AAT1265 Low Voltage 2MHz Step-Up DC/DC Converter in SC70JW Package General Description Features The AAT1265 is a member of Analogic Tech's Total Power Management IC™ (TPMIC™) product family and is designed for single-cell or dual-cell alkaline, NiMH, or NiCd battery-powered applications. It is a high efficiency, synchronous, fixed frequency, stepup converter with true output disconnect during shutdown (<1.0µA), start-up inrush current limit, and short-circuit protection. • • • • • • • The high 2MHz switching frequency and completely integrated control circuitry minimize the total solution footprint area while maintaining excellent regulation, ripple, and transient response throughout the full load range. Light load switching frequency modulation and low quiescent current maintain high efficiency performance for light load and sleep mode conditions. With a 1A peak switch current limit, the AAT1265 is capable of delivering 100mA to a 3.3V load with a single AA cell or up to 250mA from a dual AA cell. The device has a 1.0V start-up voltage with operation down to 0.8V. The AAT1265 is available in a Pb-free, space-saving 2.0x2.1mm 8-pin SC70JW package and is rated over the -40°C to +85°C temperature range. SwitchReg™ 100mA Output from a Single AA Cell Input 250mA Output from a Dual AA Cell Input VIN Operation Range: 0.8V to VOUT Up to 93% Efficiency Low Start-Up Voltage: 1.0V Typical Internal Synchronous Rectifier Current Mode Control with Internal Feedback and Compensation 2MHz Fixed Switching Frequency 1A Current Limit Maintains High Efficiency Over the Output Current Range for Improved Battery Life Low 40µA No Load Bias Current True Load Disconnect Short-Circuit and Over-Current Protection Inrush Current Limit and Soft Start Low Shutdown Current: <1.0µA -40°C to +85°C Temperature Range 2.0x2.1mm SC70JW-8 Package • • • • • • • • • • Applications • • • • • Bluetooth™ Headsets Digital Cameras Medical Instruments Mobile Handsets MP3 and Portable Music Players Typical Application VIN Dual-Cell to 3.3V Efficiency vs. Output Current VOUT 100 AAT1265 LX VCC VIN OUT VIN = 3.0V 90 4.7µF 4.7µF EN GND Efficiency (%) 2.2µH 80 VIN = 2.4V VIN = 2.0V 70 60 50 0.1 1.0 10.0 100.0 1000.0 Output Current (mA) 1265.2006.05.1.1 1 AAT1265 Low Voltage 2MHz Step-Up DC/DC Converter in SC70JW Package Pin Descriptions Pin # Symbol 1 2 VCC EN 3 4 VIN LX 5 OUT 6, 7, 8 GND Function Bias supply voltage after start-up and feedback to the output voltage error amplifier. Enable pin. Logic high enables the IC. Logic low disables the IC and disconnects the load from the input. Shutdown current is <1µA. Battery input voltage. Supplies the IC at start-up. Inductor connection. Ties to the drains of the P-channel synchronous rectifier and the N-channel MOSFET switch. Boost converter output voltage; connects to the P-channel synchronous MOSFET source. Bypass with ceramic capacitor to GND. Signal and power ground. Connect output capacitor return. Pin Configuration SC70JW-8 (Top View) VCC EN VIN LX 2 1 8 2 7 3 6 4 5 GND GND GND OUT 1265.2006.05.1.1 AAT1265 Low Voltage 2MHz Step-Up DC/DC Converter in SC70JW Package Absolute Maximum Ratings Symbol VN TJ TLEAD Description VIN, OUT, VCC, EN, LX to GND Operating Junction Temperature Range Maximum Soldering Temperature (at leads, 10 sec) Value Units -0.3 to 6.0 -40 to 150 300 V °C °C Value Units 160 625 °C/W mW Thermal Characteristics1 Symbol θJA PD Description Maximum Thermal Resistance Maximum Power Dissipation 1. Mounted on an FR4 board. 1265.2006.05.1.1 3 AAT1265 Low Voltage 2MHz Step-Up DC/DC Converter in SC70JW Package Electrical Characteristics1 VIN = 1.2V, VOUT = 3.3V, TA = -40°C to +85°C, unless otherwise noted. Typical values are TA = 25°C. Symbol VIN VOUT IQ ISHDN RDS(ON)H RDS(ON)L ILIMIT IPFM η ΔVOUT/VOUT ΔVOUT(VOUT*ΔVIN) FOSC DTYMAX VTH(L-IN) VTH(H-IN) Description Conditions Minimum Start-Up Voltage Operating Input Voltage Range ILOAD = 1mA Output Voltage Accuracy Quiescent Supply Current (PFM Operation)2 Shutdown Current PMOS On-Resistance NMOS On-Resistance NMOS Current Limit PFM Light Load Current Threshold Efficiency Load Regulation Line Regulation Switching Frequency Maximum Duty Cycle Logic Input Low Threshold for EN Logic Input High Threshold for EN Min Typ 1.0 0.8 VIN = 0.8V to 2.5V, PWM Mode 3.2 No Load EN = 0V, VIN = 5.5V TA = 25°C TA = 25°C IOUT = 50mA, L = 2.2µH ILOAD = 0 to 100mA VIN = 0.8V to 2.5V TA = 25°C Max 1.8 VOUT V 3.3 3.4 V 40 70 µA 1.0 µA mΩ mΩ A mA % % %/V MHz % V V 750 400 1.0 20 82 1.5 0.2 2.0 90 2.2 0.4 1.0 Units 1. The AAT1265 is guaranteed to meet performance specifications over the -40°C to +85°C operating temperature range and is assured by design, characterization, and correlation with statistical process controls. 2. IQ = IQ_VOUT = IQ_VCC. 4 1265.2006.05.1.1 AAT1265 Low Voltage 2MHz Step-Up DC/DC Converter in SC70JW Package Typical Characteristics Single-Cell to 3.3V Efficiency Dual-Cell to 3.3V Efficiency 100 100 VIN = 3.0V 90 VIN = 1.5V Efficiency (%) Efficiency (%) 90 80 70 VIN = 1.2V 80 VIN = 2.4V 70 60 60 50 50 0.1 1 10 100 0.1 1000 1 Output Current (mA) 10 2.0 1.5 1.5 1.0 1.0 VOUT Error (%) VOUT Error (%) (VO = 3.3V) 2.0 0.5 0.0 VIN = 1.5V -1.0 -1.5 0.1 0.5 VIN = 3.0V 0.0 VIN = 2.4V -0.5 -1.0 -1.5 VIN = 1.2V -2.0 1000 Dual-Cell Load Regulation (VO = 3.3V) -0.5 100 Output Current (mA) Single-Cell Load Regulation VIN = 2.0V -2.0 1 10 0.1 100 1 10 100 1000 Output Current (mA) Output Current (mA) Minimum Start-Up Voltage vs. Load Current PFM Mode Output Current Threshold vs. Input Voltage 120 2.4 Output Current (mA) 2.2 Constant Current Load 2.0 Voltage (V) VIN = 2.0V 1.8 1.6 1.4 Resistive Load 1.2 1.0 100 Increasing Load 80 60 40 Decreasing Load 20 0 0.8 0 2 40 60 80 100 Current (mA) 1265.2006.05.1.1 120 140 160 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4 2.6 2.8 3.0 Input Voltage (V) 5 AAT1265 Low Voltage 2MHz Step-Up DC/DC Converter in SC70JW Package Typical Characteristics Switching Frequency vs. Temperature Input Current (µA) 200 160 120 80 40 0 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4 2.6 2.8 3.0 Switching Frequency Change (%) No Load Input Current vs. Input Voltage 0.5 0.0 -0.5 -1.0 -1.5 -2.0 -2.5 -40 -15 10 35 60 85 Temperature (°°C) Input Voltage (V) Load Transient Response Maximum Load Current Capacity for a 4% Drop in Output Voltage vs. Input Voltage (VIN = 1.2V; L = 2.2µH; CO = 4.7µF) (VOUT = 3.3V) 3.40 Output Current (A) 500 400 300 200 100 0 1.0 1.2 1.4 1.6 1.8 2.0 2.2 2.4 2.6 2.8 3.35 3.30 3.25 3.20 0.15 0.10 100mA 0.05 Output Voltage (V) Load Current (mA) 600 50mA 0.00 3.0 Time (50µs/div) Input Voltage (V) Output Voltage vs. Temperature Line Transient Response (VIN = 1.5V; IO = 10mA) (IO = 50mA; L = 2.2µH; CO = 4.7µF) 2.50 2.4V Output Voltage (V) 0.20 0.00 -0.20 -0.40 -0.60 -0.80 -40 -20 0 20 40 Temperature (°°C) 6 60 80 2.25 2.00 1.9V 3.34 1.75 1.50 3.32 3.30 Input Voltage (V) Output Voltage Error (%) 0.40 3.28 3.26 Time (50µs/div) 1265.2006.05.1.1 AAT1265 Low Voltage 2MHz Step-Up DC/DC Converter in SC70JW Package Soft-Start Inrush Current (VIN = 2.4V; IO = 100mA; VO = 3.3V) 1.75 4 3 Output Voltage 1.5 1 Enable 0 0.75 0.5 -1 -2 1 Input Current 0.25 -3 0 -4 -0.25 3 Output Voltage 1.5 1.25 2 1 1 Enable 0 -1 -3 0.75 0.5 -2 0.25 Input Current -4 Time (500µs/div) 0 -0.25 Time (500µs/div) Full Load Output Ripple Light Load Output Ripple (VIN = 1.2V; 100mA Load) (VIN = 1.2V; 10mA Load) VOUT (AC Coupled) (20mV/div) VOUT (AC Coupled) (20mV/div) IL (100mA/div) IL (200mA/div) VLX (2V/div) VLX (2V/div) Time (250ns/div) 1265.2006.05.1.1 1.75 4 Input Current (A) 1.25 2 Enable and Output Voltage (V) Soft-Start Inrush Current (VIN = 1.2V; IO = 40mA; VO = 3.3V) Input Current (A) Enable and Output Voltage (V) Typical Characteristics Time (1µs/div) 7 AAT1265 Low Voltage 2MHz Step-Up DC/DC Converter in SC70JW Package Functional Block Diagram VCC VIN Start-Up Inrush Control OUT Low Voltage Start-Up VREF Voltage Reference DH Mode Control 2MHz Oscillator Current Sense Comp. LX Logic DL Error Amp. GND Functional Description The AAT1265 synchronous step-up converter is targeted for single- or dual-cell alkaline, NiMH, and NiCd battery applications. It has a 1V typical startup voltage with operation after start-up to less than 0.8V. The high 2MHz switching frequency of the AAT1265 facilitates output filter component size reduction for improved power density and reduced overall footprint. It also provides greater bandwidth and improved transient response over other lower frequency step-up converters. The compensation and feedback is integrated with only three external components (CIN, COUT, L). Low RDS(ON) synchronous power switches provide high efficiency for heavy load conditions. Switching 8 EN GND frequency modulation and low quiescent current maintains this high efficiency for light load and sleep mode conditions. In addition to the improved efficiency, the synchronous boost has the added performance advantage of true load disconnect during shutdown (<1µA shutdown current), inrush current limit, and shortcircuit protection. PWM / PFM Control The AAT1265 is a fixed frequency PWM peak current mode control step-up converter. For light load conditions (10 to 20mA and below), the converter transitions to a variable frequency (PFM) mode to reduce the dominant switching losses. In addition to PFM operation, a zero current comparator blocks reverse current in the P-channel synchro1265.2006.05.1.1 AAT1265 Low Voltage 2MHz Step-Up DC/DC Converter in SC70JW Package nous MOSFET, forcing DCM operation at light load. These controls, along with very low quiescent current, help to maintain high efficiency over the complete load range without the compromise of increased output voltage ripple during light load conditions. Start-up and Inrush Current Limit The start-up sequence of the AAT1265 varies depending upon whether the input voltage is greater than or less than 2V. Above 1V, a start-up oscillator operating at 25% duty cycle controls the synchronous power stage and charges the output to 2V. For an input voltage greater than 2V, the output is charged at a constant current of 300mA until the output reaches a voltage level just below the input voltage. The step-up converter then takes control and continues to charge the output to the steady-state voltage. The step-up converter Nchannel switch current is limited to 1A and the typical start-up time is 2.5ms. Shutdown and Output Disconnect A typical synchronous step-up (boost) converter has a conduction path from the input to the output via the body diode of the P-channel MOSFET. The AAT1265 design disconnects this body diode from the output and eliminates this conduction path. This enables the AAT1265 to provide true load disconnect during shutdown and inrush current limit at turn-on. Short-Circuit Protection The P-channel synchronous MOSFET body diode disconnect feature also gives the AAT1265 the ability to provide output short-circuit current limit protection. 1265.2006.05.1.1 Applications Information Inductor Selection The AAT1265 is designed to operate with a 2.2µH inductor for all input/output voltage combinations. The inductor saturation current rating should be greater than the NMOS current limit specification listed in the Electrical Characteristics table. If necessary, the peak inductor current can exceed the saturation level by a small amount with no significant effect on performance. Table 1 provides a list of some suggested inductor manufacturers and their part numbers. Output and Input Capacitor Selection Surface mount X5R or X7R ceramic capacitors are suggested for both the output and the input. For the output capacitor (C1 in Figure 4) a 4.7µF, 10V, X5R ceramic capacitor is necessary for stability, transient response, and ripple performance. The same 0805 sized capacitor is used for the input (C2 of Figure 4). If desired, a smaller, 0603 sized, 4.7µF, 6.3V, X5R ceramic capacitor can be substituted for the input capacitor (C2). Suggested ceramic capacitor suppliers are listed in Table 1. PCB Layout Guidelines Figures 1, 2, and 3 display the evaluation board layout and suggested component placement. Due to the high switching speed of the AAT1265, it is important that the evaluation board layout be followed. Even the best switch-mode power supply design cannot overcome the problems that can be caused by a poor layout. For the AAT1265, it is necessary that C1 and C2 be placed as close as possible to the IC with a good low impedance path to the GND pins of the IC. It is also good practice to minimize the length of the trace from the OUT pin to the output inductor. This prevents switching noise from radiating into other high noise sensitive, high impedance circuits. 9 AAT1265 Low Voltage 2MHz Step-Up DC/DC Converter in SC70JW Package Figure 1: AAT1265 Evaluation Board Top Side. Figure 2: Component Placement. Figure 3: AAT1265 Evaluation Board Bottom Side. VIN U1 AAT1265 1 2 3 Enable L1 2.2µH C2 4.7µF 1 VCC GND 8 2 EN GND 7 3 VIN GND 6 4 LX OUT 5 VOUT C1 4.7µF U1 AAT1265 SC70JW-8 L1 SD3118-2R2 C1, C2 4.7µF 10V 0805 X5R Figure 4: AAT1265 Evaluation Board Schematic. 10 1265.2006.05.1.1 AAT1265 Low Voltage 2MHz Step-Up DC/DC Converter in SC70JW Package Manufacturer Murata www.murata.com TDK www.tdk.com Taiyo Yuden www.t-yuden.com Manufacturer Sumida www.sumida.com Cooper Electronics www.cooperet.com Value Part Output or Input Capacitor Input Capacitor Output or Input Capacitor Input Capacitor Output or Input Capacitor Input Capacitor 4.7µF 4.7µF 4.7µF Value Part 2.2µH 2.2µH Voltage Case Size 10V 6.3V 10V 6.3V 10V 6.3V 0805 0603 0805 0603 0805 0603 Part Number GRM21BR61A475KA73L GRM188R60J475KE19D C2012X5R1A475K C1608X5ROJ475K LMK212BJ475MG JMK107BJ475MA ISAT Voltage Case Size Part Number Inductor 1.50A 75mΩ 3.2 x 3.2 x 1.55 CDRH2D14-2R2 Inductor 1.62A 69mΩ 3.1 x 3.1 x 1.85 SD3118-2R2 Table 1: Suggested Component Selection. 1265.2006.05.1.1 11 AAT1265 Low Voltage 2MHz Step-Up DC/DC Converter in SC70JW Package Ordering Information Voltage Package Marking1 Part Number (Tape and Reel)2 3.3V SC70JW-8 RLXYY AAT1265IJS-3.3-T1 All AnalogicTech products are offered in Pb-free packaging. The term “Pb-free” means semiconductor products that are in compliance with current RoHS standards, including the requirement that lead not exceed 0.1% by weight in homogeneous materials. For more information, please visit our website at http://www.analogictech.com/pbfree. Package Information SC70JW-8 2.20 ± 0.20 1.75 ± 0.10 0.50 BSC 0.50 BSC 0.50 BSC 0.225 ± 0.075 2.00 ± 0.20 0.100 7° ± 3° 0.45 ± 0.10 4° ± 4° 0.05 ± 0.05 0.15 ± 0.05 1.10 MAX 0.85 ± 0.15 0.048REF 2.10 ± 0.30 All dimensions in millimeters. 1. XYY = assembly and date code. 2. Sample stock is generally held on part numbers listed in BOLD. 12 1265.2006.05.1.1 AAT1265 Low Voltage 2MHz Step-Up DC/DC Converter in SC70JW Package © Advanced Analogic Technologies, Inc. AnalogicTech cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in an AnalogicTech product. No circuit patent licenses, copyrights, mask work rights, or other intellectual property rights are implied. AnalogicTech reserves the right to make changes to their products or specifications or to discontinue any product or service without notice. Customers are advised to obtain the latest version of relevant information to verify, before placing orders, that information being relied on is current and complete. All products are sold subject to the terms and conditions of sale supplied at the time of order acknowledgement, including those pertaining to warranty, patent infringement, and limitation of liability. AnalogicTech warrants performance of its semiconductor products to the specifications applicable at the time of sale in accordance with AnalogicTech’s standard warranty. Testing and other quality control techniques are utilized to the extent AnalogicTech deems necessary to support this warranty. Specific testing of all parameters of each device is not necessarily performed. AnalogicTech and the AnalogicTech logo are trademarks of Advanced Analogic Technologies Incorporated. All other brand and product names appearing in this document are registered trademarks or trademarks of their respective holders. Advanced Analogic Technologies, Inc. 830 E. Arques Avenue, Sunnyvale, CA 94085 Phone (408) 737-4600 Fax (408) 737-4611 1265.2006.05.1.1 13