FL7760LED1GEVK ON Semiconductor

FL7760LED1GEVK 3W SPI Controllable LED Driver Evaluation Board www.onsemi.com User s Manual EVAL BOARD USERS MANUAL OVERVIEW This manual covers the specification, theory of operation, testing and construction of the FL7760LED1GEVK demonstration kit. The FL7760 kit demonstrates a 1 A buck LED driver intended for a single highpower LED. The SPI (Serial Peripheral Interface) bus does both analog and PWM dimming. The kit includes a load/SPI interface board to facilitate operation of the driver. The driver can be driven independently from any SPI controller. The nominal input voltage is 12 V. Table 1. SPECIFICATIONS Input Voltage 10.8 V dc 13.2 V dc Output Voltage 2.5 V dc 5.0 V dc Output Current 1 A Max Output Ripple 40 mA PP Efficiency 85% Typ. FL7760LED1GEVK Evaluation Board Switching Frequency 200 kHz Rise/Fall Time < 20 s Dimming Interface SPI Dimming Resolution 8 bits PCB Size 30 mm 30 mm The key features of this demo kit include: Low Parts Count Single Sided Assembly Small Footprint Very Fast Rise/Fall Times SPI Dimming Control for Analog and PWM Dimming 12 V Operation Integrated Thermal Shutdown and UVLO THEORY OF OPERATION Power Stage The power stage is a CCM inverted buck converter. The output inductor sets the switching frequency because the control operates in hysteretic control mode. The peak and valley current are fixed percentages of the current reference. This fixes the inductor ripple current and eliminates the need for closed loop compensation. A novel high side current sense enables direct accurate control of the output current. Semiconductor Components Industries, LLC, 2012 1 Publication Order Number: January, 2019 Rev. 0 EVBUM2607/DFL7760LED1GEVK HV Start OVP The FL7760 supplies its own Vcc power greatly The output voltage is inherently limited to be less than or simplifying implementation. The input voltage range is 8 V equal to Vin. As such, no OVP is required due this inherent 70V. The internal Vcc regulates to 5 V 10%. The internal limitation. Vcc supplies a 3.3 V LDO for powering the DAC. The Load Board Operation regulator and DAC draw less than 1mA combined. The load board connects to the LED driver via an 8 conductor FPC cable. The FPC cable makes a simple and Dimming convenient interconnection. The load board serves 2 major The FL7760 dim input controls both amplitude and on/off functions: 1) provide an easy connection to an LED load 2) control. This makes the dim interface controllable by provide a USBSPI bridge for computer control of the LED analog, PWM, or both at the same time. The DAC has an driver. output range of 0 V 3.3 V for 8 bits of resolution. A dim signal below 0.5 V turns off the output and a dim signal The daughter card on the load has a mini USBA above 3 V is 100% output. connection for attachment to your computer. See the test procedure for details of the setup of the SPI terminal Protection application. Thermal Protection The thermal protection is built into the FL7760 and shuts down the FL7760 when the die temperature exceeds 150C. SCHEMATIC L1 CONN JACK PWR 4.7uH R1 J3 1 1 2 2 3 3 200m 4 5 +12V 6 CS 7 J1 8 C1 C2 SCLK 4.7uF 25V 4.7uF 25V FH128S0.5SH(55) MOSI D1 C3 FSV330AF 4.7uF 25V L2 U1 47uH 1 6 Vin Sens U2 Vcc 2 5 Gnd Vcc SPI DAC 6 1 3 4 Q1 nSyncVout DIM GDrv CS FL7760 MGSF1N03LT1G C4 5 2 Sclk Gnd SCLK 4.7uF 25V 4 3 Din Vdd +3.3V MOSI DAC081S101CIMK/NOPB R2 R3 R4 10k 10k 10k U3 Vcc 5 1 Vout Vin +3.3V 2 Gnd R5 C5 10k 1uF 3 EN TLV71333PDBVR Figure 1. LED Driver Circuit www.onsemi.com 2