Using the EL7536 Evaluation Board ® Technical Brief TB419.2 February 17, 2005 Using the Evaluation Board 2. Chip Enable EL7536 is a high efficiency 1A synchronous step-down PWM regulator in a tiny MSOP10 package. The internal compensation makes it possible for the full-featured 1A converter to occupy less than 0.18in2 of PCB area with all components on one side. When EN pin is pulled to Ground, the regulator is disabled. It consumes less than 1µA of current. R5 can be connected to VIN directly if this function is not needed, reducing the component counts. 1. Output Adjustment When powering up, the open-collector Power-On-Reset output holds low for 100ms after VO reaches the preset voltage. When a reset signal RSI is issued, POR goes to low for the same period of time while the output power is still on (Please refer to the datasheet for the timing diagram). When the function is not used, connect RSI to ground and leave R4 open, further reduce the total components counts and the overall PCB area to less than 0.18in2. 3. RSI/POR Function Use R1 and R2 to adjust output voltage according to the following formula: R V O = 0.8 × 1 + ------2- R 1 The evaluation board is set to VO = 1.8V. The POR output also serves as a 100ms delayed Power Good signal when the pull-up resister R4 is installed. The RSI pin needs to be directly (or indirectly through R6) connected to Ground for this to function properly. R1 R1 80.6K 100K 11 2 2 L1 L1 VVo O 33 1.8uH 1.8µH VVin IN GND GND C1 C1 10µF 10uF C2 C2 10uF 10µF R3 100Ω 44 55 SGND SGND FB FB U1 U1 EL7536IY EL7535CY PGND V0 PGND V0 LX LX POR PG VIN VIN EN EN VDD VDD RSI SYNC R2 R2 10 10 100K 124K 99 88 POR PG/POR 77 EN EN 66 RSI SYNC/RSI R6 R6 100K 100K C3 0.1µF R4 R4 100K 100K R5 R5 100K 100K FIGURE 1. DEMO BOARD SCHEMATIC Evaluation Board Bill of Materials REFERENCE DESIGNATOR VALUE PACKAGE MANUFACTURER MANUFACTURER’S PART NUMBER MANUFACTURER’S PHONE NUMBER C1, C2 10µF/MLCC, X7R 1206 TDK C3216X7R1A106K 847-803-6100 C3 0.1µF 0603/0402 L1 1.8µH 1008PS-182M 847-639-6400 EL7536IY 888-ELANTEC Any Coilcraft R2 124K, 1% 0603/0402 Any R1, R4, R5, R6 100K, 1% 0603/0402 Any R3 100Ω, 1% 0603/0402 Any U1 EL7536IY MSOP10 Intersil 1 CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures. 1-888-INTERSIL or 1-888-352-6832 | Intersil (and design) is a registered trademark of Intersil Americas Inc. Copyright Intersil Americas Inc. 2005. All Rights Reserved All other trademarks mentioned are the property of their respective owners. Technical Brief 419 Demo Board Layout (Actual Size - 3” x 2”) FIGURE 2. SILKSCREEN FIGURE 4. BOTTOM LAYER FIGURE 3. TOP LAYER All Intersil U.S. products are manufactured, assembled and tested utilizing ISO9000 quality systems. Intersil Corporation’s quality certifications can be viewed at www.intersil.com/design/quality Intersil products are sold by description only. Intersil Corporation reserves the right to make changes in circuit design, software and/or specifications at any time without notice. Accordingly, the reader is cautioned to verify that data sheets are current before placing orders. Information furnished by Intersil is believed to be accurate and reliable. However, no responsibility is assumed by Intersil or its subsidiaries for its use; nor for any infringements of patents or other rights of third parties which may result from its use. No license is granted by implication or otherwise under any patent or patent rights of Intersil or its subsidiaries. For information regarding Intersil Corporation and its products, see www.intersil.com 2