AS2300 0.85V Startup, 1.2MHz Synchronous Step-Up Converter DESCRIPTION FEATURES The AS2300 is a 1.2MHz constant frequency, current High Efficiency: Up to 92% mode PWM step-up converter. It can supply 3.3V 1.2MHz Constant Switching Frequency output voltage at 100mA from a single AA Cell. 3.3V@100mA Output from 1 Single AA Cell; The device integrates a main switch and a 3.3V@400mA Output from 2 AA cells synchronous rectifier for high efficiency without an Low Start-up Voltage: 0.85V external Schottky diode. A switching frequency of Integrated main switch and sync. rectifier. 1.2MHz allows the use of tiny, low profile inductors 2.5V to 5V Output Voltage Range and ceramic capacitors. The current mode PWM Automatic Pulse Skipping Mode Operation operation provides Tiny External Components excellent line and load transient characteristics. The <1 µA Shutdown Current AS2300 features Pulse Skipping Mode operation at Anti-ringing Control Reduces EMI light loads to avoid unacceptable ripple voltage. Space Saving 6-Pin Thin SOT23 Package with internal compensation The AS2300 is offered in a low profile (1 mm) small 6-Pin SOT23 Package. APPLICATIONS ORDER INFORMATION Cellular and Smart Phones Part Number Output Voltage Microprocessors and DSP Core Supplies AS2300EHT-adj Adjustable Wireless and DSL Modems MP3 Player Digital Still and Video Cameras Portable Instruments EVALUATION BOARD Board Number EV2300EH-00A Dimensions mm 50 mm X x 50 mm Y x 1.4 Z “ANI” and “ANISEM” is Trademarks of ANISEM Semiconductor, Inc. TYPICAL APPLICATION 100 EFFICIENCY vs LOAD CURRENT VIN=2.4V 90 VIN = 1.5V EFFICIENCY (%) 80 70 60 50 40 30 VOUT = 3.3V L = 4.7uH 20 10 0 10 100 1000 LOAD CURRENT (mA) AS2300 Rev.1.6 08/25/2009 www.anisem.com ANISEM Proprietary Information. Unauthorized Photocopy and Duplication Prohibited. © 2008 ANISEM All Rights Reserved. 1 AS2300 – 1.2MHz SYNCHRONOUS STEP-UP CONVETTER ABSOLUTE MAXIMUM RATINGS(1) PACKAGE REFERENCE MARKING VIN to GND… ………………………..….. -0.3V to 6V VSW to GND …………………...…. -0.3V to VIN +0.3V VEN, VFB Voltage ………………….…. -0.3V to +6.0V Junction Temperature ……………….……….. 125°C Lead Temperature (Soldering, 10sec.) …..…+300°C Storage Temperature Range …….... -65℃ to 150°C Part Number* Package Temperature AS2300EHT-adj TSOT23-6L -40°C to 85°C Recommended Operating Conditions(2) Supply Voltage VIN……………….………1.0V to 5.0V Output Voltage VOUT………….…….……2.5V to 5.0V Operating Temperature …………….… -40°C to 85°C ƟJA ƟJC Thermal Resistance (3) TSOT23-6L……………….…220…….110…...°C/W *For output voltage adjustable, add suffix –adj (eg. AS2300EHT-adj) For fixed 3.3V output voltage, add suffix –3.3 (eg. AS2300EHT-3.3) NOTEs: 1) Exceeding these ratings may damage the device. 2) The device is not guaranteed to function outside of its operating conditions. 3) Measure on approximately 1’’square of 1 oz copper. ELECTRICAL CHARACTERISTICS VIN =1.2V, VOUT =3.3V, TA = 25°C Unless otherwise noted. PARAMETER CONDITIONS Minimum Start-Up Voltage Minimum Operating Voltage MIN ILOAD = 1mA VEN = VIN (Note 4) Output Voltage Range TYP MAX UNITS 0.85 1 V 0.5 0.65 V 5 V 1.268 V 2.5 Feedback Voltage 1.192 (Note 3) 1.230 Feedback Input Current VFB = 1.25V Quiescent Current(ISD) VSHDN= 0V,No Include Switch Leakage 0.01 1 µA Quiescent Current(Active) Measured on VOUT 300 500 µA NMOS Switch Leakage VSW = 5V 0.1 5 µA PMOS Switch Leakage VSW = 0V 0.1 5 µA NMOS Switch ON VOUT = 3.3V 0.40 Ω Resistance VOUT = 5V 0.35 Ω PMOS Switch ON VOUT = 3.3V 0.70 Ω Resistance VOUT = 5V 0.60 Ω 850 mA 40 ns 80 85 % Switching Frequency 0.9 1.2 1.5 MHz EN Input Threshold 0.35 0.60 0.80 V 0.01 1 µA www.anisem.com ANISEM Proprietary Information. Unauthorized Photocopy and Duplication Prohibited. © 2008 ANISEM All Rights Reserved. 2 NMOS Current Limit Current Limit Delay 600 Note 3 Max Duty Cycle EN Input Current 1 VFB = 1.15V VEN = 5.5V nA Note 3: Specification is guaranteed by design and not 100% tested in production. Note 4: Minimum VIN operation after start-up is only limited by the battery’s ability to provide the necessary power as it enters a deeply discharged state.. AS2300 Rev.1.6 08/25/2009 AS2300 – 1.2MHz SYNCHRONOUS STEP-UP CONVETTER TYPICAL PERFORMANCE CHARACTERISTICS Vin=1.5V, Vout=3.3V,L=4.7uH, Cin=4.7uF, Cout=4.7uF; TA = +25°C; unless otherwise noted. QUIESCENT CURRENT vs SUPPLY VOLTAGE ENABLE VOLTAGE vs SUPPLY VOLTAGE 500 400 300 1.40 OSCILLATOR FREQUENCY (MHz) 1.00 ENABLE VOLTAGE (V) 0.80 0.60 0.40 200 0.20 100 ILOAD=50mA 0 0.00 2 2.5 3 3.5 1.20 1.15 1.10 ILOAD=150mA 2.5 3 3.5 1 3.40 VIN = 1.8V EFFICIENCY (%) 70 60 50 40 30 3.35 60 50 40 30 VOUT = 3.3V L = 4.7uH 20 VOUT = 5.0V L = 4.7uH 20 10 10 0 1000 LOAD CURRENT (mA) 3.30 3.25 3.20 3.15 VIN=2.4V 3.10 3.05 0 100 5 3.45 80 70 4 3.50 VIN=3.6V 90 VIN = 1.5V 3 OUTPUT VOLTAGE vs LOAD CURRENT 100 VIN=2.4V 90 2 SUPPLY VOLTAGE (V) EFFICIENCY vs LOAD CURRENT 100 EFFICIENCY (%) 1.25 SUPPLY VOLTAGE (V) EFFICIENCY vs LOAD CURRENT 10 1.30 1.00 2 SUPPLY VOLTAGE (V) 80 1.35 1.05 OUTPUT VOLTAGE(V) QUIESCENT CURRENT (uA) 600 OSCILLATOR FREQUENCY vs SUPPLY VOLTAGE 3.00 10 100 LOAD CURRENT (mA) 1000 0 100 200 300 400 500 LOAD CURRENT (mA) OUTPUT VOLTAGE vs SUPPLY VOLTAGE 5.50 5.40 5.30 OUTPUT VOLTAGE(V) 5.20 5.10 5.00 4.90 4.80 4.70 ILOAD=150mA 4.60 4.50 0 1 2 3 4 5 SUPPLY VOLTAGE (V) AS2300 Rev.1.6 08/25/2009 www.anisem.com ANISEM Proprietary Information. Unauthorized Photocopy and Duplication Prohibited. © 2008 ANISEM All Rights Reserved. 3 AS2300 – 1.2MHz SYNCHRONOUS STEP-UP CONVETTER PIN FUNCTIONS PIN NUMBER PIN NAME FUNCTION Switch Pin. Connect inductor between SW and VIN. Optional Schottky diode is 1 connected between SW and VOUT. Keep these PCB trace lengths as short and wide as SW possible to reduce EMI and voltage overshoot. If the inductor current falls to zero, or EN is low, an internal antiringing switch is connected from SW to VIN to minimize EMI. 2 GND 3 FB Ground . Feedback Input to the Error Amplifier. Connect resistor divider tap to this pin. The output voltage can be adjusted from 2.5V to 5V by: VOUT = 1.23V • [1 + (R1/R2)] Logic Controlled Shutdown Input. EN = High: Normal free running operation, 1.2MHz 4 EN typical operating frequency. EN = Low: Shutdown, quiescent current <1uATypically, EN should be connected to VIN through a 1M pull-up resistor. Output Voltage Sense Input and Drain of the Internal Synchronous Rectifier 5 VOUT MOSFET. Bias is derived from VOUT. PCB trace length from VOUT to the output filter capacitor(s) should be as short and wide as possible. VOUT is held at VIN – 0.6V in shutdown due to the body diode of the internal PMOS. Battery Input Voltage. The device gets its start-up bias from VIN. Once VOUT 6 VIN exceeds VIN, bias comes from VOUT. Thus, once started, operation is completely independent from VIN. Operation is only limited by the output power level and the battery’s internal series resistance. FUNCTION BLOCK DIAGRAM AS2300 Rev.1.6 08/25/2009 www.anisem.com ANISEM Proprietary Information. Unauthorized Photocopy and Duplication Prohibited. © 2008 ANISEM All Rights Reserved. 4 AS2300 – 1.2MHz SYNCHRONOUS STEP-UP CONVETTER OPERATION The AS2300 is a synchronous step-up DC-DC the main switch is turned off and the synchronous converter. It utilizes internal MOSFETs to achieve switch(PMOS) is turn on. This control topology high efficiency over the full load current range. It features cycle by cycle current limiting which can operates at a fixed switching frequency of 1.2MHz, prevent the main switch from overstress and and uses the slope compensated current mode prevent external inductor from saturation. architecture. The device can operate with input voltage even below 1 V and the typical start-up PULSE SKIPPING MODE voltage is 0.85V. At very light load, the AS2300 automatically switches into Pulse Skipping Mode to improve LOW VOLTAGE START-UP efficiency. During this mode, the PWM control will The AS2300 can start up at supply voltage down to skip some pulses to maintain regulation. If the load 0.85V. During start-up, the internal low voltage increases and the output voltage drops, the device start-up circuitry controls the NMOS switch to will automatically switch back to normal PWM mode maximum peak inductor current. The device leaves and maintain regulation. the start-up mode once the VOUT exceeds 2.3V. A Comparator (VOUT GOOD Comp) monitors the output ANTIRINGING CONTROL voltage and allows the chip into normal operation An antiringing circuitry is included to remove the once the VOUT exceeds 2.3V. The device is biased by high frequency ringing that appears on the SW pin VIN during start-up while biased by VOUT once VOUT when the inductor current goes to zero. In this case, exceeds VIN then the operation will be independent a ringing on the SW pin is induced due to remaining of VIN energy stored in parasitic components of switch and inductor. The antiringing circuitry clamps the SYNCHRONOUS RECTIFICATION voltage internally to battery voltage and therefore The AS2300 integrates a synchronous rectifier to dampens this ringing. improve efficiency as well as to eliminate the external Schottky diode. The synchronous rectifier is DEVICE SHUTDOWN used to reduce the conduction loss contributed by When EN is set logic high, the AS2300 is put into the The operation. If EN is set logic low, the device is put synchronous rectifier is realized by a P-ch MOSFET into shutdown mode and consumes lower than 1 µA with gate control circuitry that incorporates relatively current. After start-up timing, the internal circuitry is complicated timing concerns. supplied by VOUT, however, if shutdown mode is forward voltage of Schottky diode. enabled, the internal circuitry will be supplied by CURRENT MODE PWM CONTROL battery again The AS2300 is based on a slope compensated current mode control topology. It operates at a fixed frequency of 1.2MHz. At the beginning of each clock cycle, the main switch (NMOS) is turned on and the inductor current starts to ramp. After the maximum duty cycle or the sense current signal equals to the error amplifier (EA) output. AS2300 Rev.1.6 08/25/2009 www.anisem.com ANISEM Proprietary Information. Unauthorized Photocopy and Duplication Prohibited. © 2008 ANISEM All Rights Reserved. 5 AS2300 – 1.2MHz SYNCHRONOUS STEP-UP CONVETTER APPLICATION INFORMATION AS2300: SETTING THE OUTPUT VOLTAGE An external resistor divider is used to set the output PART voltage. The output voltage of the switching NUMBER L MAX RATED SIZE DCR D.C. WxLxH (µH) (mΩ) Current(A) (mm) regulator (VOUT) is determined by the following Sumida 4.7 108.7 1.15 equation: CR43 10 182 1.04 4.7 72 1.32 Sumida 5.6 101 1.17 CDRH4D28 6.8 109 1.12 10 128 1.00 4.7 45 1.87 6.8 68 1.51 10 90 1.33 R1 ⎞ ⎛ VOUT = 1.23V × ⎜1 + ⎟ ⎝ R2 ⎠ Table 1 list the resistor selection for output voltage setting. VOUT R1(Ω) R2(Ω) 3.3V 1.02M 604K 5.0V 1.02M 332K Table 1.Resistor selection for output voltage setting Tokoy D53LC 4.3x4.8x3.5 5.0x5.0x3.0 5.0x5.0x3.0 OUTPUT CAPACITOR SELECTION The output capacitor is required to keep the output INDUCTOR SELECTION voltage ripple small and to ensure regulation loop The high switching frequency of 1.2MHz allows for stability. A 2.2µF to 10µF output capacitor is small surface mount inductors. For most designs, sufficient for most applications. If output capacitor is the AS2300 operates with inductors of 4.7µH to larger than 10µF, a phase lead capacitor must be 10µH.The equation below can help to select the included to maintain enough phase margin. The inductor, the maximum output current can be get by output capacitor must have low impedance at the this equation; where η is the efficiency, IPEAK is the switching frequency. Ceramic capacitors with X5R or peak current limit, f is the switching frequency, L is X7R dielectrics are recommended due to their low the inductance value and D is the duty cycle. ESR and high ripple current ratings. ⎛ V ×D ⎞ I OUT = η × ⎜ Ipeak − IN ⎟ × (1 − D ) 2× f × L ⎠ ⎝ Larger inductors mean less inductor current ripple and usually less output voltage ripple. Larger inductors also mean more load power can be delivered. But large inductors are also with large profile and costly. The inductor ripple current is typically set for 20% to 40% of the maximum inductor current. When selecting an inductor, the DC current rating must be high enough to avoid saturation at peak current. For optimum load transient and efficiency, the low DCR should be INPUT CAPACITOR SELECTION The input capacitor reduces the surge current drawn from the input and switching noise from the device. A minimum 4.7µF input capacitor is needed for most applications. The input capacitor impedance at the switching frequency should be less than input source impedance to prevent high frequency switching current passing to the input. A low ESR input capacitor sized for maximum RMS current must be used. Ceramic capacitors with X5R or X7R dielectrics are highly recommended because of their low ESR and small temperature coefficients. selected. Table 2 lists some typical surface mount inductors that meet target applications for the AS2300 Rev.1.6 08/25/2009 www.anisem.com ANISEM Proprietary Information. Unauthorized Photocopy and Duplication Prohibited. © 2008 ANISEM All Rights Reserved. 6 AS2300 – 1.2MHz SYNCHRONOUS STEP-UP CONVETTER OUTPUT DIODE SELECTION An Shottky diode should be included when the conduction path exists from battery to output through output voltage is above 4.5V. The Schottky diode is the backgate of the P-ch MOSFET during shutdown. optional for the output voltage not more than 4.5V, A special application circuitry is provided to but can improve efficiency by about 2% to 3%. disconnect the load from the battery during shutdown as below. LOAD DISCONNECT IN SHUTDOWN In conventional synchronous step-up converter, a D1 MBR0520 4.7uH INPUT 0.85V Startup OFF ON 6 VIN VOUT SI2305 5 1.02M 1% AS2300 4.7uF 4 1 SW FB EN 3 510K OUTPUT 3.3V/100mA 4.7uF 604K 1% GND 2 510K 2N3904 SINGLE LITHIUM CELL to 5V APPLICATION AS2300 Rev.1.6 08/25/2009 www.anisem.com ANISEM Proprietary Information. Unauthorized Photocopy and Duplication Prohibited. © 2008 ANISEM All Rights Reserved. 7 AS2300 – 1.2MHz SYNCHRONOUS STEP-UP CONVETTER PACKAGE DESCRIPTION Package 6-Lead Plastic TSOT23-6L AS2300 Rev.1.6 08/25/2009 www.anisem.com ANISEM Proprietary Information. Unauthorized Photocopy and Duplication Prohibited. © 2008 ANISEM All Rights Reserved. 8 AS2300 – 1.2MHz SYNCHRONOUS STEP-UP CONVETTER © ANISEM Semiconductor Co., Ltd ANISEM assume responsibility for use of any circuitry other than circuitry entirely embodied in an ANISEM product. No circuit patent licenses, copyrights, mask work rights, or other intellectual property rights are implied. ANISEM 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. ANISEM warrants performance of its semiconductor products to the specifications applicable at the time of sale in accordance with ANISEM’s standard warranty. Testing and other quality control techniques are utilized to the extent ANISEM deems necessary to support this warranty. Specific testing of all parameters of each device is not necessarily performed. AS2300 Rev.1.6 08/25/2009 www.anisem.com ANISEM Proprietary Information. Unauthorized Photocopy and Duplication Prohibited. © 2008 ANISEM All Rights Reserved. 9 EV2300-1.0 1.2MHz, Sync. Boost Converter FEATURES GENERAL DESCRIPTION High Efficiency: Up to 92% The AS2300 is a 1.2MHz constant frequency, 1.2MHz Constant Switching Frequency current mode PWM step-up converter. It can supply 3.3V@100mA Output from 1 Single AA Cell; 3.3V output voltage at 100mA from a single AA Cell. 3.3V@400mA Output from 2 AA cells Low Start-up Voltage: 0.85V The device integrates a main switch and a Integrated main switch and sync. rectifier. synchronous rectifier for high efficiency without an 2.5V to 5V Output Voltage Range external Schottky diode. A switching frequency of Automatic Pulse Skipping Mode Operation 1.2MHz allows the use of tiny, low profile inductors Tiny External Components and ceramic capacitors. The current mode PWM <1 µA Shutdown Current operation with internal compensation provides Anti-ringing Control Reduces EMI excellent line and load transient characteristics. The Space Saving 6-Pin Thin SOT23 Package AS2300 features Pulse Skipping Mode operation at APPLICATIONS light loads to avoid unacceptable ripple voltage. Cellular and Smart Phones The AS2300 is offered in a low profile (1 mm) small Microprocessors and DSP Core Supplies 6-Pin SOT23 Package. Wireless and DSL Modems MP3 Player Digital Still and Video Cameras Portable Instruments EV2300-1.0 EVALUATION BOARD Figure1. High Performance Step-Up Converter EV2300 Rev.1.0 6/25/2008 www.anisem.com ANISEM Proprietary Information. Unauthorized Photocopy and Duplication Prohibited. © 2008 ANISEM All Rights Reserved. 1