AME, Inc. White LED Boost Converter In Tiny Package AME5142 n Pin Configuration SOT-25/TSOT-25 Top View 5 4 SOT-26/TSOT-26 Top View AME5142AEEV 6 5 4 1. SW 1. SW 2. GND AME5142 3. FB 2. GND AME5142 4. EN 2 3. FB 4. EN 5. IN 1 AME5142AEEY 5. OVP 1 3 * Die Attach: 2 3 6. IN * Die Attach: Conductive Epoxy Conductive Epoxy n Pin Description AME5142AEEV Pin Number Pin Name Pin Description 1 SW Power Switch input. This is the drain of the internal NMOS power switch. Minimize the metal trace area connected to this pin to minimize EMI. 2 GND Ground. Tie directly to ground plane. 3 FB Output voltage feedback input. Connect the ground of the feedback network to an AGND (Analog Ground) plane which should be tied directly to the GND pin. 4 EN Enable control input, active high. The enable pin is an active high control. Tie this pin above 1.5V to enable the device. Tie this pin below 0.4V to turn off the device. 5 IN Analog and Power input. Input Supply Pin. Bypass this pin with a capacitor as close to the device as possible. Rev. A.01 3 AME, Inc. White LED Boost Converter In Tiny Package AME5142 n Pin Description AME5142AEEY 4 Pin Number Pin Name Pin Description 1 SW Power Switch input. This is the drain of the internal NMOS power switch. Minimize the metal trace area connected to this pin to minimize EMI. 2 GND Ground. Tie directly to ground plane. 3 FB Output voltage feedback input. Connect the ground of the feedback network to an AGND(Analog Ground) plane which should be tied directly to the GND pin. 4 EN Enable control input, active high. The enable pin is an active high control. Tie this pin above 1.5V to enable the device. Tie this pin below 0.4V to turn off the device. 5 OVP 6 IN Over Voltage Protection. Analog and Power input. Input Supply Pin. Bypass this pin with a capacitor as close to the device as possible. Rev. A.01 AME, Inc. White LED Boost Converter In Tiny Package AME5142 n Ordering Information AME5142 x x x x xxx x Special Feature Output Voltage Number of Pins Package Type Operating Ambient Temperature Range Pin Configuration Pin Configuration A (SOT-25) (TSOT-25) A (SOT-26) (TSOT-26) 1. SW 2. GND 3. FB 4. EN 5. IN Operating Ambient Temperature Range Package Type E: -40OC to 85OC E: SOT-2X Number of Pins V: 5 Y: 6 Output Voltage Special Feature ADJ: Adjustable Y: Lead free & Low profile Z: Lead free 1. SW 2. GND 3. FB 4. EN 5. OVP 6. IN n Ordering Information Part Number Marking* Output Voltage Package Operating Ambient Temperature Range AME5142AEEYADJZ BJGww ADJ SOT-26 -40OC to 85OC AME5142AEEYADJY BJGww ADJ TSOT-26 -40OC to 85OC AME5142AEEVADJZ BJHww ADJ SOT-25 -40OC to 85OC AME5142AEEVADJY BJHww ADJ TSOT-25 -40OC to 85OC Note: ww represents the date code and pls refer to Date Code Rule page on Package Dimension. * A line on top of the first letter represents lead free plating such as BJGww. Please consult AME sales office or authorized Rep./Distributor for the availability of package type. Rev. A.01 5 AME, Inc. White LED Boost Converter In Tiny Package AME5142 n Absolute Maximum Ratings Parameter Symbol Maximum Unit VIN 6 V V EN ,VFB VIN V V SW,VOVP 30 V Input Supply Voltage EN, FB Voltages SW, OVP Voltage B* ESD Classification Caution: Stress above the listed in absolute maximum ratings may cause permanent damage to the device. * HBM B: 2000V ~ 3999V n Recommended Operating Conditions Parameter Symbol Rating Ambient Temperature Range TA -40 to 85 Junction Temperature Range TJ -40 to 125 Storage Temperature Range TSTG -65 to 150 Unit o C n Thermal Information Parameter Thermal Resistance* (Junction to Case) Thermal Resistance (Junction to Ambient) Package SOT-25 TSOT-25 SOT-26 TSOT-26 Die Attach Symbol Maximum θJC 81 Unit o C/W Conductive Epoxy Internal Power Dissipation Solder Iron (10Sec)** θJA 260 PD 400 350 mW o C * Measure θJC on center of molding compound if IC has no tab. ** MIL-STD-202G 210F 6 Rev. A.01 AME, Inc. White LED Boost Converter In Tiny Package AME5142 n Electrical Specifications VIN = 4.2V, EN = VIN, TA = 25oC, Unless otherwise noted. Parameter Input Voltage Quiescent Current Symbol V IN IQ Feedback Trip Point VFB FB Pin Bias Current IFB Switch Current Limit ICL Switch On-Resistance Test Condition RDSON Min Typ 2.7 5.5 V 0.85 1 mA Not Switching, VFB = 0.2V 180 250 µA 0.15 0.163 V 0.1 1 µA 850 1000 mA 0.7 1.4 Ω 1 10 µA 1.5 MHz 0.137 VFB = 0.2V 650 ISW = 100mA, VFB = 0.2V ISW VSW = 20V Swich frequency fSW VFB = 0.1V 0.9 1.2 Dmax VFB = 0V 88 92 ISD VEN = 0V 0.01 OTP Shutdown, temperature increasing 160 TRS Restore, temperature decreasing 140 Shutdown Supply Current Units Switching, VFB = 0V SW Leakage Current Maximum Duty Cycle Max % 1 o Over Temperature Protection C Over Voltage Protection OVP Rising edge Input Undervoltage Lockout UVP VIN rising or falling EN Input Low V EL EN Input High VEH EN Input Current IEN Rev. A.01 µA 24 26 28 V 2.35 2.5 2.65 V 0.4 V 1.5 EN = GND or VIN 0.1 2 µA 7 AME, Inc. AME5142 White LED Boost Converter In Tiny Package n Detailed Description n Application Hints The AME5142 is a constant frequency step-up converter with an internal switch. The operations of AME5142 can be understood from block diagram clearly figure.2. The oscillator triggers the SET input of SR latch to turn on the power switch MS at the start of each cycle. A current sense voltage sum with a stabilizing ramp is connected to the positive terminal of the PWM comparator. When this voltage exceeds the output voltage of the error amplifier, the SR latch is reset to turn off the power switch till next cycle starts. The output voltage of the error amplifier is amplified from the difference between the reference voltage 0.15V and the feedback voltage. In this manner, if the error amplifiers voltage increases, more current is delivered to the output; if it decreases, less current is delivered. A 26V Zener diode connects from OVP pin to FB pin internally to provide an optional protection function which prevents SW pin from over-voltage damage. Especially when the case of the feedback loop broken due to component wear-out or improper connection occurs. The behavior of OVP is to clamp the output voltage to 26V typically. This function is suitable for the applications while driving white LEDs less than 6 in series. Inductor Selection The recommended value of inductor for AME5142 applications is 10µH. Small size and better efficiency are the major concerns for portable device, such as AME5142 used for dual panel mobile phone. The inductor should have low DCR for better efficiency. To avoid inductor saturation, current rating should be at least 1A. The input range is 2.7V to 5.5V. Current Limit Protection The AME5142 has current limiting protection to prevent excessive stress on itself and external components during overload conditions. The internal current limit comparator will disable the NMOS power device at a typical switch peak current limit of 850mA. Output Over-Voltage Protection The AME5142 contains dedicated circuitry for monitoring the output voltage. In the event that the primary LED network is disconnected the output will increase and be limited to 26V (TYP), which will turn the NMOS off when the output voltage is at 26V (max.) until the output voltage reach 26V (TYP.) or lower. The 26V limit allows the use of 26V 1µF ceramic output capacitors creating an overall small solution for white LED applications. Capacitor Selection 4.7µF input capacitor can reduce input ripple. For better voltage stability, to increase the input capacitor value or using LC filter is feasible, especially in the Li-ion battery application. 1µF output capacitor is sufficient to reduce output voltage ripple. For better voltage filtering, ceramic capacitors with low ESR are recommended. X5R and X7R types are suitable because of their wider voltage and temperature ranges. Diode Selection Schottky diode is a good choice for AME5142 because of its lower forward voltage drop and faster reverse recovery. Using schottky diode can get better efficiency. The high speed rectification is also a good characteristic of schottky diode for high switching frequency. Current rating of the diode must meet the root mean square of the peak current and output average current multiplication. Duty Cycle The maximum duty cycle of the switching regulator determines the maximum boost ratio of output-toinput voltage that the converter can attain in mode of operation. The duty cycle for a given boost application is defined as: This applies for continuous mode operation. D= VOUT + VDIODE - VIN VOUT + VDIODE - VSW Under Voltage Protection The AME5142 has an UVP comparator to turn the NMOS power device off in case the input voltage or battery voltage is too low preventing an on state of the power device conducting large amounts of current. 8 Rev. A.01 AME, Inc. White LED Boost Converter In Tiny Package AME5142 n Application Hints Calculating Load Current Dimming Control The load current is related to the average inductor current by the relation: ILOAD = IIND (AVG) x (1 - D) Where “D” is the duty cycle of the application. The switch current can be found by: ISW = IIND (AVG) + 1 /2 (IRIPPLE) A. Using a PWM Signal to EN Pin For controlling the LED brightness, the AME5142 can perform the dimming control by applying a PWM signal to EN pin. The average LED current is proportional to the PWM signal duty cycle. The magnitude of the PWM signal should be higher than the maximum enable voltage of EN pin, in order to let the dimming control perform correctly. Inductor ripple current is dependent on inductance, duty cycle, input voltage and frequency: IRIPPLE = D x (VIN-VSW ) / (f x L) Combining all terms, we can develop an expression which allows the maximum available load current to be calculated: ILOAD = ( 1-D ) x ( ISW (max) - L1 10µH VIN 2.7V to 5.5V D ( VIN-VSW ) ) 2fL Thermal Considerations At higher duty cycles, the increased ON time of the FET means the maximum output current will be determined by power dissipation within the AME5142 switch. The switch power dissipation from ON-state conduction is calculated by: CIN 4.7µF VOUT IN EN Dimming Control 25KHz to 100KHz COUT 1µF SW AME5142 OVP GND FB R1 7.5Ω Figure 5. PWM Dimming Control Using the EN Pin P(SW) = D x IIND(AVE)2 x RDS(ON) There will be some switching losses as well, so some derating needs to be applied when calculating IC power dissipation. Shutdown Pin Operation The device is turned off by pulling the shutdown pin low. If this function is not going to be used, the pin should be tied directly to VIN. If the SHDN function will be needed, a pull-up resistor must be used to VIN (approximately 50k100k recommended). The EN pin must not be left unterminated. Rev. A.01 9 AME, Inc. White LED Boost Converter In Tiny Package AME5142 n Application Hints Dimming Control B. Using a DC Voltage C. Using a Filtered PWM Signal Using a variable DC voltage to adjust the brightness is a popular method in some applications. The dimming control using a DC voltage circuit is shown in Figure 6. According to the Superposition Theorem, as the DC voltage increases, the voltage contributed to VFB increases and the voltage drop on R2 decreases, i.e. the LED current decreases. For example, if the VDC range is from 0V to 3V, the selection of resistors in Figure 6 sets dimming control of LED current from 20mA to 0mA. L1 10µH VIN 2.7V to 5.5V CIN 4.7µF The filtered PWM signal can be considered as an adjustable DC voltage. It can be used to replace the variable DC voltage source in dimming control. The circuit is shown in Figure 7. L1 10µH VIN 2.7V to 5.5V CIN 4.7µF VOUT IN EN AME5142 OVP VOUT IN EN COUT 1µF SW R3 5.1K FB GND R4 91K AME5142 OVP RDC 10K R3 5.1K GND R2 7.5Ω CDC 0.1µF 3V FB R4 91K COUT 1µF SW R2 7.5Ω 0V PWM Signal Figure 7. Dimming Control Using a Filtered PWM Signal VDC Dimming 0V to 3V Figure6. Dimming Control Using a DC Voltage 10 Rev. A.01 AME, Inc. White LED Boost Converter In Tiny Package AME5142 92.0 91.8 91.6 91.4 91.2 91.0 90.8 90.6 90.4 90.2 90.0 89.8 89.6 89.4 89.2 89.0 88.8 88.6 88.4 88.2 88.0 -25 Oscillator Frequency vs. Temperature 1.50 Oscillator Frequency (MHz) Max Duty Cycle (%) Max Duty Cycle vs. Temperature 0 25 50 75 o 100 125 1.45 1.40 1.35 1.30 1.25 1.20 1.15 1.10 1.05 1.00 0.95 0.90 -25 0 25 50 75 100 Temperature ( C) Temperature (oC) Switch RDSON Efficiency vs. Load Current Dirving 3 LEDs 125 100 1.80 1.60 90 1.20 Efficiency (%) RDSON (Ω) 1.40 TA = 85oC 1.00 0.80 o TA = 25 C 0.60 80 70 60 0.40 3.1 3.5 3.9 4.3 4.7 5.1 50 2.7 5.5 3.9 4.3 4.7 5.1 Efficiency vs. Load Current Dirving 4 LEDs Efficiency vs. Load Current Dirving 6 LEDs 100 90 90 80 70 60 5.5 80 70 60 3.1 3.5 3.9 4.3 VIN (V) Rev. A.01 3.5 VIN (V) 100 50 2.7 3.1 VIN (V) Efficiency (%) Efficiency (%) 0.20 2.7 4.7 5.1 5.5 50 2.7 3.1 3.5 3.9 4.3 4.7 5.1 5.5 VIN (V) 11 AME, Inc. White LED Boost Converter In Tiny Package AME5142 Current Limit vs. VIN VFB vs. Temperature 1000 0.177 0.173 0.169 900 0.165 VFB (V) Current Limit (mA) 950 850 0.161 0.157 800 0.153 750 0.149 0.145 700 0.141 650 2.7 3.1 3.5 3.9 4.3 4.7 5.5 0.137 -25 0 25 50 75 100 125 VIN (V) Temperature (oC) Dimming Control for Driving 6LEDs Dimming Control for Driving 6LEDs 2 2 3 3 1 1 1mS / div 12 5.1 1mS / div VIN = 2.7V; 6 LEDs IOUT = 20mA VIN = 5.5V; 6 LEDs IOUT = 20mA 2) EN = 1V / div, DC f = 200Hz 3) VOUT , 10V / div, DC 1) VSW = 10V / div, DC 2) EN = 1V / div, DC f = 200Hz 3) VOUT , 10V / div, DC 1) VSW = 10V / div, DC Rev. A.01 AME, Inc. White LED Boost Converter In Tiny Package AME5142 Dimming Control for Driving 6LEDs Dimming Control for Driving 6LEDs 2 2 3 3 1 1 4µS / div 4µS / div VIN = 2.7V; 6 LEDs IOUT = 20mA VIN = 5.5V; 6 LEDs IOUT = 20mA 2) EN = 1V / div, DC f = 200KHz 3) VOUT , 10V / div, DC 1) VSW = 10V / div, DC 2) EN = 1V / div, DC f = 200KHz 3) VOUT , 10V / div, DC 1) VSW = 10V / div, DC Start-Up / Shutdown Start-Up / Shutdown 1 1 2 2 3 3 200µS / Div Rev. A.01 200µS / div VIN = 2.7V; 1 LEDs IOUT = 20mA VIN = 2.7V; 6 LEDs IOUT = 20mA 1) EN = 2V/div, DC 2) Inductor Current, 100mA / div, DC 3) VOUT , 2V / div, DC 1) EN = 2V / div, DC 2) Inductor Current, 500mA / div, DC 3) VOUT , 10V / div, DC 13 AME, Inc. White LED Boost Converter In Tiny Package AME5142 Start-Up / Shutdown Typical Switching Waveform 1 1 2 2 3 3 200µS / div 1µS / div VIN = 5.5V; 6 LEDs IOUT = 20mA VIN = 2.7V; 6 LEDs IOUT = 20mA 1) EN = 2V / div, DC 2) Inductor Current, 500mA / div, DC 3) VOUT , 10V / div, DC 1) VSW = 10V / div, DC 2) VOUT , 20mV / div, AC 3) Input Current, 100mA / div, DC Inductor = 10µH, COUT = 1µF Typical Switching Waveform 1 2 3 1µS / div VIN = 5.5V; 6 LEDs IOUT = 20mA 1) VSW = 10V / div, DC 2) VOUT , 20mV / div, AC 3) Input Current, 100mA / div, DC Inductor = 10µH, COUT = 1µF 14 Rev. A.01 AME, Inc. White LED Boost Converter In Tiny Package AME5142 n Date Code Rule Marking Date Code Year A A A W W xxx0 A A A W W xxx1 A A A W W xxx2 A A A W W xxx3 A A A W W xxx4 A A A W W xxx5 A A A W W xxx6 A A A W W xxx7 A A A W W xxx8 A A A W W xxx9 n Tape and Reel Dimension SOT-25 P W AME AME PIN 1 Carrier Tape, Number of Components Per Reel and Reel Size Rev. A.01 Package Carrier Width (W) Pitch (P) Part Per Full Reel Reel Size SOT-25 8.0±0.1 mm 4.0±0.1 mm 3000pcs 180±1 mm 15 AME, Inc. White LED Boost Converter In Tiny Package AME5142 n Tape and Reel Dimension TSOT-25 P W AME AME PIN 1 Carrier Tape, Number of Components Per Reel and Reel Size Package Carrier Width (W) Pitch (P) Part Per Full Reel Reel Size TSOT-25 8.0±0.1 mm 4.0±0.1 mm 3000pcs 180±1 mm SOT-26 P W AME AME PIN 1 Carrier Tape, Number of Components Per Reel and Reel Size 16 Package Carrier Width (W) Pitch (P) Part Per Full Reel Reel Size SOT-26 8.0±0.1 mm 4.0±0.1 mm 3000pcs 180±1 mm Rev. A.01 AME, Inc. White LED Boost Converter In Tiny Package AME5142 n Tape and Reel Dimension TSOT-26 P W AME AME PIN 1 Carrier Tape, Number of Components Per Reel and Reel Size Rev. A.01 Package Carrier Width (W) Pitch (P) Part Per Full Reel Reel Size TSOT-26 8.0±0.1 mm 4.0±0.1 mm 3000pcs 180±1 mm 17 AME, Inc. White LED Boost Converter In Tiny Package AME5142 n Package Dimension SOT-25 Top View Side View SYMBOLS D MILLIMETERS MAX MIN MAX L MIN INCHES 1.20REF E H A θ1 S1 A1 0.00 0.15 0.0000 0.0059 b 0.30 0.55 0.0118 0.0217 D 2.70 3.10 0.1063 0.1220 E 1.40 1.80 0.0551 0.0709 1.90 BSC e H e 2.60 θ1 0 o 3.00 10 0.10236 0.11811 0.0146BSC o 0o 10 o 0.95BSC 0.0374BSC MILLIMETERS INCHES S1 A1 A 0.07480 BSC 0.37BSC L Front View 0.0472REF b TSOT-25 Top View Side View SYMBOLS MIN MAX MIN MAX A+A1 0.90 1.25 0.0354 0.0492 b 0.30 0.50 0.0118 0.0197 c 0.09 0.25 0.0035 0.0098 D 2.70 3.10 0.1063 0.1220 E 1.40 1.80 0.0551 0.0709 E H L D θ1 S1 e H e 1.90 BSC 2.40 b 18 S1 0 o 10 0.95BSC 0.09449 0.11811 0.0138BSC o 0o 10 o 0.0374BSC A1 A θ1 3.00 0.35BSC L Front View 0.07480 BSC Rev. A.01 AME, Inc. White LED Boost Converter In Tiny Package AME5142 n Package Dimension SOT-26 Top View Side View MILLIMETERS MIN E L D e H SYMBOLS θ1 A 0.0472REF 0.15 0.0000 0.0059 b 0.30 0.55 0.0118 0.0217 D 2.70 3.10 0.1063 0.1220 E 1.40 1.80 0.0551 0.0709 e θ1 S1 1.90 BSC 2.60 3.00 0.37REF 0o 10 o 0.0748 BSC 0.10236 0.11811 0.0146REF 0o 10 o 0.95REF 0.0374REF MILLIMETERS INCHES A1 A MAX 0.00 L Front View 1.20REF MIN A1 H S1 MAX INCHES b TSOT-26 Top View Side View SYMBOLS MIN MAX MIN MAX A+A1 0.90 1.25 0.0354 0.0492 b 0.30 0.50 0.0118 0.0197 D 2.70 3.10 0.1063 0.1220 E 1.40 1.80 0.0551 0.0709 L E H D e θ1 e H S1 L θ1 Front View 2.40 3.00 0.35BSC 0o 10o 0.95BSC 0.07480 BSC 0.09449 0.11811 0.0138BSC 0o 10o 0.0374BSC A1 A S1 1.90 BSC b Rev. A.01 19 www.ame.com.tw E-Mail: [email protected] Life Support Policy: These products of AME, Inc. are not authorized for use as critical components in life-support devices or systems, without the express written approval of the president of AME, Inc. AME, Inc. reserves the right to make changes in the circuitry and specifications of its devices and advises its customers to obtain the latest version of relevant information. AME, Inc. , July 2007 Document: 1229-DS5142-A.01 Corporate Headquarter U.S.A. (Subsidiary) AME, Inc. Analog Microelectronics, Inc. 2F, 302 Rui-Guang Road, Nei-Hu District Taipei 114, Taiwan. 3100 De La Cruz Blvd., Suite 201 Santa Clara, CA. 95054-2438 Tel: 886 2 2627-8687 Fax: 886 2 2659-2989 Tel : (408) 988-2388 Fax: (408) 988-2489