LP3204A-28B5

LP3204 1.5MHz, 800mA, High Efficiency Synchronous PWM Step-Down DC/DC Convert General Description The LP3204 is a constant frequency, current mode, PWM step-down converter. The device integrates a main switch and a synchronous rectifier for high efficiency. The 2.5V to 5.5V input voltage range makes the LP3204 is ideally suited for portable electronic devices that are powered from 1-cell Li-ion battery or from other power sources within the range such as cellular phones, PDAs and handy-terminals. Internal synchronous rectifier with low RDS(ON) dramatically reduces conduction loss at PWM mode. The internal synchronous switch increases efficiency while eliminate the need for an external Schottky diode.The switching ripple is easily smoothed-out by small package filtering elements due to a fixed operation frequency of 1.5MHz. This along with small SOT-23-5 package provide small PCB area application. Other features include soft start, lower internal reference voltage with 2% accuracy, over temperature protection, and over current protection. Features High Efficiency: 96% 1.5MHz Fixed-Frequency PWM Operation Adjustable Output From 0.6V to VIN 800mA Output Current, 1.1A Peak Current No Schottky Diode Required 100% Duty Cycle Low Dropout Operation Available in SOT23-5 Package Short Circuit and Thermal Protection Over Voltage Protection Low than 1µA Shutdown Current Applications Portable Media Players/MP3 players Cellular and Smart mobile phone PDA DSC Wireless Card Pin Configurations Ordering Information LP3204 □ - □ □ □ □ A-Type Package Type B5: SOT-23-5 Output Voltage: 15: 1.5V 18: 1.8V 25: 2.5V 28: 2.8V AD:Adjust Output Type: A:A-Type B:B-Type B-Type Marking Information RoHS compliant and compatible with the current require ments of IPC/JEDEC J-STD-0202. Suitable for use in SnPb or Pb-free soldering processes. LP3204-datasheet Feb.-2006 1 -1 LP3204 Typical Application Circuit LP3204-datasheet Feb.-2006 2 -2 LP3204 Functional Pin Description Function Block Diagram Absolute Maximum Ratings LP3204-datasheet Feb.-2006 3 -3 LP3204 Electrical Characteristics (VIN = 3.6V, VOUT = 2.5V, VREF = 0.6V, L = 2.2µH, CIN= 4.7µF, COUT= 10µF, TA= 25°C, IMAX = 650mA unless otherwise specified) Parameter Input Voltage Range Quiescent Current Shutdown Current Reference Voltage Adjustable Output Range Symbol VIN IQ ISHDN VREF VOUT Δ VOUT Δ VOUT Fix Output Voltage Accuracy Δ VOUT Δ VOUT Δ VOUT Δ VOUT Δ VOUT VFB = VIN IOUT = 200mA IOUT = 200mA VIN = 2.2 to 5.5 V VIN = 3.6V VIN = 3.6V VIN = 2.2 to 5.5V, VOUT = 1.0V 0A < IOUT < 600mA VIN = 2.2 to 5.5V, VOUT = 1.2V 0A < IOUT < 600mA VIN = 2.2 to 5.5V, VOUT = 1.5V 0A < IOUT < 600mA VIN = 2.2 to 5.5V, VOUT = 1.8V 0A < IOUT < 600mA VIN = 2.8 to 5.5V, VOUT = 2.5V 0A < IOUT < 600mA VIN = 3.5 to 5.5V, VOUT = 3.3V 0A < IOUT < 600mA VIN = VOUT + 0.2V to 5.5V, VIN ≧ Adjustable 3.5V 0A < IOUT < 600mA VIN = VOUT + 0.4V to 5.5V, VIN ≧ 2.2V 0A < IOUT < 600mA FB Input Current PMOSFET RON NMOSFET RON P-Channel Current Limit EN Threshold EN Leakage Current IFB IOUT = 0mA, VFB = VREF + 5% EN = GND For adjustable output voltage 0.588 VREF −3 −3 −3 −3 −3 −3 −3 −3 -30 0.16 0.19 Test Conditions Min 2.5 270 0.1 0.6 Typ Max 6 370 1 0.612 VIN − 0.2 +3 +3 +3 +3 +3 +3 +3 +3 30 0.26 Units V μA μA V V % % % % % % % % nA Ω Ω PRDS(ON) NRDS(ON) IP(LM) 1 1.2 1.4 VEN 0.3 1.0 1.5 V VENL -- 1 uA LP3204-datasheet Feb.-2006 4 -4 LP3204 Typical Operating Characteristics LP3204-datasheet Feb.-2006 5 -5 LP3204 LP3204-datasheet Feb.-2006 6 -6 LP3204 LP3204-datasheet Feb.-2006 7 -7 LP3204 Applications Information The basic LP3204 application circuit is shown in Typical Application Circuit. External component selection is determined by the maximum load current and begins with the selection of the inductor value and operating frequency followed by CIN and COUT. LP3204-datasheet Feb.-2006 8 -8 LP3204 LP3204-datasheet Feb.-2006 9 -9 LP3204 Checking Transient Response The regulator loop response can be checked by looking at the load transient response. Switching regulators take several cycles to respond to a step in load current. When a load step occurs, VOUT immediately shifts by an amount equal to ∆ILOAD (ESR), where ESR is the effective series resistance of COUT. ∆ILOAD also begins to charge or discharge COUT generating a feedback error signal used by the regulator to return VOUT to its steady-state value. During this recovery time, VOUT can be monitored for overshoot or ringing that would indicate a stability problem. Layout Considerations Follow the PCB layout guidelines for optimal performance of LP3204. For the main current paths as indicated in bold lines, keep their traces short and wide. Put the input capacitor as close as possible to the device pins (VIN and GND). LX node is with high frequency voltage swing and should be kept small area. Keep analog components away from LX node to prevent stray capacitive noise pick-up. Connect feedback network behind the output capacitors. Keep the loop area small. Place the feedback components near the LP3204. Connect all analog grounds to a command node and then connect the command node to the power ground behind the output capacitors. LP3204-datasheet Feb.-2006 10 -10 LP3204 LP3204-datasheet Feb.-2006 11 -11