Supertex inc. HV9911DB1 High Brightness Boost LED Driver Demoboard with 1:3000 Dimming Ratio and Excellent Current Regulation General Description The HV9911DB1 is an LED driver capable of driving up to 20 one-watt LEDs in series from an input of 21 - 27VDC. 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 2.0μs, which will allow high PWM dimming ratios. 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. The HV9911DB1 includes and RC filter to prevent false triggering of the short circuit protection during PWM dimming, which was noticed with the HV9911DB1. This improvement makes the HV9911DB1 immune to turn-on current spikes in most cases. For a detailed explanation of the origin of the turn-on spike and the effect of the RC filter on the short circuit response time, please refer to the HV9911 datasheet. Specifications Parameter Value Input voltage (steady state): Output LED string voltage: Output current: 21V – 27VDC 35V min - 80V max 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 1:3000 dimming ratio at 200Hz PWM dimming: Board Layout and Connection Diagram + - VIN + 4 3 2 1 Actual size: 64mm x 34.5mm Connections: Input - The input is connected between the terminals of connector J1 as shown in the Connection Diagram. Output - The output is connected between the terminals of connector J2 as shown. 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 pushpull waveform source between terminals PWMD and GND of connector J3 as shown by the solid lines. Doc.# DSDB-HV9911DB1 A032713 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. 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. Supertex inc. www.supertex.com 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%. Efficiency (%) 95 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. 94 93 92 91 90 35 40 45 50 55 60 65 70 75 80 Output Voltage (V) Fig. 1. Efficiency vs. Output Voltage Efficiency (%) 95 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). 94 93 92 91 90 20 22 24 26 28 Input Voltage (V) Fig. 2. Efficiency vs. Input Voltage Output Current (A) 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. 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 1.0kHz PWM dimming frequency, the widest PWM dimming ratio can be obtained at lower frequencies like 100 or 200Hz. 0.354 0.352 0.35 0.348 0.346 35 40 45 50 55 60 65 70 75 80 Output Voltage (V) Output Current (A) Fig. 3. Output Current vs. Output Voltage 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. 0.354 0.352 0.350 0.348 0.346 20 22 24 26 28 Input Voltage (V) Fig. 4. Output Current vs. Input Voltage 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%. Doc.# DSDB-HV9911DB1 A032713 2 Supertex inc. www.supertex.com HV9911DB1 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. 0.4 1.6 0.3 1.4 0.2 1.2 0.1 25 20 15 10 Input Current (A) Output Current (A) 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. Output Voltage Output Current 1.0 Input Voltage (V), Sweep Input Current Output Current Fig. 5. Input Under Voltage Behavior Fig. 7:Output Short Circuit Protection (500ns/div) 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. Output Voltage LED Current Drain Voltage of Q1 Fig. 6: Open LED Protection (20μs/div) Doc.# DSDB-HV9911DB1 A032713 3 Supertex inc. www.supertex.com HV9911DB1 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 80 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. 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) Silk Screen: Doc.# DSDB-HV9911DB1 A032713 4 Supertex inc. www.supertex.com Doc.# DSDB-HV9911DB1 A032713 REF REF J1A J1B J4 1 2 5 J5 R13 REF J6 C8 6.8nF C7 2.2nF 8.66kΩ C6 0.1μF 16V J3A 7.87kΩ R9 C1 2.2μF 25V J7 17.4kΩ R8 20kΩ R7 IO_SNS 16.2kΩ R12 C1 2.2μF 25V OPEN R4 J3B J3D J3C 9 14 16 15 10 8 CLIM 1 VDD VIN 2 13 6 R11 49.9kΩ 4 PWM SC GND OVP FAULT CS 2 453kΩ R2 1.0kΩ R5 IO_SNS R6 0.15Ω 1/2W Q2 FDS 3692 D1 B1100-13 C4 1.0μF 100V C9 1.0μF 100V C10 470pF Specifications: Input: 21 - 27VDC Output Voltage: 40 - 80V Output Current: 350mA Overvoltage: 92V Short Circuit Protection Included 12 11 5 3 RT 7 GATE HV9911 COMP FDBK IREF REF SYNC C5 1.0μF 16V L1 220μH (CDRH127/LDNP-221MC) 1 1kΩ R14 R3 1.13kΩ 2 J2B C11 10nF J2A R10 1.24Ω 1/4W Q1 TN251DN8 R1 82.5kΩ 1 HV9911DB1 Circuit Schematic: Supertex inc. www.supertex.com HV9911DB1 Bill of Materials Item Quan Ref Des Description Package Manufacturer Manufacturer’s Part Number SMD1210 TDK Corp C3225X7R1H225K Radial EPCOS Inc B32522C1105J 1 2 C1, C2 2.2µF, 25V, X7R ceramic chip capacitor 2 2 C4, C9 1µF, 100V metal polyester capacitor 3 1 C5 1µF, 16V X7R ceramic chip capacitor SMD0805 TDK Corp C2012X7R1C105K 4 1 C6 0.1µF, 16V X7R ceramic chip capacitor SMD0805 Murata GRM219R71C104KA01D 5 1 C7 SMD0805 TDK Corp C2012C0G1H222J 6 1 C8 SMD0805 TDK Corp C2012C0G1H682J 7 1 C10 470pF, 50V X7R ceramic chip capacitor SMD0805 AVX Corp 08055C471KAT2A 8 1 C11 10nF, 50V X7R ceramic chip capacitor SMD0805 TDK Corp C2012X7R1H103K 9 1 D1 100V, 1A schottky diode SMA Diodes Inc. B1100-13 10 2 Thru-Hole JST Sales S2B-EH 11 1 J3 Side Entry 4-pin male header Thru-Hole JST Sales S4B-EH 12 1 L1 220µH, 2.0A sat, 1.5A rms inductor SMT Sumida CDRH127/LDNP-221MC 13 1 Q1 100V, 4.55A N-Channel MOSFET SO-8 Fairchild FDS3692 14 1 Q2 100V, 1.5ohm N-Channel MOSFET SOT-89 Supertex TN2510N8 15 1 R1 82.5kΩ, 1%, 1/8W chip resistor SMD0805 Yageo RC0805FR-0782K5L 16 1 R2 453kΩ, 1%, 1/8W chip resistor SMD0805 Yageo RC0805FR-07453KL 17 1 R3 1.13kΩ, 1%, 1/8W chip resistor SMD0805 Yageo RC0805FR-071K13L 18 1 R4 open - - - 19 2 SMD0805 Yageo RC0805FR-071KL 20 1 R6 0.15Ω, 1%, 1/2W chip resistor SMD2010 Vishay/ Dale WSL2010R1500FEA 21 1 R7 20kΩ, 1%, 1/8W chip resistor SMD0805 Yageo RC0805FR-0720KL 22 1 R8 17.4kΩ, 1%, 1/8W chip resistor SMD0805 Yageo RC0805FR-0717K4L 23 1 R9 7.87kΩ, 1%, 1/8W chip resistor SMD0805 Yageo RC0805FR-077K87L 24 1 R10 1.24Ω, 1%, 1/4W chip resistor SMD1206 Yageo RC1206FR-071R24L 25 1 R11 49.9kΩ, 1%, 1/8W chip resistor SMD0805 Yageo RC0805FR-0749K9L 26 1 R12 16.2kΩ, 1%, 1/8W chip resistor SMD0805 Yageo RC0805FR-0716K2L 27 1 R13 8.66kΩ, 1%, 1/8W chip resistor SMD0805 Yageo RC0805FR-078K66L 28 1 U1 Switchmode LED Driver with High Current Accuracy SO-16 Supertex HV9911NG-G 2.2nF, 5%, 50V C0G ceramic chip capacitor 6.8nF, 5%, 50V C0G ceramic chip capacitor J1, J2 Side Entry 2-pin male header R5, R14 1.0kΩ, 1%, 1/8W chip resistor 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-HV9911DB1 A032713 6 1235 Bordeaux Drive, Sunnyvale, CA 94089 Tel: 408-222-8888 www.supertex.com