ACT6308 Rev PrB, 20-Feb-08 Preliminary Product Information―All Information Subject to Change Low Input High Efficiency Synchronous Step-Up DC/DC Converter FEATURES GENERAL DESCRIPTION • • • • • • The ACT6308 is a high efficiency synchronous step-up DC/DC converter that consumes just 17µA of quiescent supply current using only three external components. This device achieves a typical startup voltage of just 1V, making it ideal for applications operating from 1 or 2 alkaline cells. 1V Typical Startup Voltage Up to 89% Efficiency Fully Integrated Power Stage Fixed 3.3V/5V or Adjustable Output Voltage NanoStandbyTM Shutdown Mode This device incorporates an internal synchronous rectifier, and achieves excellent peak efficiency of up to 89% and features a proprietary control scheme that ensures high efficiency over a wide load current range. Tiny SOT23-5 Package − RoHS Compliant Package APPLICATIONS • • • • • • The ACT6308 features pin-selectable output voltages of 3.3V or 5V, or it can also be set externally to any voltage between 2V and 5V. The ACT6308 is available in a tiny SOT23-5 package. Hand-Held Devices One to Three Cell Battery Operated Devices PDAs Cellular Phones Digital Cameras GPS TYPICAL APPLICATION CIRCUIT Efficiency vs. Output Current OUT VOUT 1.00 3.3V 0.90 ACT6308 EN G FB C1 2.2µF C2 4.7µF Efficiency (%) ENABLE LX ACT6308-001 VIN L 2.2µH VIN = 2.4V 0.80 0.70 Pb-free VIN = 1.8V 0.60 0.50 VIN = 1.5V 0.1 1.0 VOUT = 3.3V FB = GND 10 100 1000 Output Current (mA) Innovative Products. Active Solutions. -1- www.active-semi.com Copyright © 2008 Active-Semi, Inc. ACT6308 Rev PrB, 20-Feb-08 ORDERING INFORMATION PART NUMBER TEMPERATURE RANGE ACT6308UC-T -40°C to 85°C PACKAGE PINS SOT23-5 PACKING METHOD TOP MARK TAPE & REEL HBCB 5 All Active-Semi components are RoHS Compliant and with Pb-free plating unless specified differently. The term “Pb-free” means semiconductor products that are in compliance with current RoHS (Restriction of Hazardous Substances) standards. PIN CONFIGURATION FB 1 G 2 EN 3 5 OUT 4 LX ACT6308 SOT23-5 PIN DESCRIPTION PIN NUMBER PIN NAME PIN DESCRIPTION 1 FB Output Voltage Selection and Feedback Input. Connect this pin to G for VOUT = 5V, to OUT for VOUT = 3.3V. Connect FB to a resistor divider to set the output voltage between 2V and 5V. See the Output Voltage Selection section for more information. 2 G Ground. 3 EN Shutdown Input. Drive EN to OUT or to a logic high for normal operation, drive EN to G or to a logic low to disable the regulator. 4 LX Inductor Connection. 5 OUT Output. ACT6308 regulates voltage at this pin. OUT also provides power to the IC. Innovative Products. Active Solutions. -2- www.active-semi.com Copyright © 2008 Active-Semi, Inc. ACT6308 Rev PrB, 20-Feb-08 ABSOLUTE MAXIMUM RATINGSc PARAMETER VALUE UNIT -0.3 to 6 V FB, LX to G -0.3 to VOUT + 0.3 V Continuous LX Current Internally Limited A Maximum Power Dissipation (derate 5mV/°C above TA = 50°C) 0.53 W Junction to Ambient Thermal Resistance (θJA) 190 °C/W Operating Junction Temperature -40 to 150 °C Storage Temperature -55 to 150 °C 300 °C OUT, EN to G Lead Temperature (Soldering, 10 sec) c: Do not exceed these limits to prevent damage to the device. Exposure to absolute maximum rating conditions for long periods may affect device reliability. ELECTRICAL CHARACTERISTICS (VIN = 1.5V, VOUT = 3.3V, TA = 25°C, unless otherwise specified.) PARAMETER SYMBOL Minimum Operating Input Voltage VIN Maximum Operating Input Voltage VIN Startup Voltage VIN Output Voltage VOUT Output Voltage Range TEST CONDITIONS MIN TYP MAX 0.6 ILOAD = 1mA V 5 V 1 1.18 V FB = OUT; 60mVPP Ripple 3.2 3.3 3.4 FB = G; 40mVPP Ripple 4.85 5 5.15 External Feedback Divider UNIT 2 V 5 V Quiescent Current at OUT IQ VFB = 1.3V 17 34 µA Shutdown Supply Current ISD EN = G 0.1 1 µA Startup to Normal Transition Threshold FB Feedback Voltage 1.85 VFB FB Input Current Power Switch Current Limit VOUT = 2V to 5V 1.15 FB = 1.3V ILIM 1.180 V 1.21 50 0.35 V nA 0.4 0.6 A Power Switch On Resistance RONN ILX = 100mA 0.19 0.4 Ω Synchronous Rectifier On Resistance RONP ILX = -100mA 0.21 0.4 Ω EN = G, VLX = 0 or 3.3V 0.1 1 µA LX Leakage Current Maximum Switch On-Time tONMAX 1.2 1.5 1.8 µs Minimum Switch Off-Time tOFFMIN 0.24 0.3 0.36 µs EN Logic Low Threshold VIL 0.4 V EN Logic High Threshold VIH 0.6 1 EN Input Current Innovative Products. Active Solutions. V -3- µA www.active-semi.com Copyright © 2008 Active-Semi, Inc. ACT6308 Rev PrB, 20-Feb-08 TYPICAL PERFORMANCE CHARACTERISTICS (Typical Application Circuit, L = 2.2µH, C1 = 2.2µF ceramic, C2 = 4.7µF ceramic, unless otherwise specified.) Efficiency vs. Output Current Efficiency vs. Output Current Efficiency (%) Efficiency (%) VIN = 3.7V 90 0.70 VIN = 1.2V 0.60 0.50 VIN = 2.4V 0.1 1.0 100 10 VIN = 2.4V 80 70 VIN = 1.8V 60 VOUT = 5V FB = GND VIN = 1.5V VOUT = 3.3V FB = GND 50 0.1 1000 1.0 10 100 1000 Output Current (mA) Output Current (mA) Startup Voltage vs. Constant Resistance Load Startup Voltage vs. Constant Current Load 1.50 Startup Voltage (V) 1.75 1.25 1.00 ACT6308-004 2.00 ACT6308-003 2.00 Startup Voltage (V) ACT6308-002 0.90 0.80 100 ACT6308-001 1.00 1.75 1.50 1.25 1.00 0.75 0.75 VOUT = 3.3V 0.50 0 20 40 60 80 100 0 Constant Current Load (mA) Innovative Products. Active Solutions. VOUT = 3.3V 0.50 200 20 40 60 80 100 200 Current Load at 3.3V (mA) -4- www.active-semi.com Copyright © 2008 Active-Semi, Inc. ACT6308 Rev PrB, 20-Feb-08 TYPICAL PERFORMANCE CHARACTERISTICS CONT’D (Typical Application Circuit, L = 2.2µH, C1 = 2.2µF ceramic, C2 = 4.7µF ceramic, unless otherwise specified.) Startup Voltage vs. Temperature Maximum On-Time (µS) 6.5 1.0 0.5 5.5 4.5 -40 -20 0 20 40 60 80 100 120 -40 0 20 40 60 80 100 120 Temperature (°C) Minimum Off-Time vs. Temperature Quiescent Supply Current vs. Temperature Quiescent Supply Current (µA) 1.3 1.2 1.1 1.0 -20 0 20 40 60 80 100 120 20 15 10 5 0 -40 Temperature (°C) Innovative Products. Active Solutions. 25 ACT6308-008 ACT6308-007 1.4 -40 -20 Temperature (°C) 1.5 Minimum Off-Time (µS) ACT6308-006 Startup Voltage (V) ACT6308-005 1.5 Maximum On-Time vs. Temperature -20 0 20 40 60 80 100 120 Temperature (°C) -5- www.active-semi.com Copyright © 2008 Active-Semi, Inc. ACT6308 Rev PrB, 20-Feb-08 TYPICAL PERFORMANCE CHARACTERISTICS CONT’D (Typical Application Circuit, L = 2.2µH, C1 = 2.2µF ceramic, C2 = 4.7µF ceramic, unless otherwise specified.) Light Load Operation for Low ESR COUT Light Load Operation for Low ESR COUT ACT6308-010 CH1 ACT6308-009 VVOUT = 3.3V 3.3V OUT = VIN = 1.8V ILOAD = 5mA VOUT = 5V VIN = 3.6V ILOAD = 5mA CH1 CH2 CH2 CH1: VOUT, 20.0mV/div CH2: ILX, 200mA/div TIME: 10.0µs/div CH1: VOUT, 20.0mV/div CH2: ILX, 200mA/div TIME: 20.0µs/div Medium Load Operation for Low ESR COUT Medium Load Operation for Low ESR COUT ACT6308-012 CH1 ACT6308-011 VOUT = 3.3V VIN = 1.8V ILOAD = 50mA VOUT = 5V VIN = 3.6V ILOAD = 50mA CH1 CH2 CH2 CH1: VOUT, 20.0mV/div CH2: ILX, 200mA/div TIME: 2.00µs/div CH1: VOUT, 20.0mV/div CH2: ILX, 200mA/div TIME: 2.00µs/div Heavy Load Operation for Low ESR COUT ACT6308-014 CH1 ACT6308-013 VOUT = 3.3V VIN = 1.8V ILOAD = 100mA Heavy Load Operation for Low ESR COUT VOUT = 5V VIN = 3.6V ILOAD = 110mA CH1 CH2 CH2 CH1: VOUT, 20.0mV/div CH2: ILX, 200mA/div TIME: 2.00µs/div Innovative Products. Active Solutions. CH1: VOUT, 20.0mV/div CH2: ILX, 200mA/div TIME: 2.00µs/div -6- www.active-semi.com Copyright © 2008 Active-Semi, Inc. ACT6308 Rev PrB, 20-Feb-08 FUNCTIONAL BLOCK DIAGRAM OUT EN REFERENCE LOW INPUT START UP VREF 0.3µs ONE-SHOT SET LATCH Q RESET 1.5µs ONE-SHOT DRIVER LX – ERROR COMPARATOR – + FB + – FEEDBACK SELECT + VREF CURRENT LIMIT COMPARATOR G FUNCTIONAL DESCRIPTION Light Load Operation As seen in the Functional Block Diagram, the ACT6308 comprises a reference, low input startup circuitry, feedback select, error comparator, control logic and timers, internal power MOSFETs and current comparators. Under light load conditions, the IC automatically enters a power-saving mode by extending the OFF time. This reduces switching losses and allows the ACT6308 to maintain high efficiency across a very wide load range. Main Control Loop Low Voltage Startup The ACT6308 control architecture utilizes a series of one-shot and current sense circuits to regulate the output voltage with a very low quiescent supply current of just 17µA. An ON cycle begins when FB falls below the ACT6308’s internal reference voltage. During an ON cycle, the N-channel power switch is turned on to connect the LX node to ground, transferring energy from input supply to the inductor. The ON cycle persists or the 0.4A current limit is reached. When either of these conditions occurs, the N-channel power switch turns off and the OFF cycle begins. During the OFF cycle, the energy stored in the inductor is released into the output capacitor and load through the synchronous rectifier. Once the 0.3µs minimum OFF time expires, another ON cycle begins when the FB voltage drops below the reference voltage. The ACT6308 uses proprietary start-up circuitry that allows it to achieve very low voltage startup down to 1V. The ACT6308 remains in low voltage startup mode until VOUT exceeds 1.85V. The ACT6308 cannot support its full rated load current when operating in low-voltage startup mode. Care should be taken to minimize load current during startup. Innovative Products. Active Solutions. Shutdown In shutdown mode, all internal circuits including the power switch and the synchronous rectifier are disabled, reducing quiescent supply current to less than 1µA. Note that in shutdown mode, a DC path from the input supply to the output still exists due to the body diode of the synchronous rectifier. -7- www.active-semi.com Copyright © 2008 Active-Semi, Inc. ACT6308 Rev PrB, 20-Feb-08 APPLICATIONS INFORMATION output current. Choose inductors with low series resistance to obtain the highest efficiency. Output Voltage Selection The ACT6308 provides fixed output voltage options of 3.3V or 5V, or the output voltage may be adjusted over a 2V to 5V range by connecting an external resistive voltage divider. When Output Voltage is set by external resistive voltage divider, add a 47pF to 150pFcapacitor as feed forward capacitor (CFF) as shown in Figure 1. Table 1: VOUT = 3.3V FB = G VOUT = 5V FB connect to resistive divider To reduce noise and increase efficiency, high current traces should be wide and direct, and an extended ground plane should be used. Switching current paths should be laid out as tightly as possible, with the inductor and input and output capacitors located close to the IC in order to reduce electromagnetic radiation. If an external resistor divider is used, place the resistors very close to the FB and G pins, and keep them away from the high switching current paths. Output Voltage Programming FB = OUT Board Layout VOUT = 1.18V (1 + RFB1/RFB2) Figure 1: Output Voltage Setting VOUT OUT ACT6308 CFF RFB1 FB RFB2 Output Capacitor Selection A minimum value of output capacitance is required to maintain loop stability and normal operation of the IC. The output capacitor value should be in the range of 2.2µF to 100µF. To obtain small output ripple, use a large capacitor with low ESR. Ceramic capacitors should be used for highest performance. If a tantalum capacitor is used, choose only low ESR types and a smaller low ESR capacitor of about 1µF can be connected in parallel to filter high frequency noise. Inductor Selection For most applications, the inductor value should be in the range of 1.5µH to 22µH. Smaller inductors provide faster load transient response and have a smaller physical size, but they also result in higher ripple current and reduce the maximum available Innovative Products. Active Solutions. -8- www.active-semi.com Copyright © 2008 Active-Semi, Inc. ACT6308 Rev PrB, 20-Feb-08 PACKAGE OUTLINE SOT23-5 PACKAGE OUTLINE AND DIMENSIONS D θ b SYMBOL L E E1 L1 0.2 c e e1 MAX MIN MAX A 1.050 1.250 0.041 0.049 A1 0.000 0.100 0.000 0.004 A2 1.050 1.150 0.041 0.045 b 0.300 0.400 0.012 0.016 c 0.100 0.200 0.004 0.008 D 2.820 3.020 0.111 0.119 E 1.500 1.700 0.059 0.067 E1 2.650 2.950 0.104 0.116 e1 A A2 DIMENSION IN INCHES MIN e A1 DIMENSION IN MILLIMETERS L 0.950 TYP 1.800 2.000 0.700 REF 0.037 TYP 0.071 0.079 0.028 REF L1 0.300 0.600 0.012 0.024 θ 0° 8° 0° 8° Active-Semi, Inc. reserves the right to modify the circuitry or specifications without notice. Users should evaluate each product to make sure that it is suitable for their applications. Active-Semi products are not intended or authorized for use as critical components in life-support devices or systems. Active-Semi, Inc. does not assume any liability arising out of the use of any product or circuit described in this datasheet, nor does it convey any patent license. Active-Semi and its logo are trademarks of Active-Semi, Inc. For more information on this and other products, contact firstname.lastname@example.org or visit http://www.active-semi.com. For other inquiries, please send to: 1270 Oakmead Parkway, Suite 310, Sunnyvale, California 94085-4044, USA Innovative Products. Active Solutions. -9- www.active-semi.com Copyright © 2008 Active-Semi, Inc.