DN06004/D Design Note – DN06004/D SEPIC LED Driver Device Application Input Voltage Output Power Topology I/O Isolation CS5171 Miners Light 4 Vdc 2W SEPIC NO Other Specifications Output Voltage Nominal Current Output 1 Output 2 Output 3 Output 4 3.5 V 350 mA N/A N/A N/A N/A N/A N/A Minimum Efficiency 70% Operating Temp. Range 0 to +70˚C Circuit Description Key Features This application is for the LED driver to be powered from a source that can be higher or lower than the LED voltage and must be efficient as possible. The SEPIC topology was chosen. The schematic in the following page shows a 4 V SEPIC LED driver using the CS5171 as a DC-DC boost regulator. The CS5171 operates at 260 KHz with about 65% efficiency with a 4.0V input. The MBRM110LT1 is a 10V schottky diode with a forward drop of < 0.3V. The NCS2001 operates as amplifier for the current sense voltage across R2 and drives the feedback pin on the CS5171. • SEPIC LED Driver • 350 mA LED Current July 2006, Rev. 0 www.onsemi.com 1 DN06004/D Schematic D1 C2 U1 C1 1 10nF 2 3 C3 R1 200nF 5.1kOhm_5% + 4 Volts 4 Vc Vsw FB Test SS PGnd AGnd Vcc MBRM110LT1 8 LED1 7 22uF 6 L1 5 22uH C4 22uF L2 CS5171 22uH J1 R2 C5 2.2uF .56Ohm_5% R3 5.1kOhm_5% 1 Out Vcc 2 Vee 3 U2 + - NCS2001 5 4 R5 R4 1.0kOhm_5% July 2006, Rev. 0 www.onsemi.com 1.0kOhm_5% 2 DN06004/D Layout July 2006, Rev. 0 www.onsemi.com 3 DN06004/D July 2006, Rev. 0 www.onsemi.com 4 DN06004/D Bill of Materials 1 Ref. Qty. Description Value Package Vendor Vendor PN SO-8 SOT23-5 ON Semi ON Semi CS5171ED8 NCS2001SN2T1 Powermite ON Semi MBRM110LT1 STAR / O LUXON LXHL-NW98 Phoenix Contact 1715035 805 smd 805 smd 1206 Panasonic Panasonic Panasonic Panasonic Panasonic ECJ-2VB1H103K EEF-CD1B220R ECJ-2VB1C224K EEF-CD1B220R ECJ-3YB1C225K 5.1 K ohm .56 ohm 1% 5.1 K ohm 1% 1 K ohm 1% 1 K ohm 1% 1206 1206 1206 1206 1206 Panasonic Panasonic Panasonic Panasonic Panasonic 22 uh 22 uh smd smd Coil_craft Coil_craft U1 U2 1 1 IC Boost Controller Amplifier D1 1 Diode LED1 1 J1 1 C1 C2 C3 C4 C5 1 1 1 1 1 Capacitor Capacitor Capacitor Capacitor Capacitor .01 uf 22 uf 200 nf 22 uf 2.2 uf R1 R2 R3 R4 R5 1 1 1 1 1 Resistor Resistor Resistor Resistor Resistor L1 L2 1 1 Inductor Inductor PCB 1 CS5171 SEPIC raw board 10 V Schottky Digikey # PCC103BNCT-ND PCE3168CT-ND PCC1816CT-ND PCE3168CT-ND PCC1931TR-ND P5.1KECT-ND P.56RCT-ND P5.1KFCT-ND P1.0KFCT-ND P1.0KFCT-ND MSS6132-223MXD MSS6132-223MXD CS5171 Rev A 1 © 2006 ON Semiconductor. Disclaimer: ON Semiconductor is providing this design note “AS IS” and does not assume any liability arising from its use; nor does ON Semiconductor convey any license to its or any third party’s intellectual property rights. This document is provided only to assist customers in evaluation of the referenced circuit implementation and the recipient assumes all liability and risk associated with its use, including, but not limited to, compliance with all regulatory standards. ON Semiconductor may change any of its products at any time, without notice. Design note created by Roger Miller, e-mail: [email protected] July 2006, Rev. 0 www.onsemi.com 5