AME, Inc. Low Cost Micro Power Boost DC/DC Converter AME5170 n General Description The AME5170 is a fixed off-time step-up DC/DC converter in a small SOT-25 package. The AME5170 is ideal for LCD panels requiring low current and high efficiency as well as LED application for cellular phone backlighting, PDAs, and other hand-held devices. The low 400ns off time allows the use of tiny external components. AME5170 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 L1 2.2µH VIN 1.5V to 5V CIN 4.7µF IN VOUT = 5V COUT 4.7µF SW R1 100KΩ EN CF 20pF AME5170 FB GND R2 33KΩ Figure.1 Typical 5V Application n Features l 0.7Ω Internal Switch L1 10µH VIN 1.5V to 5.5V CIN 4.7µF IN l Use Small Surface Mount Components l Adjust Output Voltage up to 28V VOUT = 12V SW R1 240KΩ AME5170 l Input under Voltage Lockout COUT 1µF EN l 0.1µA Shutdown Current Typical FB GND l Small SOT-25 Package R2 27KΩ l All AME's Lead Free Products Meet RoHS Standards Figure.2 Typical 12V Application n Applications l LCD Bias Supplies l White LED Back-Lighting l Handheld Devices l Digital Cameras L1 10µH VIN 1.5V to 5.5V CIN 4.7µF IN VOUT = 20V COUT 1µF SW R1 510KΩ l Portable Applications EN AME5170 GND FB R2 33KΩ Figure.3 Typical 20V Application Rev.A.02 1 AME, Inc. Low Cost Micro Power Boost DC/DC Converter AME5170 n Typical Application L1 10µH VIN 2.7V to 5.5V C IN 4.7µF VOUT IN EN COUT 1µF SW AME5170 FB GND R2 62Ω Figure.4 White LED Application n Function Block Diagram SW IN + Enable Comp FB 1:8 VIN CL Adjust Current Limit + VREF 400ns one Shot Cs Logic Control Driver UVP EN GND Figure.5 Function Block Diagram 2 Rev.A.02 AME, Inc. Low Cost Micro Power Boost DC/DC Converter AME5170 n Pin Configuration SOT-25/TSOT-25 Top View 5 AME5170AEEV 4 1. SW 2. GND AME5170 3. FB 4. EN 1 2 5. IN 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 R 1 = R 2 out − 1 1 . 23 V Connect the ground of the feedback network to an AGND(Analog Ground) plane which should be tied directly to the GND pin. Rev.A.02 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. 3 AME, Inc. Low Cost Micro Power Boost DC/DC Converter AME5170 n Ordering Information AME5170 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) 1. SW 2. GND 3. FB 4. EN 5. IN Operating Ambient Temperature Range E: -40OC to 85OC Package Type E: SOT-2X Number of Pins Output Voltage Special Feature V: 5 ADJ: Adjustable Z: Lead free Y: Lead free & Low profile n Ordering Information Part Number Marking* Output Voltage Package Operating Ambient Temperature Range AME5170AEEVADJZ BLEww ADJ SOT-25 -40OC to 85OC AME5170AEEVADJY BLEww ADJ TSOT-25 -40OC to 85OC Note: ww represents the date code and pls refer to Date Code Rule on Package Dimension. * A line on top of the first letter represents lead free plating such as BLEww. Please consult AME sales office or authorized Rep./Distributor for the availability of package type. 4 Rev.A.02 AME, Inc. Low Cost Micro Power Boost DC/DC Converter AME5170 n Absolute Maximum Ratings Parameter Symbol Maximum Unit VIN 6 V EN,VFB VIN V SW Voltage VSW VOUT + 0.3 V N-Channel Switch Sink Current ISW 600 mA Input Supply Voltage EN, FB Voltages B* ESD Classification Caution: Stress above the listed absolute rating may cause permanent damage to the device. * HBM B: 2000~3999V n Recommented 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 Package Die Attach Symbol Maximum θ JC 81 Thermal Resistance* (Junction to Case) Thermal Resistance (Junction to Ambient) Unit o SOT-25 TSOT-25 Conductive Epoxy Internal Power Dissipation Solder Iron (10Sec)** θJA 260 PD 400 350 C/W mW o C * Measure θJC on backside center of molding compund if IC has no tab. ** MIL-STD-202G 210F Rev.A.02 5 AME, Inc. Low Cost Micro Power Boost DC/DC Converter AME5170 n Electrical Specifications VIN = 3.6V, EN = VIN, TA = 25oC, CIN = 4.7µF, IL = 0A, unless otherwise noted. Parameter Input Voltage Symbol Test Condition VIN Min 1.5 Output Voltage Line Regulation Max Units 5.5 V 0.05 %V Quiescent Current IQ VIN = 2V 65 75 µA Shutdown Current ISD EN = 0V 0.1 1 µA FB Regulation Voltage VFB 1.23 1.26 V FB Comparator Hysteresis ICL FB Pin Bias Current IFB Switch Off Time Input Undervoltage Lockout EN Input Threshold (High) (Enable the device) EN Input Threshold (Low) (Shutdown) 1.20 VFB Hysteresis Switch Current Limit Switch RDSON 6 Typ RDSON 5 300 375 VFB = 1.23V 0.6 1.0 t OFF 400 UVLO 1.2 mV 450 mA 1.0 µA 1.4 Ω nS 1.4 V 1.5 EN Threshold V 0.4 Rev.A.02 AME, Inc. AME5170 Low Cost Micro Power Boost DC/DC Converter n Detailed Description The AME5170 features a constant off-time control scheme. Operation can be best understood by referring to Figure 5. When the voltage at the FB pin is less than 1.23V, the Enable Comp in Figure.5 enables the device and the NMOS switch is turned on, pulling the SW pin to ground. When the NMOS switch is on, load 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 inductor current will begin to decrease as shown in Figure3. During this time the energy stored in the inductor is transferred to COUT and the load. After the 400ns offtime 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 pin reaches 1.23V. When FB pin reaches this voltage, the enable comparator then disables the device turning off the NMOS switch and reducing the quiescent current of the device to 65µA typical. 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 AME5170 and reduce the IQ to 0.1µA. In shutdown mode the output voltage will be a diode drop lower than the input voltage. DIODE SELECTION To maintain high efficiency, the average current rating of the schottky diode should be larger than the peak inductor current. 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 Rev.A.02 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 AME5170. 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. 7 AME, Inc. Low Cost Micro Power Boost DC/DC Converter AME5170 n Characterization Curve(For reference only) Efficiency vs. Loading Switch off Time vs. Temperature 90 700 VIN=4.2V 650 Switch off time (ns) Efficiency(%) 85 VIN=3.3V 80 VIN=2.7V 75 70 65 600 550 500 450 VOUT=12V 60 0 5 10 15 20 25 30 35 40 400 -40 45 50 55 60 65 70 -15 IOUT(mA) 10 35 60 85 o Temperature( C) IFB vs. Temperature IQ vs. Temperature 1.0 75 0.9 60 0.8 I Q(µA) I FB(µA) 0.7 0.6 0.5 45 30 0.4 0.3 15 0.2 0.1 -40 -15 10 35 60 0 -40 85 -15 1.5 1. 5 1.4 1. 4 1.3 1. 3 1.2 1. 2 1.1 1.0 0.9 0.8 0.7 8 0. 8 0. 7 0. 5 35 85 0. 9 0. 6 10 60 1. 0 0.5 Temperature(oC) o 1. 1 0.6 -15 35 EN Threshold Low vs. Temperature EN Threshold(V) EN Threshold(V) EN Thershold High vs. Temperature 0.4 -40 10 Temperature( C) Temperature(oC) 60 85 0. 4 -40 -15 10 35 60 85 Temperature(oC) Rev.A.02 AME, Inc. Low Cost Micro Power Boost DC/DC Converter AME5170 n Characterization Curve(For reference only) RDSON vs Temperature Switch Current Limit vs Temperature 1.4 1.3 600 1.2 RDSON(Ω) Switch Current Limit(mA) 700 500 400 1.1 1.0 0.9 0.8 0.7 300 0.6 200 -40 -15 10 35 60 o 0.5 -40 85 -15 10 35 60 Temperature( C) Temperature(oC) VFB vs. Temperature UVLO vs. Temperature 85 1. 50 1.26 1.45 1.25 1. 40 1.35 UVLO(V) VFB(V) 1.24 1.23 1.22 1. 30 1.25 1. 20 1.15 1. 10 1.21 1.05 1.20 -40 -15 10 35 60 o Temperature( C) Rev.A.02 85 1. 00 -40 -15 10 35 o 60 85 Temperature( C) 9 AME, Inc. Low Cost Micro Power Boost DC/DC Converter AME5170 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 10 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 Rev.A.02 AME, Inc. Low Cost Micro Power Boost DC/DC Converter AME5170 n Tape and Reel Dimension TSOT-25 P W AME AME PIN 1 Carrier Tape, Number of Components Per Reel and Reel Size Rev.A.02 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 11 AME, Inc. Low Cost Micro Power Boost DC/DC Converter AME5170 n Package Dimension SOT-25 Top View Side View SYMBOLS D MILLIMETERS MIN θ1 1.20REF E H A L S1 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 1.90 BSC e θ1 2.60 0.07480 BSC 3.00 0.37BSC 0 o 10 0.10236 0.11811 0.0146BSC o 0o 10o 0.95BSC 0.0374BSC MILLIMETERS INCHES S1 A1 A MAX 0.00 L Front View MIN A1 H e MAX INCHES b TSOT-25 Top View Side View D E H θ1 L S1 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 H e 1.90 BSC e 2.40 θ1 0 o 10 0.95BSC 0.09449 0.11811 0.0138BSC o 0 o 10 o 0.0374BSC b 12 A1 A S1 3.00 0.35BSC L Front View 0.07480 BSC Rev.A.02 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. , December 2007 Document: 1231-DS5170-A.02 Corporate Headquarter AME, Inc. 2F, 302 Rui-Guang Road, Nei-Hu District Taipei 114, Taiwan, R.O.C. Tel: 886 2 2627-8687 Fax: 886 2 2659-2989 U.S.A.(Subsidiary) Analog Microelectronics, Inc. 3100 De La Cruz Blvd., Suite 201 Santa Clara, CA. 95054-2438 Tel : (408) 988-2388 Fax: (408) 988-2489