Supertex inc. HV9912DB1 High Brightness Boost LED Driver Demoboard with 1:3000 Dimming Ratio and Hiccup Mode Protection General Description The HV9912DB1 is an LED driver demoboard capable of driving up to 20 one-watt LEDs in series from an input of 21 - 27VDC. It uses the Supertex HV9912 in a boost topology. The converter has 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%. Specifications Parameter Input voltage (steady state): Output LED string voltage: Output current: Value 21 - 27VDC 35V min - 80V max 350mA +/-5% Output current ripple: 10% typical The HV9912DB1 is protected against open LED and output short circuit conditions. It is also protected under input under-voltage conditions by limiting the input current. It has an excellent PWM dimming response, with typical rise and fall times less than 1.0μs, which allows high PWM dimming ratios. The switching frequency of the HV9912DB1 can be synchronized to other HV9912 boards or to an external 200kHz clock by connecting the clock to the SYNC pin of the HV9912DB1. Switching frequency: 200kHz The HV9912DB1 features hiccup mode short circuit and open LED protection. Upon detection of either fault condition, the IC shuts down the driver and periodically attemps to restart until the fault condition ends. The HV9912DB1 also features a built-in 500ns blanking to prevent false tripping of the over-current comparator due to parasitic capacitance spikes during PWM dimming. PWM dimming: 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 Board Layout and Connection Diagram VIN + Actual size: 64.0mm 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-HV9912DB1 A032913 SYNC - To synchronize two or more boards, connect the SYNC pins of all the boards together. To synchronize the HV9912DB1 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 HV9912DB1 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 HV9912DB1 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. 93 92 91 90 35 40 45 50 55 60 65 70 Output Voltage (V) 75 80 Fig. 1 Efficiency vs. Output Voltage Efficiency (%) 95 Open LED test: Connect a voltmeter across the output terminals of the HV9912DB1. 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 the HV9912DB1 will shut down. Once the LED string is reconnected, the driver will start regulating current. 94 93 92 91 90 20 22 24 26 Input Voltage (V) 28 Fig. 2 Efficiency 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%. Output Current (A) Short Circuit Test: When the HV9912DB1 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. Removing the jumper will cause the HV9912DB1 to restart and continue to regulate the LED current. 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 0.350 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. Doc.# DSDB-HV9912DB1 A032913 94 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 Supertex inc. www.supertex.com HV9912DB1 0.4 1.6 0.3 1.4 0.2 1.2 0.1 Output Voltage COMP Voltage LED Current 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. Fig. 7 Recovery from an Open LED Condition 1.0 25 20 15 Input Voltage (V), Sweep Input Current Fig. 7 shows the recovery of the HV9912DB1 from an over voltage condition. In this case, the LED has reconnected at some point when the converter is turned off. When the converter attempts to restart, if finds the fault condition has disappeared and it starts up normally. There is no overshoot in the LED current . 10 Output Current Fig. 5 Input Under-Voltage Behavior 4. Open LED Protection: Figs 6 and 7 show the hiccupmode over voltage protection. Fig. 6 shows the open LED condition occurs when the LED current goes to zero. At that point, the inductor current charges the output capacitor and the COMP voltage rails to VDD. Once the output voltage reaches the over voltage threshold, the converter shuts down and the output voltage slowly decays because the output capacitor is discharged by the over-voltage sensing resistor network. Once the output voltage falls to 90% of its trip point, the converter tries to restart. Since the fault conditions still persists, the converter shuts down almost immediately. Thus, the HV9912 maintains the output voltage in a band until the LED reconnects. Short Circuit Protection: Figs 8 and 9 show the operation of the short circuit protection in the HV9912DB1. In Fig. 8, the onset of the output short circuit is indicated by the first spike in the LED current. At this point, the HV9912DB1 shuts down and the hiccup mode protection takes over. A constant current source charges the COMP pin to 5.0V and then another current source discharges it to 1.0V. This charge/discharge cycle determines the hiccup time. When the COMP pin reaches 1.0V, the converter attempts to restart and finding the fault condition still present, shuts down again. Output Voltage Output Voltage COMP Voltage COMP Voltage LED Current LED Current Fig. 8 Short Circuit Condition Fig. 6 Open LED Condition Doc.# DSDB-HV9912DB1 A032913 3 Supertex inc. www.supertex.com HV9912DB1 Fig. 9 shows the recovery of the HV9912DB1 from a short circuit condition. It can be seen that the LED current recovers normally with no overshoots. 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. 6. PWM Dimming: The rise and fall transitions of the LED current during PWM dimming are shown in Figs. 10 and 11, PWM dimming input PWM dimming input Output Voltage Output Voltage LED Current LED Current Fig. 10a Rise time of LED Current at 80V output Fig. 11a Rise time of LED Current at 40V output (5.0μs/div) (5.0μs/div) PWM dimming input PWM dimming input Output Voltage Output Voltage LED Current LED Current Fig. 11b Fall time of LED Current at 40V output Fig. 10b Fall time of LED Current at 80V output (5.0μs/div) (5.0μs/div) Silk Screen Doc.# DSDB-HV9912DB1 A032913 4 Supertex inc. www.supertex.com Doc.# DSDB-HV9912DB1 A032913 5 REF REF J1A J1B 1 2 J4 C6 0.1μF 16V J5 R9 7.87kΩ C8 6.8nF C7 2.2nF R13 8.66kΩ REF C1 2.2μF 25V J6 R8 17.4kΩ R7 20kΩ IO_SNS R12 16.2kΩ J3A C2 2.2μF 25V J7 R4 OPEN J3B J3D J3C 9 14 16 15 10 8 VIN 1 13 6 RT R11 49.9kΩ 4 OVP FAULT CS GATE PWM SC GND COMP CLIM VDD 2 HV9912 FDBK IREF REF SYNC C5 1.0μF 16V L1 2 R5 1.0kΩ IO_SNS R6 0.15Ω 1/2W Q2 FDS 3692 C4 1.0μF 100V D1 B1100-13 C10 open C9 1.0μF 100V Input: 21 - 27VDC Output Voltage: 40 - 80V Output Current: 350mA Overvoltage: 92V Short Circuit Protection Included Specifications: 12 11 5 3 7 R2 280kΩ 220μH (CDRH127/LDNP-221MC) 1 R14 short R3 49.9kΩ J2B C11 10nF J2A R10 1.24Ω 1/4W Q1 TN251DN8 2 R1 866kΩ 1 HV9912DB1 Circuit Schematic: Supertex inc. www.supertex.com HV9912DB1 Bill of Materials # Quan Ref Des Description Package Manufacturer Manufacturer’s Part Number SMD1210 TDK Corp C3225X7R1H225K 1 2 C1,C2 2.2µF, 25V, X7R ceramic chip capacitor 2 2 C4,C9 1µF, 100V metal polyester capacitor Radial EPCOS Inc B32522C1105J 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 C11 10nF, 50V X7R ceramic chip capacitor SMD0805 TDK Corp C2012X7R1H103K 8 1 D1 100V, 1.0A schottky diode SMA Diodes Inc. B1100-13 9 2 J1,J2 Side Entry 2-pin male header Thru-Hole JST Sales S2B-EH 10 1 J3 Side Entry 4-pin male header Thru-Hole JST Sales S4B-EH 11 1 L1 220µH, 2.0A sat, 1.5A rms inductor SMT Sumida CDRH127/LDNP-221MC 12 1 Q1 100V, 4.55A N-Channel MOSFET SO-8 Fairchild FDS3692 13 1 Q2 100V, 1.5Ω N-Channel MOSFET SOT-89 Supertex TN2510N8 14 1 R1 866kΩ, 1%, 1/8W chip resistor SMD0805 Yageo RC0805FR-07866KL 15 1 R2 280kΩ, 1%, 1/8W chip resistor SMD0805 Yageo RC0805FR-07280KL 16 2 R3, R11 49.9kΩ, 1%, 1/8W chip resistor SMD0805 Yageo RC0805FR-0749K9L 17 1 R4, C10 open --- --- --- 18 1 R5 1.0kΩ, 1%, 1/8W chip resistor SMD0805 Yageo RC0805FR-071KL 19 1 R6 0.15Ω, 1%, 1/2W chip resistor SMD2010 Vishay/ Dale WSL2010R1500FEA 20 1 R7 20kΩ, 1%, 1/8W chip resistor SMD0805 Yageo RC0805FR-0720KL 21 1 R8 17.4kΩ, 1%, 1/8W chip resistor SMD0805 Yageo RC0805FR-0717K4L 22 1 R9 7.87kΩ, 1%, 1/8W chip resistor SMD0805 Yageo RC0805FR-077K87L 23 1 R10 1.24Ω, 1%, 1/4W chip resistor SMD1206 Yageo RC1206FR-071R24L 24 1 R12 16.2kΩ, 1%, 1/8W chip resistor SMD0805 Yageo RC0805FR-0716K2L 25 1 R13 8.66kΩ, 1%, 1/8W chip resistor SMD0805 Yageo RC0805FR-078K66L 26 1 R14 0.0Ω, 1/8W chip resistor SMD0805 Panasonic ERJ-6GEY0R00V 27 1 U1 Switchmode LED Driver with High Current Accuracy SO-16 Supertex HV9912NG 2.2nF, 5%, 50V C0G ceramic chip capacitor 6.8nF, 5%, 50V C0G ceramic chip capacitor 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-HV9912DB1 A032913 6 1235 Bordeaux Drive, Sunnyvale, CA 94089 Tel: 408-222-8888 www.supertex.com