EVAL5983

EVAL5983 1.5 A step-down switching regulator demonstration board based on the L5983 Data Brief Features ■ 1.5 A DC output current ■ 2.9 V to 18 V input voltage ■ Output voltage adjustable from 0.6 V to 16 V ■ 250 kHz switching frequency, programmable up to 1 MHz ■ Internal soft-start and inhibit ■ Low dropout operation: 100 % duty cycle ■ Zero-load current operation ■ Over-current and thermal protection ■ VFQFPN8 3 mm x 3 mm package EVAL5983 Description The compensation network on the demonstration board allows the use of MLCC as output filter to keep the loop stable. The inductor saturation current and forward current of the Schottky diode are within the current limit values. The EVAL5983 demonstration board provides the design engineer with a fully functional step-down switching regulator with an output current of up to 1.5 A. The L5983 integrates STMicroelectronics step-down switching regulator, together with all the external components required for a typical application. The switching frequency on the demonstration board is set to 500 kHz by means of the R5 resistor connected to pin Fsw. The rated voltage of the input capacitor and the Schottky diode rectifier repetitive peak reverse voltage are both 25 V, making the board capable of covering the entire 2.9 V - 18 V input voltage range of the L5983 device. The board features an external resistor divider (R1 and R2) designed for an output voltage of 3.3 V. The output voltage can be set to a level from 0.6 V up to the rated voltage of the output capacitor (16 V). March 2009 Rev 1 For further information contact your local STMicroelectronics sales office. 1/6 www.st.com 6 EVAL5983 1 EVAL5983 application circuit and component list EVAL5983 application circuit and component list Figure 1. Application circuit VIN=3.3V to 18V VCC INH GND C1 C6 10uF 68nF L1 6.8uH OUT 8 1 3 2 D1 SYNCH STPS2L25U L5985 L5983 7 Vout=3.3V C2 R1 4.99K FB 22uF 5 6 FSW 4 C4 10nF COMP R5 100K R3 330 R4 2.49K C3 2.2nF R2 1.1K C5 220pF Table 1. Component list Reference Part number Description Manufacturer C1 GRM31CR61E106KA12 10 μF, 25 V MURATA C2 GRM31CR61C226KE15B 22 μf, 16 V MURATA C3 2.2 nF, 50 V C4 10 nF, 50 V C5 220 pF, 50 V C6 68 nF, 25 V R1 4.99 kΩ, 1 %, 0.1 W 0603 R2 1.1 kΩ, 1 %, 0.1 W 0603 R3 330 Ω, 1 %, 0.1 W 0603 R4 2.99 kΩ, 1 %, 0.1 W 0603 R5 100 kΩ, 1 %, 0.1 W 0603 L1 7447779006 6.8 uH, 30 %, 2.91 A Coilcraft D1 STPS2L25V 2 A, 2 5V STMicroelectronics 2/6 EVAL5983 2 PCB layout PCB layout Figure 2. PCB layout (component side) Figure 3. PCB layout (bottom side) Figure 4. PCB layout (front side) 3/6 EVAL5983 3 Package mechanical data Package mechanical data In order to meet environmental requirements, ST offers these devices in different grades of ECOPACK® packages, depending on their level of environmental compliance. ECOPACK® specifications, grade definitions and product status are available at: www.st.com. ECOPACK® is an ST trademark. 4/6 EVAL5983 4 Revision history Revision history Table 2. Document revision history Date Revision 02-Mar-2009 1 Changes Initial release 5/6 EVAL5983 Please Read Carefully: Information in this document is provided solely in connection with ST products. STMicroelectronics NV and its subsidiaries (“ST”) reserve the right to make changes, corrections, modifications or improvements, to this document, and the products and services described herein at any time, without notice. All ST products are sold pursuant to ST’s terms and conditions of sale. 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