AP1513. PWM Control 2A Step-Down Converter. Features. General Description. Applications. Pin Descriptions. Pin Assignments

Transcription

1 Features Input voltage: 3.6V to 18V. voltage: 0.8V to V CC. Duty ratio: 0% to 100% PWM control Oscillation frequency: 300KHz typ. Softstart, Current limit, Enable function Thermal Shutdown function Builtin internal SW Pchannel MOS SOP8L PbFree Package. Applications PC Motherboard LCD Monitor Graphic Card DVDVideo Player Telecom Equipment ADSL Modem Printer and other Peripheral Equipment Microprocessor core supply Networking power supply Pin Assignments General Description consists of stepdown switching regulator with PWM control. These devices include a reference voltage source, oscillation circuit, error amplifier, internal PMOS and etc. provides lowripple power, high efficiency, and excellent transient characteristics. The PWM control circuit is able to vary the duty ratio linearly from 0 up to 100%. This converter also contains an error amplifier circuit as well as a softstart circuit that prevents overshoot at startup. An enable function, an over current protect function and a short circuit protect function are built inside, and when OCP or SCP happens, the operation frequency will be reduced from 300KHz to 30KHz. Also, an internal compensation block is built in to minimum external component count. With the addition of an internal Pchannel Power MOS, a coil, capacitors, and a diode connected externally, these ICs can function as stepdown switching regulators. They serve as ideal power supply units for portable devices when coupled with the SOP 8L minipackage, providing such outstanding features as low current consumption. Since this converter can accommodate an input voltage up to 18V, it is also suitable for the operation via an AC adapter. Pin Descriptions Vss Vss Name Pin Description 1 Feedback pin. 2 Poweroff pin H: Normal operation (Stepdown operation) L: Stepdown operation stopped (All circuits deactivated) 3 Add an external resistor to set max output current. 4 IC power supply pin 5 6 Switch Pin. Connect external inductor/diode here. Minimize trace area at this pin to reduce EMI. VSS 7 8 GND Pin 1/7

2 Ordering Information AP 1513 X X Package Packing S: SOP8L Blank : Tube A : Taping Block Diagram Vcc Oscillation Circuit Reference Voltage Source with Soft Start Thermal Shutdown PWMSwitched Control Circuit V 100uA Vss Absolute Maximum Ratings Symbol Parameter Rating Unit V CC Pin Voltage V SS 0.3 to V SS 20 V V Feedback Pin Voltage V SS 0.3 to V CC V V Pin Voltage V SS 0.3 to V IN 0.3 V V OUTPUT Switch Pin Voltage V SS 0.3 to V IN 0.3 V P D Power Dissipation Internally limited mw T OPR Operating Temperature Range 20 to 125 o C T STG Storage Temperature Range 40 to 150 Caution: The absolute maximum ratings are rated values exceeding which the product could suffer physical damage. These values must therefore not be exceeded under any conditions. o C 2/7

3 Electrical Characteristics (VIN = 12V, T a =25 C, unless otherwise specified) Symbol Parameter Conditions Min. Typ. Max. Unit V IN Input Voltage V V Feedback Voltage I OUT =0.1A V I Feedback Bias Current I OUT =0.1A µa I SW Switch Current 2.5 A I SSS Current Consumption During Power Off V =0V 10 µa V OUT /V OUT V OUT /V OUT Line Regulation V IN =5V~18V 1 2 % Load Regulation I OUT =0.1 to 2A % f OSC Oscillation Frequency Measure waveform at SW pin KHz f OSC1 Frequency of Current Limit Measure waveform at SW pin or Short Circuit Protect 10 KHz V SH Evaluate oscillation at SW pin 2.0 Pin Input Voltage V SL Evaluate oscillation stop at SW pin 0.8 V I SH Pin Input Leakage 20 µa I SL Current 10 µa I Pin Bias Current µa T SS SoftStart Time ms V IN =5V, V =0V R DSON Internal MOSFET Rdson EFFI θ JA Efficiency Thermal Resistance JunctiontoAmbient Typical Application Circuit V IN =12V, V =0V V IN =12V, V OUT = 5V I OUT =2A mω 92 % 65 o C/W V IN Vcc L1 33uH V OUT =5V/2A C IN 470uF CVcc 0.1uF R 3K C Option R 100K C 0.1uF V SS D1 C C Optional R A 6.8K R B 1.3K C 0.1uF C OUT 470uF Note: V OUT = V x (1R A /R B ) R B =0.7K~5K ohm V IN =12V, I MAX =2A V OUT 2.5V 3.3V 5V L1 Value 22uH 27uH 33uH 3/7

4 Typical Performance Characteristics Fosc (KHz) Vin v.s. Frequency (Vout=3.3V; Iout=0.2A) Vin (V) (V) Vin v.s. (Vout=3.3V; Iout=0.2A) Vin (V) Vout (V) Line Regulation (Vout=3.3V; Iout=0.2A) Vin (V) Vout (V) Load Regulation (Vin=12V) Iout (A) Efficiency (%) Efficiency Vout:5.0V Vout:3.3V Iout (A) 4/7

5 Typical Performance Characteristics (Continued) Vout Ripple (Vin=12V; Vout=3.3V; Iout=0.1A) Vout Ripple (Vin=12V; Vout=3.3V; Iout=2A) Test Circuit A open OUTPUT VSS open Oscillation A OUTPUT VSS OUTPUT VSS V 5/7

6 Function Description PWM Control The consists of DC/DC converters that employ a pulsewidth modulation (PWM) system. In converters of the, the pulse width varies in a range from 0 to 100%, according to the load current. The ripple voltage produced by the switching can easily be removed through a filter because the switching frequency remains constant. Therefore, these converters provide a lowripple power over broad ranges of input voltage and load current. Under Voltage Lockout The under voltage lockout circuit of the assures that the highside MOSFET driver outputs remain in the off state whenever the supply voltage drops below 3.3V. Normal operation resumes once V CC rises above 3.5V. R DS(ON) Current Limiting The current limit threshold is setting by the external resistor connecting from V CC supply to. The internal 100uA sink current crossing the resistor sets the voltage at the pin of. When the PWM voltage is less than the voltage at, an overcurrent condition is triggered. I LOAD R DS(ON) = I R See above formula for setting the current limit value. Marking Information ( Top View ) 8 5 YY WW X 1 4 Logo Part no. ID code: internal Xth week: 01~52 Year: "01" =2001 "02" =2002 ~ 6/7

7 Package Information Package Type: SOP8L E H L VIEW "A" 7 (4X) D 0.015x45 7 (4X) A2 A e B A1 y C VIEW "A" Symbol Dimensions In Millimeters Dimensions In Inches Min. Nom. Max. Min. Nom. Max. A A A B C D E e H L y θ 0 O 8 O 0 O 8 O 7/7