Advanced Power Electronics Corp. APE1581 3A, 23V, 350kHz SYNCHRONOUS RECTIFIED STEP-DOWN CONVERTER DESCRIPTION FEATURES The APE1581 is a monolithic synchronous buck regulator. The device integrates two 100mΩ MOSFETs, and provides 3A of continuous load current over a wide input voltage of 4.75V to 23V. Current mode control provides fast transient response and Cycle-by-Cycle current limit. An adjustable soft-start prevents inrush current at turnon, and in shutdown mode the supply current drops to 1μA. This device, available in an ESOP-8 package, provides a very compact solution with minimal external components. Wide 4.75V to 23V Operating Input Range Integrated 100mΩ Power MOSFET Switches Output Adjust from VFB to 20V Up to 95% Efficiency 3A Output Current Programmable Soft-Start Stable with Low ESR Ceramic Output Capacitors Fixed 350KHz Frequency Cycle-by-Cycle Over Current Protection Thermal Shutdown and Short Circuit Protections ESOP-8 Package TYPICAL APPLICATION C5 10nF INPUT C1 10 µF/25V R4 100 k IN EN L1 10uH BS SW APE1581 SS OUTPUT 3.3V 3A FB R1 25.7k COMP GND C4 0.1 µF C3 3.3nF R3 2.2k R2 10k C2 10µF/ 6.3Vx2 VOUT=VFB × (1+ R1/R2 ), VFB = 0.925V, R2 suggest 10k~30KΩ Table Recommended Component Selection VIN (V) VOUT (V) R1 (KΩ) R2 (KΩ) R3 (KΩ) C3 (nF) L1 (μH) COUT (μ F) 12 5 44.1 10 2.2 3.3 15 10 X 2 5 or 12 5 or 12 3.3 25.7 10 2.2 3.3 10 10 X 2 1.8 9.5 10 2.2 3.3 4.7 10 X 2 5 or 12 1.2 3 10 2.2 3.3 3.3 10 X 2 5 or 12 1 0.81 10 2.2 3.3 2.2 10 X 2 Data and specifications subject to change without notice 1 201202061 Advanced Power Electronics Corp. APE1581 PACKAGE/ORDERING INFORMATION ( Top View ) APE1581X BS 1 IN 2 Package Type SW 3 MP : ESOP-8 GND 4 8 SS 7 EN GND 6 COMP 5 FB ESOP-8 ABSOLUTE MAXIMUM RATINGS (at TA=25oC) Input Voltage (VIN) ------------------------------------------ - 0.3V to + 24V Switch Node Voltage (VSW ) ------------------------------ -1V to VIN+0.3V Boost Voltage (VBS) ---------------------------------------- VSW – 0.3V to VSW + 6V All Other Pins ------------------------------------------------ - 0.3V to + 6V Power Dissipation (PD) ------------------------------------ Internally Limited Lead Temperature (TLead) -------------------------------- 260°C Storage Temperature Range (TST) --------------------- -65°C To 150°C Junction Temperature (TJ) ------------------------------- 150°C Output Voltage (VOUT) ------------------------------------- 0.925V to 20V Ambient Operating Temperature (TA) ----------------- -40°C To 85°C Thermal Resistance from Junction to case (Rthjc) 15°C/W Thermal Resistance from Junction to ambient (Rthja) Note 40°C/W 2 Note: Rthja is measured with the PCB copper area of approximately 1 in (Multi-layer). ELECTRICAL SPECIFICATIONS o (VIN = 12V, TA=25 C, unless otherwise noted) Characteristics Operating Voltage Symbol VIN Conditions Min 4.75 Typ - Max 23 Units V Shutdown Supply Current ISD VEN = 0V - 1 3 μA Feedback Voltage High-Side Switch On Resistance (Note) Low-Side Switch On Resistance (Note) High-Side Switch Leakage Current VFB 4.75V < VIN < 23V 0.9 0.925 0.95 V RDS(ON)1 - 100 - mΩ RDS(ON)2 - 100 - mΩ - - 10 μA VEN = 0V, VSW = 0V Switch Current Limit Oscillation Frequency FOSC1 Short Circuit Oscillation Frequency FOSC2 Maximum Duty Cycle DMAX EN Shutdown Threshold Voltage EN Shutdown Threshold Voltage Hysterisis Soft-Start Current ENH 3.8 - - A 280 350 430 KHz VFB = 0V - 90 - KHz VFB = 0.8V - 90 - % VEN Rising 1.1 1.5 2 V - 210 - mV VSS = 0V - 6 - μA CSS = 0.1µF - 15 - ms Thermal Shutdown TSD - 160 - °C Thermal Shutdown Hysterisis TSH - 35 - °C ISS Soft-Start Period Note: Guaranteed by design. 2 Advanced Power Electronics Corp. APE1581 PIN DESCRIPTIONS PIN SYMBOL PIN DESCRIPTION High-Side Gate Drive Boost Input. BS supplies the drive for the high-side N-Channel MOSFET switch. Connect a 0.01μF or greater capacitor from SW to BS BS to power the high side switch. Power Input. IN supplies the power to the IC, as well as the step-down converter switches. Drive IN with a 4.75V to 23V power source. Bypass IN to GND with a IN suitably large capacitor to eliminate noise on the input to the IC. See Input Capacitor. Power Switching Output. SW is the switching node that supplies power to the output. Connect the output LC filter from SW to the output load. Note that a SW capacitor is required from SW to BS to power the high-side switch. Ground. GND Feedback Input. FB senses the output voltage to regulate that voltage. Drive FB with a resistive voltage divider from the output voltage. The feedback threshold is FB 0.925V. See Setting the Output Voltage. Compensation Node. COMP is used to compensate the regulation control loop. Connect a series RC network from COMP to GND to compensate the regulation COMP control loop. In some cases, an additional capacitor from COMP to GND is required. See Compensation Components. Enable Input. EN is a digital input that turns the regulator on or off. Drive EN high to turn on the regulator, drive it low to turn it off. Pull up with 100kΩ resistor EN for automatic startup. Soft-Start Control Input. SS controls the soft start period. Connect a capacitor from SS to GND to set the soft-start period. A 0.1μF capacitor sets the soft-start period to 15ms. To disable the soft-start feature, leave SS unconnected. SS BLOCK DIAGRAM CURRENT SENSE AMPLIFIER OSCILLATOR FB 5 RAMP 2 ∑ 5V - CLK IN + 90/350KHz 1 BS + SS 8 0.925V + + - ERROR AMPLIFIER S Q R Q M1 100mΩ CURRENT COMPARATOR 3 SW M2 100mΩ 6µA 4 GND COMP 6 EN IN + EN 7 7V Zener 1.5V - INTERNAL REGULATORS 5V SHUTDOWN COMPARATOR 3 Advanced Power Electronics Corp. APE1581 FUNCTION DESCRIPTION The APE1581 is a synchronous rectified, current-mode, step-down regulator. It regulates input voltages from 4.75V to 23V down to an output voltage as low as 0.925V, and supplies up to 3A of load current. The APE1581 uses current-mode control to regulate the output voltage. The output voltage is measured at FB through a resistive voltage divider and amplified through the internal Tran conductance error amplifier. The voltage at the COMP pin is compared to the switch current measured internally to control the output voltage. The converter uses internal N-Channel MOSFET switches to step-down the input voltage to the regulated output voltage. Since the high side MOSFET requires a gate voltage greater than the input voltage, a boost capacitor connected between SW and BS is needed to drive the high side gate. The boost capacitor is charged from the internal 5V rail when SW is low. APPLICATION INFORMATION COMPONENT SELECTION Setting the Output Voltage The output voltage is set using a resistive voltage divider from the output voltage to FB pin. The voltage divider divides the output voltage down to the feedback voltage by the ratio: VFB=VOUT × [R2/(R1+R2)] Where VFB is the feedback voltage and VOUT is the output voltage. Thus the output voltage is: VOUT=0.925 ×(R1+R2)/R2 R2 can be as high as 100kΩ, but a typical value is 10kΩ. Using the typical value for R2, R1 is determined by: R1= 10.811 × (VOUT － 0.925) (kΩ) For example, for a 3.3V output voltage, R2 is 10kΩ, and R1 is 25.7kΩ. 4 Advanced Power Electronics Corp. APE1581 TYPICAL PERFORMANCE CHARACTERISTICS Output=3.3V Output=5V 5 Advanced Power Electronics Corp. APE1581 TYPICAL PERFORMANCE CHARACTERISTICS VIN = 12V, VOUT = 3.3V, ILOAD = No Load VIN = 12V, VOUT = 3.3V, ILOAD = 3A VIN = 12V, VOUT = 3.3V, ILOAD = No Load VIN = 12V, VOUT = 3.3V, ILOAD = 3A VIN = 12V, VOUT = 3.3V, IOUT = 1A ←→ 2A VIN = 12V, VOUT = 3.3V, IOUT = 1A ←→ 3A 6 Advanced Power Electronics Corp. APE1581 MARKING INFORMATION ESOP-8 Part Number Package Code 1581MP YWWSSS Date Code (YWWSSS) Y：Last Digit Of The Year WW：Week SSS：Sequence 7