NOT RECOMMENDED FOR NEW DESIGN CONTACT US AP1539 18V 4A 300KHz BUCK CONVERTER Description AP1539 consists of step-down switching regulator with PWM control. These devices include a reference voltage source, oscillation circuit, error amplifier, internal PMOS. AP1539 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 Pchannel 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-DEP mini-package, 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. Features * * Input voltage: 3.6V to 18V Output voltage: 0.8V to VCC * * * * * * * * * * Output current: up to 4A 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-DEP: Available in "Green" Molding Compound (No Br, Sb) Totally Lead-Free & Fully RoHS Compliant (Notes 1 & 2) Halogen and Antimony Free. "Green" Device (Note 3) For automotive applications requiring specific change control (i.e. parts qualified to AEC-Q100/101/200, PPAP capable, and manufactured in IATF 16949 certified facilities), please contact us or your local Diodes representative. https://www.diodes.com/quality/product-definitions/ Notes: Pin Assignments ( T o p V ie w ) FB EN 1 2 OCSET 3 VCC 4 1 2 (N o te 4 ) 8 V ss 7 V ss 6 O u tp u t 5 O u tp u t SOP-8L-DEP (Dual Exposed Pads) Note: 4. Exposed pad 1 is connected to VSS and exposed pad 2 is connected to Output. The board layout for exposed pads needs to be considered to avoid short circuit. Applications * * * * * * * * PC Motherboard LCD Monitor Graphic Card DVD-Video Player Telecom Equipment ADSL Modem Printer and other Peripheral Equipment Microprocessor core supply 1. No purposely added lead. Fully EU Directive 2002/95/EC (RoHS), 2011/65/EU (RoHS 2) & 2015/863/EU (RoHS 3) compliant. 2. See https://www.diodes.com/quality/lead-free/ for more information about Diodes Incorporated's definitions of Halogen- and Antimony-free, "Green" and Lead-free. 3. Halogen- and Antimony-free "Green" products are defined as those which contain <900ppm bromine, <900ppm chlorine (<1500ppm total Br + Cl) and <1000ppm antimony compounds. AP1539 Document number: DS31477 Rev. 6 - 3 1 of 12 www.diodes.com February 2020 (c) Diodes Incorporated AP1539 Typical Application Circuit Vcc VIN Output ROCSET COCSET 3.9K Option C IN AP 1539 OCSET 470uF CVcc 0.1uF EN R EN 100K FB VOUT = 5V/4A L1 22uH Cc Option* RA 6.8K + V SS D1** C EN 0.1uF RB 1.3K - C + 0.1uF - COUT 470uF*** VOUT = V FB x (1+ R A /RB ) R B = 0.7K~5K ohm Notes: * Typical feedback compensation (Cc): 5600pF. ** Suggested SuggestedDiodes DIODES Power Schottky B540 series orseries PDS540. Incorporated Power P/N: Schottky P/N: B540 or PDS540. *** Suggested COUT for VOUT < 1V; 680uF. 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 AP1539 Document number: DS31477 Rev. 6 - 3 Description 2 of 12 www.diodes.com February 2020 (c) Diodes Incorporated AP1539 Block Diagram Output Oscillation Circuit Reference Voltage Source with Soft Start Vcc + PWM-Switched Control Circuit FB - Thermal Shutdown VEN EN 90uA Vss OCSET Absolute Maximum Ratings Symbol Parameter Rating Unit ESD HBM Human Body Model ESD Protection 5.5 KV ESD MM Machine Model ESD Protection 200 V VSS - 0.3 to VSS + 20 V VCC VCC Pin Voltage VFB Feedback Pin Voltage VSS - 0.3 to VCC V VEN EN Pin Voltage VSS - 0.3 to VCC V VOUT Switch Pin Voltage VSS - 0.3 to VCC V PD Power Dissipation Internally limited mW TJ Operating Junction Temperature Range TST Caution: Storage Temperature Range -40 to +125 o -65 to +150 o C 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 Note: Parameter Input Voltage (Note 5) Output Current Operating Ambient Temperature Min Max Unit 3.6 0 -20 18 4 +85 V A o C 5. For the operations in low input voltage, AP1539 can tolerate down to 3.6V but max output current loading will be less than 4A. For nominal applications in such low input voltage range, especially lower than 4V, a higher ROCSET with larger heat sink is recommended. AP1539 Document number: DS31477 Rev. 6 - 3 3 of 12 www.diodes.com February 2020 (c) Diodes Incorporated AP1539 Electrical Characteristics (VIN = 12V, TA = +25C, unless otherwise specified) Symbol VFB IFB ISHDN VOUT / VIN VOUT / VOUT fOSC fOSC1 VIH VIL ISH ISL Parameter Min Typ. Max Unit 0.784 -- 0.8 0.1 0.816 0.5 V A VEN = 0V -- 10 -- A Line Regulation VIN = 5V~18V -- 1 2 % Load Regulation IOUT = 0.1 to 4A -- 0.2 0.5 % Oscillation Frequency Frequency of Current Limit or Short Circuit Protection Measure waveform at SW pin 240 300 400 KHz Measure waveform at SW pin -- 50 -- KHz 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 = 4A -- -- 2.0 -- -- -- 75 -- -- -- -- 20 -10 90 90 50 -- 0.8 -- -- 105 -- -- -- 92 -- % -- -- +150 +55 -- -- C C -- 26 -- IOUT = 0.1A IOUT = 0.1A EN Pin Input Voltage EN Pin Input Leakage Current IOCSET OCSET Pin Bias Current RDS(ON) Internal MOSFET RDS(ON) EFFI Efficiency TSHDN THYS Thermal shutdown threshold Thermal shutdown hysteresis Thermal Resistance Junction-to-Case SOP-8L-DEP (Note 6) JC Note: Conditions Feedback Voltage Feedback Bias Current Current Consumption During Power Off V A A A m o C/W 6. Test condition for SOP-8L-DEP: Devices mounted on 2oz copper, minimum recommended pad layout on top & bottom layer with thermal vias, double sided FR-4 PCB. AP1539 Document number: DS31477 Rev. 6 - 3 4 of 12 www.diodes.com February 2020 (c) Diodes Incorporated AP1539 Typical Performance Characteristics 326 VIN vs. Frequency VIN vs. VFB (V OUT = 3.3V, IOUT = 0.2A) (V OUT = 3.3V, IOUT = 0.2A) 0.820 324 322 0.815 0.810 320 FOSC (kHz) 0.805 V FB (V) 318 0.800 316 314 0.795 312 0.790 310 308 0.785 0.780 306 0 2 4 6 8 10 V IN (V) 12 14 16 0 18 2 4 Line Regulation 12 14 16 18 (V IN = 12V) 3.35 3.34 3.35 3.33 3.32 3.31 3.30 V OUT (V) V OUT (V) 3.25 3.20 3.30 3.29 3.28 3.27 3.15 3.10 3.05 3.00 0 2 4 6 8 10 V IN (V) 12 14 16 18 3.26 3.25 0.0 0.5 Efficiency 90 80 Current Limit (A) 70 60 50 40 30 VOUT=3.3V 20 10 0 0.0 AP1539 VOUT=5V 1.0 Document number: DS31477 Rev. 6 - 3 2.0 IOUT (A) 1.0 1.5 2.0 2.5 IOUT (A) 3.0 3.5 4.0 Switch Current Limit (V IN = 12V) 100 Efficiency (%) 8 10 V IN (V) Load Regulation (V OUT = 3.3V, IOUT = 0.2A) 3.40 6 3.0 (TA = 25) 7.5 7.0 6.5 6.0 5.5 5.0 4.5 4.0 3.5 3.0 2.5 4.0 5 of 12 www.diodes.com ROCSET=6.8k ROCSET=4.7k 0 2 4 6 8 10 V IN (V) 12 14 16 18 February 2020 (c) Diodes Incorporated AP1539 Typical Performance Characteristics (continued) Current Limit vs. Temperature (V IN = 12V, ROCSET = 6.8k) Current Limit (A) 9.0 8.5 8.0 7.5 7.0 6.5 6.0 5.5 5.0 4.5 4.0 -25 0 25 50 75 Ambient AmbientTemperature Temperature(C) (C) VOUT Ripple (VIN=12V, VOUT=3.3V, IOUT=0.1A) 100 VOUT Ripple (VIN=12V, VOUT=3.3V, IOUT=4.0A) Load Transient Response (VIN =12V, VOUT =3.3V, IOUT =0.1~4A) AP1539 Document number: DS31477 Rev. 6 - 3 6 of 12 www.diodes.com February 2020 (c) Diodes Incorporated AP1539 Test Circuit O u tp u t V CC FB Oscillation open open OCSET A EN A + V SS - E n a b le fu n c tio n te s t V CC + - O u tp u t V CC OCSET EN O u tp u t FB V SS F e e d b a c k fu n c tio n te s t FB OCSET EN + V SS V - O p e ra tio n fu n c tio n te s t Functional Description PWM Control The AP1539 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 AP1539 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 x R DS(ON) = IOCSET x R OCSET (I) IPEAK > IOUT(MAX) + 2 where, I = VIN - VOUT VOUT x fs x L VIN IPEAK is the output peak current; RDS (ON) is the MOSFET ON resistance; FS is the PWM frequency (300KHz typical). Also, the inductor value will affect the ripple current I. AP1539 Document number: DS31477 Rev. 6 - 3 7 of 12 www.diodes.com February 2020 (c) Diodes Incorporated AP1539 Functional Description (continued) 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 +100C, higher ROCSET is recommended. The recommended minimum ROCSET value is summarized below: VOUT (V) 0.8 1.0 1.2 1.8 2.5 3.3 5.0 5V 6.8K 6.8K 6.8K 6.8K 6.8K 6.8K N/A VIN (V) 12V 3.9K 3.9K 3.9K 3.9K 3.9K 3.9K 3.9K 18V 4.7K 4.7K 4.7K 4.7K 4.7K 4.7K 5.6K Inductor Selection For most designs, the operates with inductors of 22H to 33H. The inductor value can be derived from the following equation: L= VIN - VOUT VOUT x fs x I VIN Where IL is inductor Ripple Current. Large value inductors lower ripple current and small value inductors result in high ripple current. Choose inductor ripple current approximately 15% of the maximum load current 4A, IL=0.6A. 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 (4A+0.3A). Input Capacitor Selection This capacitor should be located close to the IC using short leads and the voltage rating should be approximately 1.5 times the maximum input voltage. The RMS current rating requirement for the input capacitor of a buck regulator is approximately 12 the DC load current. A low ESR input capacitor sized for maximum RMS current must be used. A 470F low ESR capacitor for most applications is sufficient. Output Capacitor Selection The output capacitor is required to filter the output voltage and provides regulator loop stability. The important capacitor parameters are the 100KHz Equivalent Series Resistance (ESR), the RMS ripples current rating, voltage rating and capacitance value. For the output capacitor, the ESR value is the most important parameter. The output ripple can be calculated from the following formula. V RIPPLE = IL x ESR The bulk capacitor's ESR will determine the output ripple voltage and the initial voltage drop after a high slew-rate transient. An aluminum electrolytic capacitor's ESR value is related to the capacitance and its voltage rating. In most case, higher voltage electrolytic capacitors have lower ESR values. Most of the time, capacitors with much higher voltage ratings may be needed to provide the low ESR values required for low output ripple voltage. PCB Layout Guide If you need low TC & TJ or large PD (Power Dissipation), The dual SW pins(5& 6) and VSS pins(7& 8)on the SOP-8L package are internally connected to die pad, The evaluation board should be allowed for maximum copper area at output (SW) pins. 1. Connect FB circuits (R1, R2, C1) as closely as possible and keep away from inductor flux for pure VFB. 2. Connect C3 to VCC and VSS pin as closely as possible to get good power filter effect. 3. Connect R4 to VCC and OCSET pin as closely as possible. 4. Connect ground side of the C2 & D1 & C4 as closely as possible and use ground plane for best performance. AP1539 Document number: DS31477 Rev. 6 - 3 8 of 12 www.diodes.com February 2020 (c) Diodes Incorporated AP1539 Functional Description (continued) Recommended exposed-pads gap: 30~40mil (0.75~1mm) Keep the gap of exposed pads from short circuit. Top Side Layout Guide Brown: IC exposed pads. Red: recommended layout. Reference pads layout dimension: Output: 90 x 50 mil Vss: 90 x 60 mil Use vias to conduct the heat into the backside of PCB layer. The heat sink at output (SW) pins should be allowed for maximum solder-painted area. Bottom Side Layout Guide Vcc VIN R4 Output C7 Option C2 AP1539 FB OCSET C3 R5 EN L1 C1 Option VOUT R1 + V SS D1 C8 + C4 - R2 C6 Layout numbering comparison AP1539 Document number: DS31477 Rev. 6 - 3 9 of 12 www.diodes.com February 2020 (c) Diodes Incorporated AP1539 Ordering Information AP 1539 SDP G - 13 Package SDP : SOP-8L-DEP Device AP1539SDPG-13 Note: Package Code SDP Packaging (Note 7) SOP-8L-DEP Green Packing G : Green 13 : Tape & Reel 13" Tape and Reel Quantity Part Number Suffix 2500/Tape & Reel -13 7. Pad layout as shown as shown in Diodes Incorporated's package outline PDFs, which can be found on our website at http://www.diodes.com/package-outlines.html. Marking Information (1) SOP-8L-DEP AP1539 Document number: DS31477 Rev. 6 - 3 10 of 12 www.diodes.com February 2020 (c) Diodes Incorporated AP1539 Package Outline Dimensions (All Dimensions in mm) Please see http://www.diodes.com/package-outlines.html for the latest version. (1) Package type: SOP-8L-DEP CL 1.8 1.65 1.8 0.95 8 5 8x-1.55 8 EXPOSED PAD 1.0 5.4 2.35 3.85/3.95 5.90/6.10 5 CL Top View 4 1 0.35Typ. 6x-1.27 8x-0.60 0.254 1.15Typ. 2.05Typ. 0.15/0.25 4.85/4.95 8 View"A" 1.27Typ. R0 0/ 1.4/1.5 .1 1.63Max. 45 9(all side) 0.685 4 1 0.3/0.5 4 1 Gauge Plane Seating Plane EXPOSED PAD 0.9 8 CL 0.62/0.82 0/0.13 0.20 2.15Typ. Land Pattem Recommendation (Unit: mm) View"A" 5 1.7 1.7 0.713 CL Bottom view AP1539 Document number: DS31477 Rev. 6 - 3 11 of 12 www.diodes.com February 2020 (c) Diodes Incorporated AP1539 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 (c) 2020, Diodes Incorporated www.diodes.com AP1539 Document number: DS31477 Rev. 6 - 3 12 of 12 www.diodes.com February 2020 (c) Diodes Incorporated