ACT4050

ACT4050 ACTIVE-SEMI | Alldatasheet

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Technical content

• 1 - www.active-semi.com Copyright © 2011 Active-Semi, Inc. Innovative PowerTM TYPICAL APPLICATION CIRCUIT ACT4050 Wide Input 3.5A Step Down Converter Active- Semi Rev 2, 01-Jul-11

FEATURES

• 3.5A Output Current
• Up to 96% Efficiency
• 4.5V to 15V Input Range
• 12µA Shutdown Supply Current
• 400kHz Switching Frequency
• Adjustable Output Voltage From 0.817V
• Cycle-by-Cycle Current Limit Protection
• Thermal Shutdown Protection
• Frequency Fold-Back at Short Circuit
• Stability with Wide Range of Capacitors, Including Low ESR Ceramic Capacitors
• SOP-8/EP (Exposed Pad) Package

APPLICATIONS

• Digital TV
• Portable DVDs
• Car-Powered or Battery-Powered Equipments
• Set-Top Boxes
• Telecom Power Supplies
• Consumer Electronics GENERAL DESCRIPTION The ACT4050 is a current-mode step-down DC/DC converter that provides up to 3.5A of output current at 400kHz switching frequency. The device utilizes Active-Semi’s proprietary high voltage process for operation with input voltages up to 15V. The ACT4050 provides fast transient response and eases loop stabilization while providing excellent line and load regulation. This device features a very low ON-resistance power MOSFET which provides peak operating efficiency up to 96%. In shutdown mode, the ACT4050 consumes only 12 μA of supply current. This device also integrates protection features including cycle-by-cycle current limit, thermal shutdown and frequency fold-back at short circuit. The ACT4050 is available in a SOP-8/EP (Exposed Pad) package and requires very few external devices for operation. ACT4050-001 Efficiency vs. Load Current Efficiency (%) Load Current (mA) 0 500 1000 1500 2000 2500 3000 3500 100 VOUT = 5V VIN = 7V VIN = 12V

Rev 2, 01-Jul-11 - 2 - www.active-semi.com Copyright © 2011 Active-Semi, Inc. Innovative PowerTM

ORDERING INFORMATION

PART NUMBER TEMPERATURE RANGE PACKAGE PINS PACKING ACT4050YH -40°C to 85°C SOP-8/EP 8 TUBE ACT4050YH-T -40°C to 85°C SOP-8/EP 8 TAPE & REEL PIN CONFIGURATION PIN DESCRIPTIONS PIN NAME DESCRIPTION 1 BS Bootstrap. This pin acts as the positive rail for the high-side switch’s gate driver. Connect a 10nF capacitor between BS and SW. 2 IN Input Supply. Bypass this pin to GND with a low ESR capacitor. See Input Capacitor in the Application Information section. 3 SW Switch Output. Connect this pin to the switching end of the inductor. 4 GND Ground. 5 FB Feedback Input. The voltage at this pin is regulated to 0.817V. Connect to the resistor divider between output and ground to set output voltage. 6 COMP Compensation Pin. See Stability Compensation in the Application Information section. 7 EN Enable Input. When higher than 1.3V, this pin turns the IC on. When lower than 0.9V, this pin turns the IC off. Output voltage is discharged when the IC is off. When left unconnected, EN is pulled up to 4.5V typical with a 2µA pull-up current. 8 N/C Not Connected. EP EP Exposed Pad shown as dashed box. The exposed thermal pad should be connected to board ground plane and pin 4. The ground plane should include a large exposed copper pad under the package for thermal dissipation (see package outline). The leads and exposed pad should be flush with the board, without offset from the board surface. SOP-8/EP

Rev 2, 01-Jul-11 - 3 - www.active-semi.com Copyright © 2011 Active-Semi, Inc. Innovative PowerTM ABSOLUTE MAXIMUM RATINGSc PARAMETER VALUE UNIT IN Supply Voltage -0.3 to 15 V SW Voltage -1 to VIN + 1 V BS Voltage V SW - 0.3 to VSW + 8 V EN, FB Voltage -0.3 to 6 V Continuous SW Current Internally Limited A Junction to Ambient Thermal Resistance (θ JA) 46 °C/W Maximum Power Dissipation 1.8 W Operating Junction Temperature -40 to 150 °C Storage Temperature -55 to 150 °C Lead Temperature (Soldering, 10 sec) 300 °C

ELECTRICAL CHARACTERISTICS

(VIN = 12V, TA = 25°C, unless otherwise specified.) PARAMETER SYMBOL TEST CONDITIONS MIN TYP MAX UNIT Feedback Voltage V FB 5V ≤ VIN ≤ 15V 0.8 0.817 0.834 V High-Side Switch On Resistance R ONH 0.15 Ω Low-Side Switch On Resistance R ONL 4.5 Ω SW Leakage V EN = 0 0 10 µA High-Side Switch Peak Current Limit ILIM Duty Cycle = 50% 5.4 A COMP to Current Limit Transconductance GCOMP 2.5 A/V Error Amplifier Transconductance G EA ΔICOMP = ±10µA 650 µA/V Error Amplifier DC Gain A VEA 4000 V/V Switching Frequency f SW 350 400 450 kHz Short Circuit Switching Frequency V FB = 0 60 kHz Maximum Duty Cycle D MAX V FB = 0.7V 95 % Minimum Duty Cycle V FB = 0.9V 0 % Enable Threshold Voltage Hyst eresis = 0.1V 0.8 1.1 1.4 V Enable Pull-Up Current Pin pulled up to 4.5V typically when left unconnected 2 µA Supply Current in Shutdown V EN = 0 12 20 µA IC Supply Current in Operation V EN = 3V, VFB = 0.9V 0.5 1 mA Thermal Shutdown Temperature Hysteresis = 10°C 160 °C Input Voltage V IN V OUT = 3V, ILOAD = 0V to 1A 4.5 15 V Minimum On Time Ton_Min 400 ns c: Do not exceed these limits to prevent damage to the device. Exposure to absolute maximum rati ng conditions for long periods m ay affect device reliability.

Rev 2, 01-Jul-11 - 4 - www.active-semi.com Copyright © 2011 Active-Semi, Inc. Innovative PowerTM FUNCTIONAL BLOCK DIAGRAM FUNCTIONAL DESCRIPTION As seen in Functional Block Diagram, the ACT4050 is a current mode pulse width modulation (PWM) converter. The converter operates as follows: A switching cycle starts when the rising edge of the Oscillator clock output caus es the High-Side Power Switch to turn on and the Low-Side Power Switch to turn off. With the SW side of the inductor now connected to IN, the inductor current ramps up to store energy in the magnetic field. The inductor current level is measured by the Current Sense Amplifier and added to the Oscillator ramp signal. If the resulting summation is higher than the COMP voltage, the output of the PWM Comparator goes high. When this happens or when Oscillator clock output goes low, the High-Side Power Switch turns off and the Low-Side Power Switch turns on. At this point, the SW side of the inductor swings to a diode voltage below ground, causing the inductor current to decrease and magnetic energy to be transferred to output. This state contin ues until the cycle starts again. The High-Side Power Switch is driven by logic using BS as the positive rail. This pin is charged to V SW + 6V when the Low-Side Power Switch turns on. The COMP voltage is the integration of the error between FB input and the internal 0.817V reference. If FB is lower than the reference voltage, COMP tends to go higher to increase current to the output. Current limit happens when COMP reaches its maximum clamp value of 2.15V. The Oscillator normally switches at 400kHz. However, if FB voltage is less than 0.7V, then the switching frequency decreases until it reaches a typical value of 60kHz at V FB = 0.5V. Shutdown Control The ACT4050 EN pin contains a precision 1.1V comparator with 100mV hysteresis, as well as a 2µA pull-up current source. This combination can be used to control the on/off operation of ACT4050 using several methods: 1) First, "always-on" operation can be enabled simply by floating the EN pin. Any time power is applied to VIN, the EN pull-up current source will bring the pin above 1.1V and enable the IC. In this case, under-voltage lockout will be controlled by an internal 4.2V comparator on VIN. 2) Second, an open-drain or open-collector logic device can be used to pull the EN pin low to provide digital ON/OFF control. When the logic pull-down is disabled, the internal 2µA pull-up current will bring the EN pin high and enable the chip. 3) Third, a known startup delay time can be created by adding a small capacitor from EN to GND in

Rev 2, 01-Jul-11 - 5 - www.active-semi.com Copyright © 2011 Active-Semi, Inc. Innovative PowerTM CAPACITOR VALUE DELAY TIME (ms) 2.2nF 1.2 3.3nF 1.9 10nF 5.5 addition to the open-drain or open-collector logic device. When the logic pull-down is disabled, the voltage at EN will ramp up at a rate determined by the 2µA EN pull-up current and the capacitor. Once the voltage at EN exceeds the 1.1V threshold, the device will be enabled. For the case of using multiple ACT4050, time-based output sequencing can be generated by placing different capacitors at each ACT4050 EN pin. The start up time delay can be calculated as a simple function of the EN capacitor using the equation: T (ms) = 0.55 × C EN (nF) Table 1: Enable Delay Time vs. EN Capacitor Value 4) Fourth, by using the 1.1V precision comparator in the EN circuitry, "power-OK" type output sequencing can be generated. By connecting the EN pin of one ACT4050 to the output of another device, the ACT4050 will only start up once the second device's output has exceeded the 1.1V level. A resistor divider can be used to adjust the ACT4050 startup to any point on the second device's output range. 5) Finally, the EN comparator can be used for "Line UVLO" to prevent the ACT4050 from starting up before the input voltage is high enough to support the output. By using a resistor divider from VIN to GND (center tap = 1.1V EN threshold), the device can be enabled and disabled based on the voltage at VIN. Since the internal UVLO voltage is 4.2V, Line UVLO is recommended for outputs above this 4.2V level to ensure clean startup. For the example of a 5V output, it is desirable to prevent IC startup until VIN has exceeded the 5V level. To start the IC at 6V input, we place a 10k Ω/47kΩ resistor divider from VIN to EN to GND, which enables the IC at VIN greater than 6.3V and disables the IC when VIN decreases below 5.2V. Thermal Shutdown The ACT4050 automatically turns off when its junction temperature exceeds 160°C and automatically turns on again when the junction temperature falls below 140°C .

Rev 2, 01-Jul-11 - 8 - www.active-semi.com Copyright © 2011 Active-Semi, Inc. Innovative PowerTM Figure 3: ACT4050 1.8V/3.5A Output Applicationc c: D1 is a 30V, 5A Schottky diode with low forward voltage, a B530C equivalent. C4 can be either a ceramic capacitor (Panasonic ECJ-3YB1C226M) or SP-CAP (Specialty Polymer) Aluminum Electrolytic Capacitor such as Panasonic EEFCD0J470XR. The SP-Cap is based on aluminum electrolytic capacitor technology, but us es a solid polymer electrolyt e and has very stable capacitance characteristics in both operating temperature and frequency compared to ceramic, polymer, and low ESR tantalum capacitors. ITEM DESCRIPTION MANUFACTURER QTY REFERENCE

1 IC, ACT4050 Active-Semi 1 U1

2 Resistor, 12.1k Ω , 1%, SMT, 0603 FengHua, Neohm, Yageo 1 R1

3 Resistor, 10k Ω, 1%, SMT, 0603 FengHua, Neohm, Yageo 1 R2

4 Resistor, 10k Ω, 5%, SMT, 0603 FengHua, Neohm, Yageo 1 R3

5 Capacitor, Ceramic, 10µF/35V, X7R, SMT,

Panasonic, Kemet, Murata, TDK, FengHua, Taiyo Yuden 1 C1 6 Capacitor, Ceramic, 22µF/6.3V, X7R, SMT, 1206 Panasonic, Kemet, Murata, TDK, FengHua, Taiyo Yuden 2 C4

7 Capacitor, Ceramic, 10nF/50V, X7R, SMT,

Panasonic, Kemet, Murata, TDK, FengHua, Taiyo Yuden 1 C3 8 Capacitor, Ceramic, 2.7nF/6.3V, X7R, SMT, 0603 Panasonic, Kemet, Murata, TDK, FengHua, Taiyo Yuden 1 C2 9 Capacitor, Ceramic, 220pF/6.3V, X7R, SMT, 0603 Panasonic, Kemet, Murata, TDK, FengHua, Taiyo Yuden 1 C5 (OPTIONAL)

10 Schottky Diode SK53/30V, 5A, SMC Diodes 1 D1

11 Inductor, CDRH8D43-6R8NC, 6.8µH Sumida 1 L1 Table 3: ACT4050EV Bill of Materials (Apply for 1.8V Output Application)

Rev 2, 01-Jul-11 - 9 - www.active-semi.com Copyright © 2011 Active-Semi, Inc. Innovative PowerTM c: D1 is a 30V, 5A Schottky diode with low forward voltage, a B530C equivalent. C4 can be either a ceramic capacitor (Panasonic ECJ-3YB1C226M) or SP-CAP (Specialty Polymer) Aluminum Electrolytic Capacitor such as Panasonic EEFCD0J470XR. The SP-Cap is based on aluminum electrolytic capacitor technology, but us es a solid polymer electrolyt e and has very stable capacitance characteristics in both operating temperature and frequency compared to ceramic, polymer, and low ESR tantalum capacitors. Figure 4: ACT4050 3.3V/3.5A Output Applicationc Table 4: ACT4050EV Bill of Materials (Apply for 3.3V Output Application) ITEM DESCRIPTION MANUFACTURER QTY REFERENCE 2 Resistor, 30.5k Ω , 1%, SMT, 0603 FengHua, Neohm, Yageo 1 R1

4 Resistor, 12k Ω, 5%, SMT, 0603 FengHua, Neohm, Yageo 1 R3

5 Capacitor, Ceramic, 10µF/35V, X7R, SMT, 1206 Panasonic, Kemet, Murata,

TDK, FengHua, Taiyo Yuden 1 C1 6 Capacitor, Ceramic, 22µF/6.3V, X7R, SMT, 1206 Panasonic, Kemet, Murata, TDK, FengHua, Taiyo Yuden 2 C4

7 Capacitor, Ceramic, 10nF/50V, X7R, SMT, 0603 Panasonic, Kemet, Murata,

TDK, FengHua, Taiyo Yuden 1 C3 8 Capacitor, Ceramic, 1.5nF/6.3V, X7R, SMT, 0603 Panasonic, Kemet, Murata, TDK, FengHua, Taiyo Yuden 1 C2 9 Capacitor, Ceramic, 220pF/6.3V, X7R, SMT, 0603 Panasonic, Kemet, Murata, TDK, FengHua, Taiyo Yuden 1 C5 (OPTIONAL)

11 Inductor, CDRH8D43-100NC, 10µH Sumida 1 L1

Rev 2, 01-Jul-11 - 10 - www.active-semi.com Copyright © 2011 Active-Semi, Inc. Innovative PowerTM Figure 5: ACT4050 5V/3A Output Applicationc c: D1 is a 30V, 5A Schottky diode with low forward voltage, a B 530C equivalent. C4 can be either a ceramic capacitor (Panasonic ECJ-3YB1C226M) or SP-CAP (Specialty Polymer) Aluminum Electrolytic C apacitor such as Panasonic EEFCD0J470XR. The SP-Cap is based on aluminum electrolytic capacitor technology, but us es a solid polymer electrolyt e and has very stable capacitance characteristics in both operating temperature and frequency compared to ceramic, polymer, and low ESR tantalum capacitors. Table 5: ACT4050EV Bill of Materials (Apply for 5V Output Application) ITEM DESCRIPTION MANUFACTURER QTY REFERENCE

2 Resistor, 51k Ω , 1%, SMT, 0603 FengHua, Neohm, Yageo 1 R1

4 Resistor, 15k Ω, 5%, SMT, 0603 FengHua, Neohm, Yageo 1 R3

TDK, FengHua, Taiyo Yuden 1 C1 6 Capacitor, Ceramic, 22µF/6.3V, X7R, SMT, 1206 Panasonic, Kemet, Murata, TDK, FengHua, Taiyo Yuden 2 C4 TDK, FengHua, Taiyo Yuden 1 C3 8 Capacitor, Ceramic, 1.5nF/6.3V, X7R, SMT, 0603 Panasonic, Kemet, Murata, TDK, FengHua, Taiyo Yuden 1 C2 9 Capacitor, Ceramic, 220pF/6.3V, X7R, SMT, 0603 Panasonic, Kemet, Murata, TDK, FengHua, Taiyo Yuden 1 C5 (OPTIONAL)

Rev 2, 01-Jul-11 - 11 - www.active-semi.com Copyright © 2011 Active-Semi, Inc. Innovative PowerTM TYPICAL PERFORMANCE CHARACTERISTICS (Circuit of Figure 5, unless otherwise specified.) Efficiency vs. Load Current Efficiency (%) Load Current (mA) ACT4050-001 VIN = 7V VIN = 12V Efficiency vs. Load Current ACT4050-002 VIN = 7V Temperature (°C) Switching Frequency (MHz) ACT4050-005 Switching Frequency vs. Temperature 400 310 280 340 370 430 Temperature (°C) Feedback Voltage (V) ACT4050-006 Feedback Voltage vs. Temperature 0.75 0.76 250 Efficiency (%) 100 VIN = 5V ACT4050-004 Inductor Peak Current Limit vs. Duty Cycle Inductor Peak Current Limit (mA) 2000 4000 5000 2500 3000 Duty Cycle (% ) 20 0 40 80 100 60 6000 ACT4050-003 Shutdown Current vs. Input Voltage Shutdown Current (µA) Input Voltage (V) 100 500 1000 1500 3000 3500 Load Current (mA) 500 1000 1500 2000 2500 3000 6 8 10 12 14 3500 2500 2000 VOUT = 5V VOUT = 3.3V -40 0 40 130 80 -40 0 40 130 80 0.77 0.78 0.79 0.80 0.81 0.82 0.83 0.84 0.85 460 490 3500 4500 VIN = 12V 5500

Rev 2, 01-Jul-11 - 12 - www.active-semi.com Copyright © 2011 Active-Semi, Inc. Innovative PowerTM TYPICAL PERFORMANCE CHARACTERISTICS CONT’D (Circuit of Figure 5, unless otherwise specified.) ACT4050-008 ACT4050-009 ACT4050-010 CH2 CH1 Start-up/Shutdown by VIN Pin CH1: VEN, 2.0V/div CH2: VOUT, 2.0V/div TIME: 400µs/div CH1 CH2 Start-up/Shutdown by EN Pin CH1: VEN, 2.0V/div CH2: VOUT, 2.0V/div TIME: 200µs/div CH1 CH2 Start-up/Shutdown by EN Pin ACT4050-007 CH2 CH1 Start-up/Shutdown by VIN Pin VIN = 12V VOUT = 5V ILOAD = 1A CH1: VIN, 5.0V/div CH2: VOUT, 2V/div TIME: 100µs/div CH1: VIN, 5.0V/div CH2: VOUT, 2V/div TIME: 100µs/div VIN = 12V VOUT = 5V No Load ACT4050-012 CH1 CH2 Switching Waveform CH1: VOUT, 20mV/div (AC COUPLED) CH2: VSW, 5.0V/div TIME: 1µs/div VIN = 12V VOUT = 5V 1Ω Load ACT4050-011 CH1 CH2 Switching Waveform CH1: VOUT, 20mV/div (AC COUPLED) CH2: VSW, 5.0V/div TIME: 1µs/div VIN = 12V VOUT = 3.3V ILOAD = 1A VIN = 12V VOUT = 5V ILOAD = 1A VIN = 12V VOUT = 5V No Load VIN = 12V VOUT = 5V 2Ω Load

Rev 2, 01-Jul-11 - 13 - www.active-semi.com Copyright © 2011 Active-Semi, Inc. Innovative PowerTM PACKAGE OUTLINE SOP-8/EP PACKAGE OUTLINE AND DIMENSIONS SYMBOL DIMENSION IN MILLIMETERS DIMENSION IN INCHES MIN MAX MIN MAX A 1.350 1.700 0.053 0.067 A1 0.000 0.100 0.000 0.004 A2 1.350 1.550 0.053 0.061 b 0.330 0.510 0.013 0.020 c 0.170 0.250 0.007 0.010 D 4.700 5.100 0.185 0.200 D1 3.202 3.402 0.126 0.134 E 3.800 4.000 0.150 0.157 E1 5.800 6.200 0.228 0.244 E2 2.313 2.513 0.091 0.099 e 1.270 TYP 0.050 TYP L 0.400 1.270 0.016 0.050 θ 0° 8° 0° 8° b E c D A e θ Active-Semi, Inc. reserves the right to modify the circuitr y or specifications without not ice. Users should evaluate each product to make sure that it is suitable for their applications. Active-Semi products are not intended or authorized for use as critical components in life-support devices or systems. Acti ve-Semi, Inc. does not assume any liability arising out of the use of any product or circuit described in this datasheet, nor does it convey any patent license. Active-Semi and its logo are trademarks of Active-Semi, Inc. For more information on this and other products, contact sales@active-semi.com or visit http://www.active-semi.com. is a registered trademark of Active-Semi.