AP65201 TSOT26 LIGHT LOAD IMPROVED 2A SYNCH DC/DC BUCK CONVERTER Description Pin Assignments The AP65201 is a 500kHz switching frequency internal compensated synchronous DC/DC buck converter. It has integrated low RDS(ON) ADVANCED INFORMATION high and low side MOSFETs. Top View The AP65201 enables continuous load current of up to 2A with efficiency as high as 97%. The AP65201 implements an automatic custom light load efficiency improvement algorithm. GND 1 6 BST SW 2 5 EN IN 3 4 FB The AP65201 features current mode control operation, which enables fast transient response times and easy loop stabilization. The AP65201 simplifies board layout and reduces space requirements with its high level of integration and minimal need for external components, making it ideal for distributed power architectures. TSOT26 The AP65201 is available in a standard Green TSOT26 package and is RoHS compliant. Features Applications VIN 4.5V to 16V 2A Continuous Output Current, 3A Peak Efficiency Up to 97% Automated Light Load improvement VOUT Adjustable from 0.8V 500kHz Switching Frequency Internal Soft-Start Enable Pin Overcurrent Protection (OCP) with Hiccup Thermal Protection Totally Lead-Free & Fully RoHS Compliant (Notes 1 & 2) Halogen and Antimony Free. “Green” Device (Note 3) Notes: Gaming Consoles Flat Screen TV Sets and Monitors Set-Top Boxes Distributed Power Systems Home Audio Consumer Electronics Network Systems FPGA, DSP and ASIC Supplies Green Electronics 1. No purposely added lead. Fully EU Directive 2002/95/EC (RoHS) & 2011/65/EU (RoHS 2) compliant. 2. See http://www.diodes.com/quality/lead_free.html 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. Typical Applications Circuit INPUT 6 BST 3 IN VIN 12V ON OFF 5 EN C5 1µF 2 SW 4 FB OUTPUT VOUT 3.3V AP65201 C1 22μF L1 4.7μH R1 40.2kΩ R3 75kΩ R2 13kΩ C2 22μF 1 GND Figure 1. Typical Application Circuit AP65201 Document number: DS36109 Rev. 2 - 2 1 of 14 www.diodes.com September 2015 © Diodes Incorporated AP65201 Pin Descriptions GND Pin Number TSOT26 1 SW 2 IN 3 FB 4 EN 5 BST 6 Function Ground 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 capacitor is required from SW to 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 4.5V to 16V power source. Bypass IN to GND with a suitably large capacitor to eliminate noise on the input to the IC. See Input Capacitor. Feedback Input. FB senses the output voltage and regulates it. Drive FB with a resistive voltage divider connected to it from the output voltage. The feedback threshold is 0.8V. See Setting the Output Voltage. Enable Input. EN is a digital input that turns the regulator on or off. Drive EN high to turn on the regulator; low to turn it off. Attach to IN with a 100kΩ pull up resistor for automatic startup. High-Side Gate Drive Boost Input. BS supplies the drive for the high-side N-Channel MOSFET a 0.01µF or greater capacitor from SW to BS to power the high side switch. Functional Block Diagram 0.3V 0.8V 1.1V INTERNAL REFERENCE EN Vcc REGULATOR + IN OVP RAMP 1.1V OSCILLATOR E CURRENT SENSE AMPLIFIER - + FB + ADVANCED INFORMATION Pin Name 500KHz CLK BST Logic 0.3 V + Internal SS + SW - + CURRENT COMPARATOR 0.8 V GND AP65201 Document number: DS36109 Rev. 2 - 2 2 of 14 www.diodes.com September 2015 © Diodes Incorporated AP65201 Absolute Maximum Ratings (@TA = +25°C, unless otherwise specified.) (Note 4) ADVANCED INFORMATION Symbol Parameter Unit -0.3 to 20 V VIN VSW Switch Node Voltage -1.0 to VIN +0.3 V VBS Bootstrap Voltage VSW -0.3 to VSW +6.0 V VFB Feedback Voltage -0.3V to +6.0 V VEN Enable/UVLO Voltage -0.3V to +6.0 V TST Storage Temperature -65 to +150 °C TJ Junction Temperature +160 °C +260 °C 2.5 1 KV KV Lead Temperature TL ESD Susceptibility (Note 5) HBM Human Body Model CDM Charged Device Model Notes: Rating Supply Voltage 4. Stresses greater than the 'Absolute Maximum Ratings' specified above may cause permanent damage to the device. These are stress ratings only; functional operation of the device at these or any other conditions exceeding those indicated in this specification is not implied. Device reliability may be affected by exposure to absolute maximum rating conditions for extended periods of time. 5. Semiconductor devices are ESD sensitive and may be damaged by exposure to ESD events. Suitable ESD precautions should be taken when handling and transporting these devices. Thermal Resistance (Note 6) Note: Symbol Parameter Rating Unit θJA Junction to Ambient TSOT26 120 °C/W θJC Junction to Case TSOT26 30 °C/W 6. Test condition for SOT26: Device mounted on FR-4 substrate, single-layer PC board, 2oz copper, with minimum recommended pad layout Recommended Operating Conditions (@TA = +25°C, unless otherwise specified.) (Note 7) Symbol Note: Parameter Min Max Unit VIN Supply Voltage 4.5 16 V TA Operating Ambient Temperature Range -40 +85 °C 7. The device function is not guaranteed outside of the recommended operating conditions. AP65201 Document number: DS36109 Rev. 2 - 2 3 of 14 www.diodes.com September 2015 © Diodes Incorporated AP65201 Electrical Characteristics Symbol Parameter Test Conditions Min VEN = 0V — Supply Current (Quiescent) VEN = 2.0V, VFB = 0.85V — RDS(ON)1 High-Side Switch On-Resistance (Note 8) — RDS(ON)2 Low-Side Switch On-Resistance (Note 8) — HS Current Limit (Note 8) Minimum duty cycle ISHDN IQ ADVANCED INFORMATION (@TA = +25°C, VIN = 12V, unless otherwise specified.) ILIMIT Shutdown Supply Current Typ Max Unit 1.0 µA 0.83 — mA — 160 — mΩ — 85 — mΩ 2.8 3.5 — A High-Side Switch Leakage Current VEN = 0V, VSW =12V — — 1 μA FSW Oscillator Frequency VFB = 0.75V 400 500 600 kHz DMAX Maximum Duty Cycle VFB = 700mV 88 92 — % TON Minimum On Time — — 90 — nS VFB Feedback Voltage TA = -40°C to +85°C 776 800 824 mV VEN_RISING EN Rising Threshold — 1.4 1.5 1.6 V VEN_FALLING EN Falling Threshold — ISW_LKG EN Input Current IEN 1.23 1.32 1.41 V VEN = 2V — 2.85 — μA VEN = 0V — 0 — μA INUVVTH VIN Undervoltage Threshold Rising — 3.7 4.05 4.4 V INUVHYS VIN Undervoltage Threshold Hysteresis — — 250 — mV Soft-Start Period — — 1 — mS TSHDN Thermal Shutdown (Note 8) — — +160 — °C THYS Thermal Hysteresis (Note 8) — — +20 — °C TSS Note: 8. Guaranteed by design. AP65201 Document number: DS36109 Rev. 2 - 2 4 of 14 www.diodes.com September 2015 © Diodes Incorporated AP65201 ADVANCED INFORMATION Typical Performance Characteristics (@TA = +25°C, VIN = 12V, VOUT = 3.3V, L = 4.7µH, unless otherwise specified) VIN=6.5V VIN=4.7V VIN=12V VIN=12V VIN=16V VIN=16V VIN=4.7V VIN=4.7V VIN=12V VIN=12V VIN=16V VIN=16V AP65201 Document number: DS36109 Rev. 2 - 2 5 of 14 www.diodes.com September 2015 © Diodes Incorporated AP65201 ADVANCED INFORMATION Typical Performance Characteristics (cont.) (@TA = +25°C, VIN = 12V, VOUT = 3.3V, L = 4.7µH, unless otherwise specified.) VIN=4.7V VIN=4.7V VIN=12V VIN=12V VIN=16V VIN=16V VIN=16V IOUT=2A IOUT=1.5A VIN=12V IOUT=0A VIN=4.7V AP65201 Document number: DS36109 Rev. 2 - 2 6 of 14 www.diodes.com September 2015 © Diodes Incorporated AP65201 Typical Performance Characteristics (cont.) (@T A ADVANCED INFORMATION Startup Through VEN 2A Load = +25°C, VIN = 12V, VOUT = 3.3V, L = 4.7µH, C1 = 22µF, C2 = 22µF, unless otherwise specified.) Startup Through VIN 2A Load VEN (5V/DIV) VIN (12V/DIV) VOUT (3.3V/DIV) VOUT (3.3V/DIV) IOUT (2A/DIV) IOUT (2A/DIV) SW (10V/DIV) SW (10V/DIV) Short Circuit Test VOUT (2V/DIV) IOUT (2A/DIV) Time-1ms/div Time-1ms/div Time-5ms/div Shutdown Through VEN 2A Load Shutdown Through VIN 2A Load Short Circuit Recovery VEN (5V/DIV) VIN (12V/DIV) VOUT (2V/DIV) VOUT (3.3V/DIV) VOUT (3.3V/DIV) IOUT (2A/DIV) IOUT (2A/DIV) SW (10V/DIV) SW (10V/DIV) IOUT (2A/DIV) Time-50µs/div Time-200µs/div Startup Through VEN 0A Load Startup Through VIN 0A Load VEN (5V/DIV) Time-5ms/div Transient Response (1 to 2A) VOUT_AC (200mV/DIV) VIN (12V/DIV) VOUT (3.3V/DIV) VOUT (3.3V/DIV) IOUT (100mA/DIV) IOUT (100mA/DIV) SW (10V/DIV) SW (10V/DIV) Time-1ms/div Time-1ms/div Shutdown Through VEN 0A Load IOUT (1A/DIV) Time-100µs/div Shutdown Through VIN 0A Load Input/Output Ripple (IO=2A) VOUT_AC (200mV/DIV) VEN (5V/DIV) VIN (12V/DIV) VIN_AC (200mV/DIV) VOUT (3.3V/DIV) VOUT (3.3V/DIV) IOUT (100mA/DIV) IOUT (100mA/DIV) SW (10V/DIV) SW (10V/DIV) SW (10V/DIV) IL (2A/DIV) Time-500ms/div AP65201 Document number: DS36109 Rev. 2 - 2 Time-500ms/div 7 of 14 www.diodes.com Time-2µs/div September 2015 © Diodes Incorporated AP65201 Application Information Theory of Operation ADVANCED INFORMATION The AP65201 is a 2A current mode control, synchronous buck regulator with built-in power MOSFETs. Current mode control assures excellent line and load regulation and a wide loop bandwidth for fast response to load transients. Figure 1 depicts the functional block diagram of AP65201. The operation of one switching cycle can be explained as follows: The rising edge of the 500kHz oscillator clock signal sets the RS Flip-Flop. Its output turns on HS MOSFET. When the HS MOSFET is on, inductor current starts to increase. The current sense amplifier senses and amplifies the inductor current. Since the current mode control is subject to sub-harmonic oscillations that start at half of the switching frequency, ramp slope compensation is utilized. This will help to stabilize the power supply. This ramp compensation is summed to the current sense amplifier output and compared to the error amplifier output by the PWM comparator. When the sum of the current sense amplifier output and the slope compensation signal exceeds the EA output voltage, the RS Flip-Flop is reset and HS MOSFET is turned off. When the HS MOSFET turns off, the synchronous LS MOSFET turns on until the next clock cycle begins. There is a “dead time” between the HS turn off and LS turn on that prevents the switches from “shooting through” from the input supply to ground. For one whole cycle, if the sum of the current sense amplifier output and the slope compensation signal does not exceed the EA output, then the falling edge of the oscillator clock resets the Flip-Flop, and forces the MOSFET to turn off. The voltage loop is compensated internally. Enable The enable (EN) input allows the user to control turning on or off the regulator. The AP65201 has an internal pull down resistor on the EN pin and when the EN is not actively pulled up the part turns off. Quiescent Current Above the ‘EN Rising Threshold’, the internal regulator is turned on and the quiescent current can be measured above this threshold. Automated No-Load and Light-Load Operation The AP65201 operates in light load high efficiency mode during low load current operation. The advantage of this light load efficiency mode is lower power losses at no-load and light-load conditions. The AP65201 automatically detects the peak inductor current and enters the light load high efficiency mode when the inductor peak current goes below 500mA. Once the inductor peak current exceeds this level, the AP65201 transitions from light load high efficiency mode to continuous PWM mode. AP65201 Document number: DS36109 Rev. 2 - 2 8 of 14 www.diodes.com September 2015 © Diodes Incorporated AP65201 Application Information (continued) ADVANCED INFORMATION Current Limit Protection In order to reduce the total power dissipation and to protect the application, AP65201 has cycle-by-cycle current limiting implementation. The voltage drop across the internal high-side MOSFET is sensed and compared with the internally set current limit threshold. This voltage drop is sensed at about 30ns after the HS turns on. When the peak inductor current exceeds the set current limit threshold, current limit protection is activated. When the voltage at the FB pin reaches 0.2V the device enters Hiccup mode to periodically restart the part. This protection mode greatly reduces the power dissipated on chip and reduces the thermal issue to protect the device. AP65201 will exit Hiccup mode when the over current situation is resolved. Undervoltage Lockout (UVLO) Undervoltage Lockout is implemented to prevent the IC from insufficient input voltages. The AP65201 has a UVLO comparator that monitors the input voltage and the internal bandgap reference. If the input voltage falls below 4.4V, the AP65201 will latch the undervoltage fault. In this event, the output will be pulled low and power has to be re-cycled to reset the UVLO fault. Overvoltage Protection When the AP65201 FB pin exceeds 115% of the nominal regulation voltage of 0.8V, the overvoltage comparator is tripped. Thermal Shutdown The AP65201 has on-chip thermal protection that prevents damage to the IC when the die temperature exceeds safe margins. It implements a thermal sensing to monitor the operating junction temperature of the IC. Once the die temperature rises to approximately +160°C, the thermal protection feature gets activated. The internal thermal sense circuitry turns the IC off thus preventing the power switch from damage. A hysteresis in the thermal sense circuit allows the device to cool down to approximately +120°C before the IC is enabled again through soft start. This thermal hysteresis feature prevents undesirable oscillations of the thermal protection circuit. Setting the Output Voltage The output voltage can be adjusted from 0.8V using an external resistor divider. Table 1 shows a list of resistor selection for common output voltages. Resistor R1 is selected based on a design tradeoff between efficiency and output voltage accuracy. For high values of R1 there is less current consumption in the feedback network. R1 can be determined by the following equation: V R 1 R 2 OUT 1 0.8 R1 RT FB Vout R2 VOUT (V) R1 (kΩ) R2 (kΩ) RT (kΩ) L1 (µH) 1.05 1.2 1.8 2.5 3.3 5 10 20.5 40.2 40.2 40.2 40.2 32.4 41.2 32.4 19.1 13 7.68 300 249 120 100 75 75 1.5 1.5 2.2 2.2 4.7 6.5 Figure 2. Feedback Divider Network AP65201 Document number: DS36109 Rev. 2 - 2 Table 1. Recommended Component Selection 9 of 14 www.diodes.com September 2015 © Diodes Incorporated AP65201 Application Information (cont.) Inductor ADVANCED INFORMATION Calculating the inductor value is a critical factor in designing a buck converter. For most designs, the following equation can be used to calculate the inductor value; L VOUT (VIN VOUT ) VIN ΔIL fSW Where ΔIL is the inductor ripple current and fSW is the buck converter switching frequency. Choose the inductor ripple current to be 30% of the maximum load current. The maximum inductor peak current is calculated from: IL(MAX) ILOAD ΔIL 2 Peak current determines the required saturation current rating, which influences the size of the inductor. Saturating the inductor decreases the converter efficiency while increasing the temperatures of the inductor and the internal MOSFETs. Hence choosing an inductor with appropriate saturation current rating is important. A 1µH to 10µH inductor with a DC current rating of at least 25% higher than the maximum load current is recommended for most applications. For highest efficiency, the inductor’s DC resistance should be less than 20mΩ. Use a larger inductance for improved efficiency under light load conditions. Input Capacitor The input capacitor reduces the surge current drawn from the input supply and the switching noise from the device. The input capacitor has to sustain the ripple current produced during the on time on the upper MOSFET. It must hence have a low ESR to minimize the losses. The RMS current rating of the input capacitor is a critical parameter that must be higher than the RMS input current. As a rule of thumb, select an input capacitor which has RMs rating that is greater than half of the maximum load current. Input Capacitor The input capacitor reduces the surge current drawn from the input supply and the switching noise from the device. The input capacitor has to sustain the ripple current produced during the on time on the upper MOSFET. It must hence have a low ESR to minimize the losses. The RMS current rating of the input capacitor is a critical parameter that must be higher than the RMS input current. As a rule of thumb, select an input capacitor which has RMs rating that is greater than half of the maximum load current. Due to large dI/dt through the input capacitors, electrolytic or ceramics should be used. If a tantalum must be used, it must be surge protected. Otherwise, capacitor failure could occur. For most applications, a 10/22µF ceramic capacitor is sufficient. Output Capacitor The output capacitor keeps the output voltage ripple small, ensures feedback loop stability and reduces the overshoot of the output voltage. The output capacitor is a basic component for the fast response of the power supply. In fact, during load transient, for the first few microseconds it supplies the current to the load. The converter recognizes the load transient and sets the duty cycle to maximum, but the current slope is limited by the inductor value. Maximum capacitance required can be calculated from the following equation: ESR of the output capacitor dominates the output voltage ripple. The amount of ripple can be calculated from the equation below: Vout capacitor ΔIinductor * ESR An output capacitor with ample capacitance and low ESR is the best option. For most applications, a 22µF ceramic capacitor will be sufficient. ΔIinductor 2 ) 2 Co (Δ V Vout )2 Vout2 L(Iout Where ΔV is the maximum output voltage overshoot. AP65201 Document number: DS36109 Rev. 2 - 2 10 of 14 www.diodes.com September 2015 © Diodes Incorporated AP65201 Application Information (cont.) PC Board Layout ADVANCED INFORMATION This is a high switching frequency converter. Hence, attention must be paid to the switching currents interference in the layout. Switching current from one power device to another can generate voltage transients across the impedances of the interconnecting bond wires and circuit traces. These interconnecting impedances should be minimized by using wide, short printed circuit traces. Figure 3—PC Board Layout External Bootstrap Diode It is recommended that an external bootstrap diode be added when the input voltage is no greater than 5V or the 5V rail is available in the system. This helps to improve the efficiency of the regulator. This solution is also applicable for D > 65%. The bootstrap diode can be a low cost one such as BAT54 or a Schottky that has a low VF. 5V BST AP65201 BOOST DIODE 10nF SW Figure 4—External Bootstrap Compensation Components Recommended Diodes: Voltage/Current Part Number Rating B130 30V, 1A SK13 30V, 1A AP65201 Document number: DS36109 Rev. 2 - 2 11 of 14 www.diodes.com Vendor Diodes Inc. Diodes Inc. September 2015 © Diodes Incorporated AP65201 Ordering Information Package Packing WU : TSOT26 7 : Tape & Reel Part Number Package Code Package Identification Code AP65201WU-7 WU TSOT26 SA Tape and Reel Quantity Part Number Suffix 3,000 -7 Marking Information TSOT26 ( Top View ) 6 5 4 7 ADVANCED INFORMATION AP65201WU - 7 XX Y W X 1 AP65201 Document number: DS36109 Rev. 2 - 2 2 3 XX : Identification Code Y : Year 0~9 W : Week : A~Z : 1~26 week; a~z : 27~52 week; z represents 52 and 53 week X : Internal Code Part Number Package Identification Code AP65201WU-7 TSOT26 SA 12 of 14 www.diodes.com September 2015 © Diodes Incorporated AP65201 Package Outline Dimensions Please see AP02002 at http://www.diodes.com/datasheets/ap02002.pdf for the latest version. TSOT26 ADVANCED INFORMATION D e1 TSOT26 Dim Min Max Typ A 1.00 A1 0.010 0.100 A2 0.840 0.900 D 2.800 3.000 2.900 E 2.800 BSC E1 1.500 1.700 1.600 b 0.300 0.450 c 0.120 0.200 e 0.950 BSC e1 1.900 BSC L 0.30 0.50 L2 0.250 BSC θ 0° 8° 4° θ1 4° 12° All Dimensions in mm 01(4x) E1/2 E/2 E1 c E Gauge Plane 0 L L2 01(4x) b e Seating Plane A2 A1 A Seating Plane Suggested Pad Layout Please see AP02001 at http://www.diodes.com/datasheets/ap02001.pdf for the latest version. TSOT26 C Dimensions Value (in mm) C 0.950 X 0.700 Y 1.000 Y1 3.199 Y1 Y X AP65201 Document number: DS36109 Rev. 2 - 2 13 of 14 www.diodes.com September 2015 © Diodes Incorporated AP65201 IMPORTANT NOTICE ADVANCED INFORMATION 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). 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Customers represent that they have all necessary expertise in the safety and regulatory ramifications of their life support devices or systems, and acknowledge and agree that they are solely responsible for all legal, regulatory and safety-related requirements concerning their products and any use of Diodes Incorporated products in such safety-critical, life support devices or systems, notwithstanding any devices- or systems-related information or support that may be provided by Diodes Incorporated. Further, Customers must fully indemnify Diodes Incorporated and its representatives against any damages arising out of the use of Diodes Incorporated products in such safety-critical, life support devices or systems. Copyright © 2015, Diodes Incorporated www.diodes.com AP65201 Document number: DS36109 Rev. 2 - 2 14 of 14 www.diodes.com September 2015 © Diodes Incorporated