ON-Display™

38 • ON-Display FEATUREON SEMICONDUCTOR 1Q-2001MULTI-MARKETREFERENCES[1] http://www.ridleyengineering.com[2] ON Semiconductor SMPS PowerSupply Seminar Materials.[3] Ridley Engineering; POWER 4-5-6Help Files.[4] Ridley Engineering; POWER 4-5-6Users Manual.[5] Ken Coffman, Power Supply DesignSoftware.[6] Feedback Loop Stability Analysis,Walter S. Friauf; McGraw-Hill, 1998.SMPSSoftwareFigure 18. Core LibraryAvailableLiteratureNL27WZ04/DCDROM DOWNLOAD HARDCOPYMany times a designrequires a small, lowpower oscillator toprovide a clock signal that does notneed to be particularly accurate,just reliable. Many suppliers offercrystal oscillators, with highaccuracy that cost several dollarseach. This design concept showshow to build a 500 KHz oscillatoroccupying 1/ 2 -in2, and costing lessthan $0.50 each for all thecomponents. The circuit iscomprised of a single 6-pin device(NL27WZ04 from ON Semiconductor),2 resistors and onecapacitor. The NL27WZ04 ispackaged in the micro-miniatureSC88 (SOT-363) package thatMULTI-MARKETTiny 6-Pin Device Forms Tiny RC Oscillatoroccupies only 4.2 mm2. Thenominal operating volts will be 2.3to 5.0 volts and the approximatedevice frequency can be describedas follows:f = 1/(2.2 R1C) HzR 2 > 8 R 1 , C > 50 pfTo operate at 500 KHz, we allowC=75 pf, and R1 to be 12 KΩ, andR2 to be 100 KΩ.Figure 1 shows a simple circuitbased on a new dual gate logic ICthat functions as a 500 KHzOscillator with strong driveoperating at 3.3 volts with a minimumnumber of components. bFred Zlotnick,Applications ManagerV CC2.3 to 5.0 VOSCOut51 6CNL27WZ04A1GNDA2R1R232GNDY1VCCY2Figure 1. Tiny RC Oscillator4To order literature on any of these products, see the Literature Distribution Center Information on page 39.