Supertex inc. AT9919DB1 Single, High Current, LED Driver Demoboard General Description The AT9919BDB1 demoboard is a high current LED driver designed to drive one LED at 1.0A from a 9.0 - 16VDC input. The demoboard uses Supertex’s AT9919 hysteretic buck LED driver IC. The AT9919DB1 includes two PWM dimming modes. The analog control of the PWM dimming mode allows the user to dim the LED using a 0 - 2.0V analog signal applied between the ADIM and GND pins (0V gives 0% and 2.0V gives 100%). In this mode, the PWM dimming frequency is set to 1kHz on the board. The digital control of PWM dimming mode allows the user to dim the LEDs using an external, TTL-compatible square wave source applied between DIM and GND. In this case, the PWM dimming frequency and duty ratio are set by the external square wave source. Specifications Parameter Input voltage Connections Input Connection: Connect the input DC voltage between VIN and GND terminals of connector J1 as shown in the connection diagram. Output Connection: Connect the LEDs between LED+ (anode of LED string) and LED- (cathode of LED string) of connector J2. PWM Dimming Connection: 1. If no PWM dimming is required, short DIM, VDD and ADIM terminals of connector J3. Doc.# DSDB-AT9919DB1 A032713 9.0 - 16VDC (steady state) 40V max (transient) Reverse polarity protection 60V (max) Output voltage 2.0 - 5.0V Output current 1.0A ± 5% Output current ripple (@13.5V input and 3.3V output) Full load efficiency (@13.5V input) 16% (peak to peak) 84% Open LED protection Yes Output short circuit protection Yes Dimensions Connection Diagram Value 25.4mm X 25.4mm Silk Screen 2. If dimming using an external PWM dimming source, connect the PWM source between the DIM and GND terminals of connector J3 and short terminals ADIM and VDD. The recommended PWM dimming frequency is ≤1.0kHz. 3. If dimming using an external analog voltage source, connect the source between the ADIM and GND terminals of connector J3 and short terminals DIM and VDD. The voltage range for control of the PWM dimming is 0 - 2.0V. Supertex inc. www.supertex.com AT9919DB1 Typical Results Fig. 1. Efficiency vs. Input Voltage Plot Fig. 2. Line Regulation of LED Current Plot 1.0 85.0 % change in LED Current 0.8 Efficiency (%) 84.8 84.6 84.4 84.2 84.0 8 10 12 14 Input Voltage (V) 16 18 -0.2 -0.4 -0.6 75 70 2 3 4 (Full Load) Switching Frequency (kHz) 350 300 250 200 Doc.# DSDB-AT9919DB1 A032713 14 18 16 2 3 4 Load Voltage (V) 5 (@13.5V input) 400 12 16 Fig. 6. Switching Frequency vs. Load Voltage Plot 400 Input Voltage (V) 14 0 450 10 12 Input Voltage (V) 0.5 450 8 10 1.0 -0.5 5 Load Voltage (V) Fig. 5. Switching Frequency vs. Input Voltage Plot 150 8 1.5 % change in LED Current Efficiency (%) 0 Fig. 4. Load Regulation of LED Current Plot 80 Switching Frequency (kHz) 0.2 -1.0 85 0.4 -0.8 Fig. 3. Efficiency vs. Load Voltage Plot (@13.5V input) 65 0.6 350 300 250 200 150 18 2 3 4 Load Voltage (V) 5 Supertex inc. 2 www.supertex.com AT9919DB1 Typical Waveforms (All waveforms are at 13.5V input and 3.3V LED Voltage unless otherwise noted) Figure 7. Steady State Waveforms Drain Voltage LED Current C1 (Yellow) C4 (Green) Time Scale Figure 8. : : : Drain Voltage (5V/div) LED Current (500mA/div) 1μs/div Transient Response of the LED Current Input Voltage LED Current C1 (Yellow) C4 (Green) Time Scale Doc.# DSDB-AT9919DB1 A032713 : : : Input Voltage (20V/div) LED Current (500mA/div) 20μs/div Supertex inc. 3 www.supertex.com AT9919DB1 Typical Waveforms (All waveforms are at 13.5V input and 3.3V LED Voltage unless otherwise noted) Figure 9. PWM Dimming using the DIM input PWM Dimming Input LED Current (a) PWM Dimming Performance Time Scale : 1ms/div PWM Dimming Input PWM Dimming Input LED Current LED Current (b) PWM Dimming Rise Time Time Scale : 10µs/div C1 (Yellow) C4 (Green) Figure 10. (c) PWM Dimming Fall Time Time Scale : : : 10µs/div PWMD Input Voltage (5V/div) LED Current (500mA/div) PWM Dimming using the ADIM pin RAMP Voltage ADIM Voltage LED Current C1 (Yellow) C2 (Pink) C4 (Green) Time Scale Doc.# DSDB-AT9919DB1 A032713 : : : : ADIM Voltage (1V/div) RAMP Voltage (1V/ div) LED Current (500mA/div) 200μs/div Supertex inc. 4 www.supertex.com AT9919DB1 AT9919DB1 Schematic Diagram D2 J1 C6 4.7µF 25V 2 2 2.2µH (LPS3008-222) B160 1 L2 1 C2 4.7uF 25V C1 4.7uF 25V D1 STPS2L60A R1 0.2 1/2W C3 1.0uF 25V Input 4 C4 1.0n J3A 2 1 J3B U1 R5 1.0k R4 10k D4 4.7V J3D Doc.# DSDB-AT9919DB1 A032713 3 5 3 2 1 Output C7 1.0n J3C J2 1 2 1 VIN CS ADIM AT9919 R2 0.0 GT 8 RAMP GND DIM TAB Q1 Si7308DN 2 L1 22µH (DRA74-220) 7 9 VDD 6 C5 1.0uF 10V Supertex inc. 5 www.supertex.com AT9919DB1 Bill of Materials Item # Qty RefDes Description Package Manufacturer Manufacturer’s Part Number 1 3 C1, C2, C6 4.7µF, 25V, 10% X7R ceramic capacitor SMD1206 Murata GRM31CR71E475KA88L 2 1 C3 1.0µF, 25V, 10% X7R ceramic capacitor SMD1206 Kemet C1206C105K3RACTU 3 2 C4, C7 1.0nF, 50V, 5%, C0G ceramic capacitor SMD0603 TDK Corp C1608C0G1H102J 4 1 C5 1.0µF, 10V, 10% X7R ceramic capacitor SMD0603 Taiyo Yuden LMK107B7105KA-T 5 1 D1 60V, 2A schottky diode SMA ST Micro STPS2L60A 6 1 D2 60V, 1A schottky diode SMA ST Micro STPS1L60A 7 1 D4 4.7V, 350mW zener diode SOT-23 Diodes Inc BZX84C4V7-7-F 8 2 J1, J2 2 position, 5mm pitch, vertical header Thru-Hole On Shore Tech EDSTL130/02 9 1 J3 4 position, 0.100” pitch, vertical header Thru-Hole Molex 22-03-2041 10 1 L1 22µH, 1.8A rms, 1.7A sat inductor SMT Coiltronics DRA74-220-R 11 1 L2 2.2µH, 1.0A rms, 1.0A sat inductor SMT Coilcraft LPS3008-222 12 1 Q1 60V, 72mΩ, 9nC N-channel FET Powerpak 1212-8 Vishay SI7308DN-T1-E3 13 1 R1 0.2Ω, 1/2W, 1% chip resistor SMD1210 Rohm MCR25JZHFLR200 14 1 R2 0.0Ω, 1/10W, 5% chip resistor SMD0603 Panasonic ERJ-3GEY0R00V 15 1 R4 10kΩ, 1/10W, 5% chip resistor SMD0603 Panasonic ERJ-3GEYJ103V 16 1 R5 1kΩ, 1/10W, 5% chip resistor SMD0603 Panasonic ERJ-3GEYJ102V 17 1 U1 Hysteretic Buck LED Driver DFN-8 Supertex AT9919 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-AT9919DB1 A032713 6 1235 Bordeaux Drive, Sunnyvale, CA 94089 Tel: 408-222-8888 www.supertex.com