AX3514ASA

AX3514/A/B 1.2MHz, 2A Synchronous Step-Down Converter  GENERAL DESCRIPTION The AX3514/A/B is a 1.2MHz constant frequency current mode PWM step-down converter. It is ideal for portable equipment requiring very high current up to 2A from single-cell Lithium-ion batteries while still achieving over 90% efficiency during peak load conditions. The AX3514/A/B also can run at 100% duty cycle for low dropout operation, extending battery life in portable systems while light load operation provides very low output ripple for noise sensitive applications. The AX3514/A/B can supply up to 2A output load current from a 2.6V to 5.5V input voltage and the output voltage can be regulated as low as 0.6V. The high switching frequency minimizes the size of external components while keeping switching losses low. The internal slope compensation setting allows the device to operate with smaller inductor values to optimize size and provide efficient operation. The AX3514/A/B is available in adjustable (0.6V to VIN) output voltage. The device is available in SOP-8L Pb-free and TDFN-10L packages.  FEATURES - 2.6V to 5.5V Input Voltage Range Output Voltages from 0.6V to VIN High Efficiency: Up to 96% 1.2MHz Constant Frequency Operation Up to 2A Output Current No Schottky Diode Required Low RDS(ON) Internal Switches: 0.15Ω Current Mode Operation for Excellent Line and Load Transient Response Current limit, Enable function Short Circuit Protect (SCP) Build-in Soft Start function ≤ 1µA Shutdown Current SOP-8L Pb-Free and TDFN-10L packages 1/12 AXElite Confidential Materials, do not copy or distribute without written consent . Rev.1.8 Nov.09, 2011 AX3514/A/B  BLOCK DIAGRAM SLOPE COMP OSC PVIN + REF Isense AMP - SVIN 0.6V SET Soft-Star + - FB - PWM LOGIC RESET Icomp + NON-OVERLAP CONTROL LX + Izero COMP PGND - SGND Over-Temperature and Short-Circuit Protection Enable Logic EN  PIN ASSIGNMENT The packages of AX3514/A/B are SOP-8L and TDFN-10L; the pin assignment is given by: EN 1 PVIN 2 SVIN SGND 3 4 FB 5 AX3514 AX8101/A (GND) 10 PGND 9 7 PGND LX LX 6 SGND 8 TDFN-10L (3*3) ( Top View ) AX3514A SVIN 1 8 PVIN NC 2 7 LX SGND 3 6 PGND FB 4 5 EN SOP-8L 2/12 AXElite Confidential Materials, do not copy or distribute without written consent . Rev.1.8 Nov.09, 2011 AX3514/A/B Name EN Description Enable pin H：normal operation L：Shutdown PVIN Power Supply Input Pin SVIN Signal Supply Input Pin LX Switch output pin. Connect external inductor here. Minimize trace area at this pin to reduce EMI. SGND Signal Ground Pin PGND Power Ground Pin FB Output Feedback pin NC No connect pin  ORDER/MARKING INFORMATION Order Information AX3514 X XXX X Pin Define Package Type Packing S: SOP-8L Blank : Taping Blank: AX3514 A : Taping A: AX3514 (SOP-8L Only) J10: TDFN-10L (3*3) B: AX3514 (SOP-8L Only) Top Marking (SOP-8L) Logo AX 3 5 1 4 XY Y W WX Part number ID code: internal WW: 01~52 Year: 10=2010 11=2011 Blank:AX3514 A : AX3514A (SOP8 Only) B : AX3514B (SOP8 Only) Top Marking (TDFN-10L) 3 5 1 4 YY W WX Part number ID code: internal WW: 01~52 Year: 10=2010 11=2011 3/12 AXElite Confidential Materials, do not copy or distribute without written consent . Rev.1.8 Nov.09, 2011 AX3514/A/B  ABSOLUTE MAXIMUM RATINGS (at TA=25°C) Characteristics Symbol Rating PVIN, SVIN Pin Voltage VIN VSS - 0.3 to VSS + 6 Feedback Pin Voltage VFB VSS - 0.3 to VIN + 0.3 EN Pin Voltage VEN VSS - 0.3 to VIN + 0.3 Switch Pin Voltage VLX VSS - 0.3 to VIN + 0.3 Power Dissipation PD ( TJ-TA ) / θJA Storage Temperature Range TST -40 to +150 Operating Temperature Range TOP -40 to +85 Junction Temperature TJ +125 SOP-8L 40 Thermal Resistance from Junction to case θJC TDFN-10L 15 SOP-8L 120 Thermal Resistance from Junction to ambient θJA TDFN-10L 45 Unit V V V V mW °C °C °C °C/W °C/W Note: θJA is measured with the PCB copper area of approximately 1 in2(Multi-layer). That need connect to LX pin or Exposed pad of the AX3514.  ELECTRICAL CHARACTERISTICS (VIN = VEN=3.6V, TA =25°C, unless otherwise specified) Characteristics Symbol Conditions Min Typ Max Units Supply Voltage Range VIN 2.6 5.5 V 0.5880 0.6000 0.6120 TA= +25°C Feedback Voltage VFB TA= 0°C ≤ TA≤ 85°C 0.5865 0.6000 0.6135 V TA = -40°C ≤ TA ≤ 85°C 0.5820 0.6000 0.6180 Feedback Bias Current IFB VFB=0.65V ±30 nA Quiescent Current ICCQ VFB=0.8V 250 400 uA Shutdown Supply Current ISD VEN =0V 0.1 1 uA Switching Current Limit ILIMIT 2.2 2.5 A Line Regulation △VOUT/VOUT VIN = 2.6V~5.5V 0.04 0.4 %/V Load Regulation △VOUT/VOUT IOUT = 0.01 to 2A 0.5 1 % Oscillation Frequency FOSC LX pin 1 1.2 1.4 MHz RDS(ON) of P-CH MOSFET RDSON VFB=0V, IOUT=1A 0.15 0.25 Ω RDS(ON) of N-CH MOSFET 0.11 0.20 Ω RDSON (Note1) 0.4 VENL EN pin logic input V threshold voltage VENH 1.5 EN Pin Input Current IEN ±0.1 ±1 uA VIN=5V, 91 % Efficiency EFFI VOUT=3.3V,IOUT=1.5A Thermal Shutdown TSD 140 °C Thermal Shutdown 30 °C TSH Hysteresis Note1: Guaranteed by design. 4/12 AXElite Confidential Materials, do not copy or distribute without written consent . Rev.1.8 Nov.09, 2011 AX3514/A/B  APPLICATION CIRCUIT VIN=2.6 to 5.5V U1 PVIN SVIN R1 C1 22uF 10R VOUT=1.8V L1 LX FB C3 EN 100nF PGND SGND 3.3uH R2 600K C5 15pF C2 22uF AX3514 R3 300K VOUT = 0.6 * (1+R2/R3) R2=510K~820K  FUNCTION DESCRIPTIONS Operation AX3514/A/B 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 2000mA output current at input voltage range from 2.6V to 5.5V. 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. 5/12 AXElite Confidential Materials, do not copy or distribute without written consent . Rev.1.8 Nov.09, 2011 AX3514/A/B  APPLICATION INFORMATION Setting the Output Voltage Application circuit item shows the basic application circuit with AX3514/A/B adjustable output version. The external resistor sets the output voltage according to the following equation: R2   V OUT  0.6V  1  R3  Table 1: Resistor select for output voltage setting VOUT R3 R2 1.2V 680K 680K 1.5V 420K 630K 1.8V 300K 600K 2.5V 180K 560K 3.3V 150K 680K Inductor Selection For most designs, the AX3514/A/B operates with inductors of 2.2µH 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 15% of the maximum load current 2000mA, ΔIL=300mA. Table 2 Inductor select for output voltage setting (VIN=3.6V) VOUT 1.2V 1.5V Inductor 3.3uH 3.3uH Part Number 744062003 744062003 WE-TPC 1.8V 3.3uH 2.5V 2.2uH 744062003 744043022 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 30mΩ to 100mΩ 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 (2000mA+350mA). 6/12 AXElite Confidential Materials, do not copy or distribute without written consent . Rev.1.8 Nov.09, 2011 AX3514/A/B 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 22µF 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 capacitor (C5) for improving phase margin provides additional stability. Refer to Demo Board Schematic. The optimum value is 15pF for all conditions. Layout Guide C1 must be placed between PVIN and PGND as closer as possible, VIN trace should be wide and short. C1 VIN EN 1 PVIN 2 SVIN 3 R1 C3 GND AX3514 Expose Pad 8 PGND 7 SW 6 SGND SW should be connected to Inductor by wide and short trace, keep sensitive components away from this trace L1 C2 SGND 4 5 FB R3 R2 VOUT C5 C3 must be placed between SVIN and SGND as closer as possible 7/12 AXElite Confidential Materials, do not copy or distribute without written consent . Rev.1.8 Nov.09, 2011 AX3514/A/B C1 must be placed between PVIN and PGND as closer as possible, VIN trace should be wide and short. C1 VIN GND AX3514J10 R1 C3 C3 must be placed between SVIN and SGND as closer as possible EN 1 PVIN 2 SVIN 3 PGND 9 PGND 8 LX LX SGND SGND 4 7 FB 5 6 R2 C5 Exposed Pad 10 SW should be connected to Inductor by wide and short trace, keep sensitive components away from this trace L1 VOUT R3 VOUT C2 R1 C3 must be placed between SVIN and SGND as closer as possible R2, R3 and C5 should be connected to FB pin by short trace C1 must be placed between PVIN and PGND as closer as possible, VIN trace should be wide and short. VIN AX3514A SVIN 1 FB 2 SGND 3 C3 R3 Expose Pad 8 PVIN 7 LX 6 PGND SW should be connected to Inductor by wide and short trace, keep sensitive components away from this trace C1 L1 C2 C5 5 4 EN R2 SGND VOUT VIN GND R1 C3 must be placed between SVIN and SGND as closer as possible C1 must be placed between PVIN and PGND as closer as possible, VIN trace should be wide and short. VIN AX3514B C3 C5 SVIN 1 NC 2 SGND 3 FB 4 R2 R3 Expose Pad 8 PVIN 7 LX 6 PGND 5 EN SW should be connected to Inductor by wide and short trace, keep sensitive components away from this trace C1 VIN GND L1 C2 VOUT 8/12 AXElite Confidential Materials, do not copy or distribute without written consent . Rev.1.8 Nov.09, 2011 AX3514/A/B  TYPICAL CHARACTERISTICS VOUT VS. Efficiency (VIN=3.3) VOUT VS Efficiency (VIN=5V) 100 100 90 80 EFFICIENCY (%) EFFICIENCY (%) 70 60 50 40 30 VOUT =3.3V VOUT =2.5V VOUT =1.8V VOUT =1.2V 90 VOUT =2.5V VOUT =1.8V VOUT =1.2V 80 70 60 50 40 30 20 20 10 10 0 0 0 10 50 100 500 1000 1500 0 2000 10 50 500 1000 1500 2000 Line Regulation 1.22 1.22 1.215 1.215 1.21 1.21 1.205 1.205 VOUT (V) VOUT (V) Load Rrgulation 1.2 1.195 1.2 1.195 1.19 1.19 1.185 IOUT =500mA 1.185 VIN=3.6V 1.18 1.18 0 500 1000 1500 IOUT (mA) 2000 2.5 2500 3 VIN VS. Frequency 3.5 4 VIN (V) 4.5 5 5.5 VIN VS. ICCQ 400 1.34 1.32 1.3 1.28 1.26 1.24 1.22 1.2 1.18 1.16 1.14 1.12 1.1 350 300 ICCQ (uA) Frequency (MHZ) 100 IOUT (mA) IOUT (mA) 250 200 150 VFB=0.8V 100 2.5 3 3.5 4 VIN (V) 4.5 5 5.5 2.5 3 3.5 4 VIN (V) 4.5 5 5.5 9/12 AXElite Confidential Materials, do not copy or distribute without written consent . Rev.1.8 Nov.09, 2011 AX3514/A/B  TYPICAL CHARACTERISTICS (CONTINUOUS) Temperature VS. ICCQ 400 350 300 ICCQ (uA) VOUT (V) Temperature VS. VOUT 1.34 1.32 1.3 1.28 1.26 1.24 1.22 1.2 1.18 1.16 1.14 1.12 1.1 250 200 150 100 VIN=3.6V VFB=0.8V 50 IOUT =10mA VIN=3.6V 0 -40 ℃ -20 ℃ 0℃ 25 ℃ 50 ℃ -40 ℃ -20 ℃ 85 ℃ 105 ℃ 125 ℃ 0℃ 25 ℃ Rds (on) VS. VIN 220 P-MOS 140 120 N-MOS 100 80 Frequency (MHZ) Rds (on) mΩ 160 1.45 1.40 1.35 1.30 1.25 1.20 1.15 1.10 1.05 1.00 -40 ℃ -20 ℃ 3 3.5 V IN (V) 4 105 ℃ 125 ℃ Temperature VS. Frequency 180 2.5 85 ℃ 1.50 IOUT =1A 200 50 ℃ Temperature Temperature 4.5 Power ON VIN=5V, VOUT=1.2V, Load=1A 5 0℃ 25 ℃ 50 ℃ 85 ℃ 105 ℃ 125 ℃ Temperature Load transient response VIN=5V, VOUT=1.2V, IOUT= 0.2A~1.8A 10/12 AXElite Confidential Materials, do not copy or distribute without written consent . Rev.1.8 Nov.09, 2011 AX3514/A/B H A1 C A A2 E  PACKAGE OUTLINES (1) SOP-8L Dimensions in Millimeters Min. Nom. Max. A 1.75 A1 0 0.15 A2 1.25 C 0.1 0.2 0.25 D 4.7 4.9 5.1 E 3.7 3.9 4.1 H 5.8 6 6.2 L 0.4 1.27 b 0.31 0.41 0.51 e 1.27 BSC y 0.1 X 2.34 Y 2.34 θ 0O 8O Mold flash shall not exceed 0.25mm per side JEDEC outline: MS-012 BA Symbol Dimensions in Inches Min. Nom. Max. 0.069 0 0.06 0.049 0.0075 0.008 0.01 0.185 0.193 0.2 0.146 0.154 0.161 0.228 0.236 0.244 0.015 0.05 0.012 0.016 0.02 0.050 BSC 0.004 0.092 0.092 0O 8O 11/12 AXElite Confidential Materials, do not copy or distribute without written consent . Rev.1.8 Nov.09, 2011 AX3514/A/B (2) TDFN-10L (3*3*0.75mm) Symbol A A1 A3 b D D2 E E2 e L Dimensions in Millimeters Min. Nom. Max. 0.70 0.75 0.80 0.00 0.02 0.05 0.20 REF. 0.18 0.25 0.30 2.90 3.00 3.10 2.20 2.40 2.50 2.90 3.00 3.10 1.50 1.60 1.70 0.50 BSC. 0.30 0.40 0.50 Dimensions in Inches Min. Nom. Max. 0.028 0.030 0.031 0.000 0.001 0.002 0.008 REF. 0.007 0.010 0.012 0.114 0.118 0.122 0.087 0.094 0.098 0.114 0.118 0.122 0.059 0.063 0.070 0.020 BSC. 0.012 0.016 0.020 12/12 AXElite Confidential Materials, do not copy or distribute without written consent . Rev.1.8 Nov.09, 2011