AME, Inc. Micropower Step-Up DC/DC Converter AME5138 n General Description The AME5138 is a fixed off-time step-up DC/DC converter in a small 5-lead SOT-25 package.The AME5138 is ideal for LCD panels requiring low current and high efficiency as well as LED applications for cellular phone backlighting, PDAs,and other hand-held devices. The low 400ns off-time allows the use of tiny external components. AME5138 is designed to drive up to four white LEDs in series with a constant current from a single Li-lon battery. To control LED brightness, the LED current can be adjusted by applying a PWM (pulse width modulated) signal with a frequency range of 100Hz to 50KHz to the EN pin. n Typical Application L 10µH V IN 2.5V-4.2V 5 1 V IN CIN 4.7µF Ceramic Option for 4LEDs D SW ILED COUT 1µF Ceramic AME5138 >1.1V 4 3 EN FB GND 0V R2 80Ω 2 * ILED =VFB/R2 n Features Figure 1： Four White LEDs Application in Li-lon Battery l 0.7Ω internal switch l Uses small surface mount components l Adjustable output voltage up to 20V l 2V to 5.5V input range VIN 2.5V-4.2V L 15µH 20V 10mA D l Input undervoltage lockout l 0.01µA shutdown current l Small 5-Lead SOT-25 package l All AME's lead free Product Meet RoHS Standard 5 1 VIN CIN 4.7µF Ceramic 4 R1 200K SW AME5138 FB 3 EN GND 2 COUT 1µF Ceramic R2 13K n Applications l White LED Back-Lighting l Hand-held Devices l Digital Cameras l Portable Applications l LCD Bias Power Figure 2： Typical 20V Application 1 AME, Inc. Micropower Step-Up DC/DC Converter AME5138 n Function Block Diagram L D VIN CIN VIN COUT SW VOUT Vref=1.23 R1 FB + Enable Comp - + CL Comp - R2 400ns one Shot Current sensing CL Adjust Driver Under Voltage Lockout Logic control EN Figure 3： AME5138 Block Diagram 2 VOUT GND AME, Inc. Micropower Step-Up DC/DC Converter AME5138 n Pin Configuration SOT-25 Top View 5 4 AME5138 1. SW 2. GND AME5138 3. FB 4. EN 5. VIN 1 2 3 * Die Attach: Conductive Epoxy n Pin Description 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. Output voltage feedback input. Set the output voltage by selecting values for R1 and R2 using: 3 FB V R1 = R 2 out − 1 1 . 23V Connect the ground of the feedback network to an AGND(Analog Ground) plane which should be tied directly to the GND pin. 4 5 EN Shutdown control input, active low. The shutdown pin is an active low control. Tie this pin above 1V to enable the device. Tie this pin below 0.4V to turn off the device. VIN Analog and Power input. Input Supply Pin. Bypassed this pin with a capacitor as close to the device as possible. 3 AME, Inc. Micropower Step-Up DC/DC Converter AME5138 n Ordering Information AME5138 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) 1. SW 2. GND 3. FB 4. EN 5. VIN Operating Ambient Package Type Temperature Range Number of Pins Output Voltage E: -40OC to +85OC V: 5 ADJ: Adjustable E: SOT-2X Special Feature Y: Lead free & Low profile Z: Lead free n Ordering Information Part Number Marking* Output Voltage Package Operating Ambient Temperature Range AME5138AEEVADJY BDYww ADJ TSOT-25 -40OC to +85OC AME5138AEEVADJZ BDYww ADJ SOT-25 -40OC to +85OC Note: ww represents the date code and pls refer to Date Code Rule before Package Dimension. * A line on top of the first letter represents lead free plating such as BDYww. Please consult AME sales office or authorized Rep./Distributor for the availability of package type. 4 AME, Inc. Micropower Step-Up DC/DC Converter AME5138 n Absolute Maximum Ratings Parameter Symbol Maximum Unit VIN 6 V VEN ,VFB VIN V SW Voltage VSW VOUT+0.3 V N-Channel Switch Sink Current ISW 800 mA Input Supply Voltage EN, VFB Voltages ESD Classification B* Caution: Stress above the listed absolute maximum rating may cause permanent damage to the device * HBM B:2000V~3999V n Recommended Operating Conditions Parameter Symbol Rating Unit Input Supply Voltage VIN 2 to 5.5 V Ambient Temperature Range TA -40 to +85 TJ -40 to +125 o C Junction Temperature Range n Thermal Information Parameter Package Die Attach Thermal Resistance* (Junction to Case) Symbol Maximum θJC 81 Unit o C/W Thermal Resistance (Junction to Ambient) SOT-25 Conductive Epoxy Internal Power Dissipation θJA 260 PD 400 mW Maximum Junction Temperature 150 o Solder Iron (10 Sec)** 350 o C C * Measure θJC on backside center of molding compund if IC has no tab. ** MIL-STD-202G210F 5 AME, Inc. Micropower Step-Up DC/DC Converter AME5138 n Electrical Specifications VIN=2.2V, EN = VIN, TA= 25oC Unless otherwise noted. Parameter Input Voltage Range Symbol VIN Test Condition Min o 2 o TA=-40 C to +85 C FB = 1.3V (Not Switching) Quiescent Crrrent IQ EN = 0V Feedback Trip Point VFB TA=-40oC to +85oC Switch Current Limit Switch RDSON IFB ICL RDSON Switch Off Time tOFF Switch Leakage Current ISW Input Undervoltage Lockout EN Input Threshold (Low) (Shutdown) EN Input Threshold (High) (Enable the device) EN input Current UVP Units 5.5 V 80 90 1.199 0.01 2 1.23 1.261 8 FB = 1.23V TA= -40 to 85oC IOUT=10mA TA=25oC 325 VOUT=20V TA= -40 to 85oC 300 V mV 0.2 0.7 350 375 µA mA TA= -40 to 85oC 400 0.7 1.6 400 VSW = 20V 0.05 ON/OFF Threshold 1.6 EN Threshold µA 150 TA= 25oC Ω ns 5.0 µΑ V 0.4 V o TA= -40 to 85 C 1 EN = VIN , TA = 25oC 0 EN = VIN , TA = 85oC 15 EN = GND 6 69 TA= -40 to 85oC IEN Max 150 TA= -40 to 85oC TA= -40 to 85oC ISC FB Pin Bias Current VIN =5.5V VIN =5.5V Shutdown Current VFB Hysteresis 64 TA=25oC FB = 1.15V (Switching) Feedback Hysteresis TA=25oC Typ 0 nA AME, Inc. AME5138 n Detailed Description The AME5138 features a constant off-time control scheme. Operation can be best understood by referring to Figure 3. When the voltage at the FB pin is less than 1.23V, the Enable Comp in Figure 3 enables the device and the NMOS switch is turmed on pulling the SW pin to ground. When the NMOS switch is on, current is supplied by the output capacitor COUT. Once the current in the inductor reaches the peak current limit, the 400ns One Shot turns off the NMOS switch. The SW voltage will then rise to the output voltage plus a diode drop and the inductor current will begin to decrease as shown in Figure 3. During this time the energy stored in the inductor is transferred to COUT and the load. After the 400ns off-time the NMOS switch is turned on and energy is stored in the inductor again. This energy transfer from the inductor to the output causes a stepping effect in the output ripple. This cycle is continued until the voltage at FB reaches 1.23V. When FB reaches this voltage, the enable comparator then disables the device turning off the NMOS switch and reducing the Iq of the device to 64µA. The load current is then supplied solely by COUT indicated by the gradually decreasing slope at the output. When the FB pin drops slightly below 1.23V, the enable comparator enables the device and begins the cycle described previously. The EN pin can be used to turn off the AME5138 and reduce the Iq to 0.01µA. In shutdown mode the output voltage will be a diode drop lower than the input voltage. Micropower Step-Up DC/DC Converter n Application Information INDUCTOR SELECTION The appropriate inductor for a given application is calculated using the following equation: V − VIN(min) + VD TOFF L = OUT ICL Where V D is the schottky diode voltage, ICL is the switch current limit found in the Typical Performance Characteristics section, and TOFF is the switch off time. When using this equation be sure to use in minimum input voltage for the application, such as for battery powered applications. Choosing inductors with low ESR decrease power lossed and increase efficiency. Care should be taken when choosing an inductor. For applications that require an input voltage that approaches the output voltage, such as when converting a Li-ion battery voltage to 5V, the 400ns off time may not be enough time to discharge the energy in the inductor and transfer the energy to the output capacitor and load. This can cause a ramping effect in the inductor current waveform and an increased ripple on the output voltage. Using a smaller inductor will cause the IPK to increase and will increase the output voltage ripple further. This can be solved by adding a 4.7pF capacitor across the R1 feedback resistor (Figure 3) and slightly increasing the output capacitor. A smaller inductor can then be used to ensure proper discharge in the 400ns off time. DIODE SELECTION To maintain high efficiency, the average current rating of the schottky diode should be larger than the peak inductor current, IPK. Schottky diodes with a low forward drop and fast switching speeds are ideal for increasing efficiency in portable applications. Choose a reverse breakdown of the schottky diode larger than the output voltage. 7 AME, Inc. AME5138 CAPACITOR SELECTION Choose low ESR capacitors for the output to minimize output voltage ripple. Multilayer ceramic capacitors are the best choice. For most applications, a 1µF ceramic capacitor is sufficient. For some applications a reduction in output voltage ripple can be achieved by increasing the output capacitor. Local bypassing for the input is needed on the AME5138. Multilayer ceramic capacitors are a good choice for this as well. A 4.7µF capacitor is sufficient for most applications. For additional bypassing, a 100nF ceramic capacitor can be used to shunt high frequency ripple on the input. LAYOUT CONSIDERATIONS The input bypass capacitor CIN, as shown in Figure 3, must be placed close to the IC. This will reduce copper trace resistance which effects input voltage ripple of the IC. For additional input voltage filtering, a 100nF bypass capacitor can be placed in parallel with CIN to shunt any high frequency noise to ground. The output capacitor, COUT, should also be placed close to the IC. Any copper trace connections for the COUT capacitor can increase the series resistance, which directly effects output voltage ripple. The feedback network, resistors R1 and R2, should be kept close to the FB pin to minimize copper trace connections that can inject noise into the system. The ground connection for the feedback resistor network should connect directly to an analog ground plane. The analog ground plane should tie directly to the GND pin. If no analog ground plane is available, the ground connection for the feedback network should tie directly to the GND pin. Trace connections made to the inductor and schottky diode should be minimized to reduce power dissipation and increase overall efficiency. 8 Micropower Step-Up DC/DC Converter AME, Inc. Micropower Step-Up DC/DC Converter AME5138 n Application Information L 2.2µH VIN 2.5V-4.2V 5 1 VIN C IN 4.7µF Ceramic 4 5V 60mA D R1 100K SW AME5138 FB CF B 5pF 3 EN C OUT 1µF Ceramic R2 32.4K GND 2 Figure5: Li-Ion 5V Application L 10µH VIN 2.5V-4.5V 5 1 VIN C IN 4.7µF Ceramic 4 12V 20mA D R1 100K SW AME5138 FB 3 EN C OUT 1µF Ceramic R2 11.3K GND 2 Figure6: Li-Ion 12V Application L 10µH VIN 5V 5 1 VIN C IN 4.7µF Ceramic 4 R1 100K SW AME5138 FB EN GND 2 12V 40mA D 3 C OUT 1µF Ceramic R2 11.3K Figure7: 5V to 12V Application 9 AME, Inc. Micropower Step-Up DC/DC Converter AME5138 Switch Current Limit vs. VIN Efficiency vs. Load Current 90 85 VIN =4.2V 80 400 o TA =-40 C 350 o TA =25 C V IN =3.3V 75 Efficiency (%) Switch Current Limit (mA) 450 VIN =2.5V 70 65 60 55 50 300 o 45 TA=85 C VOUT =20V 40 250 2 2.5 3 3.5 4 4.5 5 35 0.5 5.5 2 6 10 90 VIN =5V VIN =3.3V V IN =4.2V V IN =2.5V 75 VIN =4.2V 85 Eff iciency (%) Efficiency (%) 80 70 65 60 55 VI N=3.3V 80 VIN =2.5V 75 70 65 60 55 50 50 V OUT =12V 45 40 0.5 VOUT=5V 45 40 2 6 10 14 18 22 24 25 26 30 0.5 31 37 38 46 6 18 34 Enable Current vs. VIN (Part Switching) 130 120 120 Disab le Current (µA) 140 130 110 100 o TA=25 C TA=85 C 80 70 60 110 130 150 190 110 100 o TA =25 C o 90 TA =85 C 80 70 60 o o TA=-40 C 50 85 Disable Current vs. VIN (Part Not Switching) 140 o 65 IOUT (mA) IOUT (mA) Enable Current ( µA) 17 95 85 TA =-40 C 50 40 40 2 2.5 3 3.5 4 VI N (V) 10 14 Efficiency vs. Load Current Efficiency vs. Load Current 90 90 13 IOUT (mA) VIN (V) 4.5 5 5.5 6 2 2.5 3 3.5 4 VIN (V) 4.5 5 5.5 6 AME, Inc. Micropower Step-Up DC/DC Converter AME5138 EN Threshold vs. VIN Switch Rdson vs. VIN 1.05 1.2 1.0 1.1 1 0.9 0.9 o TA=25 C 0.85 Rd so n (Ω ) EN Threshold (V) 0.95 o TA =-40 C 0.8 0.75 0.7 o TA=85 C 0.8 o TA=85 C 0.7 0.6 o TA=25 C o 0.5 0.65 TA =-40 C 0.4 0.6 0.3 0.55 0.5 0.2 2 2.5 3 3.5 4 4.5 5 5.5 6 2 2.5 3 VIN (V) 3.5 4 4.5 5 5.5 6 VIN (V) Efficiency vs. VIN Output Voltage vs Load Current 12.2 90 Outp ut Vo ltage (V) 12.15 Efficien cy (%) 85 o T A=25 C 80 75 4 LEDs IOUT=15mA 2.5 3 3.5 4 4.5 VIN =4.2V 12 11.95 V IN =5V 11.9 C OUT =4.7µF VOUT =12V 11.8 0.5 2 5 VI N (V) VIN =3.3V 12.05 11.85 70 2 VIN =2.5V 12.1 6 10 14 18 22 24 26 30 32 33 38 40 42 52 IOUT (mA) FB Trip Point and FB Pin Current vs Temperature 0.36 0.35 1.24 V FB 1.23 0.34 0.33 0.32 1.22 0.31 1.21 IFB 0.3 1.2 -40 -20 0 25 o 55 Feeback Biascurent (µA) Feeback Trip Point (V) 1.25 0.29 85 Ambient Temperature ( C) 11 AME, Inc. Micropower Step-Up DC/DC Converter AME5138 Typical Switching Waveform Typical Switching Waveform 1 1 3 2 2 3 VOUT=20V, VIN=2.5V VOUT = 14V, VIN=3.6V; 4LEDs 1)V SW, 20V/div,DC IOUT = 15mA 2)V OUT, 200mV/div.AC 1) VSW, 20V / div, DC 3)Inductor Current, 200mA/div,DC Load Current=10mA 2) Inductor Current, 100mA / div, DC 3) VOUT, 100mV / div. AC T=10ms/div Step Response 1 Start-Up/Shutdown 1 2 2 3 3 VOUT=20V, VIN=2.5V VOUT = 20V, VIN = 2.5V 1)Load, 1mA to 10mA to 1mA,DC 1) EN, 1V/div,DC 2)V OUT, 200mV/div.AC 2) VOUT, 20V/div,DC 3)Inductor Current 200mA/div,DC 3) Inductor Current 200mA/div,DC T=1ms/div RL =1.8kΩ, T= 200µs/div 12 AME, Inc. Micropower Step-Up DC/DC Converter AME5138 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 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 13 AME, Inc. Micropower Step-Up DC/DC Converter AME5138 n Tape and Reel Dimension TSOT-25 P W AME AME PIN 1 Carrier Tape, Number of Components Per Reel and Reel Size 14 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 AME, Inc. Micropower Step-Up DC/DC Converter AME5138 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 10o 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 θ1 S1 e 1.90 BSC e H 2.40 A θ1 b S1 3.00 0.35BSC L Front View 0.07480 BSC 0 o 10 0.95BSC 0.09449 0.11811 0.0138BSC o 0o 10o 0.0374BSC A1 H L D 15 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. , February 2006 Document: 1015-DS5138-A.01 Corporate Headquarter U.S.A. (Subsidiary) AME, Inc. Analog Microelectronics, Inc. 2F, 302 Rui-Guang Road, Nei-Hu District Taipei 114, Taiwan. Tel: 886 2 2627-8687 Fax: 886 2 2659-2989 3100 De La Cruz Blvd., Suite 201 Santa Clara, CA. 95054-2046 Tel : (408) 988-2388 Fax: (408) 988-2489