Advanced Power Electronics Corp. APE1502 1.5MHz, 1A SYNCHRONOUS STEP-DOWN CONVERTER FEATURES DESCRIPTION APE1502 is a high efficiency monolithic synchronous buck regulator using a constant frequency, current mode architecture. The device is available in an adjustable version. Supply current with no load is 350uA and drops to <1uA in shutdown. The 2.5V to 6.5V input voltage range makes APE1502 ideally suited for single Li-Ion, two to four AA battery-powered applications. 100% duty cycle provides low dropout operation, extending battery life in portable systems. PWM pulse skipping mode operation provides very low output ripple voltage for noise sensitive applications. Switching frequency is internally set at 1.5MHz, allowing the use of small surface mount inductors and capacitors. The internal synchronous switch increases efficiency and decreases need of an external Schottky diode. Low output voltages are easily supported with the 0.6V feedback reference voltage. APE1502 is available in small SOT-23-5L and SOT-89-5L packages. 2.5V to 6.5V Input Voltage Range Quiescent Current: 350uA (input < 4.2V) 1.5MHz Constant Frequency Operation 1A Output Current at VIN=3.6V & VOUT=1.8V High Efficiency: Up to 96% No Schottky Diode Required 100% Duty Cycle in Dropout 0.6V Reference Allows Low Output Voltages Current Mode Operation for Excellent Line and Load Transient Response Current Limit, Enable Function Short Circuit Protect (SCP) < 1µA Shutdown Current SOT-23-5L and SOT-89-5L Pb-Free packages TYPICAL APPLICATION VIN=2.5 to 6V U1 VIN SW EN C1 4.7u GND VOUT=1.8V L1 FB 2.2uH R1 600K C3 15p C2 10u APE1502 R2 300K VOUT = 0.6 * (1+R1/R2) R2=100K~330K ORDERING INFORMATION APE1502X Package Type G : SOT-89-5L Y5 : SOT-23-5L Data and specifications subject to change without notice 1 201005054 Advanced Power Electronics Corp. APE1502 ABSOLUTE MAXIMUM RATINGS PVIN, SVIN PIN Voltage (VIN) ……………………… VSS - 0.3V to VSS + 7V Feedback Pin Voltage (VFB) ………………………… VSS - 0.3V to VCC + 0.3V EN Pin Voltage (VEN) ………………………………… VSS - 0.3V to VCC + 0.3V Switch Pin Voltage (VSW ) …………………………… VSS - 0.3V to VCC + 0.3V Peak SW Sink & Source Current (IPSW ) …………… 1.4A Power Dissipation (PD) ……………………………… ( TJ-TA ) / Rthja mW Storage Temperature Range (TST) ………………… -40 to +150°C Operating Temperature Range (TOP) ……………… -40 to +85°C Junction Temperature (TJ) …………………………… +125°C Note1 : Rthja is measured with the PCB copper area of approximately 1 in2(Multi-layer). that need connect to VSS pin of the APE1502. PACKAGE INFORMATION FB EN 5 4 FB VIN 5 4 (Top View) SOT-23-5L (Top View) SOT-89-5L 1 2 3 VIN GND SW 1 EN 2 3 GND SW Rthja = 50 C/W Rthja = 250oC/W Rthjc = 15oC/W Rthjc = 110oC/W o ELECTRICAL SPECIFICATIONS (Note2) (VIN = VEN=3.6V, TA =25℃, unless otherwise specified) Parameter Input Voltage Range MIN TYP MAX UNITS 2.5 0.588 0.6 6 0.612 V TA = +25°C TA= 0°C < TA < 85°C 0.5865 0.6 0.6135 TA= -40°C < TA < 85°C 0.582 0.6 0.618 SYM VIN VFB Feedback Voltage TEST CONDITION V Feedback Bias Current IFB VFB=0.65V - - ±30 nA Input DC Supply Current ICC VFB=0V - 350 450 uA Shutdown Supply Current ISD VEN =0V - 0.1 1 uA Switching Current Limit ILIMIT Line Regulation △VOUT/VOUT VIN = 2.5V~5.5V Load Regulation △VOUT/VOUT IOUT = 0.01 to 1A - % 1.8 MHz ISW = 300mA - 0.4 0.45 Ω ISW = -300mA Ω RDSON RDS(ON) of N-CH MOSFET RDSON EN Pin Input Current Efficiency %/V 0.5 RDS(ON) of P-CH MOSFET Threshold A 0.4 1.5 SW pin Input - 0.04 - FOSC Logic 1.4 1.2 Oscillation Frequency EN Pin Voltage 1.2 - 0.35 0.4 VENL - - 0.6 VENH 1.2 - - V - ±0.1 ±1 uA - 92 - % IEN EFFI VIN=5V, VOUT=3.3V,IOUT=0.5A Note2: 100% production test at +25°C. Specifications over the temperature range are guaranteed by design and characterization. 2 Advanced Power Electronics Corp. APE1502 PIN DESCRIPTIONS PIN SYMBOL VIN PIN DESCRIPTION Power Supply Input Pin Enable Pin. EN H : Normal Operation L : Shutdown SW GND FB Switch output pin. Connect external inductor here. Minimize trace area at this pin to reduce EMI. Ground Pin Output Feedback Pin BLOCK DIAGRAM FUNCTION DESCRIPTION Operation APE1502 is a monolithic switching mode step-down DC-DC converter. It utilizes internal MOSFETs to achieve high efficiency and can generate very low output voltage by using internal reference at 0.6V. It operates at a fixed switching frequency, and uses the slope compensated current mode architecture. This step-down DC-DC Converter supplies 1000mA output current at Vout=1.8V with input voltage range from 2.5V to 6V. 3 Advanced Power Electronics Corp. APE1502 Current Mode PWM Control Slope compensated current mode PWM control provides stable switching and cycle-by-cycle current limit for excellent load and line responses and protection of the internal main switch (P-Ch MOSFET) and synchronous rectifier (N-CH MOSFET). During normal operation, the internal P-Ch MOSFET is turned on for a certain time to ramp the inductor current at each rising edge of the internal oscillator, and switched off when the peak inductor current is above the error voltage. The current comparator, ICOMP, limits the peak inductor current. When the main switch is off, the synchronous rectifier will be turned on immediately and stay on until either the inductor current starts to reverse, as indicated by the current reversal comparator, IZERO, or the beginning of the next clock cycle. The OVDET comparator controls output transient overshoots by turning the main switch off and keeping it off until the fault is no longer present. Idle Mode Operation At very light loads, APE1502 automatically enters pulse skipping Mode. In the pulse skipping Mode, the inductor current may reach zero or reverse on each pulse. The PWM control loop will automatically skip pulses to maintain output regulation. The bottom MOSFET is turned off by the current reversal comparator, IZERO, and the switch voltage will ring. This is discontinuous mode operation, and is normal behavior for the switching regulator. Maximum Load Current APE1502 will operate with input supply voltage as low as 2.5V, however, the maximum load current decreases at lower input due to large IR drop on the main switch and synchronous rectifier. The slope compensation signal reduces the peak inductor current as a function of the duty cycle to prevent sub-harmonic oscillations at duty cycles greater than 50%. Conversely the current limit increases as the duty cycle decreases. APPLICATION INFORMATION Setting the Output Voltage Application circuit item shows the basic application circuit with APE1502 adjustable output version. The external resistor sets the output voltage according to the following equation: V OUT ⎛ R1 ⎞ = 0.6V ×⎜1+ ⎟ ⎝ R2 ⎠ Table 1 Resistor select for output voltage setting VOUT R2 R1 1.2V 300K 300K 1.5V 300K 450K 1.8V 300K 600K 2.5V 300K 950K 4 Advanced Power Electronics Corp. APE1502 Inductor Selection For most designs, the APE1502 operates with inductors of 1µH to 4.7µH. Low inductance values are physically smaller but require faster switching, which results in some efficiency loss. The inductor value can be derived from the following equation: L = V OUT V IN × (V IN − V OUT ) × ∆I L × f OSC Where is inductor Ripple Current. Large value inductors lower ripple current and small value inductors result in high ripple currents. Choose inductor ripple current approximately 35% of the maximum load current 1000mA, ∆IL=350mA. Table 2 Inductor select for output voltage setting (VCC=3.6V) 1.2V 1.5V 1.8V 2.5V VOUT Inductor 2.7uH 2.7uH 2.7uH 2.2uH Part Number WE-TPC 7440430027 7440430027 7440430027 7440430022 Note: Part type L (www.we-online.com) For output voltages above 2.0V, when light-load efficiency is important, the minimum recommended inductor is 2.2µH. For optimum voltage-positioning load transients, choose an inductor with DC series resistance in the 50mΩ to 150mΩ range. For higher efficiency at heavy loads (above 200mA), or minimal load regulation (but some transient overshoot), the resistance should be kept below 100mΩ. The DC current rating of the inductor should be at least equal to the maximum load current plus half the ripple current to prevent core saturation (1000mA+170mA). Input Capacitor Selection The input capacitor reduces the surge current drawn from the input and switching noise from the device. The input capacitor impedance at the switching frequency shall 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. A 4.7µF ceramic capacitor for most applications is sufficient. Output Capacitor Selection The output capacitor is required to keep the output voltage ripple small and to ensure regulation loop stability. The output capacitor must have low impedance at the switching frequency. Ceramic capacitors with X5R or X7R dielectrics are recommended due to their low ESR and high ripple current. Compensation Capacitor Selection The compensation capacitors for increasing phase margin provide additional stability. It is required and more than 22p, Refer to Demo Board Schematic, The optimum values for C3 is 15pF. Layout Guidance When laying out the PC board, the following suggestions should be taken to ensure proper operation of the APE1502. These items are also illustrated graphically in below. 1. The power traces, including the GND trace, the SW trace and the VIN trace should be kept short, direct and wide to allow large current flow. Put enough multiply-layer pads when they need to change the trace layer. 2. Connect the input capacitor C1 to the VIN pin as closely as possible to get good power filter effect. 3. Keep the switching node, SW, away from the sensitive FB node. 4. Do not trace signal line under inductor. 5 Advanced Power Electronics Corp. APE1502 TYPICAL CHARACTERISTICS Temperature VS Supply Current VIN VS Supply Current 450 350 300 Supply Current (uA) Supply Current (uA) 400 250 200 150 100 VFB=0V No Load 50 0 2.5 3 3.5 4 4.5 VIN (V) 5 5.5 6 -50 0.60 0.20 0.00 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 VFB (V) 0.40 0 0 25 50 75 100 Temperature VS V FB -0.40 -0.60 Vout=0.6V Vout=1.2V Vout=3.3V -0.80 -1.00 0.65 0.64 0.63 0.62 0.61 0.6 0.59 0.58 0.57 0.56 0.55 Load=10mA VIN=3.3V -50 Iout (A) -25 Efficiency (VOUT=1.2V) 0 25 50 Temperature (℃) 75 100 Efficiency (VOUT=1.8V) 100 100 90 80 70 90 80 Efficiency (%) Efficiency (%) -25 Temperature (℃) 0.80 Load Regulation (%) VFB=0V No Load VIN=5V Load Regulation 1.00 -0.20 450 400 350 300 250 200 150 100 50 0 60 50 40 30 20 10 70 60 50 40 30 VIN=3.3 VIN=5V 0 20 VIN=3.3 VIN=5V 10 0 100 200 300 400 500 600 700 800 900 1000 100 200 300 400 500 600 700 800 900 1000 IOUT (mA) IOUT (mA) Efficiency (VOUT=3.3V) 100 90 80 Efficiency (%) 70 60 50 40 30 20 10 VIN=5V 0 100 200 300 400 500 600 700 800 900 1000 IOUT (mA) 6 Advanced Power Electronics Corp. APE1502 PACKAGE OUTLINES (1) SOT-89-5L A C 4.6 0.4 F 1.1 1.2 B E F 0.5 1.7 0.55 I 1.5 Land Pattern Recommendation (Unit: mm) H L K J G Symbol A B C E F G H I J K L Dimensions In Millimeters Min. Nom. Max. 4.40 4.50 4.60 4.05 4.15 4.25 1.50 1.60 1.70 2.40 2.50 2.60 0.80 3.00 Ref. 1.50 Ref. 0.40 0.46 0.52 1.40 1.50 1.60 0.35 0.39 0.43 5o Typ. Dimensions In Inches Min. Nom. Max. 0.173 0.177 0.181 0.159 0.163 0.167 0.059 0.063 0.067 0.094 0.098 0.102 0.031 0.118 Ref. 0.059 Ref. 0.016 0.018 0.020 0.055 0.059 0.063 0.014 0.015 0.017 5o Typ. Marking Information 1502 Y WW S Part number ID code: internal WW: 01~52 Year : 7 = 2007 7 Advanced Power Electronics Corp. APE1502 (2) SOT-23-5L E E1 C D GAUGE PLANE θ L L1 e DETAL A e1 θ 2(4x) b(5x) Symbol A A1 A2 b C D E1 E L L1 e1 e θ θ1 θ2 A DETAL A A1 A2 θ1(4x) Dimensions in Millimeters Min. 1.05 0.05 1.00 0.30 0.08 2.80 1.50 2.60 0.30 0.50 1.80 0.85 0o 5o 5o Nom. 1.10 2.90 1.60 2.80 0.60 1.90 0.95 4o 10o 10o Max. 1.35 0.15 1.20 0.50 0.22 3.00 1.70 3.00 0.60 0.70 2.00 1.05 8o 15o 15o Dimensions in Inches Min. 0.041 0.002 0.039 0.012 0.003 0.110 0.059 0.102 0.012 0.020 0.071 0.033 0o 5o 5o Nom. 0.043 0.114 0.063 0.110 0.024 0.075 0.037 4o 10o 10o Max. 0.053 0.006 0.047 0.020 0.009 0.118 0.067 0.118 0.024 0.028 0.079 0.041 8o 15o 15o Marking Information WW : 01~26(A~Z) 27~52(A~Z) Year : 6 = 2006 A = 2010 Part number : APE1502 G3XX 8