Using the EL7532 Evaluation Board ® Technical Brief February 22, 2005 TB445.1 Using the Evaluation Board 2. Chip Enable EL7532 is a high efficiency 2A synchronous step-down PWM regulator in a tiny MSOP10 package. The internal compensation makes it possible for the full-featured 2A 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 22 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 U1 FB U1 EL7532IY 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 EL7532IY 888-INTERSIL Any Coilcraft R2 124K, 1% 0603/0402 Any R1, R4, R5, R6 100K, 1% 0603/0402 Any R3 100Ω, 1% 0603/0402 Any U1 EL7532IY 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. 2003-2005. All Rights Reserved All other trademarks mentioned are the property of their respective owners. Technical Brief 445 Demo Board Layout (Actual Size - 3” x 2”) FIGURE 2. SILKSCREEN TOP FIGURE 3. TOP LAYER FIGURE 4. BOTTOM LAYER 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 the Application Note or Technical Brief is current before proceeding. For information regarding Intersil Corporation and its products, see www.intersil.com 2 TB445.1 February 22, 2005