EVAL5986 EVAL5986A 2.5 A step-down switching regulator demonstration board based on the L5986, L5986A Features ■ 2.5 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 ■ Overcurrent and thermal protection ■ VFQFPN8 3 mm x 3 mm package or HSOP8 for the L5986A !-V Description The EVAL5986/A demonstration board provides the design engineer with a fully functional stepdown switching regulator with an output current of up to 2.5 A. The board integrates STMicroelectronics’ L5986\A step-down switching regulator, together with all the external components required for a typical application. 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 L5986/A device. 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 switching frequency on the demonstration board is set to 500 kHz by means of the R5 resistor connected to pin Fsw. The board features an external resistor divider (R1 and R2) designed for an output voltage of 1.8 V. The output voltage can be set to a level from 0.6 V up to the input voltage. October 2009 Doc ID 16567 Rev 1 1/6 www.st.com 6 EVAL5986/A application circuit and component list 1 EVAL5986 - EVAL5986A EVAL5986/A application circuit and component list Figure 1. Application circuit 6IN66 6## # U 6 # N ).( 6 '.$ ,! &37 2 K /54 39.#( &" ,U(-33 6OUT6 # U 6 $ 3403, #/-0 2 + 2+ #H& #P& 2 K 2 #N& !-V Figure 2. Package 6&1&0.XMM (3/0EXPOSEDPAD !-V Table 1. 2/6 Component list Reference Part number Description Manufacturer C1 GRM32ER61E226KE15 22 µF, 25 V Murata C2 GRM32ER61E226KE15 22 µF, 25 V Murata C3 2.2 nF, 50 V C4 10 nF, 50 V C5 330 pF, 50 V C6 220 nF, 25 V R1 4.99 kΩ, 1%, 0.1 W 0603 R2 2.49 kΩ, 1%, 0.1 W 0603 R3 330 Ω, 1%, 0.1 W 0603 R4 2 kΩ, 1%, 0.1 W 0603 R5 100 kΩ, 1%, 0.1 W 0603 L1 MSS1038-522NL 5.2 µH, 30%, 5.28 A Coilcraft D1 STPS2L25V 2 A, 25 V STMicroelectronics Doc ID 16567 Rev 1 EVAL5986 - EVAL5986A 2 PCB layout PCB layout Figure 3. PCB layout (component side) Figure 4. PCB layout (bottom side) Figure 5. PCB layout (front side) Doc ID 16567 Rev 1 3/6 Package mechanical data 3 EVAL5986 - EVAL5986A 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 Doc ID 16567 Rev 1 EVAL5986 - EVAL5986A 4 Revision history Revision history Table 2. Document revision history Date Revision 29-Oct-2009 1 Changes Initial release Doc ID 16567 Rev 1 5/6 EVAL5986 - EVAL5986A 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. 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