RS6513 2A, Asynchronous PWM Control DC/DC Step-Down Regulator DESCRIPTION RS6513 provides low-ripple power, high efficiency, and excellent transient characteristics. The PWM control circuit is able to vary the duty ratio linearly from 0 up to 100%. This converter also contains an error amplifier circuit as well as a soft-start circuit that prevents overshoot at startup. An enable function, an over current protect function and a short circuit protect function are built inside, and when OCP or SCP happens, the operation frequency will be reduced from 350KHz to 30KHz. Also, an internal compensation block is built in to minimum external component count. With the addition of an internal P-channel Power MOS, a coil, capacitors, and a diode connected externally, these ICs can function as step-down switching regulators. They serve as ideal power supply units for portable devices when coupled with the SOP-8 mini-package, providing such outstanding features as low current consumption. Since this converter can accommodate an input voltage up to 20V, it is also suitable for the operation via an AC adapter. FEATURES Input voltage: 3.6V to 20V Output voltage: 0.8V to VCC Duty ratio: 0% to 100% PWM control Oscillation frequency: 350KHz typical Soft-start, Current limit, Enable function Thermal Shutdown function Built-in internal SW P-channel MOS SOP-8 package RoHS Compliant and 100% Lead (Pb)-Free and Green (Halogen Free with Commercial Standard) APPLICATIONS PC Motherboard LCD Monitor Graphic Card DVD-Video Player Telecom Equipment ADSL Modem Printer and other Peripheral Equipment Microprocessor core supply Networking power supply BLOCK DIAGRAM Tel: 886-66296288‧Fax: 886-29174598‧ http://www.princeton.com.tw‧2F, No. 233-1, Baociao Rd., Sindian Dist., New Taipei City 23145, Taiwan RS6513 APPLICATION CIRCUIT Note: VOUT = VFB x (1+RA/RB) RB=0.7K~5K ohm VIN=12V, IMAX = 2A VOUT L1 Value 2.5V 22uH 3.3V 27uH 5V 33uH ORDER INFORMATION Device RS6513-XX Y Z V1.0 Device Code XX is nominal output voltage designator : “Blank” =ADJ Y is package designator: S: SOP-8 Z is Lead Free designator: P: Commercial Standard, Lead (Pb) Free and Phosphorous (P) Free Package G: Green (Halogen Free with Commercial Standard) 2 August 2013 RS6513 PIN ASSIGNMENTS SOP-8 PIN DESCRIPTION Pin Name FB EN OCSET VCC OUTPUT VSS Description Feedback Pin POWER OFF Pin: H: Normal operation (Step-down operation) L: Step-down operation stopped (All circuits deactivated) Add an external resistor to set max output current Power Supply Pin Switch Pin. Connect external inductor/diode here. Minimize trace area at this pin to reduce EMI Ground Pin Pin No. 1 2 3 4 5, 6 7, 8 FUNCTION DESCRIPTION PWM CONTROL The RS6513 consists of DC/DC converters that employ a pulse-width modulation (PWM) system. In converters of the RS6513, the pulse width varies in a range from 0 to 100%, according to the load current. The ripple voltage produced by the switching can easily be removed through a filter because the switching frequency remains constant. Therefore, these converters provide a low-ripple power over broad ranges of input voltage and load current. UNDER VOLTAGE LOCKOUT The under voltage lockout circuit of the RS6513 assures that the high-side MOSFET driver outputs remain in the off state whenever the supply voltage drops below 3.3V. Normal operation resumes once VCC rises above 3.5V. RDS(ON) CURRENT LIMITING The current limit threshold is setting by the external resistor connecting from VCC supply to OCSET. The internal 100uA sink current crossing the resistor sets the voltage at the pin of OCSET. When the PWM voltage is less than the voltage at OCSET, an over-current condition is triggered. ILOAD× RDS(ON) =IOCSET ×ROCSET See above formula for setting the current limit value. V1.0 3 August 2013 RS6513 IMPORTANT NOTICE Princeton Technology Corporation (PTC) reserves the right to make corrections, modifications, enhancements, improvements, and other changes to its products and to discontinue any product without notice at any time. PTC cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a PTC product. No circuit patent licenses are implied. Princeton Technology Corp. 2F, 233-1, Baociao Road, Sindian Dist, New Taipei 23145, Taiwan Tel: 886-2-66296288 Fax: 886-2-29174598 http://www.princeton.com.tw V1.0 8 August 2013