EUP3020 Dual High-Efficiency 1.5MHz 1A PWM Step-Down DC-DC Converter DESCRIPTION FEATURES The EUP3020 contains two independent 1.5MHz constant frequency, current mode, PWM step-down converters. Each converter integrates a main switch and a synchronous rectifier for high efficiency without an external Schottky diode. The EUP3020 is ideal for powering portable equipment that runs from a single cell Lithium-Ion (Li+) battery. Each converter can supply 1A of load current from a 2.5V to 5.5V input voltage. The output voltage can be regulated as low as 0.6V. The EUP3020 can also run at 100% duty cycle for low dropout applications. EUP3020 is available in an adjustable output or fixed output 1.2V, 1.8V and 3.3V. z z z z z z z z z z z z z Up to 96% Efficiency 1.5MHz Constant Switching Frequency 1A Load Current on Each Channel 2.5V to 5.5V Input Voltage Range Output Voltage as Low as 0.6V 100% Duty Cycle in Dropout Current Mode Operation Short Circuit Protection Thermal Fault Protection <1µA Shutdown Current Soft Start Function Space Saving 3mm × 3mm 12-Pin TDFN Package RoHS Compliant and 100% Lead(Pb)-Free APPLICATIONS z z z z z Cellular and Smart Phones Microprocessors and DSP Core Supplies PDAs and Portable Media Players Wireless and DSL Modems Digital Still and Video Cameras Typical Application Circuit Figure 1. Adjustable Output Regulators DS3020 Ver1.2 Feb. 2009 1 EUP3020 Typical Application Circuit (continued) Figure 2. Fixed Output Regulators Pin Configurations Package Type Package Type Pin Configurations TDFN-12 TDFN-12 ADJ Voltage Fixed Voltage Pin Description PIN Pin VIN2 1 Power Input of Channel 2. SW2 2 Pin for Switching of Channel 2. GND 3,9 FB1/VOUT1 4 NC1,NC2 5,11 EN1 6 Chip Enable of Channel 1 (Active High).VEN1 ≤ VIN1. VIN1 7 Power Input of Channel 1. SW1 8 Pin for Switching of Channel1. FB2/VOUT2 10 Feedback/Output Voltage Pin of Channel 2. EN2 12 Chip Enable of Channel 2 (Active High).VEN2 ≤ VIN2. DS3020 Ver1.2 Feb. 2009 DESCRIPTION Ground. Feedback/Output Voltage Pin of Channel 1. No Connection or Connect to VIN. 2 Pin Configurations EUP3020 Ordering Information Order Number Package Type EUP3020-1.8/1.2JIR1 TDFN-12 EUP3020-3.3/1.2JIR1 TDFN-12 EUP3020-3.3/1.8JIR1 TDFN-12 EUP3020JIR1 TDFN-12 Marking xxxxx P3020 BK xxxxx P3020 BN xxxxx P3020 BL xxxxx P3020 1A EUP3020-□□/□□ □ □ □ □ Lead Free Code 1: Lead Free 0: Lead Packing R: Tape & Reel Operating temperature range I: Industry Standard Package Type J: TDFN Output Voltage Option *EUP3020-VOUT1/VOUT2 JIR1 Blank: Adjustable Block Diagram Figure 3. DS3020 Ver1.2 Feb. 2009 3 Operating Temperature Range -40 °C to +85°C -40 °C to +85°C -40 °C to +85°C -40 °C to +85°C EUP3020 Absolute Maximum Ratings (1) VIN1/IN2 to GND ---------------------------------------------------------------------- -0.3V to 6V VSW1/SW2 to GND ------------------------------------------------------------ -0.3V to VIN+0.3V VFB1/FB2 ,VEN1/EN2 to GND -------------------------------------------------------- -0.3V to VIN Junction Temperature --------------------------------------------------------------------- 125°C Storage Temperature --------------------------------------------------------- -65°C to +150°C Lead Temp (Soldering, 10sec) ------------------------------------------------------260°C Recommended Operating Conditions (2) Supply Voltage, VIN1/IN2 ---------------------------------------------------------- 2.5V to 5.5V Output Voltage, VOUT1/OUT2 -----------------------------------------------------0.6V to 5V Operating Temperature -------------------------------------------------------- -40°C to +85°C Note (1): Stress beyond those listed under “Absolute Maximum Ratings” may damage the device. Note (2): The device is not guaranteed to function outside the recommended operating conditions. Electrical Characteristics VIN1/IN2 =VEN1/EN2 =3.6V, TA=+25°C, Unless otherwise specified. Symbol Parameter VIN Input Voltage Range IFB Feedback Current IQ Each converter Supply Current ISHDN Conditions Min EUP3020 Typ Max. 2.5 5.5 VFB1/FB2=0.5V, SW1/SW2 Open IPK Peak Inductor Current VIN1/IN2=3V,VFB1/FB2=0.5V VFB Regulator Feedback Voltage (Note 3) VOUT Regulation Output Voltage IOUT=200mA Output Voltage Line Regulation Reference Voltage Line Regulation Output Voltage Load Regulation VIN=2.5V to 5.5V, ILOAD=0 ∆VFB ∆VLOADREG V ±30 270 Each converter Shutdown Current VEN1/EN2=0V, VIN1/IN2=4.2V ∆VOUT Unit nA 370 µA 1 µA 1.2 1.5 TA=+25℃ 0.588 0.6 0.612 -40℃≤ TA≤ +85℃ 0.585 0.6 0.615 -3 A V 3 % 0.25 0.4 %/V VIN=2.5V to 5.5V 0.25 0.4 %/V ILOAD=0 to 1A 0.5 1.2 fOSC Each converter Oscillator Frequency VFB1/FB2=0.6V VFB1/FB2=0 0.7 RPFET RDS(ON) of P-Channel FET ISW1/SW2=200mA 0.28 0.4 Ω RNFET RDS(ON) of N-Channel FET 0.3 0.4 Ω ILSW SW Leakage Current ±1 µA VEN EN Threshold ISW1/SW2= -200mA VEN1/EN2=0V, VSW1/SW2=0 or 5V, VIN1/IN2=5V -40℃≤ TA ≤ +85℃ 1.5 V 0.3 1.5 % 1.0 1.8 MHz Note (3): The EUP3020 is tested in a proprietary test mode that connects FB1/FB2 to the output of the error amplifier. DS3020 Ver1.2 Feb. 2009 4 EUP3020 Typical Operating Characteristics DS3020 Ver1.2 Feb. 2009 5 EUP3020 DS3020 Ver1.2 Feb. 2009 6 EUP3020 DS3020 Ver1.2 Feb. 2009 7 EUP3020 Operation Short Circuit Protection The EUP3020 has dual independent constant frequency current mode PWM step-down converters. The EUP3020 is optimized for low voltage, Li-Ion battery powered applications where high efficiency and small size are critical. The EUP3020 uses resistor dividers to set two output voltages independently from 0.6V to 5V. The device integrates both main switches and synchronous rectifiers, which provides high efficiency and eliminates the need for an external Schottky diode. The EUP3020 can achieve 100% duty cycle. The duty cycle D of each step-down converter is defined as: The EUP3020 has short circuit protection. When any output is shorted to ground, the own oscillator frequency is reduced to prevent the inductor current from increasing beyond the PFET current limit. The PFET current limit is also reduced to lower the short circuit current. The frequency and current limit will return to the normal values once the short circuit condition is removed and the feedback voltage reaches 0.6V. VOUT D = TON × f OSC × 100% = × 100% VIN Where TON is the main switch on time, fOSC is the oscillator frequency (1.5MHz), VOUT is the output voltage and VIN is the input voltage. Current Mode PWM Control Slope compensated current mode PWM control provides stable switching and cycle-by-cycle current limit for superior load and line response and protection of the internal main switch and synchronous rectifier. Each channel switches at a constant frequency (1.5MHz) and regulates the output voltage. During each cycle the PWM comparator modulates the power transferred to the load by changing the inductor peak current based on the feedback error voltage. During normal operation, the main switch 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 reached. When the main switch is off, the synchronous rectifier will be turned on immediately and stay on until the next cycle starts or the inductor current starts to reverse. Dropout Operation Each channel of the EUP3020 allows the main switch to remain on for more than one switching cycle and increases the duty cycle while the input voltage is dropping close to the output voltage. When the duty cycle reaches 100%, the main switch is held on continuously to deliver current to the output up to the PFET current limit. The output voltage then is the input voltage minus the voltage drop across the main switch and the inductor. DS3020 Ver1.2 Feb. 2009 8 Maximum Load Current The EUP3020 can operate down to 2.5V input voltage, 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. EUP3020 Application Information Output Voltage Programming Inductor Selection The output voltage is set by a resistive divider according to the following formula: The output inductor is selected to limit the ripple current to some predetermined value, typically 20%~40% of the full load current at the maximum input voltage. Large value inductors lower ripple currents. Higher VIN or VOUT also increases the ripple current as shown in equation. A reasonable starting point for setting ripple current is ∆IL=400mA (40% of 1A). V × VOUT × 1 − OUT (f)(L) VIN 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. Thus, a 1.2A rated inductor should be enough for most applications (1A+200mA). For better efficiency, choose a low DC-resistance inductor. ∆I L = 1 CIN and COUT Selection In continuous mode, the source current of the top MOSFET is a square wave of duty cycle VOUT/VIN. The primary function of the input capacitor is to provide a low impedance loop for the edges of pulsed current drawn by the EUP3020. A low ESR input capacitor sized for the maximum RMS current must be used. The size required will vary depending on the load, output voltage and input voltage source impedance characteristics. A typical value is around 4.7µF. The input capacitor RMS current varies with the input voltage and the output voltage. The equation for the maximum RMS current in the input capacitor is: I RMS =I O × V V O × 1 − O V V IN IN OUT 1 When choosing the input and output ceramic capacitors, choose the X5R or X7R dielectric formulations. These dielectrics have the best temperature and voltage characteristics of all the ceramics for a given value and size. DS3020 Ver1.2 Feb. 2009 For adjustable voltage package, the external resistive divider is connected to the output, allowing remote voltage sensing as shown in below figure. CX1 is a feedforward cap which can speed loop response and reduce output ripple during load transient. Choose CX1 value between 220pF and 680pF for most applications. Thermal Dissipation To avoid the EUP3020 from exceeding the maximum junction temperature, the user will need to do a thermal analysis. The goal of the thermal analysis is to determine whether the operating conditions exceed the maximum junction temperature of the part. The temperature rise is given by: TR=(PD)(θJA) The output capacitor COUT has a strong effect on loop stability. The selection of COUT is driven by the required effective series resistance (ESR). ESR is a direct function of the volume of the capacitor; that is, physically larger capacitors have lower ESR. Once the ESR requirement for COUT has been met, the RMS current rating generally far exceeds the IRIPPLE(P-P) requirement. The output ripple ∆VOUT is determined by: ∆VOUT ≅ ∆I L × ESR + 8fC R VOUTX = 0.6V × 1 + X1 R X2 9 Where PD=ILOAD2 × RDS(ON) is the power dissipated by the regulator ; θJA is the thermal resistance from the junction of the die to the ambient temperature. The junction temperature, TJ, is given by: TJ=TA+TR Where TA is the ambient temperature. TJ should be below the maximum junction temperature of 125°C. PC Board Layout The high current paths (GND1/GND2, VIN1/VIN2 and SW1/SW2) should be placed very close to the device with short, direct and wide traces. Input capacitors should be placed as close as possible to the respective VIN and GND pins. For adjustable voltage package, the external feedback resistors shall be placed next to the FB pins. Keep the switching nodes SW1/SW2 short and away from the feedback network. EUP3020 Packaging Information TDFN-12 SYMBOLS A A1 b E D D1 E1 e L DS3020 Ver1.2 Feb. 2009 MILLIMETERS MIN. MAX. 0.70 0.80 0.00 0.05 0.18 0.30 2.90 3.10 2.90 3.10 2.40 1.70 0.45 0.30 0.50 10 INCHES MIN. 0.028 0.000 0.007 0.114 0.114 MAX. 0.031 0.002 0.012 0.122 0.122 0.094 0.067 0.018 0.012 0.020