EUP2624 620kHz/1.25MHz Step-up DC/DC Converter DESCRIPTION FEATURES The EUP2624 is a high performance current mode, PWM step-up converter with pin selectable operating frequency. With an internal 2.1A, 170mΩ MOSFET, it can generate 12V at up to 500mA output current from a 5V supply. The selectable 620kHz and 1.25MHz allows smaller inductors and faster transient response. An external compensation pin gives the user greater flexibility in setting loop compensation allowing the use of low ESR Ceramic output capacitors. Soft-start is controlled with an external capacitor, which determines the input current ramp rate during start-up. z z z z z z z z z When shut down, it draws＜10µA of current and can operate down to 2.5V input supply. These features along with 1.25MHz switching frequency makes it an ideal device for portable equipment and TFT-LCD displays. APPLICATIONS z z z z z z The EUP2624 is available in an 8-pin MSOP package. The device is specified for operation over the full -40°C to +85°C temperature range. 90% Efficiency 2.1A, 170mΩ Power MOSFET 2.5V to 5.5V Input Range Adjustable Output Voltage up to 28V 620kHz/1.25MHz Switching Frequency Selection Adjustable Soft-Start Internal Thermal Protection Small MSOP-8 package RoHS Compliant and 100% Lead (Pb)-Free TFT-LCD Displays DSL Modems Set-Top Boxes PCMCIA Cards Portable Equipment Handheld Devices Typical Application Circuit Figure 1. 5V to 12V Step-Up DS2624 Ver1.0 July .2006 1 EUP2624 Figure 2. Triple Output TFT LCD Power Supply Pin Configurations Part Number Pin Configurations EUP2624 MSOP-8 Pin Description PIN PIN COMP 1 FB 2 SHDN GND SW VIN 3 4 5 6 FSEL 7 SS 8 DS2624 Ver1.0 July .2006 DESCRIPTION Compensation pin. Output of the internal error amplifier. Capacitor and resistor from COMP pin to ground. Voltage feedback pin. Internal reference is 1.24V NOMINAL. Connect a resistor divider from VOUT. VOUT=1.24V (1+R1/R2). Shutdown control pin. Pull SHDN low to turn off the device. Analog and power ground. Power switch pin. Switch connected to the drain of the internal power MOSFET. Analog power input pin. Frequency select pin. When FSEL is connected to GND, switching frequency is set to 620kHz. When connected to VIN, switching frequency is set to 1.25MHz Soft-start control pin. Connect a capacitor to control the converter start-up 2 EUP2624 Ordering Information Order Number Package Type Marking Operating Temperature range EUP2624MIR1 MSOP-8 xxxx P2624 -40 °C to 85°C EUP2624 □ □ □ □ Lead Free Code 1: Lead Free 0: Lead Packing R: Tape & Reel Operating temperature range I: Industry Standard Package Type M: MSOP Block Diagram DS2624 Ver1.0 July .2006 3 EUP2624 Absolute Maximum Ratings VIN --------------------------------------------------------------------------------------6V SW Voltages ---------------------------------------------------------------------------- 30V FB Voltage ----------------------------------------------------------------------------2V SHDN Voltage ------------------------------------------------------------------------6V Junction Temperature ------------------------------------------------------------------ 150°C Lead Temp (Soldering, 10sec) --- --------------------------------------------------300°C ESD Ratings Human Body Model ---------------------------------------------------------------- 2kV Operating Conditions Operating Temperature --------------------------------------------------------- -40°C to 85°C Supply Voltage -------------------------------------------------------------------- 2.5V to 5.5V SW Voltage Max ---------------------------------------------------------------------28V Electrical Characteristics VIN=VSHDN=3V. TA=-40℃to 85℃.Typical values are at TA=25℃.Unless otherwise noted. EUP2624 Symbol Parameter Conditions Min Typ Max. VOUT<18V 2.5 5.5 VIN Input Voltage Range 18V< VOUT<24V 4.0 5.5 UVLO IQ VIN Undercoltage Lockout Quiescent Current SW Remains off below this level. VIN Rising,20mV hysteresis Unit V 2.15 2.35 V FB=2V (Not Switching) 0.5 0.8 mA FB=0V（Switching） 1.5 2 mA VSHDN=0V 0.1 1.24 10 1.27 uA 1.92 VFB FB Regulation Voltage IB %VFB/ △VIN %VFB/ △ILOAD gm FB Input Bias Current VFB=1.24V 100 250 nA FB Line Regulation 2.5V ≤ VIN ≤ 5.5V 0.08 0.15 %/V FB Load Regulation VOUT=8V,Iload=30mA to200 mA 6.7 Error Amp Transconductance △I=4uA 1.20 20 AV Error Amp Voltage Gain Fs Switching Frequency DMAX Maximum Duty Cycle ICL Switch Current Limit 55% Duty Cycle Switch MOSFET On Resistance IL 45 V mV/A 95 500 umho V/V FSLCT=Ground 500 620 740 kHz FSLCT=VIN 900 1250 1500 kHz 94 ％ 2.1 2.8 A ISW=500mA 0.17 0.35 Ω Switch Leakage Current VSW=20V 0.2 20 uA ISS Charge Current VSS=0V 5 8 uA VIL SHDN, FREQ Input Low Voltage 0.5 V VIH SHDN, FREQ Input High Voltage RDSON IFSLCT 3 July .2006 V 2 FSLCT Pull Down Current DS2624 Ver1.0 1.5 2.4 4 5.5 8.2 uA EUP2624 Typical Operating Characteristics 620kHz Switching Frequency vs. Temperature 620kHz Efficiency vs. Load Current 630 90 SWITCHING FREQUENCY (kHA) 95 VIN=5.5V VOUT=8V 85 EFFICIENCY (%) 80 VIN=3V 75 70 VIN=2.5V 65 60 55 50 45 40 35 30 1 10 100 620 610 VIN=5.5V 600 590 VIN=2.5V 580 570 560 550 -40 -30 -20 -10 1000 LOAD CURRENT (mA) 0 10 20 30 40 50 60 70 80 90 0 TEMPERATURE( C) Switching Current Limit vs. Temperature FSLCT Pin Current vs. FSLCT Pin Voltage VOUT=8V 3.2 6.4 3.0 6.2 CURRENT LIMIT (A) FSLCT PIN CURRENT(uA) 6.6 6.0 0 T=-40 C 5.8 0 T=25 C 5.6 0 T=85 C 5.4 VIN=5.5V 2.8 2.6 2.4 VIN=3V 2.2 5.2 VIN=2.5V 2.0 5.0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 -40 -30 -20 -10 FSLCT VOLTAGE(V) 20 30 40 50 60 70 80 90 80 90 1.25MHz Switching IQ vs. Temperature 4.00 3.75 2.25 VIN=5.5V 2.00 1.75 1.50 3.25 3.00 2.75 2.50 2.25 2.00 VIN=2.5V 1.25 VIN=5.5V 3.50 SWITCHING IQ (mA) SWITCHING IQ (mA) 10 0 620kHz Switching IQ vs. Temperature 2.50 0 TEMPERATURE( C) VIN=2.5V 1.75 1.00 -40 -30 -20 -10 0 10 20 30 40 50 60 70 80 1.50 -40 90 July .2006 -20 -10 0 10 20 30 40 50 TEMPERATURE( C) TEMPERATURE( C) DS2624 Ver1.0 -30 0 0 5 60 70 EUP2624 1.25MHz Non-switching IQ vs. Input Voltage 620kHz Non-switching IQ vs. Input Voltage 0.60 0.65 0.55 0.60 0 0.50 0 NON-SWITCHING IQ (mA) NON-SWITCHING IQ (mA) T= 25 C 0 T= 85 C T= 25 C 0.45 0.40 0 T= - 40 C 0.35 0.30 2.5 3.0 3.5 4.0 4.5 5.0 0 0.55 0.50 0.45 0 T= - 40 C 0.40 0.35 2.5 5.5 T= 85 C 3.0 3.5 4.0 4.5 5.0 5.5 INPUT VOLTAGE (V) INPUT VOLTAGE (V) 620kHz Switching IQ vs. Input Voltage 4.0 2.3 1.25MHz Switching IQ vs. Input Voltage 2.2 2.1 3.5 1.9 SWITCHING IQ (mA) SWITCHING IQ (mA) 2.0 0 T= 25 C 0 T= - 40 C 1.8 1.7 1.6 1.5 0 T= 85 C 1.4 1.3 0 T= 25 C 3.0 0 T= - 40 C 2.5 0 T= 85 C 2.0 1.2 1.1 1.0 2.5 3.0 3.5 4.0 4.5 5.0 1.5 2.5 5.5 3.0 3.5 4.0 4.5 5.0 5.5 INPUT VOLTAGE (V) INPUT VOLTAGE (V) NMOS RDSON vs. Input Voltage SS Pin Current vs. Temperature 6.8 0.24 6.6 0.20 NMOS RDSON (O) SS PIN CURRENT(uA) 0.22 6.4 6.2 VIN=5.5V 6.0 5.8 5.6 5.4 VIN=2.5V 0.18 0 -30 -20 -10 0 10 20 30 0.14 0.12 40 50 60 70 80 0.10 2.5 90 TEMPERATURE( C) July .2006 0 T = - 40 C 3.0 3.5 4.0 4.5 INPUT VOLTAGE (V) 0 DS2624 Ver1.0 T = 25 C 0.16 5.2 5.0 -40 0 T = 85 C 6 5.0 5.5 EUP2624 Inductor Selection The inductor selection determines the output ripple voltage, transient response, output current capability, and efficiency. Its selection depends on the input voltage, output voltage, switching frequency, and maximum output current. For most applications, a 4.7µH inductor is recommended for 1.25MHz application and a 10µH inductor is recommended for 620kHz application. The inductor maximum DC current specification must be greater than the peak inductor current required by the regulator. The peak inductor current can be calculated: Application Information Boost Converter Operations In steady state operating and continuous conduction mode where the inductor current is continuous, the boost converter operates in two cycles. During the first cycle, the internal power FET turns on and the Schottky diode is reverse biased and cuts off the current flow to the output. The output current is supplied from the output capacitor. The voltage across the inductor is VIN and the inductor current ramps up in a rate of VIN/L, L is the inductance. The inductance is magnetized and energy is stored in the inductor. The change in inductor current is: ×V V × (V −V ) OUT OUT IN OUT IN I = + 1/2 × V L×V × FREQ L(PEAK) IN OUT I V − VOUT ∆I L = ∆T2 × IN L ∆T2 = 1- D F SW Output Capacitor Low ESR capacitors should be used to minimized the output voltage ripple. Multilayer ceramic capacitors (X5R and X7R) are preferred for the output capacitors because of their lower ESR and small packages. Tantalum capacitors with higher ESR can also be used. The output ripple can be calculated as: For stable operation, the same amount of energy stored in the inductor must be taken out. The change in inductor current during the two cycles must be the same. ∆I1+∆I2=0 I ×D OUT ∆V = +I × ESR O OUT F ×C SW O V D 1 − D VIN − VOUT × IN + × =0 L F L F SW SW Choose an output capacitor to satisfy the output ripple and load transient requirement. A 10µF to 22µF ceramic capacitor is suitable for most application. For noise sensitive application, a 0.1µF placed in parallel with the larger output capacitor is recommended to reduce the switching noise coupled from the SW switching node. V 1 OUT = 1 − D V IN Schottky Diode In selecting the Schottky diode, the reverse break down voltage, forward current and forward voltage drop must be considered for optimum converter performance. The diode must be rated to handle 2A, the current limit of the EUP2624. The breakdown voltage must exceed the maximum output voltage. Low forward voltage drop, low leakage current, and fast reverse recovery will help the converter to achieve the maximum efficiency. Output Voltage An external feedback resistor divider is required to divide the output voltage down to the nominal 1.24V reference voltage. The current drawn by the resistor network should be limited to maintain the overall converter efficiency. The maximum value of the resistor network is limited by the feedback input bias current and the potential for noise being coupled into the feedback pin. Selecting R2 in the range of 10kΩ to 50 kΩ. The boost converter output voltage s determined by the relationship: R V =V × 1 + 1 OUT FB R 2 The nominal VFB voltage is 1.24V DS2624 Ver1.0 July .2006 7 EUP2624 Input Capacitor The value of the input capacitor depends the input and output voltages, the maximum output current, the inductor value and the noise allowed to put back on the input line. For most applications, a minimum 10µF is required. For applications that run close to the maximum output current limit, input capacitor in the range of 22µF to 47µF is recommended. The EUP2624 is powered from the VIN. High frequency 0.1µF by-pass cap is recommended to be close to the VIN pin to reduce supply line noise and ensure stable operation. Maximum Output Current The output current capability of the EUP2624 is a function of current limit, input voltage, operating frequency, and inductor value. The output current capability is governed by the following equation: ( I L = I L - AVG + 1 / 2 × ∆I L Where: IL=MOSET current limit I L - AVG =average inductor current ∆I L =inductor ripple current Loop Compensation The EUP2624 incorporates an transconductance amplifier in its feedback path to allow the user some adjustment on the transient response and better regulation. The EUP2624 uses current mode control architecture which has a fast current sense loop and a slow voltage feedback loop. The fast current feedback loop does not require any compensation. The slow voltage loop must be compensated for stable operation. The compensation network is a series RC network from COMP pin to ground. The resistor sets the high frequency integrator gain for fast transient response and the capacitor sets the integrator zero to ensure loop stability. For most applications,the compensation resistor in the range of 2K to 30K and the compensation capacitor in the range of 1nF to 10nF. ∆I L = L × VO + V DIODE × F S 0.6V FS = switching frequency, 620KHz or 1.25MHz I I L - AVG = OUT 1−D D = MOSFET turn-on ratio: D =1− VIN VOUT + V DIODE Layout Considerations Good PC board layout and routing are required in high-frequency switching power supplies to achieve good regulation, high efficiency, and stability. It is strongly recommended that the evaluation kit PC board layouts be followed as closely as possible. Place power components as close together as possible, keeping their traces short, direct, and wide. Avoid interconnecting the ground pins of the power components using vias through an internal ground plane. Instead, keep the power components close together and route them in a “star” ground configuration using component-side coper, then connect the star ground to internal ground using multiple vias. Frequency Selection The EUP2624 switching frequency can be user selected to operate at either at constant 620kHz or 1.25MHz. Connecting FSEL pin to ground sets the PWM switching frequency to 620kHz. When connect FSEL high or VDD, switching frequency is set to 1.25MHz. Shut-Down Control The EUP2624 shuts down to reduce the supply current to 0.1μA when SHDN is low. In this mode, the internal reference, error amplifier, comparators, and biasing circuitry turn off while the N-channel MOSFET is turned off. The boost converter’s output is connected to IN via the external inductor and catch diode. July .2006 VIN × VO + VDIODE − V − VIN IN VDIODE = Schottky diode forward voltage, typically, Soft-Start The soft-start is provided by an internal 5µA current source charges the external CSS, the peak MOSFET current is limited by the voltage on the capacitor. This in turn controls the rising rate of the output voltage. The regulator goes through the start-up sequence as well after the SHDN pin is pulled to HI. DS2624 Ver1.0 ) 8 EUP2624 Packaging Information MSOP-8 NOTE 1. Package body sizes exclude mold flash and gate burrs 2. Dimension L is measured in gage plane 3. Tolerance 0.10mm unless otherwise specified 4. Controlling dimension is millimeter. Converted inch dimensions are not necessarily exact. SYMBOLS A A1 A2 b C D E E1 e L y θ DS2624 Ver1.0 July .2006 DIMENSIONS IN MILLIMETERS MIN. NOM. MAX. 0.81 0.95 1.10 0.05 0.09 0.15 0.76 0.86 0.97 0.28 0.30 0.38 0.13 0.15 0.23 2.90 3.00 3.10 4.70 4.90 5.10 2.90 3.00 3.10 -----0.65 ----0.40 0.53 0.66 ----------0.10 0 -----6 9 DIMENSIONS IN INCHES MIN. NOM. MAX. 0.032 0.0375 0.043 0.002 0.004 0.006 0.030 0.034 0.038 0.011 0.012 0.015 0.005 0.006 0.009 0.114 0.118 0.122 0.185 0.193 0.201 0.114 0.118 0.122 -----0.026 -----0.016 0.021 0.026 ----------0.004 0 -----6