PAM2306AYPKE

A Product Line of Diodes Incorporated PAM2306 DUAL HIGH-EFFICIENCY PWM STEP-DOWN DC-DC CONVERTER Description Pin Assignments The PAM2306 is a dual step-down current-mode, DC-DC converter. At heavy load, the constant frequency PWM control provides excellent stability and transient response. To ensure the longest battery life in portable applications, the PAM2306 provides a power saving Pulse-Skipping Modulation (PSM) mode to reduce quiescent current under light load operation. The PAM2306 supports a range of input voltages from 2.5V to 5.5V, allowing the use of a single Li+/Li-polymer cell, multiple Alkaline/NiMH cell, USB, and other standard power sources. The dual output voltages are available for 3.3V, 2.8V, 2.5V, 1.8V, 1.5V, 1.2V or adjustable. All versions employ internal power switch and synchronous rectifier to minimize external part count and realize high efficiency. During shutdown, the input is disconnected from the output and the shutdown current is less than 0.1A. Other key features include under-voltage lockout to prevent deep battery discharge. Features Applications  Efficiency up to 96%  Cellular Phone Only 40μA (typ per channel) Quiescent Current  Portable Electronics Output Current: Up to 1A per Channel  Personal Information Appliances Internal Synchronous Rectifier  Wireless and DSL Modems  1.5MHz Switching Frequency  MP3 Players  Soft Start  Under-Voltage Lockout  Short Circuit Protection  Thermal Shutdown  Small 12L WDFN3x3 Package  Pb-Free Package and RoHS Compliant    Typical Applications Circuit V OUT  VREF 1 Rx1   Rx 2  Figure 1. Adjustable Voltage Regulator PAM2306 Document number: DS36392 Rev. 1 - 2 1 of 15 www.diodes.com November 2012 © Diodes Incorporated A Product Line of Diodes Incorporated PAM2306 Typical Applications Circuit VOUT = 1.2V, 1.5V, 1.8V, 2.5V, 2.8V, 3.3V Figure 2. Fixed Voltage Regulator Pin Descriptions Pin Number 1 2 3, 9 Exposed Pad 4 5, 11 Pin Name WDFN3x3-12L VIN2 LX2 GND FB1 NC1, NC2 Function Power Input of Channel 2. Pin for Switching of Channel 2. Ground. The exposed pad must be soldered to a large PCB and connected to GND for maximum power dissipation. Feedback of Channel 1. No Connection 6 EN1 7 8 10 VIN1 LX1 FB2 Chip Enable of Channel 1 (Active High). VEN1 ≤ VIN1. Power Input of Channel 1. Pin for Switching of Channel 1. Feedback of Channel 2. 12 EN2 Chip Enable of Channel 2 (Active High). VEN2 ≤ VIN2. PAM2306 Document number: DS36392 Rev. 1 - 2 2 of 15 www.diodes.com November 2012 © Diodes Incorporated A Product Line of Diodes Incorporated PAM2306 Functional Block Diagram Absolute Maximum Ratings (@TA = +25°C, unless otherwise specified.) These are stress ratings only and functional operation is not implied. Exposure to absolute maximum ratings for prolonged time periods may affect device reliability. All voltages are with respect to ground. Parameter Input Voltage EN1, FB1, LX1, EN2, FB2 and LX2 Pin Voltage Maximum Junction Temperature Storage Temperature Range Soldering Temperature Rating -0.3 to +6.5 Unit V -0.3 to (VIN +0.3) 150 -65 to +150 260, 10sec °C °C °C V Recommended Operating Conditions (@TA = +25°C, unless otherwise specified.) Parameter Supply Voltage Ambient Temperature Range Junction Temperature Range Rating 2.5 to 5.5 -40 to +85 -40 to +125 Unit V °C °C Thermal Information Parameter Thermal Resistance (Junction to Ambient) θJA Package WDFN3x3-12 Thermal Resistance (Junction to Case) θJC Power Dissipation PD PAM2306 Document number: DS36392 Rev. 1 - 2 Symbol Maximum Unit 60 °C/W WDFN3x3-12 8.5 °C/W WDFN3x3-12 1.66 W 3 of 15 www.diodes.com November 2012 © Diodes Incorporated A Product Line of Diodes Incorporated PAM2306 Electrical Characteristics (@TA = +25°C, VIN = 3.6V, VO = 1.8V, CIN = 10µF, CO = 10µF, L = 2.2µH, unless otherwise specified.) Parameter Input Voltage Range Regulated Feedback Voltage Symbol Test Conditions Min VIN 2.5 VFB 0.588 Typ 0.6 Reference Voltage Line Regulation ∆VFB Regulated Output Voltage Accuracy VO IO = 10mA Peak Indictor Current IPK VIN = 3V, VFB = 0.5V or VO = 90% 1.5 Max V 0.612 V 0.3 -3 Units 5.5 %/V +3 % %/V A Output Voltage Line Regulation LNR VIN = 2.5V to 5V, IO = 10mA 0.2 0.5 Output Voltage Load Regulation LDR IO = 1mA to 1A 0.5 1.5 % Quiescent Current (per channel) IQ No load 40 70 µA Shutdown Current (per channel) ISD Oscillator Frequency fOSC Drain-Source On-State Resistance RDS(ON) SW Leakage Current (per channel) High Efficiency ILSW η EN Threshold High VEH EN Threshold Low VEL EN Leakage Current IEN OTP OTH Over Temperature Protection OTP Hysteresis PAM2306 Document number: DS36392 Rev. 1 - 2 VEN = 0V 1.2 VO = 100% 1 µA 1.5 1.8 MHz 500 VFB = 0V or VO = 0V IDS = 100mA 0.1 P MOSFET N MOSFET kHz 0.3 0.35 0.45 0.5 Ω Ω ±0.01 1 µA 96 % 1.5 V 0.3 4 of 15 www.diodes.com V ±0.01 µA 150 30 °C °C November 2012 © Diodes Incorporated A Product Line of Diodes Incorporated PAM2306 Typical Performance Characteristics (@TA = +25°C, CIN = 10µF, CO = 10µF, L = 4.7µH, unless otherwise specified.) PAM2306 Document number: DS36392 Rev. 1 - 2 5 of 15 www.diodes.com November 2012 © Diodes Incorporated A Product Line of Diodes Incorporated PAM2306 Typical Performance Characteristics (cont.) (@TA = +25°C, CIN = 10µF, CO = 10µF, L = 4.7µH, unless otherwise specified.) PAM2306 Document number: DS36392 Rev. 1 - 2 6 of 15 www.diodes.com November 2012 © Diodes Incorporated A Product Line of Diodes Incorporated PAM2306 Typical Performance Characteristics (cont.) (@TA = +25°C, CIN = 10µF, CO = 10µF, L = 4.7µH, unless otherwise specified.) PAM2306 Document number: DS36392 Rev. 1 - 2 7 of 15 www.diodes.com November 2012 © Diodes Incorporated A Product Line of Diodes Incorporated PAM2306 Typical Performance Characteristics (cont.) (@TA = +25°C, CIN = 10µF, CO = 10µF, L = 4.7µH, unless otherwise specified.) PAM2306 Document number: DS36392 Rev. 1 - 2 8 of 15 www.diodes.com November 2012 © Diodes Incorporated A Product Line of Diodes Incorporated PAM2306 Typical Performance Characteristics (cont.) (@TA = +25°C, CIN = 10µF, CO = 10µF, L = 4.7µH, unless otherwise specified.) PAM2306 Document number: DS36392 Rev. 1 - 2 9 of 15 www.diodes.com November 2012 © Diodes Incorporated A Product Line of Diodes Incorporated PAM2306 Application Information The basic PAM2306 application circuit is shown in Page 1. External component selection is determined by the load requirement, selecting L first and then CIN and COUT. Inductor Selection For most applications, the value of the inductor will fall in the range of 1μH to 4.7μH. Its value is chosen based on the desired ripple current. Large value inductors lower ripple current and small value inductors result in higher ripple currents. Higher VIN or VOUT also increases the ripple current as shown in Equation 1. A reasonable starting point for setting ripple current is ∆IL = 400mA (40% of 1A).  IL    1  V OUT  VIN  1 Equation f L  VOUT  (1) 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 1.4A rated inductor should be enough for most applications (1A + 400mA). For better efficiency, choose a low DC-resistance inductor. VO L 1.2V 1.5V 1.8V 2.5V 3.3V 2.2 µH 2.2 µH 2.2 µH 4.7 µH 4.7µH CIN and COUT Selection In continuous mode, the source current of the top MOSFET is a square wave of duty cycle VOUT/VIN. To prevent large voltage transients, a low ESR input capacitor sized for the maximum RMS current must be used. The maximum RMS capacitor current is given by: CIN required IRMS  IOMAX VOUT VIN  VOUT 1 / 2 VIN This formula has a maximum at VIN = 2VOUT, where IRMS = IOUT /2. This simple worst-case condition is commonly used for design because even significant deviations do not offer much relief. Note that the capacitor manufacturer's ripple current ratings are often based on 2000 hours of life. This makes it advisable to further derate the capacitor, or choose a capacitor rated at a higher temperature than required. Consult the manufacturer if there is any question. The selection of COUT is driven by the required effective series resistance (ESR). Typically, 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:  1   V OUT   IL  ESR  8fCOUT   Where f = operating frequency, COUT = output capacitance and ∆IL = ripple current in the inductor. For a fixed output voltage, the output ripple is highest at maximum input voltage since ∆IL increases with input voltage. Using Ceramic Input and Output Capacitors Higher values, lower cost ceramic capacitors are now becoming available in smaller case sizes. Their high ripple current, high voltage rating and low ESR make them ideal for switching regulator applications. Using ceramic capacitors can achieve very low output ripple and small circuit size. 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. Thermal Consideration Thermal protection limits power dissipation in the PAM2306. When the junction temperature exceeds +150°C, the OTP (Over Temperature Protection) starts the thermal shutdown and turns the pass transistor off. The pass transistor resumes operation after the junction temperature drops below +120°C. For continuous operation, the junction temperature should be maintain below +125°C. The power dissipation is defined as: PD  IO 2 V O RDS(ON)H  VIN  V O RDS(ON)L VIN  tSW FS IO  IQ  VIN IQ is the step-down converter quiescent current. The term tsw is used to estimate the full load step-down converter switching losses. 10 of 15 November 2012 PAM2306 © Diodes Incorporated www.diodes.com Document number: DS36392 Rev. 1 - 2 A Product Line of Diodes Incorporated PAM2306 Application Information (cont.) Thermal Consideration (cont.) For the condition where the step-down converter is in dropout at 100% duty cycle, the total device dissipation reduces to: PD  IO 2 RDS(ON)H  IQ VIN Since RDS(ON), quiescent current, and switching losses all vary with input voltage, the total losses should be investigated over the complete input voltage range. The maximum power dissipation depends on the thermal resistance of IC package, PCB layout, the rate of surrounding airflow and temperature difference between junction and ambient. The maximum power dissipation can be calculated by the following formula: PD  TJ(MAX )  T A JA Where TJ(MAX) is the maximum allowable junction temperature +125°C. TA is the ambient temperature and θJA is the thermal resistance from the junction to the ambient. Based on the standard JEDEC for a two layers thermal test board, the thermal resistance θJA of WDFN3X3 is 60°C/W. The maximum power dissipation at TA = +25°C can be calculated by following formula: PD = (125°C - 25°C)/60°C/W = 1.66W Setting the Output Voltage The internal reference is 0.6V (Typical). The output voltage is calculated as below: R1    V O  0 .6   1   R2  The output voltage is given by Table 1. Table 1: Resistor selection for output voltage setting VO 1.2V 1.5V 1.8V 2.5V 3.3V R1 R2 100k 150k 200k 380k 540k 100k 100k 100k 120k 120k 100% Duty Cycle Operation As the input voltage approaches the output voltage, the converter turns the P-Channel transistor continuously on. In this mode the output voltage is equal to the input voltage minus the voltage drop across the P-Channel transistor: VOUT = VIN - ILOAD (RDS(ON) + RL ) where RDS(ON) = P-Channel switch ON Resistance, ILOAD = Output Current, RL = Inductor DC Resistance. UVLO and Soft-Start The reference and the circuit remain reset until the VIN crosses its UVLO threshold. The PAM2306 has an internal soft-start circuit that limits the in-rush current during start-up. This prevents possible voltage drops of the input voltage and eliminates the output voltage overshoot. The soft-start acts as a digital circuit to increase the switch current in several steps to the PChannel current limit (1500mA). Short Circuit Prectection The switch peak current is limited cycle-by-cycle to a typical value of 1500mA. In the event of an output voltage short circuit, the device operates with a frequency of 400kHz and minimum duty cycle, therefore the average input current is typically 200mA. Thermal Shutdown When the die temperature exceeds +150°C, a reset occurs and the reset remains until the temperature decrease to +120°C, at which time the circuit can be restarted. PAM2306 Document number: DS36392 Rev. 1 - 2 11 of 15 www.diodes.com November 2012 © Diodes Incorporated A Product Line of Diodes Incorporated PAM2306 Application Information (cont.) PCB Layout Check List When laying out the printed circuit board, the following checklist should be used to ensure proper operation of the PAM2306. These items are also illustrated graphically in Figure 1. Check the following in your layout: 1. The power traces, consisting of the GND trace, the SW trace and the VIN trace should be kept short, direct and wide. 2. Does the FB pin connect directly to the feedback resistors? The resistive divider R1/R2 must be c onnected between the (+) plate of COUT and ground. 3. Does the (+) plate of CIN connect to VIN as closely as possible? This capacitor provides the AC current to the internal power MOSFETs. 4. Keep the switching node, SW, away from the sensitive FB node. 5. Keep the (–) plates of CIN and COUT as close as possible. Top Bottom Figure 1. PAM2306 Suggested Layout PAM2306 Document number: DS36392 Rev. 1 - 2 12 of 15 www.diodes.com November 2012 © Diodes Incorporated A Product Line of Diodes Incorporated PAM2306 Ordering Information Part Number Marking Package Type Packaging PAM2306AYPv1v2 2306v1v2 XXXYW W-DFN3x3-12 3000 Units/ Tape&Reel Marking Information PAM2306 Document number: DS36392 Rev. 1 - 2 13 of 15 www.diodes.com November 2012 © Diodes Incorporated A Product Line of Diodes Incorporated PAM2306 Package Outline Dimensions (All dimensions in mm.) Suggested Pad Layout PAM2306 Document number: DS36392 Rev. 1 - 2 14 of 15 www.diodes.com November 2012 © Diodes Incorporated A Product Line of Diodes Incorporated PAM2306 IMPORTANT NOTICE DIODES INCORPORATED MAKES NO WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, WITH REGARDS TO THIS DOCUMENT, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE (AND THEIR EQUIVALENTS UNDER THE LAWS OF ANY JURISDICTION). Diodes Incorporated and its subsidiaries reserve the right to make modifications, enhancements, improvements, corrections or other changes without further notice to this document and any product described herein. Diodes Incorporated does not assume any liability arising out of the application or use of this document or any product described herein; neither does Diodes Incorporated convey any license under its patent or trademark rights, nor the rights of others. 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Copyright © 2012, Diodes Incorporated www.diodes.com PAM2306 Document number: DS36392 Rev. 1 - 2 15 of 15 www.diodes.com November 2012 © Diodes Incorporated