AP1533 PWM CONTROL 1.8A STEP-DOWN CONVERTER General Description Features • • • • • • • • • • AP1533 consists of step-down switching regulator with PWM control. These devices include a reference voltage source, oscillation circuit, error amplifier, internal PMOS. Input voltage: 4V to 23V Output voltage: 0.8V to VCC Output current: 1.8A up to peak 2A Duty ratio: 0% to 99% PWM control Oscillation frequency: 300KHz typ. Soft-start like, Current limit and Enable function Thermal Shutdown function Built-in internal SW P-channel MOS SOP-8L: Available in “Green” Molding Compound (No Br, Sb) Lead Free Finish / RoHS Compliant (Note 1) AP1533 provides low-ripple power, high efficiency, and excellent transient characteristics. The PWM control circuit is able to vary the duty ratio linearly from 0 up to 99%. This converter also contains an error amplifier circuit as well as a soft-start 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 50KHz. Also, an internal compensation block is built in to minimum external component count. With the addition of an internal P-channel Power MOS, a coil, capacitors, and a diode connected externally, these ICs can function as step-down switching regulators. They serve as ideal power supply units for portable devices when coupled with the SOP-8L mini-package, providing such outstanding features as low current consumption. Since this converter can accommodate an input voltage up to 23V, it is also suitable for the operation via an AC adapter. Applications • • • • • • • • PC Motherboard LCD Monitor Graphic Card DVD-Video Player Telecom Equipment ADSL Modem Printer and other Peripheral Equipment Microprocessor core supply Ordering Information AP1533 X X X Package S : SOP-8L Note: Packing -U : Tube -13 : Taping 1. RoHS revision 13.2.2003. Glass and High Temperature Solder Exemptions Applied, see EU Directive Annex Notes 5 and 7. Device AP1533S Note: Lead Free G : Green Package Packaging Code (Note 2) S SOP-8L Tube/Bulk Quantity Part Number Suffix 100 -U 13” Tape and Reel Quantity Part Number Suffix 2500/Tape & Reel -13 2. Pad layout as shown on Diodes Inc. suggested pad layout document AP02001, which can be found on our website at http://www.diodes.com/datasheets/ap02001.pdf. AP1533 Rev. 1 1 of 8 www.diodes.com JULY 2007 © Diodes Incorporated AP1533 PWM CONTROL 1.8A STEP-DOWN CONVERTER Pin Assignments 8 VSS 7 VSS OCSET 3 6 Output VCC 4 5 Output FB 1 EN 2 AP1533 Pin Descriptions Pin Name Pin No. FB 1 Feedback pin EN 2 Power-off pin H: Normal operation (Step-down operation) L: Step-down operation stopped (All circuits deactivated) OCSET 3 Add an external resistor to set max output current VCC 4 IC power supply pin Output 5, 6 Switch Pin. Connect external inductor/diode here. Minimize trace area at this pin to reduce EMI VSS 7, 8 GND Pin AP1533 Rev. 1 Description 2 of 8 www.diodes.com JULY 2007 © Diodes Incorporated AP1533 PWM CONTROL 1.8A STEP-DOWN CONVERTER Block Diagram Output Oscillation Circuit Reference Voltage Source VCC + PWM-Switched Control Circuit FB - Thermal Shutdown VEN EN 90uA VSS OCSET Absolute Maximum Ratings Symbol Parameter Rating Unit VSS - 0.3 to VSS + 24 V VSS - 0.3 to VCC V V VCC VCC Pin Voltage VFB Feedback Pin Voltage VEN EN Pin Voltage VSS - 0.3 to VIN + 0.3 VOUT Switch Pin Voltage VSS - 0.3 to VIN + 0.3 V PD Power Dissipation Internally limited mW TJ Operating Junction Temperature Range TST Caution: Storage Temperature Range -20 to +125 o C -65 to +150 o C 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. Recommended Operating Conditions Symbol VIN IOUT TA AP1533 Rev. 1 Parameter Input Voltage Output Current Operating Ambient Temperature 3 of 8 www.diodes.com Min 4 0 -25 Max 23 1.8 85 Unit V A o C JULY 2007 © Diodes Incorporated AP1533 PWM CONTROL 1.8A STEP-DOWN CONVERTER Electrical Characteristics ( VIN = 12V, TA = 25°C, unless otherwise specified ) Symbol Parameter Conditions VFB Feedback Voltage IOUT = 0.1A IFB Feedback Bias Current IOUT = 0.1A Current Consumption During ISHDN VEN = 0V Power Off ∆VOUT Line Regulation / VIN ∆VOUT Load Regulation / VOUT fOSC Oscillation Frequency Frequency of Current Limit or fOSC1 Short Circuit Protection VIH EN Pin Input Voltage VIL ISH EN Pin Input Leakage Current ISL IOCSET OCSET Pin Bias Current RDS(ON) Internal MOSFET RDS(ON) Min 0.784 - Typ. 0.8 0.1 Max 0.816 0.5 Unit V µA - 10 - µA VIN = 5V~23V - 1 2 % IOUT = 0.1 to 1.8A - 0.2 0.5 % Measure waveform at SW pin 240 300 400 KHz Measure waveform at SW pin - 50 - KHz 2.0 75 - 20 -10 90 110 80 0.8 105 150 110 - 91 - % - 150 55 - °C °C - 134 - o C/W - 22 - o C/W Evaluate oscillation at SW pin Evaluate oscillation stop at SW pin EN Pin High EN Pin Low -VIN=5V, VFB=0V VIN=12V, VFB=0V VIN=12V, VOUT = 5V IOUT=1.8A EFFI Efficiency TSHDN THYS Thermal shutdown threshold Thermal shutdown hysteresis Thermal Resistance SOP-8L (Note 3) Junction-to-Ambient Thermal Resistance SOP-8L (Note 3) Junction-to-Case θJA θJC Note: V µA µA µA mΩ 3. Test condition: Device mounted on FR-4 PCB, 2”x2”, 2oz copper, minimum recommended pad layout, single side. For better thermal performance, larger copper pad for heatsink is needed. AP1533 Rev. 1 4 of 8 www.diodes.com JULY 2007 © Diodes Incorporated AP1533 PWM CONTROL 1.8A STEP-DOWN CONVERTER Typical Application Circuit VOUT=5V/1.8A L1 Vcc VIN Output 33uH ROCSET COCSET 3.3K Option CIN REN 100K CVcc 0.1uF EN + FB OCSET 470uF RA 6.8K CC Optional AP1533 VSS - + C 0.1uF - COUT 470uF RB 1.3K D1 (Note 4) CEN 0.1uF V OUT = VFB x (1+R A/RB) R B = 0.7K~5K ohm Note: 4. Suggested DIODES Power Schottky P/N: B340 series or PDS340. 320 318 316 314 312 310 308 306 304 302 300 VIN vs. Frequency VIN vs. VFB (VOUT=3.3V; IOUT=0.2A) (VOUT=3.3V; IOUT=0.2A) 0.820 0.815 0.810 VFB (V) FOSC (kHz) Typical Performance Characteristics 0.805 0.800 0.795 0.790 0.785 0.780 0 2 4 AP1533 Rev. 1 6 8 10 12 14 16 18 20 22 24 VIN (V) 5 of 8 www.diodes.com 0 2 4 6 8 10 12 14 16 18 20 22 24 VIN (V) JULY 2007 © Diodes Incorporated AP1533 PWM CONTROL 1.8A STEP-DOWN CONVERTER Typical Performance Characteristics ( Continued ) Line Regulation Load Regulation (VOUT=3.3V; IOUT=0.2A) 3.40 3.35 3.25 VOUT (V) VOUT (V) 3.30 3.20 3.15 3.10 3.05 3.00 0 2 4 6 8 (VIN=12V) 3.25 3.24 3.23 3.22 3.21 3.20 3.19 3.18 3.17 3.16 3.15 10 12 14 16 18 20 22 24 VIN (V) 0 0.5 1 IOUT (A) 1.5 2 Efficiency Efficiency (%) 100% 90% 80% 70% 60% 50% 40% 30% 20% 10% 0% VOUT=3.3V VOUT=5V 0 0.5 1 IOUT (A) 1.5 2 VOUT Ripple ( VIN = 12V; VOUT = 3.3V; IOUT = 0.1A ) AP1533 Rev. 1 6 of 8 www.diodes.com VOUT Ripple (VIN = 12V; VOUT = 3.3V; IOUT = 1.8A ) JULY 2007 © Diodes Incorporated AP1533 PWM CONTROL 1.8A STEP-DOWN CONVERTER Test Circuit VCC OUTPUT FB Oscillation open open OCSET A EN + + - OUTPUT OUTPUT OCSET EN - VSS Enable function test VCC VCC A FB VSS Feedback function test FB OCSET EN VSS + V - Operation function test Function Description PWM Control The AP1533 is a DC/DC converter that employs pulse width modulation (PWM) scheme. Its pulse width varies in the range of 0% to 99%, based on the output current loading. The output ripple voltage caused by the PWM high frequency switching can easily be reduced through an output filter. Therefore, this converter provides a low ripple output supply over a broad range of input voltage & output current loading Under Voltage Lockout The under voltage lockout circuit of the AP1533 assures that the high-side MOSFET driver remains in the off state whenever the supply voltage drops below 3.3V. Normal operation resumes once VCC rises above 3.5V. Current Limit Protection The current limit threshold is set by external resistor ROCSET connected from VCC supply to OCSET pin. The internal sink current IOCSET (90uA typical) across this resistor sets the voltage at OCSET pin. When the PWM voltage is less than the voltage at OCSET, an over-current condition is triggered. The current limit threshold is given by the following equation: IPEAK × RDS(ON) = IOCSET × R OCSET ( ΔI) IPEAK > IOUT (MAX) + 2 where, ΔI = VIN − VOUT FSxL x VOUT VIN IPEAK is the output peak current; RDS (ON) is the MOSFET ON resistance (115mΩ typical); FS is the PWM frequency (300KHz typical). Also, the inductor value will affect the ripple current ΔI. The above equation is recommended for input voltage range of 5V to 18V. For input voltage lower than 5V, higher than 18V or ambient temperature over 100°C, ROCSET≧3.9KΩ is recommended. The recommended minimum ROCSET value is summarized below: VOUT (V) ROCSET (Ω) VIN (V) 4 0.8 3.9K 5 3.3 3.3K 12 5 3.3K 18 12 3.3K 23 12 4.7K The maximum ROCSET value should not exceed AP1533 maximum current output. AP1533 Rev. 1 7 of 8 www.diodes.com JULY 2007 © Diodes Incorporated AP1533 PWM CONTROL 1.8A STEP-DOWN CONVERTER Marking Information (Top View) 5 8 Logo G : Green AP1533 YY WW X X Part No. 1 Internal code Xth week : 01~52 Year : "07" = 2007 "08" = 2008 4 ~ SOP-8L Package Information (unit: mm ) 0.254 0.08/0.25 5.79/6.20 3.70/4.10 Package Type: SOP-8L Gauge Plane Seating Plane 0.38/1.27 Detail "A" 7°~9° 0.20typ 1.30/1.50 1.75max. 0.35max. 45° 0.3/0.5 1.27typ 7°~9° Detail "A" 3.70/4.10 4.80/5.30 IMPORTANT NOTICE Diodes Incorporated and its subsidiaries reserve the right to make modifications, enhancements, improvements, corrections or other changes without further notice to any product herein. Diodes Incorporated does not assume any liability arising out of the application or use of any product described herein; neither does it convey any license under its patent rights, nor the rights of others. The user of products in such applications shall assume all risks of such use and will agree to hold Diodes Incorporated and all the companies whose products are represented on our website, harmless against all damages. LIFE SUPPORT Diodes Incorporated products are not authorized for use as critical components in life support devices or systems without the expressed written approval of the President of Diodes Incorporated. AP1533 Rev. 1 8 of 8 www.diodes.com JULY 2007 © Diodes Incorporated