SGM6014

SGM6014 1.4MHz, 2A Synchronous Step-Down Converter GENERAL DESCRIPTION The SGM6014 is a high efficiency monolithic synchronous step-down regulator using 1.4MHz constant frequency, current mode architecture. The device is available in an adjustable version. It is ideal for portable equipment requiring very high current up to 2A from single-cell Li-ion batteries while still achieving over 95% efficiency during peak load conditions. The SGM6014 can enter PFM (low IQ) mode with typically 55μA quiescent current for highest light load efficiency to maximize battery life. The SGM6014 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. It can supply up to 2A output load current from a 2.5V to 5.5V input voltage and the output voltage can be regulated as low as 1.2V. The high switching frequency (1.4MHz) 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 SGM6014 is available in Green TDFN-3×3-10L package and is rated over the -40℃ to +85℃ temperature range. FEATURES  High Efficiency: Up to 95%  2.5V to 5.5V Input Voltage Range  1.4MHz Constant Frequency Operation  2A Output Current  100% Duty Cycle for Lowest Dropout  Less than 2µA Shutdown Current  Low Quiescent Current: 55μA in PFM Mode  Low RDS(ON) Internal Switches: 0.135Ω  Allows Use of Ceramic Capacitors  Current Mode Control for Excellent Line and Load Transient Response  Internal Soft-Start Protection  Short Circuit and Thermal Protection  -40℃ to +85℃ Operating Temperature Range  Available in Green TDFN-3×3-10L Package APPLICATIONS PDA, Pocket PC and Smart Phones USB Powered Modems CPUs and DSPs PC Cards and Notebooks Cellular Phones Digital Cameras DSP Core Supplies Portable Instruments REV. A SG Micro Corp www.sg-micro.com 1.4MHz, 2A Synchronous Step-Down Converter 2 SGM6014 SG Micro Corp www.sg-micro.com PACKAGE/ORDERING INFORMATION MODEL VOUT (V) PIN- PACKAGE SPECIFIED TEMPERATURE RANGE ORDERING NUMBER PACKAGE MARKING PACKAGE OPTION SGM6014 Adjustable TDFN-3×3-10L -40℃ to +85℃ SGM6014-ADJYTD10G/TR SGM SHDD XXXXX Tape and Reel, 3000 NOTE: XXXXX = Date Code and Vendor Code. ABSOLUTE MAXIMUM RATINGS Input Supply Voltage................................................. -0.3V to 6V EN Voltage.................................................... -0.3V to VIN + 0.3V FB/OUT, SW Voltages.................................. -0.3V to VIN + 0.3V Power Dissipation, PD @ TA = +25℃ TDFN-3×3-10L................................................................... 2.2W Package Thermal Resistance TDFN-3×3-10L, θJA......................................................... 45℃/W Operating Temperature Range........................... -40℃ to +85℃ Junction Temperature....................................................... 150℃ Storage Temperature Range…......................... -65℃ to +150℃ Lead Temperature (Soldering, 10s).................................. 260℃ ESD Susceptibility HBM................................................................................. 3000V MM..................................................................................... 300V NOTE: Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. CAUTION This integrated circuit can be damaged by ESD if you don’t pay attention to ESD protection. SGMICRO recommends that all integrated circuits be handled with appropriate precautions. Failure to observe proper handling and installation procedures can cause damage. ESD damage can range from subtle performance degradation to complete device failure. Precision integrated circuits may be more susceptible to damage because very small parametric changes could cause the device not to meet its published specifications. SGMICRO reserves the right to make any change in circuit design, specification or other related things if necessary without notice at any time. Please contact SGMICRO sales office to get the latest datasheet. 1.4MHz, 2A Synchronous Step-Down Converter 3 SGM6014 SG Micro Corp www.sg-micro.com PIN CONFIGURATION (TOP VIEW) 4 1 3 5 TDFN-3×3-10L SGM6014 2 7 10 8 6 9 EN IN AIN GND FB PGND PGND SW SW GND G N D PIN DESCRIPTION PIN NAME FUNCTION 1 EN Enable Pin. Pulling EN to ground forces the device into shutdown mode. Pulling EN to IN enables the device. EN should not be left floating and must be terminated. 2 IN Supply Voltage Input. Must be closely decoupled to GND, with a 22µF or greater ceramic capacitor. 3 AIN Analog Supply Input. Provides bias for internal circuitry. 4, 6 GND Analog Ground. 5 FB Feedback Pin. Receives the feedback voltage from an external resistive divider across the output. The internal voltage divider is disabled for adjustable version. 7, 8 SW Switching Node Pin. Connect the output inductor to this pin. 9, 10 PGND Power Ground. Exposed Pad GND Power Ground Exposed Pad. Must be connected to GND plane. 1.4MHz, 2A Synchronous Step-Down Converter 4 SGM6014 SG Micro Corp www.sg-micro.com ELECTRICAL CHARACTERISTICS (VIN = 3.6V, TA = -40℃ to +85℃, unless otherwise noted.) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS Input Voltage Range VIN 2.5 5.5 V Regulated Output Voltage VOUT 1.2 VIN (1) V PWM Mode VFB = 0.58V 300 420 PFM Mode VFB = 0.62V 55 95 Input DC Bias Current Shutdown IQ VIN = 5.5V, VEN = 0V 0.01 2 μA Feedback Input Bias Current IFB VFB = 0.65V 0.001 1 μA VIN = 2.5V to 5.5V, TA = +25℃ 0.587 0.6 0.616 Regulated Feedback Voltage VFB VIN = 2.5V to 5.5V, TA = -40℃ to +85℃ 0.583 0.6 0.619 V Line Regulation VIN = 2.5V to 5.5V, ILOAD = 350mA 0.1 0.6 %/V Load Regulation ILOAD = 200mA to 2000mA 0.07 %/A Output Voltage Accuracy VIN = 2.5V to 5.5V, ILOAD = 350mA -3.5 +3.5 % Oscillator Frequency fOSC 1.4 MHz Startup Time tS From Enable to Output Regulation 500 μs Over-Temperature Shutdown Threshold tSD 150 ℃ Over-Temperature Shutdown Hysteresis tHYS 15 ℃ Peak Switch Current IPK 2.7 A RDS(ON) of P-Channel FET VIN = 3.6V 135 RDS(ON) of N-Channel FET RDS(ON) VIN = 3.6V 115 mΩ Logic-High Voltage VEN_H VEN Rising 1.5 EN Threshold Logic-Low Voltage VEN_L VEN Falling 0.4 V Enable Leakage Current IEN VEN = 0V or VIN 0.01 1 μA NOTE: 1. The maximum output voltage is 4.4V. 1.4MHz, 2A Synchronous Step-Down Converter 5 SGM6014 SG Micro Corp www.sg-micro.com TYPICAL PERFORMANCE CHARACTERISTICS TA = 25℃, L = 2.2μH, CIN = COUT = 22μF, unless otherwise noted. Efficiency vs. Load Current 20 40 60 80 100 0.1 1 10 100 1000 10000 Load Current (mA) E ffi ci en cy (% ) VOUT = 1.2V VIN = 3.6V VIN = 5.5V VIN = 4.2V VIN = 5.0V VIN = 2.5V Efficiency vs. Load Current 20 40 60 80 100 0.1 1 10 100 1000 10000 Load Current (mA) E ffi ci en cy (% ) VIN = 2.5V VOUT = 1.5V VIN = 5.5V VIN = 4.2V VIN = 5.0V VIN = 3.6V Efficiency vs. Load Current 20 40 60 80 100 0.1 1 10 100 1000 10000 Load Current (mA) E ffi ci en cy (% ) VIN = 2.5V VOUT = 1.8V VIN = 5.5V VIN = 5.0V VIN = 3.6V VIN = 4.2V Output Voltage vs. Load Current 1.164 1.176 1.188 1.200 1.212 1.224 1.236 0 400 800 1200 1600 2000 Load Current (mA) O ut pu t V ol ta ge (V ) VOUT = 1.2V VIN = 5.5VVIN = 5.0V VIN = 2.5V VIN = 4.2V VIN = 3.6V Output Voltage vs. Load Current 1.455 1.470 1.485 1.500 1.515 1.530 1.545 0 400 800 1200 1600 2000 Load Current (mA) O ut pu t V ol ta ge (V ) VOUT = 1.5V VIN = 5.5VVIN = 5.0V VIN = 2.5V VIN = 4.2V VIN = 3.6V Output Voltage vs. Load Current 1.746 1.764 1.782 1.800 1.818 1.836 1.854 0 400 800 1200 1600 2000 Load Current (mA) O ut pu t V ol ta ge (V ) VOUT = 1.8V VIN = 5.5VVIN = 5.0V VIN = 2.5V VIN = 4.2V VIN = 3.6V 1.4MHz, 2A Synchronous Step-Down Converter 6 SGM6014 SG Micro Corp www.sg-micro.com TYPICAL PERFORMANCE CHARACTERISTICS TA = 25℃, L = 2.2μH, CIN = COUT = 22μF, unless otherwise noted. Efficiency vs. Load Current 20 40 60 80 100 0.1 1 10 100 1000 10000 Load Current (mA) E ffi ci en cy (% ) VOUT = 3.3V VIN = 5.5V VIN = 4.2VVIN = 3.7V VIN = 5.0V Quiescent Current vs. Input Voltage 200 250 300 350 400 450 500 2.5 3 3.5 4 4.5 5 5.5 Input Voltage (V) Q ui es ce nt C ur re nt (μ A ) VOUT = 1.8V VFB = 0.58V N-Channel RDS(ON) vs. Input Voltage 60 80 100 120 140 160 180 2.5 3 3.5 4 4.5 5 5.5 Input Voltage (V) R D S( O N )_ N (m Ω) -40℃ +85℃ +25℃ Output Voltage vs. Load Current 3.201 3.234 3.267 3.300 3.333 3.366 3.399 0 400 800 1200 1600 2000 Load Current (mA) O ut pu t V ol ta ge (V ) VOUT = 3.3V VIN = 5.5VVIN = 5.0V VIN = 4.2V VIN = 3.7V Quiescent Current vs. Temperature 200 250 300 350 400 450 500 -50 -25 0 25 50 75 100 Temperature (℃) Q ui es ce nt C ur re nt (μ A ) VIN = 3.6V VOUT = 1.8V VFB = 0.58V P-Channel RDS(ON) vs. Input Voltage 80 100 120 140 160 180 200 2.5 3 3.5 4 4.5 5 5.5 Input Voltage (V) R D S (O N )_ P (m Ω) -40℃ +85℃ +25℃ 1.4MHz, 2A Synchronous Step-Down Converter 7 SGM6014 SG Micro Corp www.sg-micro.com Output Ripple 10m V /div 100m A/div VOUT ISW Time (400ns/div) VOUT = 1.8V, VIN = 3.6V, ILOAD = 2A Output Ripple 50m V/div 200m A /div VOUT ISW Time (20ms/div) Load-Transient Response 200m V /div 1A /div VOUT ISW Time (400μs/div) Load-Transient Response 200m V /div 1A /div VOUT ISW Time (400μs/div) VOUT = 1.8V, VIN = 3.6V, ILOAD = 0A TYPICAL PERFORMANCE CHARACTERISTICS TA = 25℃, L = 2.2μH, CIN = COUT = 22μF, unless otherwise noted. Reference Voltage vs. Temperature 0.58 0.59 0.60 0.61 0.62 -50 -25 0 25 50 75 100 Temperature (℃) R ef er en ce V ol ta ge (V ) VIN = 3.6V Switching Frequency vs. Temperature 1.30 1.35 1.40 1.45 1.50 -50 -25 0 25 50 75 100 Temperature (℃) Sw itc hi ng F re qu en cy (M H z) VIN = 3.6V VOUT = 1.8V VIN = 3.6V, VOUT = 1.8V VIN = 3.6V, VOUT = 1.8V 0A to 2A Step 200mA to 2A Step 1.4MHz, 2A Synchronous Step-Down Converter 8 SGM6014 SG Micro Corp www.sg-micro.com TYPICAL PERFORMANCE CHARACTERISTICS TA = 25℃, L = 2.2μH, CIN = COUT = 22μF, unless otherwise noted. Line Regulation -0.4 -0.3 -0.2 -0.1 0 0.1 0.2 0.3 0.4 2.5 3 3.5 4 4.5 5 5.5 Input Voltage (V) A cc ur ac y (% ) VOUT = 1.8V ILOAD = 1mA ILOAD = 600mA ILOAD = 10mA ILOAD = 1AILOAD = 1.5A ILOAD = 2A Soft Start 2V /div 1V /div 100m A /div EN VOUT IIN Time (400μs/div) VOUT = 1.8V, VIN = 3.6V, ILOAD = 0A Soft Start 2V /div 1V /div 500m A/div EN VOUT IIN Time (400μs/div) VOUT = 1.8V, VIN = 3.6V, ILOAD = 2A 1.4MHz, 2A Synchronous Step-Down Converter 9 SGM6014 SG Micro Corp www.sg-micro.com OPERATION The SGM6014 is a step-down switching regulator optimized for battery-powered handheld applications. The regulator operates at typically 1.4MHz fixed switching frequency under heavy load condition to allow small external inductor and capacitors to be used for minimal printed-circuit board (PCB) area. At light load, the regulator can enter PFM mode to reduce the switching frequency, to minimize the switching loss and to maximize the battery life. The quiescent current under PFM mode with no loading is typically only 55μA. The supply current is typically only 0.01μA when the regulator is disabled. PWM Control Scheme The SGM6014 uses the peak-current-mode pulse-width modulation (PWM) control scheme for fast transient response and pulse-by-pulse current limiting. The current loop consists of the oscillator, the PWM comparator (COMP), current sensing circuit, and the slope compensation for the current loop stability. The current sensing circuit consists of the resistance of the P-Channel MOSFET when it is turned on and the current sense amplifier (CSA). The control reference for the current loops comes from the error amplifier (EAMP) of the voltage loop. The PWM operation is initialized by the clock from the oscillator. The P-Channel MOSFET is turned on at the beginning of a PWM cycle and the current in the P-Channel MOSFET starts ramping up. When the sum of the CSA output and the compensation slope reaches the control reference of the current loop, the PWM comparator COMP sends a signal to the PWM logic to turn off the P-Channel MOSFET and to turn on the N-Channel MOSFET. The N-MOSFET remains on till the end of the PWM cycle. The output voltage is regulated by controlling the reference voltage to the current loop. The bandgap circuit outputs a 0.6V reference voltage to the voltage control loop. The feedback signal comes from the FB pin. The soft-start block only affects the operation during the start-up. The EAMP is a transconductance amplifier, which converts the voltage error signal to a current output. The voltage loop is internally compensated by an RC network. PFM Mode At light load the SGM6014 enters PFM mode to minimize the switching loss by reducing the switching frequency. The output voltage reduces gradually due to the load current discharging the output capacitor. When the output voltage drops to the nominal voltage, the regulator resumes normal PWM mode operation. TYPICAL APPLICATION CIRCUIT 2 EN GND IN SGM6014-ADJAIN PGND PGND SW FB SW VIN 2.5V ~ 5.5V C1 22μF L 2.2μH VOUT 1.8V/2A 1 3 4 5 10 9 8 7 6 GND C2 22μF R1 300kΩ R2 150kΩ Figure 1. Basic Application Circuit for the Adjustable Output Version 1.4MHz, 2A Synchronous Step-Down Converter 10 SGM6014 SG Micro Corp www.sg-micro.com APPLICATION INFORMATION Setting the Output Voltage Figure 1 shows the basic application circuit with the SGM6014 adjustable output version. For applications requiring an adjustable output voltage, the SGM6014 adjustable version can be externally programmed. Resistors R1 and R2 in Figure 1 program the output voltage to be equal to or higher than 1.2V. To limit the bias current required for the external feedback resistor string while maintaining good noise immunity, the minimum suggested value for R2 is 41kΩ. Although a larger value will further reduce quiescent current, it will also increase the impedance of the feedback node, making it more sensitive to external noise and interference. Table 1 summarizes the resistor values for typical output voltages. The external resistors set the output voltage according to the following equation:     2R 1R1V6.0VOUT 2R1V6.0 V 1R OUT     Table 1. Standard 1% Resistors Substituted for Calculated Values VOUT (V) R1 (kΩ) R2 (kΩ) 1.2 150 150 1.8 300 150 3.3 450 100 When the battery input voltage decreases near the value of the output voltage, the SGM6014 allows the main switch to remain on for more than one switching cycle and increases the duty cycle until it reaches 100%. The duty cycle D of a step-down converter is defined as: 100% V V 100%ftD IN OUT OSCON  where tON is the main switch on-time and fOSC is the oscillator frequency. The minimum on-time is typically 100ns; therefore, the minimum duty cycle is equal to 100 × 100ns × fOSC(Hz). Inductor Selection For most designs, the SGM6014 operates with inductor values of 1μH to 4.7μH. Small value inductors are physically smaller but require faster switching, which results in some efficiency loss. The inductor value can be derived from the following equation: OSCLIN OUTINOUT fIΔV )VV(V L   where ΔIL is inductor ripple current. Large value inductors lower ripple current and small value inductors result in high ripple current. Choose inductor ripple current approximately 30% of the maximum load current 2A, or ∆IL = 600mA. For output voltages above 2.0V, when light-load efficiency is important, the minimum recommended inductor is 2.2μH. Manufacturer’s specifications list both the inductor DC current rating, which is a thermal limitation, and the peak current rating, which is determined by the saturation characteristics. The inductor should not show any appreciable saturation under normal load conditions. Some inductors may meet the peak and average current ratings yet result in excessive losses due to a high DCR. Always consider the losses associated with the DCR and its effect on the total converter efficiency when selecting an inductor. For optimum voltage-positioning load transients, choose an inductor with DC series resistance in the 20mΩ to 100mΩ range. For higher efficiency at heavy loads (above 200mA), or best 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 (2A + 600mA). Slope Compensation The SGM6014 step-down converter uses peak current mode control with slope compensation for stability when duty cycles are greater than 50%. The slope compensation is set to maintain stability with lower value inductors which provide better overall efficiency. The output inductor value must be selected so the inductor current down slope meets the internal slope compensation requirements. 1.4MHz, 2A Synchronous Step-Down Converter 11 SGM6014 SG Micro Corp www.sg-micro.com APPLICATION INFORMATION As an example, the value of the slope compensation is set to 1.5A/μs which is large enough to guarantee stability when using a 2.2μH inductor for all output voltage levels from 1.2V to 4.4V. The worst case external current slope (m) using the 2.2μH inductor is when VOUT = 4.4V. To keep the output voltage stable when the duty cycle is above 50%, the internal slope compensation (ma) should be: OUT a V1 1m m 1A/μs 2 2 L     Therefore, to guarantee current loop stability, the slope of the compensation ramp must be greater than one-half of the down slope of the current waveform. So the internal slope compensated value of 1.5A/μs will guarantee stability using a 2.2μH inductor value for all output voltages from 1.2V to 4.4V. 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 should be less than the input source impedance to prevent high frequency switching current passing to the input. The calculated value varies with input voltage and is a maximum when VIN is double the output voltage. OSC LOAD PP IN OUT IN OUT IN fESR I V V V1 V V C             IN MIN PP OSC LOAD 1C V ESR 4 f I        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. At least a