CAT4139 22 V High Current Boost White LED Driver Description The CAT4139 is a DC/DC step−up converter that delivers an accurate constant current ideal for driving LEDs. Operation at a fixed switching frequency of 1 MHz allows the device to be used with small value external ceramic capacitors and inductor. LEDs connected in series are driven with a regulated current set by the external resistor R1. The CAT4139 is ideal for driving parallel strings of up to five white LEDs in series or up to 22 V. LED dimming can be done by using a DC voltage, a logic signal, or a pulse width modulation (PWM) signal. The shutdown input pin allows the device to be placed in power−down mode with “zero” quiescent current. In addition to thermal protection and overload current limiting, the device also enters a very low power operating mode during “Open LED” fault conditions. The device is housed in a low profile (1 mm max height) 5−lead TSOT−23 package for space critical applications. http://onsemi.com 5 1 TSOT−23 TD SUFFIX CASE 419AE PIN CONNECTIONS 1 GND Switch Current Limit 750 mA Drives LED Strings up to 22 V Up to 87% Efficiency Low Quiescent Ground Current 0.6 mA 1 MHz Fixed Frequency Low Noise Operation Soft Start “In−rush” Current Limiting Shutdown Current Less than 1 mA Open LED Overvoltage Protection Automatic Shutdown at 1.9 V (UVLO) Thermal Overload Protection TSOT−23 5−Lead (1 mm Max Height) These Devices are Pb−Free, Halogen Free/BFR Free and are RoHS Compliant • GPS Navigation Systems • Portable Media Players • Handheld Devices February, 2010 − Rev. 1 (Top View) MARKING DIAGRAM TPYM TP = Specific Device Code Y = Production Year (Last Digit) M = Production Month (1−9, A, B, C) ORDERING INFORMATION Device CAT4139TD−GT3 (Note 1) Applications © Semiconductor Components Industries, LLC, 2010 SHDN FB Features • • • • • • • • • • • • VIN SW Package Shipping TSOT−23 (Pb−Free) 3,000/ Tape & Reel 1. NiPdAu Plated Finish (RoHS−compliant) 1 Publication Order Number: CAT4139/D CAT4139 VIN L D 5V 22 mH VOUT 9 strings at 20 mA C2 C1 4.7 mF SW VIN 1 mF 35 V CAT4139 OFF ON SHDN FB GND R2 (300 mV) 1 kW IOUT 180 mA R1 1.62 W L: Sumida CDRH6D28−220 D: Central CMSH1−40 (rated 40 V) Figure 1. Typical Application Circuit Table 1. ABSOLUTE MAXIMUM RATINGS Parameters Ratings Units VIN, FB Voltage −0.3 to +7 V SHDN Voltage −0.3 to +7 V SW Voltage −0.3 to +40 V Storage Temperature Range −65 to +160 _C Junction Temperature Range −40 to +150 _C 300 _C Lead Temperature Stresses exceeding Maximum Ratings may damage the device. Maximum Ratings are stress ratings only. Functional operation above the Recommended Operating Conditions is not implied. Extended exposure to stresses above the Recommended Operating Conditions may affect device reliability. Table 2. RECOMMENDED OPERATING CONDITIONS (Typical application circuit with external components is shown above.) Parameters VIN SW pin voltage Ambient Temperature Range (Note 2) Range Units up to 5.5 V 0 to 22 V −40 to +85 _C 2. TSOT23−5 package thermal resistance qJA = 135°C/W when mounted on board over a ground plane. http://onsemi.com 2 CAT4139 Table 3. DC ELECTRICAL CHARACTERISTICS (VIN = 3.6 V, ambient temperature of 25°C (over recommended operating conditions unless otherwise specified)) Symbol Parameter Test Conditions Min Typ Max Units IQ Operating Current VFB = 0.2 V VFB = 0.4 V (not switching) 0.6 0.1 1.5 0.6 mA ISD Shutdown Current VSHDN = 0 V 0.1 1 mA VFB FB Pin Voltage 9 x 3 LEDs, IOUT = 180 mA 300 315 mV IFB FB pin input leakage 1 mA ILED Programmed LED Current 30 100 31.5 mA 0.4 0.8 0.7 1.5 V 0.8 1.0 1.3 MHz VIH VIL R1 = 10 W R1 = 3 W SHDN Logic High SHDN Logic Low Enable Threshold Level Shutdown Threshold Level FSW Switching Frequency ILIM Switch Current Limit VIN = 3.6 V VIN = 5 V RSW Switch “On” Resistance ISW = 100 mA ILEAK Switch Leakage Current Switch Off, VSW = 5 V 285 28.5 600 750 mA 1.0 2.0 W 1 5 mA TSD Thermal Shutdown 150 °C THYST Thermal Hysteresis 20 °C VUVLO Under−voltage lock out (UVLO) Threshold 1.9 V 24 V 29 V 92 16 % VOV−DET Over−voltage detection threshold VOCL Output Clamp voltage DC Maximum duty cycle Minimum duty cycle 23 “Open LED” http://onsemi.com 3 CAT4139 TYPICAL CHARACTERISTICS (VIN = 5.0 V, IOUT = 180 mA, TAMB = 25°C, with typical application circuit unless otherwise specified.) 200 2.0 QUIESCENT CURRENT (mA) QUIESCENT CURRENT (mA) VFB = 0.4 V 150 100 50 3.0 3.5 4.0 4.5 1.0 0.5 0 5.5 5.0 1.5 3.0 3.5 4.0 4.5 5.5 5.0 INPUT VOLTAGE (V) INPUT VOLTAGE (V) Figure 2. Quiescent Current vs. VIN (Not Switching) Figure 3. Quiescent Current vs. VIN (Switching) 310 303 FB PIN VOLTAGE (mV) FB PIN VOLTAGE (mV) 302 301 300 299 305 300 295 298 297 −50 0 50 100 290 150 120 140 160 180 200 Figure 4. FB Pin Voltage vs. Temperature Figure 5. FB Pin Voltage vs. Output Current 2.0 SWITCH RESISTANCE (W) SWITCHING FREQUENCY (MHz) 100 OUTPUT CURRENT (mA) 1.2 1.1 1.0 0.9 0.8 80 TEMPERATURE (°C) 3.0 3.5 4.0 4.5 5.0 1.5 1.0 0.5 0 5.5 3.0 3.5 4.0 4.5 5.0 INPUT VOLTAGE (V) INPUT VOLTAGE (V) Figure 6. Switching Frequency vs. Supply Voltage Figure 7. Switch ON Resistance vs. Input Voltage http://onsemi.com 4 5.5 CAT4139 TYPICAL CHARACTERISTICS (VIN = 5.0 V, IOUT = 180 mA, TAMB = 25°C, with typical application circuit unless otherwise specified.) 2.0 200 IOUT VARIATION (%) LED CURRENT (mA) 1.5 180 160 140 120 1.0 0.5 0 −0.5 −1.0 −1.5 3.0 3.5 4.0 4.5 −2.0 5.5 5.0 4.7 4.9 5.1 5.3 INPUT VOLTAGE (V) Figure 8. Output Current vs. Input Voltage Figure 9. Output Current Regulation 95 95 90 90 85 5.5 IOUT = 120 mA 85 IOUT = 180 mA 80 80 75 4.5 INPUT VOLTAGE (V) EFFICIENCY (%) EFFICIENCY (%) 100 80 100 120 140 160 180 75 200 4.5 4.7 4.9 5.1 5.3 OUTPUT CURRENT (mA) INPUT VOLTAGE (V) Figure 10. Efficiency vs. Output Current Figure 11. Efficiency vs. Input Voltage Figure 12. Power−up at 180 mA Figure 13. Switching Waveform http://onsemi.com 5 5.5 CAT4139 TYPICAL CHARACTERISTICS (VIN = 5.0 V, IOUT = 180 mA, TAMB = 25°C, with typical application circuit unless otherwise specified.) 1.0 SHUTDOWN VOLTAGE (V) 250 VOUT = 9 V 200 150 VOUT = 14 V 100 50 0 3.0 3.5 4.0 4.5 −25°C 85°C 0.6 125°C 0.4 0.2 5.5 5.0 −40°C 0.8 3.0 3.5 4.0 4.5 INPUT VOLTAGE (V) INPUT VOLTAGE (V) Figure 14. Maximum Output Current Figure 15. Shutdown Voltage 900 SWITCH CURRENT LIMIT (mA) MAX OUTPUT CURRENT (mA) 300 850 VOUT = 9 V 800 VOUT = 12 V 750 700 650 600 4.5 4.7 5.1 4.9 5.3 INPUT VOLTAGE (V) Figure 16. Switch Current Limit http://onsemi.com 6 5.5 5.0 CAT4139 Pin Description VIN is the supply input for the internal logic. The device is compatible with supply voltages down to 2.8 V and up to 5.5 V. It is recommended that a small bypass ceramic capacitor (4.7 mF) be placed between the VIN and GND pins near the device. If the supply voltage drops below 1.9 V, the device stops switching. SHDN is the shutdown logic input. When the pin is tied to a voltage lower than 0.4 V, the device is in shutdown mode, drawing nearly zero current. When the pin is connected to a voltage higher than 1.5 V, the device is enabled. GND is the ground reference pin. This pin should be connected directly to the ground plane on the PCB. SW pin is connected to the drain of the internal CMOS power switch of the boost converter. The inductor and the Schottky diode anode should be connected to the SW pin. Traces going to the SW pin should be as short as possible with minimum loop area. An over−voltage detection circuit is connected to the SW pin. When the voltage reaches 24 V, the device enters a low power operating mode preventing the SW voltage from exceeding the maximum rating. FB feedback pin is regulated at 0.3 V. A resistor connected between the FB pin and ground sets the LED current according to the formula: I LED + 0.3 V R1 The lower LED cathode is connected to the FB pin. Table 4. PIN DESCRIPTIONS Pin # Name 1 SW 2 GND Function Switch pin. This is the drain of the internal power switch. 3 FB 4 SHDN 5 VIN Ground pin. Connect the pin to the ground plane. Feedback pin. Connect to the last LED cathode. Shutdown pin (Logic Low). Set high to enable the driver. Power Supply input. VOUT VIN SW C2 C1 1 MHz Oscillator Ref 300 mV Over Voltage Protection – + PWM & Logic + – Current Sense ILED RS – SHDN Thermal Shutdown & UVLO + VIN Driver GND FB Figure 17. Simplified Block Diagram http://onsemi.com 7 CAT4139 Device Operation The CAT4139 is a fixed frequency (1 MHz), low noise, inductive boost converter that provides a constant current with excellent line and load regulation. The device uses a high−voltage CMOS power switch between the SW pin and ground to energize the inductor. When the switch is turned off, the stored energy in the inductor is released into the load via the Schottky diode. The on/off duty cycle of the power switch is internally adjusted and controlled to maintain a constant regulated voltage of 0.3 V across the feedback resistor connected to the feedback pin (FB). The value of the resistor sets the LED current accordingly (0.3 V/R1). During the initial power−up stage, the duty cycle of the internal power switch is limited to prevent excessive in−rush currents and thereby provide a “soft−start” mode of operation. In the event of an “Open LED” fault condition, where the feedback control loop becomes open, the output voltage will continue to increase. Once this voltage exceeds 24 V, an internal protection circuit will become active and place the device into a very low power safe operating mode. Thermal overload protection circuitry has been included to prevent the device from operating at unsafe junction temperatures above 150°C. In the event of a thermal overload condition the device will automatically shutdown and wait till the junction temperatures cools to 130°C before normal operation is resumed. Application Information External Component Selection Capacitors forward voltage should be as low as possible. The response time is also critical since the driver is operating at 1 MHz. Central Semiconductor Schottky rectifier CMSH1−40 (1 A rated) is recommended for most applications. The CAT4139 only requires small ceramic capacitors of 4.7 mF on the input and 1 mF on the output. Under normal condition, a 4.7 mF input capacitor is sufficient. For applications with higher output power, a larger input capacitor of 10 mF may be appropriate. X5R and X7R capacitor types are ideal due to their stability across temperature range. LED Current Setting The LED current is set by the external resistor R1 connected between the feedback pin (FB) and ground. The formula below gives the relationship between the resistor and the current: Inductor A 22 mH inductor is recommended for most of the CAT4139 applications. In cases where the efficiency is critical, inductances with lower series resistance are preferred. Inductors with current rating of 800 mA or higher are recommended for most applications. Sumida CDRH6D28−220 22 mH inductor has a rated current of 1.2 A and a series resistance (D.C.R.) of 128 mW typical. R1 + 0.3 V LED current Table 5. RESISTOR R1 AND LED CURRENT LED Current (mA) R1 (W) 20 15 25 12 30 10 100 3 300 1 Schottky Diode The current rating of the Schottky diode must exceed the peak current flowing through it. The Schottky diode performance is rated in terms of its forward voltage at a given current. In order to achieve the best efficiency, this http://onsemi.com 8 CAT4139 Schottky 40 V (Central CMSH05−4) Open LED Protection In the event of an “Open LED” fault condition, the CAT4139 will continue to boost the output voltage with maximum power until the output voltage reaches approximately 24 V. Once the output exceeds this level, the internal circuitry immediately places the device into a very low power mode where the total input power is limited to about 6 mW (about 1.6 mA input current with a 3.6 V supply). The SW pin clamps at a voltage below its maximum rating of 40 V. There is no need to use an external zener diode between VOUT and the FB pin. A 35 V rated C2 capacitor is required to prevent any overvoltage damage in the open LED condition. L VIN D VOUT 22 mH C1 4.7 mF C2 1 mF SW VIN CAT4139 OFF ON SHDN FB GND R1 15 W Figure 18. Open LED Protection Circuit Figure 19. Open LED Disconnect and Reconnect Figure 20. Open LED Disconnect 35 OUTPUT VOLTAGE (V) INPUT CURRENT (mA) 2.5 2.0 1.5 1.0 3.0 3.5 4.0 4.5 5.0 30 25 20 15 5.5 3.0 INPUT VOLTAGE (V) 3.5 4.0 4.5 5.0 INPUT VOLTAGE (V) Figure 21. Open LED Supply Current Figure 22. Open LED Output Voltage http://onsemi.com 9 5.5 CAT4139 Dimming Control There are several methods available to control the LED brightness. Filtered PWM Signal A filtered PWM signal used as a variable DC voltage can control the LED current. Figure 24 shows the PWM control circuitry connected to the CAT4139 FB pin. The PWM signal has a voltage swing of 0 V to 2.5 V. The LED current can be dimmed within a range from 0 mA to 20 mA. The PWM signal frequency can vary from very low frequency and up to 100 kHz. PWM Signal on the SHDN Pin LED brightness dimming can be done by applying a PWM signal to the SHDN input. The LED current is repetitively turned on and off, so that the average current is proportional to the duty cycle. A 100% duty cycle, with SHDN always high, corresponds to the LEDs at nominal current. Figure 23 shows a 1 kHz signal with a 50% duty cycle applied to the SHDN pin. The recommended PWM frequency range is from 100 Hz to 2 kHz. VIN SW CAT4139 SHDN GND PWM Signal 2.5 V VIN 0V RA 3.73 kW C3 0.22 mF LED Current FB RB 3.1 kW VFB = 300 mV R2 1 kW R1 15 W Figure 24. Circuit for Filtered PWM Signal A PWM signal at 0 V DC, or a 0% duty cycle, results in a max LED current of about 22 mA. A PWM signal with a 93% duty cycle or more, results in an LED current of 0 mA. 25 Figure 23. Switching Waveform with 1 kHz PWM on SHDN LED CURRENT (mA) 20 15 10 5 0 0 10 20 30 40 50 60 70 80 90 100 PWM DUTY CYCLE (%) Figure 25. Filtered PWM Dimming (0 V to 2.5 V) http://onsemi.com 10 CAT4139 Board Layout The CAT4139 is a high-frequency switching regulator. The traces that carry the high-frequency switching current have to be carefully laid out on the board in order to minimize EMI, ripple and noise in general. The thicker lines on Figure 26 show the switching current path. All these traces have to be short and wide enough to minimize the parasitic inductance and resistance. The loop shown on Figure 26 corresponds to the current path when the CAT4139 internal switch is closed. On Figure 27 is shown L D VIN V OUT the current loop, when the CAT4139 switch is open. Both loop areas should be as small as possible. Capacitor C1 has to be placed as close as possible to the VIN pin and GND. The capacitor C2 has to be connected separately to the top LED anode. A ground plane under the CAT4139 allows for direct connection of the capacitors to ground. The resistor R1 must be connected directly to the GND pin of the CAT4139 and not shared with the switching current loops and any other components. L D VOUT VIN SW SW VIN VIN CAT4139 SHDN C1 Switch Closed CAT4139 SHDN FB C2 R1 C1 GND GND Figure 26. Closed−switch Current Loop Switch Open FB C2 Figure 27. Open−switch Current Loop Figure 28. Recommended PCB Layout http://onsemi.com 11 R1 CAT4139 PACKAGE DIMENSIONS TSOT−23, 5 LEAD CASE 419AE−01 ISSUE O SYMBOL D MIN NOM A1 0.01 0.05 0.10 A2 0.80 0.87 0.90 b 0.30 c 0.12 A e E1 1.00 0.45 0.15 D 2.90 BSC E 2.80 BSC E1 1.60 BSC E MAX e 0.20 0.95 TYP L 0.30 0.40 L1 0.60 REF L2 0.25 BSC 0º θ 0.50 8º TOP VIEW A2 A b q L A1 c L1 SIDE VIEW END VIEW Notes: (1) All dimensions are in millimeters. Angles in degrees. (2) Complies with JEDEC MO-193. http://onsemi.com 12 L2 CAT4139 Example of Ordering Information (Note 5) Prefix Device # Suffix CAT 4139 TD −G T3 Company ID (Optional) Product Number 4139 Package TD: TSOT−23 Lead Finish G: NiPdAu Tape & Reel (Note 7) T: Tape & Reel 3: 3,000 / Reel SERIES LED DRIVERS ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ ÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁÁ Part Number 3. 4. 5. 6. 7. Description CAT4137 CMOS Boost Converter − White LED Driver CAT4237 High Voltage CMOS Boost White LED Driver CAT4238 High Efficiency 10 LED Boost Converter CAT4139 22 V High Current Boost White LED Driver CAT4240 6 Watt Boost LED Driver All packages are RoHS−compliant (Lead−free, Halogen−free). The standard lead finish is NiPdAu. The device used in the above example is a CAT4139TD−GT3 (TSOT−23, NiPdAu, Tape & Reel, 3,000/Reel). For additional package and temperature options, please contact your nearest ON Semiconductor Sales office. For information on tape and reel specifications, including part orientation and tape sizes, please refer to our Tape and Reel Packaging Specifications Brochure, BRD8011/D. ON Semiconductor and are registered trademarks of Semiconductor Components Industries, LLC (SCILLC). SCILLC reserves the right to make changes without further notice to any products herein. SCILLC makes no warranty, representation or guarantee regarding the suitability of its products for any particular purpose, nor does SCILLC assume any liability arising out of the application or use of any product or circuit, and specifically disclaims any and all liability, including without limitation special, consequential or incidental damages. “Typical” parameters which may be provided in SCILLC data sheets and/or specifications can and do vary in different applications and actual performance may vary over time. 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American Technical Support: 800−282−9855 Toll Free USA/Canada Europe, Middle East and Africa Technical Support: Phone: 421 33 790 2910 Japan Customer Focus Center Phone: 81−3−5773−3850 http://onsemi.com 13 ON Semiconductor Website: www.onsemi.com Order Literature: http://www.onsemi.com/orderlit For additional information, please contact your local Sales Representative CAT4139/D