICATION C8 8 7 6 5 SS CS+ CS- Gnd C6 Drv V12 Vfb Vhyst 1 2 3 4 12V C3 R1 L1 R3 C5 L2 R8 R7 R6 Vout C7 Q2 C1 C2 C4 R2 D1 R5 3034app1-1.0 5V R4 Typical application of US3034 Notes: P55C,Pentium II are trade marks of Intel Corp. K5 & K6 are trade marks of AMD corp. Cyrix 6X86L,M1,M2 are trade marks of Cyrix Corp. Power PC is trade mark of IBM Corp. PACKAGE ORDER INFORMATION TA (°C) 0 TO 70 Rev. 1.8 1/13/99 8 PIN PLASTIC SOIC (S) US3034CS 4-1 ABSOLUTE MAXIMUM RATINGS V12...