Supertex inc. HV9925DB1 Programmable-Current 120VAC LED Driver Demoboard with PWM Dimming Introduction The Supertex HV9925DB1 demo board is a complete LED power driver to supply a string of LEDs using the HV9925, an integrated, high-voltage, buck regulator IC featuring programmable output current and PWM dimming. The HV9925 includes a 500V switching MOSFET and can operate directly from rectified AC line voltages of 80 to 135VAC. The current in the LED string is externally programmed to 50mA ±10% by a single resistor RS. The HV9925DB1 is ideally suited for driving strings of LEDs having forward voltage from 20V to 60V at high efficiency. Specifications Parameter Input voltage range Load current Value 80 to 135VAC 50mA ± 10% LED string voltage 20~60V Conducted EMI CISPR15 Efficiency 82% typ. The HV9925DB1 is a peak current-controlled buck converter operating with a fixed off-time of 10.5µs. Its’ fixed off-time control scheme provides good stability and tight regulation of the LED current throughout the input AC line voltage range. As its switching frequency varies over the AC line cycle, the HV9925 inherently introduces frequency dither and simplifies the compliance with EMI regulations. Board Layout and Connection Diagram Actual Size: 40mm x 23mm x 16mm PWM Dimming Connections LED+: Connect the Anode of the LED string to this pin. LED-: Connect the Cathode of the LED string to this pin. AC Line 80 - 135VAC Note: The demoboard is not protected from output open/short circuit condition. Damage to the demoboard may occur if the output load is not properly connected AC1, AC2: Connect AC Line to these pins. Doc.# DSDB-HV9925DB1 A032913 Supertex inc. www.supertex.com HV9925DB1 Testing the HV9925DB1 PWM Dimming HV9925DB1 Remove the jumper J1 and connect to an output of the square-wave signal generator using an opto-isolator. Connect the LED string to the output terminals. Check the polarity of the LED connection. The anode end of the string should be connected to the positive output, and the cathode should be connected to the negative output. Connect the AC input to the input terminals. Apply the AC voltage at the input terminals and the LED string should start to glow. The HV9925DB1 will regulate constant 50mA current in the LED. An ammeter can be connected in series with the LED(s) to measure the output current. Note: The HV9925DB1 circuit is not isolated from AC mains. Connecting external devices to J1 without using optoisolators can be hazardous and may cause equipment damage. Schematic Diagram 1 + AC1 R1 2 1 100, 1/4W 4 DF06M 2 3 B1 - 1 CS + CIN 3.3µF 250V 1 C 2 1 8.2 2 3 PWMD AC2 A U1 RS DRAIN 8 PWMD DRAIN 7 HV9925 J1 DRAIN 4 VDD CDD 0.1uF RSENSE VDD 1 GND N/C D1 US1G COUT .01uF 1 L1 1 LED+ 2 LED- 2 22mH 6 5 2 2 GND Typical Performance Characteristics 84.00 Fig. 1 Typical Efficiency at VOUT = 50V Fig. 2 AC Line Regulation of LED Current at VOUT = 50V 49.0 48.8 82.00 LED Current, mA Efficiency, % 48.6 80.00 78.00 76.00 74.00 72.00 80 48.2 48.0 47.8 47.6 90 100 110 120 130 47.4 80 140 Input AC Voltage, VAC Doc.# DSDB-HV9925DB1 A032913 48.4 90 100 110 120 130 140 Input AC Voltage, VAC 2 Supertex inc. www.supertex.com HV9925DB1 Typical Performance Characteristics (cont.) Fig. 4 PWM Dimming (40µs/div.). Ch1: PWMD, Ch4: IOUT Fig. 3 Load Regulation of LED Current at VAC = 120V LED Current, (mA) 60 55 50 45 40 20 26 32 38 44 50 56 62 Output LED Voltage, (V) Bill of Materials Ref Des Description Manufacturer Manufacturer’s Part Number RS 8.2Ω 1/4W MF Resistor N/A N/A R1 100Ω 1/4W Fusible Resistor N/A N/A CO 0.01μF, 100V, X7R, MLCC N/A N/A CDD 0.1μF, 50V, X7R, MLCC N/A N/A CIN 3.3μF, 250V, Aluminum Elec. Capacitor Panasonic ECQ-E4104KF L1 22mH, 60mA, Mini-Drum Renco Electronics RL-5480-3-22000 D1 Diode, UF 400V 1A 50ns On Semiconductor US1G B1 Diode Bridge, 600V 1A Diodes, Inc DF06M U1 LED Driver IC Supertex, Inc HV9925N3 Supertex inc. does not recommend the use of its products in life support applications, and will not knowingly sell them for use in such applications unless it receives an adequate “product liability indemnification insurance agreement.” Supertex inc. does not assume responsibility for use of devices described, and limits its liability to the replacement of the devices determined defective due to workmanship. No responsibility is assumed for possible omissions and inaccuracies. Circuitry and specifications are subject to change without notice. For the latest product specifications refer to the Supertex inc. (website: http//www.supertex.com) Supertex inc. ©2013 Supertex inc. All rights reserved. Unauthorized use or reproduction is prohibited. Doc.# DSDB-HV9925DB1 A032913 3 1235 Bordeaux Drive, Sunnyvale, CA 94089 Tel: 408-222-8888 www.supertex.com