AP6501

AP6501

Document overview

• Manufacturer or author: Diodes Incorporated
• PDF pages: 15

Technical content

Features

• V IN 4.75V to 23V
• 2A continuous Output Current, 3A Peak
• V OUT Adjustable to 0.925 to 20V
• 340kHz Switching Frequency
• Programmable Soft-Start
• Enable Pin
• Protection ƒ OCP ƒ Thermal Shutdown
• Totally Lead-Free & Fully RoHS Compliant (Notes 1 & 2)
• Halogen and Antimony Free. “Green” Device (Note 3)

Applications

• 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 Notes: 1. No purposely added lead. Fully EU Directiv e 2002/95/EC (RoHS) & 2011/65/EU (RoHS 2) compliant. 2. See http://www.diodes.com for more in formation 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 Application Circuit

Figure 2. Typical Application Circuit

1 BS 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 to power the high side switch. input to the IC. See Input Capacitor. 4 GND Ground (Connect the exposed pad to Pin 4, not applicable in the SO-8 package).

6 COMP

network from COMP to GND. In some cases, an additional capacitor from COMP to GND is required. See Compensation Components. regulator; low to turn it off. Attach to IN with a 100kΩ pull up resistor for automatic startup. EP EP EP exposed thermal pad connect to Pin 4 GND, not applicable in the SO-8 package. Figure 3. Functional Block Diagram

Document number: DS36059 Rev. 1 - 2 3 of 15 www.diodes.com September 2012 © Diodes Incorporated AP6501 NEW PRODUCT Absolute Maximum Ratings (Note 4) (@TA = +25°C, unless otherwise specified.) Symbol Parameter Rating Unit VIN Supply Voltage -0.3 to +26 V VSW Switch Node Voltage -1.0 to VIN +0.3 V VBS Bootstrap Voltage VSW-0.3 to VSW + 6 V VFB Feedback Voltage -0.3V to +6 V VEN Enable/UVLO Voltage -0.3V to +6 V VCOMP Comp Voltage -0.3V to +6 V TST Storage Temperature -65 to +150 °C TJ Junction Temperature +150 °C TL Lead Temperature +260 °C ESD Susceptibility (Note 5) HBM Human Body Model 3 kV MM Machine Model 250 V Notes: 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 ma ximum 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 ta ken when handling and transporting these devices. Thermal Resistance (Note 6) (@TA = +25°C, unless otherwise specified.) Symbol Parameter Rating Unit θJA Junction to Ambient SO-8EP 74 °C/W SO-8 126 θJC Junction to Case SO-8EP 16 SO-8 28 Note: 6. Test condition: SO-8: Device mounted on 1"x1 " FR-4 substrate PCB, 2oz copper, with minimum recommended pad layout. SO-8EP: Device mounted on 1" x 1" FR-4 substrate PC board, 2oz copper, with minimum recommended pad on top layer and thermal vias to bottom layer ground plane. Recommended Operating Conditions (Note 7) (@TA = +25°C, unless otherwise specified.) Symbol Parameter Min Max Unit VIN Supply Voltage 4.75 23 V TA Operating Ambient Temperature Range -40 +85 °C Note: 7. The device function is not guaranteed outside of the recommended operating conditions.

Document number: DS36059 Rev. 1 - 2 4 of 15 www.diodes.com September 2012 © Diodes Incorporated AP6501 NEW PRODUCT Electrical Characteristics (VIN = 12V, @TA = +25°C, unless otherwise specified.) Symbol Parameter Test Conditions Min Typ Max Unit IIN Shutdown Supply Current VEN = 0V 0.3 3.0 µA IIN Supply Current (Quiescent) VEN = 2.0V, VFB = 1.0V 0.6 1.5 mA RDS(ON)1 High-Side Switch On-Resistance (Note 8) 130 m Ω RDS(ON)2 Low-Side Switch On-Resistance (Note 8) 130 m Ω ILIMIT HS Current Limit Minimum duty cycle 4.4 A ILIMIT LS Current Limit From Drain to Source 0.9 A High-Side Switch Leakage Current VEN = 0V, VSW = 0V, VSW = 12V 0 10 μA AVEA Error Amplifier Voltage Gain (Note 8) 800 V/V GEA Error Amplifier Transconductance ΔIC = ±10µA 1000 uA/V GCS COMP to Current Sense Transconductance 2.8 A/V FSW Oscillator Frequency VFB = 0.75V 300 340 380 kHz FFB Fold-back Frequency VFB = 0V 0.30 fSW DMAX Maximum Duty Cycle VFB = 800mV 90 % TON Minimum On Time 130 ns VFB Feedback Voltage TA = -40°C to +85°C 900 925 950 mV Feedback Overvoltage Threshold 1.1 V VEN_Rising EN Rising Threshold 0.7 0.8 0.9 V EN Lockout Threshold Voltage 2.2 2.5 2.7 V EN Lockout Hysteresis 220 mV INUVVth V IN Under Voltage Threshold Rising 3.80 4.05 4.40 V INUVHYS V IN Under Voltage Threshold Hysteresis 250 mV Soft-Start Current VSS = 0V 6 μA Soft-Start Period CSS = 0.1µF 15 ms TSD Thermal Shutdown (Note 8) 160 °C Note: 8. Guaranteed by design

Document number: DS36059 Rev. 1 - 2 5 of 15 www.diodes.com September 2012 © Diodes Incorporated AP6501 NEW PRODUCT Typical Performance Graphs (VIN = 12V, @TA = +25°C, unless otherwise specified.) QUIESCENT SUPPLY CURRENT (mA) 0.48 0.5 0.52 0.54 0.56 0.58 0.6 0 5 10 15 20 25 INPUT VOLTAGE (V) Quiescent Supply Current vs. Input Voltage SHUTDOWN SUPPLY CURRENT (µA) 0 5 10 15 20 25 INPUT VOLTAGE (V) Shutdown Supply Current vs. Input Voltage 0.004 0.014 0.024 0.034 0.044 0.054 0.064 0.074 CURRENT LIMIT (A) 4.8 5.2 5.4 5.6 5.8 6.2 -60 -40 -20 0 20 40 60 80 100 TEMPERATURE (C) Current Limit vs. Temperature OUTPUT VOLTAGE (V) V = 1 2 VIN 3.32 3.321 3.322 3.323 3.324 3.325 3.326 3.327 3.328 3.329 3.33 INPUT VOLTAGE (V) Line Regulation -60 -40 -20 0 20 40 60 80 100 TEMPERATURE (°C) Feedback Voltage vs. Temperature FEEDBACK VOLTAGE (V) 0.9 0.902 0.904 0.906 0.908 0.91 0.912 0.914 0.916 0.918 0.92 350 355 360 365 370 375 -60 -40 -20 0 20 40 60 80 100 TEMPERATURE (°C) Oscillator Frequency vs. Temperature OSCILLATOR FREQUENCY (Khz)

Document number: DS36059 Rev. 1 - 2 6 of 15 www.diodes.com September 2012 © Diodes Incorporated AP6501 NEW PRODUCT Typical Performance Graphs (cont.) (VIN = 12V, VOUT = 3.3V, (@TA = +25°C, unless otherwise specified.) 0 0.4 0.8 1.2 1.6 2 V = 12VIN LOAD CURRENT (A) Efficiency vs. Load Current EFFICIENCY (%) V = 1.2V L = 3.3µH OUT 0 0.4 0.8 1.2 1.6 2 V = 5 VIN V = 1 2 VIN LOAD CURRENT (A) Efficiency vs. Load Current EFFICIENCY (%) V = 1.8V L = 3.3µH OUT LOAD CURRENT (A) Efficiency vs. Load Current 02 0.4 0.8 1.2 1.6 100 EFFICIENCY (%) V = 12V V = 5 V L = 10µH IN OUT

Document number: DS36059 Rev. 1 - 2 7 of 15 www.diodes.com September 2012 © Diodes Incorporated AP6501 NEW PRODUCT Typical Performance Characteristics (VIN = 12V, VOUT = 3.3V, L = 10µH, C1 = 22µF, C2 = 47µF, @TA = +25°C, unless otherwise specified.) Steady State Test no load Time -2µs/div Steady State Test 2A Time -2µs/div Startup Through Enable_no load Time -10ms/div Startup Through Enable 2A Time -2ms/div Shutdown Through Enable_no load Time -10ms/div Shutdown Through Enable 2A Time -5ms/div Load Transient Test 1.0A to 2.0A Time -100µs/div Short Circuit Test Time -20µs/div Short Circuit Recovery Time -20µs/div

Document number: DS36059 Rev. 1 - 2 8 of 15 www.diodes.com September 2012 © Diodes Incorporated AP6501 NEW PRODUCT Applications Information Theory of Operation The AP6501 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 respons e to load transients. Figure 3 depicts the functional block diagram of AP6501. The operation of one switching cycle can be explained as follows. At the beginning of each cycle, HS (high-side) MOSFET is off. The error amplifier (EA) output voltage is higher than the current sense amplifier output, and the current comparator’s output is low. The rising edge of the 340kHz oscillator clock signal sets the RS Flip-Flop. Its output turns on HS MOSFET . The current sense amplifier is reset f or every switching cycle. 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 peak at half the switching frequency, ramp slope compensa tion 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 compensat ion signal exceeds the EA output voltage, the RS Flip-Flop is reset and HS MOSFET is turned off. For one whole cycle, if the sum of the current sense amplifier output and the slope compensati on signal does not exceed the EA output, then the falling edge of the oscillator clock resets the Flip-Flop. The output of the error amplifier increases when feedback voltag e (VFB) is lower than the reference voltage of 0.925V. This also increases the inductor current as it is proportional to the EA voltage. If in one cycle the current in the power MOSFET does not reach t he COMP set current value, the power MOSFET will be forced to t urn off. When the HS MOSFET turns off, the synchronous LS MOSFET turns on until the next clock cycle begins. There is a “dead time” bet ween the HS turn off and LS turn on that prevents the switches from “shooting through” from the input supply to ground. The voltage loop is compensated through an internal transconduct ance amplifier and can be adjusted through the external compens ation components. Enable Above the ‘EN Rising Threshold’, the internal regulator is turned on and the quiescent current can be measured above this thres hold. The enable (EN) input allows the user to control turning on or off the regulator. To enable the AP6501, EN must be pulled above the ‘EN Lockout Threshold Voltage’ and to disable the AP6501, EN must be pulled below ‘EN Lockout Threshold Voltage - EN Lockout Hysteresis’ External Soft Start Soft start is traditionally implemented to prevent the excess inrush current. This in turn prevents the converter output voltage from overshooting when it reaches regulation. The AP6501 has an internal current source with a soft start capacitor to ramp the refe rence voltage from 0V to 0.925V. The soft start current is 6uA. The soft star t sequence is reset when there is a Thermal Shutdown, Under Volt age Lockout (UVLO) or when the part is disabled using the EN pin. External Soft Start can be calculated from the formula below: DT DV* CSSI = Where; ISS = Soft Start Current C = External Capacitor DV = change in feedback voltage from 0V to maximum voltage DT = Soft Start Time Current Limit Protection In order to reduce the total power dissipation and to protect t he application, AP6501 has cycle-by-cycle current limiting imple mentation. The voltage drop across the internal high-side MOSF ET is sensed and compared with the inter nally set current limit threshold. This voltage drop is sensed at about 30ns after the HS turns on. When the peak induct or current exceeds the set current limit threshold, current limit protection is activated. During this time the feedback voltage (VFB) drops down. When the voltage at the FB pin reaches 0.3V, the interna l oscillator shifts the frequency from the normal operating frequency of 340kHz to a fold-back frequency of 102kHz. The current limit is red uced to 70% of nominal current limit when the part is operating at 102kHz. This low fold-back frequency prevents runaway current.

event the output will be pulled low and power has to be re-cycled to reset the UVLO fault. pin and the SS pin are discharged to GND, forcing the high-side switch off. protection feature gets activated. The internal thermal sense circuitry turns the IC off thus preventing the power switch from damage. start. This thermal hysteresis feature prevents undesirable oscillations of the thermal protection circuit. Figure 4. Feedback Divider Network When output voltage is low, network as shown in Figure 4 is recommended. error amplifier voltage gain.

Where GEA is the error amplifier trans-conductance.

3 R 3 C 2

where the feedback loop has the unity gain is crucial.

1. Choose the compensation resistor (R3) to set the desired crossover frequency. Determine the R3 value by the following equation:

Where fC is the crossover frequency, which is typically less than one tenth of the switching frequency.

1. Choose the compensation capacitor (C3) to achieve the desired phase margin set the compensation zero, f Z1, to below one fourth of the

23 C × × π>

Where R3 is the compensation resistor value. Table 2. Recommended Component Selection Where LΔI is the inductor ripple current. And SWf is the buck converter switching frequency.

Document number: DS36059 Rev. 1 - 2 11 of 15 www.diodes.com September 2012 © Diodes Incorporated AP6501 NEW PRODUCT Applications Information (cont.) Inductor (cont.) Peak current determines the required saturation current rating, wh ich influences the size of the inductor. Saturating the induc tor decreases the converter efficiency while increasing t he temperatures of the inductor and the inte rnal 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% percent higher than the maximum load current is recommended for most applications. For highest efficiency, the inductor’s DC resistance should be less than 200m Ω. Use a larger inductance for improved efficiency under light load conditions. Input Capacitor The input capacitor reduces the surge current drawn from the i nput supply and the switching noise from the device. The input ca pacitor 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 b e surge protected. Otherwise, capacitor failure could occur. For most applications, a 4.7µF ceramic capacitor is sufficient. Output Capacitor The output capacitor keeps the output voltage ripple small, ens ures feedback loop stability and reduces the overshoot of the ou tput voltage. The output capacitor is a basic component for the fast response of the power supply. In fact, during load transient, for the fi rst few microseconds it supplies the current to t he load. The converter recognizes the load transient and sets the duty cycle to maximu m, 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: ESR *inductorΔIcapacitorVout = An output capacitor with ample capacitance and low ESR is the bes t option. For most applications, a 22µF ceramic capacitor will be sufficient. out out 2inductor out o V ) V V (Δ ΔIL(I C − + Where ΔV is the maximum output voltage overshoot.

circuit traces. These interconnecting impedances should be minimized by using wide, short printed circuit traces. help to increase the power dissipation. This is not applicable for the AP6501S-13. cost one such as BAT54 or a schottky that has a low Vf. Figure 7. External Bootstrap

Document number: DS36059 Rev. 1 - 2 13 of 15 www.diodes.com September 2012 © Diodes Incorporated AP6501 NEW PRODUCT

Ordering Information

Code Packaging 13” Tape and Reel Quantity Part Number Suffix AP6501SP-13 SP SO-8EP 2500/Tape & Reel -13 AP6501S-13 S SO-8 2500/Tape & Reel -13 Marking Information Package Outline Dimensions (All dimensions in mm.) (1) SO-8EP SO-8EP (SOP-8L-EP) Dim Min Max Typ A 1.40 1.50 1.45 A1 0.00 0.13 - b 0.30 0.50 0.40 C 0.15 0.25 0.20 D 4.85 4.95 4.90 E 3.80 3.90 3.85 E0 3.85 3.95 3.90 E1 5.90 6.10 6.00 e - - 1.27 F 2.75 3.35 3.05 H 2.11 2.71 2.41 L 0.62 0.82 0.72 N - - 0.35 Q 0.60 0.70 0.65 All Dimensions in mm Gauge Plane Seating Plane E N e b A 45° H F Exposed Pad Bottom View L Q C 4° ± 3° 9° (All sides) D

Document number: DS36059 Rev. 1 - 2 14 of 15 www.diodes.com September 2012 © Diodes Incorporated AP6501 NEW PRODUCT Package Outline Dimensions (cont.) (All dimensions in mm.) (2) SO-8 Suggested Pad Layout (All dimensions in mm.) (1) SO-8EP (2) SO-8 SO-8 Dim Min Max A - 1.75 A1 0.10 0.20 A2 1.30 1.50 A3 0.15 0.25 b 0.3 0.5 D 4.85 4.95 E 5.90 6.10 E1 3.85 3.95 e 1.27 Typ h - 0.35 L 0.62 0.82 0° 8 ° All Dimensions in mm Dimensions Value (in mm) X 0.60 Y 1.55 X1 3.30 Y1 2.66 C1 5.4 C2 1.27 Dimensions Value (in mm) X 0.60 Y 1.55 C1 5.4 C2 1.27 X Y Exposed Pad Gauge Plane Seating Plane Detail ‘A’ Detail ‘A’ EE1 h L D e b A 45° 7°~9° 0.254 X Y

Document number: DS36059 Rev. 1 - 2 15 of 15 www.diodes.com September 2012 © Diodes Incorporated AP6501 NEW PRODUCT 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 ot her 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. Any Customer or user of this document or products desc ribed herein in such applications shall assume all risks of such use and will agree to hold Diodes Incorporated and all the companies whose products are represented on Diodes Incorporated website, harmless against all damages. Diodes Incorporated does not warrant or accept any liability whatsoever in respect of any products purchased through unauthoriz ed sales channel. Should Customers purchase or use Diodes Incorporated products for any unintended or unauthorized application, Customers shall indemnify and hold Diodes Incorporated and its representatives harmless against all claims, damages, expenses, and attorney fee s arising out of, directly or indirectly, any claim of personal injury or death associated with such unintended or unauthorized application. Products described herein may be covered by one or more United States, international or foreign patents pending. Product names and markings noted herein may also be covered by one or more United States, international or foreign trademarks. LIFE SUPPORT Diodes Incorporated products are specifically not authorized for use as critical components in life support devices or systems without the express written approval of the Chief Executive Officer of Diodes Incorporated. As used herein: A. Life support devices or systems are devices or systems which: 1. are intended to implant into the body, or 2. support or sustain life and whose failure to perform when properly used in accordance with instructions for use provided in the labeling can be reasonably expected to result in significant injury to the user. B. A critical component is any component in a life support device or system whose failure to perform can be reasonably expected to cause the failure of the life support device or to affect its safety or effectiveness. Customers represent that they have all necessary expertise in the safety and regulatory ramifications of their life support dev ices 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 © 2012, Diodes Incorporated www.diodes.com