Supertex inc. HV9911DB1 High Brightness Boost LED Driver with 1:3000 Dimming Ratio and Excellent Current Regulation General Description Specifications The HV9911DB1 is an LED driver capable of driving up to 20 one-watt LEDs in series from an input of 21 – 27V DC. The demoboard uses Supertex’s HV9911 in a boost topology. The converter has a very good initial regulation (+/-5%) and excellent line and load regulation over the entire input and output voltage range (<+/- 1%). The full load efficiency of the converter is typically greater than 90%. The HV9911DB1 is also protected against open LED and output short circuit conditions. It is also protected under input undervoltage conditions by limiting the input current. It has an excellent PWM dimming response, with typical rise and fall times less than 2μs, which will allow high PWM dimming ratios. Input Voltage (steady state): 21V – 27V DC Output LED string voltage: 35V min - 80V max Output current: 350mA +/-5% Output Current Ripple: 10% typical Switching Frequency: 200kHz Full Load Efficiency: 93% (at 24V input) Open LED protection: Shuts down at 92V Output short circuit protection: Included Input under voltage protection: Included PWM Dimming: 1:3000 dimming ratio at 200Hz The switching frequency of the HV9911DB1 can be synchronized to other HV9911 boards or to an external 200kHz clock by connecting the clock to the SYNC pin of the HV9911DB1. Actual size: 64mm x 34.5mm Board Layout and Connection Diagram VIN + 4 3 2 1 Connections: Input: The input is connected between the terminals of connector J1 as shown in the Connection Diagram. Note: During PWM dimming, pin 2 of connector J3 should be left open. Also, the PWM signal must have the proper polarity with the positive connected to pin 3 of J3. Note that pin 4 of J3 is internally connected to the return path of the input voltage. Output: The output is connected between the terminals of connector J2 as shown. SYNC: To synchronize two or more boards, connect the SYNC pins of all the boards together. To synchronize the HV9911DB1 to an external 200kHz clock, connect the clock between the SYNC and GND pins of terminal J3. Enable/PWM Dimming: To just enable the board, short pins PWMD and VDD of connector J3 as shown by the dashed lines. To PWM dim the board, connect the external push-pull waveform source between terminals PWMD and GND of connector J3 as shown by the solid lines. Supertex inc. A032006 · 1235 Bordeaux Drive, Sunnyvale, CA 94089 · Tel: (408) 222-8888 · FAX: (408) 222-4895 · www.supertex.com 1 HV9911DB1 Testing The Demoboard: Normal Operation: Connect the input source and the output LEDs as shown in the Connection Diagram and enable the board. The LEDs will glow with a steady intensity. Connecting an ammeter in series with the LEDs will allow measurement of the LED current. The current will be 350mA +/- 5%. Short Circuit Test: When the HV9911DB1 is operating in steady state, connect a jumper across the terminals of the LED string. Notice that the output current will immediately go to zero and the converter will shut down. To restart the HV9911DB1, recycle the input power to the demoboard. Current Regulation: With the input power to the converter disconnected, change the LED string voltage within the specifications mentioned. The current output of the HV9911DB1 will remain very steady over the entire load range. Vary the input voltage while the circuit is operational. The current will be regulated over the entire line range. PWM Dimming: With the input voltage to the board disconnected, apply a TTL compatible, push-pull square wave signal between PWMD and GND terminals of connector J3 as shown in the Connection Diagram. Turn the input voltage back on and adjust the duty cycle and / or frequency of the PWM dimming signal. The output current will track the PWM dimming signal. Note that although the converter operates perfectly well at 1kHz PWM dimming frequency, the widest PWM dimming ratio can be obtained at lower frequencies like 100 or 200Hz. Open LED test: Connect a voltmeter across the output terminals of the HV9911DB1. Start the demoboard normally and once the LED current reaches steady state, unplug one end of the LED string from the demoboard. The output voltage will rise to about 92V and then the HV9911DB1 will shut down. To restart the converter, disconnect and reconnect the input voltage (recycle the power to the board). Typical Results: 1. Efficiency: The efficiency of the converter at various LED string voltages are shown in Fig.1 (measured at the nominal input voltage of 24V). Fig.2 shows the full load efficiency of the converter at varying input voltages. The minimum efficiency of 93% for the converter occurs at 21V input and full load output. 2. Current Regulation: Figs. 3 and 4 show the output current regulation vs. output voltage and input voltage respectively. The total current regulation (line and load combined) is found to be less than 1%. Output Current (A) Efficiency (%) 95 94 93 92 91 90 35 40 45 50 55 60 65 70 75 0.354 0.352 0.35 0.348 0.346 80 35 40 45 Output Voltage (V) Output Current (A) Efficiency (%) 94 93 92 91 90 24 60 65 70 75 80 Fig. 3. Output Current vs. Output Voltage 95 22 55 Output Voltage (V) Fig. 1. Efficiency vs. Output Voltage 20 50 26 0.354 0.352 0.35 0.348 0.346 20 28 22 24 26 28 Input Voltage (V) Input Voltage (V) Fig. 2. Efficiency vs. Input Voltage Fig. 4. Output Current vs. Input Voltage A032006 2 HV9911DB1 3. Input Under Voltage Protection: Input under voltage protection is provided by limiting the input current at low input voltages. Fig. 5 shows the output and input currents at voltages less than the minimum rated voltage. The LED current will decrease as the input voltage falls and the input current limits to about 1.4A. Note that the input current limit is not a hard limit as the slope compensation added to the peak current sense signal will allow a small change in the input current with a decrease in the input voltage. 6. PWM Dimming: The rise and fall transitions of the LED current during PWM dimming are shown in Figs. 8 and 9, at output voltages of 80V and 40V respectively. The timescale for all waveforms is set at 5.0μs/div. The rise and fall times are less than 1.0μs in each case. Thus, a PWM dimming ratio of 1:3000 is achievable at a PWM dimming frequency of 200Hz. Input Under Voltage Behavior 1.6 Output Voltage 0.3 1.4 0.2 1.2 0.1 Input Current (A) Output Current (A) 0.4 Output Current 1 25 20 15 Input Voltage (V), Sweep Input Current 10 Output Current Fig. 7:Output Short Circuit Protection (500ns/div) Fig. 5. Input Under Voltage Behavior 4. Open LED Protection: Open LED protection for the circuit is set at 92V. The waveforms in Fig. 6 show the output voltage, drain voltage and output current during an open LED condition. The time taken for the over voltage protection to shut the IC down will depend on the size of the output capacitor. 5. Output Short Circuit Protection: Fig. 7 shows the waveforms for output short circuit condition. The disconnect FET is turned off in less than 300ns. The rise in the output current will depend on the input voltage and the value of inductor L1. The same protection will also help in protecting the LEDs in case the output voltage increases beyond the LED string voltage. Output Voltage LED Current Drain Voltage of Q1 Fig. 6: Open LED Protection (20μs/div) A032006 3 HV9911DB1 PWM dimming input PWM dimming input Output Voltage Output Voltage LED Current LED Current Fig. 8a: Rise time of LED Current at 80V output (5μs/div) Fig. 8b: Fall time of LED Current at 80V output (5μs/div) PWM dimming input PWM dimming input Output Voltage Output Voltage LED Current LED Current Fig. 9a: Rise time of LED Current at 40V output (5μs/div) Fig. 9b: Fall time of LED Current at 40V output (5μs/div) A032006 4 J1A J1B REF 1 2 5 J4 REF J5 C6 0.1µF 16V C8 6.8nF R13 8.66K REF C1 2.2µF 25V J6 R7 20K J7 R8 17.4K IO_SNS R9 7.87K C7 2.2nF R12 16.2K J3A C1 2.2µF 25V R4 OPEN J3B J3D J3C 9 14 16 15 10 8 6 PWM SC 13 CLIM VDD 2 1 VIN 4 GND R11 49.9K CS GATE RT OVP FAULT HV9911 COMP FDBK IREF REF SYNC C5 1.0µF 16V L1 2 12 11 5 3 7 R2 453K 220µH (CDRH127/LDNP-221MC) 1 Specifications R6 0.15K 1/2W C4 1.0µF 100V Input: 21VDC -27VDC Output Voltage: 40V- 80V Output Current: 350mA Overvoltage: 92V Short Circuit Protection Included R5 1.0K Q2 FDS 3692 D1 TN251DN8 C9 1.0µF 100V IO_SNS R3 1.13k R1 82.5K J2B J2A R10 1.24K 1/4W Q1 TN251DN8 2 1 HV9911DB1 Circuit Schematic: A032006 HV9911DB1 Top Layer: Bottom Layer: Silk Screen: A032006 6 HV9911DB1 Bill of Materials Item # Quantity RefDes Description Package Manufacturer Manufacturer’s Part Number 1 2 C1,C2 2.2uF, 25V, X7R ceramic chip capacitor SMD1210 TDK Corp C3225X7R1H225K 2 2 C4,C9 1uF, 100V metal polyester capacitor Radial EPCOS Inc B32522C1105J 3 1 C5 1uF, 16V X7R ceramic chip capacitor SMD0805 TDK Corp C2012X7R1C105K 4 1 C6 0.1uF, 16V X7R ceramic chip capacitor SMD0805 Murata GRM219R71C104KA01D 5 1 C7 2.2nF, 5%, 50V C0G ceramic chip capacitor SMD0805 TDK Corp C2012C0G1H222J 6 1 C8 6.8nF, 5%, 50V C0G ceramic chip capacitor SMD0805 TDK Corp C2012C0G1H682J 7 1 D1 100V, 1A schottky diode SMA Diodes Inc. B1100-13 8 2 J1,J2 Side Entry 2-pin male header Thru-Hole JST Sales Amer. S2B-EH 9 1 J3 Side Entry 4-pin male header Thru-Hole JST Sales Amer. S4B-EH 10 1 L1 220uH, 2A sat, 1.5A rms inductor SMT Sumida CDRH127/LDNP-221MC 11 1 Q1 100V, 4.55A N-Channel MOSFET SO-8 Fairchild FDS3692 12 1 Q2 100V, 1.5ohm N-Channel MOSFET SOT-89 Supertex TN2510N8 13 1 R1 82.5k, 1%, 1/8W chip resistor SMD0805 Yageo RC0805FR-0782K5L 14 1 R2 453k, 1%, 1/8W chip resistor SMD0805 Yageo RC0805FR-07453KL 15 1 R3 1.13k, 1%, 1/8W chip resistor SMD0805 Yageo RC0805FR-071K13L 16 1 R4 open 17 1 R5 1k, 1%, 1/8W chip resistor SMD0805 Yageo RC0805FR-071KL 18 1 R6 0.15, 1%, 1/2W chip resistor SMD2010 Vishay/ Dale WSL2010R1500FEA 19 1 R7 20k, 1%, 1/8W chip resistor SMD0805 Yageo RC0805FR-0720KL 20 1 R8 17.4k, 1%, 1/8W chip resistor SMD0805 Yageo RC0805FR-0717K4L 21 1 R9 7.87k, 1%, 1/8W chip resistor SMD0805 Yageo RC0805FR-077K87L 22 1 R10 1.24, 1%, 1/4W chip resistor SMD1206 Yageo RC1206FR-071R24L 23 1 R11 49.9k, 1%, 1/8W chip resistor SMD0805 Yageo RC0805FR-0749K9L 24 1 R12 16.2k, 1%, 1/8W chip resistor SMD0805 Yageo RC0805FR-0716K2L 25 1 R13 8.66k, 1%, 1/8W chip resistor SMD0805 Yageo RC0805FR-078K66L 26 1 U1 Switchmode LED Driver with High Current Accuracy SO-16 Supertex HV9911NG Supertex inc. does not recommend the use of its products in life support applications, and will not knowingly sell its products for use in such applications, unless it receives an adequate "product liability indemnification insurance agreement". Supertex 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 or inaccuracies. Circuitry and specifications are subject to change without notice. For the latest product specifications, refer to the Supertex website: http//www.supertex.com. ©2006 Supertex inc. All rights reserved. Unauthorized use or reproduction is prohibited. Supertex inc. 1235 Bordeaux Drive, Sunnyvale, CA 94089 TEL: (408) 222-8888 / FAX: (408) 222-4895 www.supertex.com A032006 7