AP1537 PWM Control 3A Step-Down Converter Features General Description - Input voltage: 3.6V to 18V. - Output voltage: 0.8V to VCC. - Duty ratio: 0% to 100% PWM control - Oscillation frequency: 500KHz typ. - Soft-start, Current Limit, Enable function - Thermal Shutdown function - Built-in internal SW P-channel MOS - Low ESR output capacitor (Multi-layer chip capacitor (MLCC)) application - SOP-8L Pb-Free Package. AP1537 consists of step-down switching regulator with PWM control. These devices include a reference voltage source, oscillation circuit, error amplifier, internal PMOS and etc. AP1537 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 100%. 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 500KHz to 50KHz. Also, an internal compensation block is built in to minimum external component count. Applications - PC Motherboard - LCD Monitor - Graphic Card - DVD-Video Player - Telecom Equipment - ADSL Modem - Printer and other Peripheral Equipment - Microprocessor core supply - Networking power supply 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 18V, it is also suitable for the operation via an AC adapter. Pin Assignments Pin Descriptions ) 8 Vss 7 Vss Comp 3 6 Output VCC 4 5 Output FB 1 EN 2 Name FB EN AP1537 Comp VCC Output VSS Pin 1 Description Feedback pin Power-off pin H: Normal operation (Step-down operation) 2 L: Step-down operation stopped (All circuits deactivated) 3 Compensation pin 4 IC power supply pin Switch Pin. Connect external 5、6 inductor/diode here. Minimize trace area at this pin to reduce EMI. 7、8 GND Pin This datasheet contains new product information. Anachip Corp. reserves the rights to modify the product specification without notice. No liability is assumed as a result of the use of this product. No rights under any patent accompany the sale of the product. Rev. 1. 3 1/7 May 09, 2006 AP1537 PWM Control 3A Step-Down Converter Ordering Information AP 1537 X X Packing Blank : Tube A : Taping Package S: SOP-8L Block Diagram Output Oscillation Circuit Reference Voltage Source with Soft Start Vcc + PWM-Switched Control Circuit FB - Thermal Shutdown 100uA VEN EN Vss Comp Absolute Maximum Ratings Symbol VCC*1 VFB VEN VOUTPUT PD TOPR TSTG θJC θJA Parameter VCC Pin Voltage Feedback Pin Voltage EN Pin Voltage Switch Pin Voltage Power Dissipation Junction Operating Temperature Range Storage Temperature Range Thermal Resistance Junction-to-Case 3 inch2 Copper as a heat-sink Thermal Resistance Junction-to-Case 3 inch2 Copper as a heat-sink Rating VSS - 0.3 to VSS + 20 VSS - 0.3 to VCC VSS - 0.3 to VIN + 0.3 VSS - 0.3 to VIN + 0.3 1000 -20 to +125 -40 to +150 Unit V V V V mW o C o C 15 o C/W 65 o C/W 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. Anachip Corp. www.anachip.com.tw Rev. 1.3 2/7 May 09, 2006 AP1537 PWM Control 3A Step-Down Converter Electrical Characteristics (VIN = 12V, Ta=25°C, unless otherwise specified) Symbol VIN VFB IFB ISW ISSS Parameter Input Voltage Feedback Voltage Feedback Bias Current Switch Current Current Consumption During Power Off Conditions ∆VOUT Line Regulation /VOUT ∆VOUT Load Regulation /VOUT fOSC Oscillation Frequency Frequency of Current Limit fOSC1 or Short Circuit Protect VSH EN Pin Input Voltage VSL ISH EN Pin Input Leakage Current ISL TSS Soft-Start Time RDSON Internal MOSFET Rdson EFFI Min. 3.6 0.784 3.5 Typ. 0.8 0.1 - Max. 18 0.816 0.5 - Unit V V µA A VEN =0V - 10 - µA VIN = 5V~18V, IOUT=0.2A - 1 2 % IOUT = 0.1 to 3A - 0.2 0.5 % Measure waveform at SW pin 400 500 600 KHz Measure waveform at SW pin 40 - - KHz Evaluate oscillation at SW pin Evaluate oscillation stop at SW pin VIN = 12V --VIN=5V, VFB=0V VIN=12V, VFB=0V VIN = 12V, VOUT = 5V IOUT = 3A 2.0 -10 -10 0.3 - 2 110 70 0.8 10 10 5 150 100 - 91 - -IOUT=0.1A IOUT=0.1A -- Efficiency V µA µA ms mΩ % Typical Application Circuit Vcc VIN REN 100K CIN 22uF 0.1uF 22uH CC 10nF AP1537 FB EN VSS CVcc L1 Output VOUT =5V RA 6.8K + Comp 1K CEN 0.1uF D1 1800pF - + C 0.1uF - COUT 33uF RB 1.3K Note: V OUT = VFB x (1+R A/RB) R B=0.7K~5K ohm VOUT L1 Value VIN=12V, IMAX=3A 2.5V 3.3V 18uH 22uH Anachip Corp. www.anachip.com.tw 5V 22uH Rev. 1.3 3/7 May 09, 2006 AP1537 PWM Control 3A Step-Down Converter AP1537 Vin v.s. Frequency (Vout=3.3V; Iout=0.2A) 450 445 440 435 430 425 420 415 410 405 400 FB (V) Fosc (KHz) Typical Performance Characteristics 0 5 10 15 Vin (V) 0 3.35 Vout (A) Vout(V) 3.30 3.25 3.20 3.15 3.10 0 5 10 15 Vin(V) 0.84 0.83 0.82 0.81 0.80 0.79 0.78 0.77 0.76 0.75 0.74 20 AP1537 Line Regulation ( Iout=0.2A) 3.40 20 AP1537 Vin v.s. FB (Vout=3.3V; Iout=0.2A) 5 10 15 Vin (V) 20 AP1537 Load Regulation (Vin=12V) 5.10 5.09 5.08 5.07 5.06 5.05 5.04 5.03 5.02 5.01 5.00 0.0 1.0 2.0 3.0 Rev. 1.3 May 09, 2006 Iout (A) AP1537 Efficiency Efficiency (%) 100 90 80 70 60 50 40 30 20 Vout:5.0V Vout:3.3V 10 0 0.0 1.0 Iout (A) 2.0 3.0 Anachip Corp. www.anachip.com.tw 4/7 AP1537 PWM Control 3A Step-Down Converter Typical Performance Characteristics (Continued) AP1537 Vout Ripple (Vin=12V; Vout=5V; Iout=0.2A) AP1537 Vout Ripple (Vin=12V; Vout=5V; Iout=3A) Test Circuit VCC OUTPUT FB Comp EN A Oscillation open open A open - VSS OUTPUT OUTPUT FB Comp + Enable function test VCC VCC EN VSS Feedback function test FB + EN - VSS Comp + V - Operation function test Anachip Corp. www.anachip.com.tw Rev. 1.3 5/7 May 09, 2006 AP1537 PWM Control 3A Step-Down Converter Function Description PWM Control The AP1537 consists of DC/DC converters that employ a pulse-width modulation (PWM) system. In converters of the AP1537, 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 low-ripple power over broad ranges of input voltage and load current. Under Voltage Lockout The under voltage lockout circuit of the AP1537 assures that the high-side MOSFET driver outputs remain in the off state whenever the supply voltage drops below 3.3V. Normal operation resumes once VCC rises above 3.5V. RDS(ON) Current Limiting The current limit threshold is setting by the internal circuit. Marking Information ( Top View ) 8 5 Logo AP1537 Part no. YY WW X 4 Anachip Corp. www.anachip.com.tw ~ 1 ID code: internal Xth week: 01~52 Year: "01" =2001 "02" =2002 Rev. 1.3 6/7 May 09, 2006 AP1537 PWM Control 3A Step-Down Converter Package Information H E Package Type: SOP-8L L VIEW "A" D 0.015x45 7 (4X) e B A1 C A A2 7 (4X) VIEW "A" y Symbol A A1 A2 B C D E e H L y θ Dimensions In Millimeters Min. Nom. Max. 1.40 1.60 1.75 0.10 0.25 1.30 1.45 1.50 0.33 0.41 0.51 0.19 0.20 0.25 4.80 5.05 5.30 3.70 3.90 4.10 1.27 5.79 5.99 6.20 0.38 0.71 1.27 0.10 8O 0O Anachip Corp. www.anachip.com.tw Dimensions In Inches Min. Nom. Max. 0.055 0.063 0.069 0.040 0.100 0.051 0.057 0.059 0.013 0.016 0.020 0.0075 0.008 0.010 0.189 0.199 0.209 0.146 0.154 0.161 0.050 0.228 0.236 0.244 0.015 0.028 0.050 0.004 0O 8O Rev. 1.3 7/7 May 09, 2006