Is Now Part of To learn more about ON Semiconductor, please visit our website at www.onsemi.com Please note: As part of the Fairchild Semiconductor integration, some of the Fairchild orderable part numbers will need to change in order to meet ON Semiconductor's system requirements. Since the ON Semiconductor product management systems do not have the ability to manage part nomenclature that utilizes an underscore (_), the underscore (_) in the Fairchild part numbers will be changed to a dash (-). This document may contain device numbers with an underscore (_). Please check the ON Semiconductor website to verify the updated device numbers. The most current and up-to-date ordering information can be found at www.onsemi.com. Please email any questions regarding the system integration to Fairchild_questions@onsemi.com. ON Semiconductor and the ON Semiconductor logo are trademarks of Semiconductor Components Industries, LLC dba ON Semiconductor or its subsidiaries in the United States and/or other countries. ON Semiconductor owns the rights to a number of patents, trademarks, copyrights, trade secrets, and other intellectual property. A listing of ON Semiconductor's product/patent coverage may be accessed at www.onsemi.com/site/pdf/Patent-Marking.pdf. ON Semiconductor reserves the right to make changes without further notice to any products herein. ON Semiconductor makes no warranty, representation or guarantee regarding the suitability of its products for any particular purpose, nor does ON Semiconductor assume any liability arising out of the application or use of any product or circuit, and specifically disclaims any and all liability, including without limitation special, consequential or incidental damages. Buyer is responsible for its products and applications using ON Semiconductor products, including compliance with all laws, regulations and safety requirements or standards, regardless of any support or applications information provided by ON Semiconductor. "Typical" parameters which may be provided in ON Semiconductor data sheets and/or specifications can and do vary in different applications and actual performance may vary over time. All operating parameters, including "Typicals" must be validated for each customer application by customer's technical experts. ON Semiconductor does not convey any license under its patent rights nor the rights of others. ON Semiconductor products are not designed, intended, or authorized for use as a critical component in life support systems or any FDA Class 3 medical devices or medical devices with a same or similar classification in a foreign jurisdiction or any devices intended for implantation in the human body. Should Buyer purchase or use ON Semiconductor products for any such unintended or unauthorized application, Buyer shall indemnify and hold ON Semiconductor and its officers, employees, subsidiaries, affiliates, and distributors harmless against all claims, costs, damages, and expenses, and reasonable attorney fees arising out of, directly or indirectly, any claim of personal injury or death associated with such unintended or unauthorized use, even if such claim alleges that ON Semiconductor was negligent regarding the design or manufacture of the part. ON Semiconductor is an Equal Opportunity/Affirmative Action Employer. This literature is subject to all applicable copyright laws and is not for resale in any manner. FAN53541 2.4 MHz, 5 A TinyBuckTM Synchronous Buck Regulator Features Description The FAN53541 is a step-down switching voltage regulator that delivers an adjustable output from an input voltage supply of 2.7 V to 5.5 V. Using a proprietary architecture with synchronous rectification, the FAN53541 is capable of delivering 5 A at over 90% efficiency, while maintaining a very high efficiency of over 80% at load currents as low as 2 mA. The regulator operates at a nominal fixed frequency of 2.4 MHz, which reduces the value of the external components to 470 nH for the output inductor and 20 F for the output capacitor. Additional output capacitance can be added to improve regulation during load transients without affecting stability and inductance up to 1.2 H may be used with additional output capacitance. 2.4 MHz Fixed-Frequency Operation Best-in-Class Load Transient Response 5 A Output Current Capability 2.7 V to 5.5 V Input Voltage Range Adjustable Output Voltage: 0.8 V to 90% of VIN PFM Mode for High Efficiency in Light Load (Forced PWM Available on MODE Pin) 50 A Typical Quiescent Current in PFM Mode External Frequency Synchronization Low Ripple Light-Load PFM Mode with Forced PWM Control Power Good Output Internal Soft-Start Input Under-Voltage Lockout (UVLO) Thermal Shutdown and Overload Protection No External Compensation Required 20-Bump WLCSP Applications Set-Top Box Hard Disk Drive Communications Cards DSP Power At moderate and light loads, pulse frequency modulation (PFM) is used to operate the device in power-save mode with a typical quiescent current of 50 A. Even with such a low quiescent current, the part exhibits excellent transient response during large load swings. At higher loads, the system automatically switches to fixed-frequency control, operating at 2.4 MHz. In shutdown mode, the supply current drops below 1 A, reducing power consumption. PFM mode can be disabled if constant frequency is desired. The FAN53541 is available in a 20-bump 1.96 mm x 1.56 mm Wafer-Level Chip-Scale Package (WLCSP). PGOOD VIN CIN 10F L1 SW CIN1 0.47H 10nF FAN53541 GND COUT COUT 10F 10F VOUT EN R1 FB MODE R2 Figure 1. Typical Application Ordering Information Part Number Temperature Range FAN53541UCX -40 to 85C (c) 2013 Semiconductor Components Industries, LLC. FAN53541 * Rev. 1.1 Package 20-Ball Wafer-Level, Chip-Scale Package (WLCSP), 4x5 Array, 0.4 mm Pitch, 250 m Ball Packing Method Tape and Reel www.fairchildsemi.com www.onsemi.com FAN53541 -- 2.4MHz, 5A TinyBuckTM Synchronous Buck Regulator May 2017 Table 1. Recommended External Components for 5 A Maximum Load Current Component Description Vendor Parameter Typical Unit L1 470 nH Nominal See Table 2 L 0.47 H COUT 10 F, 6.3V, X5R, 0805, 2 Pieces C 20 F CIN 10 F, 6.3 V, X5R, 0805 GRM21BR60J106M (Murata) C2012X5R0J106M (TDK) C 10 F CIN1 10 nF, 25 V, X7R, 0402 Any C 10 nF Table 2. Recommended Inductors Component Dimensions DCR (m) IMAXDC 1 ( ) Manufacturer Part# L (nH) Bourns SRP5012-R47M 470 19 Bourns SRP4012-R47M 470 20 L W H 6.0 5.1 4.5 1.2 5.5 4.6 4.0 1.2 Coilcraft XPL4020-471ML 470 19 7.2 4.2 4.2 2.0 Inter-Technical(2) SC2511-R47M 470 2.6 16.0 6.5 6.5 3.0 TDK VLC5020T-R47M 470 15 5.4 5.0 5.0 2.0 Vishay IHLP1616ABERR47M01 470 20 5.0 4.5 4.1 1.2 Notes: 1. IMAXDC is the lesser current to produce 40C temperature rise or 30% inductance roll-off. 2. Inductor used for efficiency and temperature rise measurements. (c) 2013 Semiconductor Components Industries, LLC. FAN53541 * Rev. 1.1 2 www.fairchildsemi.com www.onsemi.com FAN53541 -- 2.4 MHz, 5 A TinyBuckTM Synchronous Buck Regulator Recommended External Components PGOOD EN FB VOUT A1 A2 A3 A4 A4 A3 A2 A1 MODE GND B1 B2 B3 B4 B4 B3 B2 B1 C1 C2 C3 C4 C4 C3 C2 C1 D1 D2 D3 D4 D4 D3 D2 D1 E1 E2 E3 E4 E4 E3 E2 E1 VIN SW Figure 2. Top View Figure 3. Top View Bottom View Pin Definitions Bump # Name Description A1 PGOOD A2 EN Enable. The device is in Shutdown Mode when this pin is LOW. Do not leave this pin floating. A3 FB FB. Connect to resistor divider. The IC regulates this pin to 0.8 V. A4 VOUT VOUT. Sense pin for VOUT. Connect directly to COUT. B1 MODE MODE / SYNC. A logic 0 allows the IC to automatically switch to PFM during light loads. When held HIGH, the IC to stays in PWM Mode. The regulator also synchronizes its switching frequency to four times (4X) the frequency provided on this pin (fMODE). Do not leave this pin floating. B2, B3, C1 - C4 GND Ground. Low-side MOSFET is referenced to this pin. CIN and COUT should be returned with a minimal path to these pins. B4 AGND D1, D2, E1, E2 VIN Power Input Voltage. Connect to input power source. Connect to CIN with minimal path. D3, D4, E3, E4 SW Switching Node. Connect to inductor. Power Good. This open-drain pin pulls LOW if the output falls out of regulation or is in soft-start. Analog Ground. All signals are referenced to this pin. Avoid routing high dV/dt AC currents through this pin. (c) 2013 Semiconductor Components Industries, LLC. FAN53541 * Rev. 1.1 3 www.fairchildsemi.com www.onsemi.com FAN53541 -- 2.4 MHz, 5 A TinyBuckTM Synchronous Buck Regulator Pin Configuration Stresses exceeding the absolute maximum ratings may damage the device. The device may not function or be operable above the recommended operating conditions and stressing the parts to these levels is not recommended. In addition, extended exposure to stresses above the recommended operating conditions may affect device reliability. The absolute maximum ratings are stress ratings only. Symbol Parameter SW, VIN Pins VIN Other Pins Min. Max. -0.3 7.0(3) Tied without Series Impedance -0.3 4.5 Tied through Series Resistance 100 -0.3 VIN4 Human Body Model per JESD22-A114 2250 Charged Device Model per JESD22-C101 1500 Unit V ESD Electrostatic Discharge Protection Level TJ Junction Temperature -40 +150 C TSTG Storage Temperature -65 +150 C +260 C TL Lead Soldering Temperature, 10 Seconds V Note: 3. VIN slew rate is limited to 1 V/s. 4. Lesser of 7 V or VIN+0.3 V. Recommended Operating Conditions The Recommended Operating Conditions table defines the conditions for actual device operation. Recommended operating conditions are specified to ensure optimal performance to the datasheet specifications. ON Semiconductor does not recommend exceeding them or designing to Absolute Maximum Ratings. Symbol Parameter Min. Typ. Max. Unit VIN Supply Voltage Range 2.7 5.5 V VOUT Output Voltage Range 0.8 90% Duty Cycle V IOUT Output Current 0 5 A 1.20 H L CIN COUT Inductor 0.47 Input Capacitor 10 Output Capacitor F 20 F TA Operating Ambient Temperature -40 +85 C TJ Operating Junction Temperature -40 +125 C Typical Unit 38(5) C/W Thermal Properties Symbol JA Parameter Junction-to-Ambient Thermal Resistance Note: 5. See Thermal Considerations in the Applications section. (c) 2013 Semiconductor Components Industries, LLC. FAN53541 * Rev. 1.1 4 www.fairchildsemi.com www.onsemi.com FAN53541 -- 2.4 MHz, 5 A TinyBuckTM Synchronous Buck Regulator Absolute Maximum Ratings Minimum and maximum values are at V IN=2.7 V to 5.5 V, and TA=-40C to +85C, unless otherwise noted. Typical values are at TA=25C, VIN=5 V, and VOUT=1.2 V. Symbol Parameter Condition Min. Typ. Max. Unit ILOAD=0, MODE=0 (AUTO PFM/PWM) 15 50 200 A ILOAD=0, MODE=1 (Forced PWM) 8 30 100 mA Power Supplies IQ Quiescent Current I SD Shutdown Supply Current VUVLO Under-Voltage Lockout Threshold VUVHYST Under-Voltage Lockout Hysteresis EN=GND 0.1 10 A VIN Rising 2.67 2.80 V VIN Falling 2.1 2.3 V 365 mV Logic Pins VIH High-Level Input Voltage VIL Low-Level Input Voltage VLHYST IIN 1.05 V 0.4 Logic Input Hysteresis Voltage 140 Input Bias Current Input Tied to GND or 1 k Resistor to VIN IOUTL PGOOD Pull-Down Current VPGOOD=0.4 V IOUTH PGOOD HIGH Leakage Current VPGOOD=VIN 0.01 V mV 1.00 1 A mA 0.01 1.00 A VOUT Regulation VREF Output Reference DC Accuracy, Measured at FB Pin TA=25C, Forced PWM 0.792 0.800 0.808 V TA=-40C to 85C, Forced PWM 0.787 0.800 0.813 V AUTO PFM/PWM 0.784 0.800 0.824 V VOUT ILOAD Load Regulation MODE=VIN (Forced PWM) -0.02 %/A VOUT VIN Line Regulation 2.7 V VIN 5.5 V, IOUT(DC)=1.5 A -0.16 %/V FB Pin Leakage Current FB=0.8 V Transient Response ILOAD Step 0.1 A to 1.5 A, tR=100 ns IREF 1 nA -30 mV RDS(ON)P P-Channel MOSFET On Resistance 33 m RDS(ON)N N-Channel MOSFET On Resistance 28 m VOUT Power Switch and Protection ILIMPK P-MOS Peak Current Limit TLIMIT Thermal Shutdown THYST Thermal Shutdown Hysteresis VSDWN Input OVP Shutdown Open Loop 5.8 Closed Loop 8.8 A 8 A 155 C 20 C 6.1 V 5.5 5.8 V 2.1 2.4 3.0 MHz 525 600 700 kHz Rising Threshold Falling Threshold 7.5 Frequency Control fSW fMODE Oscillator Frequency MODE Pin Synchronization Range External Square-Wave, 30% to 70% Duty Cycle Soft-Start and Output Discharge tSS RDIS Regulator Enable to Regulated VOUT (Rising PGOOD) Output Discharge Resistance (c) 2013 Semiconductor Components Industries, LLC. FAN53541 * Rev. 1.1 EN=0 V 5 1.2 ms 175 www.fairchildsemi.com www.onsemi.com FAN53541 -- 2.4 MHz, 5 A TinyBuckTM Synchronous Buck Regulator Electrical Characteristics 95% 95% 90% 90% Efficiency Efficiency Unless otherwise specified; VIN=5 V, VOUT=1.2 V, VMODE=0 V, TA=25C, circuit in Figure 1, and components per Table 1. 85% 80% 2.7 VIN 75% 85% 80% -40C 75% 3.3 VIN +25C 5.0 VIN +85C 5.5 VIN 70% 70% 0 1000 2000 3000 4000 5000 0 1000 Load Current (mA) 3000 4000 Figure 5. Efficiency vs. ILOAD, 1.2 VOUT 95% 90% 90% Efficiency 95% 85% 80% 2.7 VIN 75% 85% 80% -40C 75% 3.3 VIN +25C 5.0 VIN +85C 5.5 VIN 70% 70% 0 1000 2000 3000 4000 5000 0 1000 Load Current (mA) 2000 3000 4000 5000 Load Current (mA) Figure 6. Efficiency vs. ILOAD, 1.8 VOUT Figure 7. Efficiency vs. ILOAD, 1.8 VOUT 100% 100% 95% 95% Efficiency Efficiency 5000 Load Current (mA) Figure 4. Efficiency vs. ILOAD, 1.2 VOUT Efficiency 2000 90% 85% 4.2 VIN 80% 90% 85% -40C 80% 5.0 VIN +25C 5.5 VIN +85C 75% 75% 0 1000 2000 3000 4000 5000 0 Load Current (mA) 2000 3000 4000 5000 Load Current (mA) Figure 8. Efficiency vs. ILOAD, 3.3 VOUT (c) 2013 Semiconductor Components Industries, LLC. FAN53541 * Rev. 1.1 1000 Figure 9. Efficiency vs. ILOAD, 3.3 VOUT 6 www.fairchildsemi.com www.onsemi.com FAN53541 -- 2.4 MHz, 5 A TinyBuckTM Synchronous Buck Regulator Typical Characteristics Unless otherwise specified; VIN=5 V, VOUT=1.2 V, VMODE=0 V, TA=25C, circuit in Figure 1, and components per Table 1. 70 35 30 25 2.7 VIN 65 4.2 VIN 3.3 VIN 60 5.0 VIN 5.0 VIN 55 5.5 VIN 5.5 VIN 50 VOUT Shift (mV) VOUT Shift (mV) 45 20 15 10 40 35 30 25 20 15 5 10 0 5 -5 -5 0 1000 2000 3000 4000 0 5000 1000 2000 3000 4000 Load Current (mA) Load Current (mA) Figure 10. Regulation, 1.2 VOUT Figure 11. Regulation, 3.3 VOUT 1,400 1,400 1,200 1,200 1,000 1,000 Load Current (mA) Load Current (mA) 0 800 600 400 PFM Exit 200 5000 800 600 400 PFM Exit 200 PFM Enter PFM Enter 0 0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 3.5 4.0 Input Voltage (V) 4.5 5.0 5.5 Input Voltage (V) Figure 12. PFM / PWM Boundaries, 1.2 VOUT Figure 13. PFM / PWM Boundaries, 3.3 VOUT 30 3,000 3.6VIN, Auto 3.6VIN, PWM 2,500 5.0VIN, Auto Switching Frequency (KHz) Output Ripple (mVpp) 25 5.0VIN, PWM 20 15 10 5 2,000 1,500 1,000 3.6VIN, Auto 5.0VIN, Auto 500 0 0 0 1000 2000 3000 4000 0 5000 Figure 14. Output Voltage Ripple (c) 2013 Semiconductor Components Industries, LLC. FAN53541 * Rev. 1.1 1000 2000 3000 4000 5000 Load Current (mA) Load Current (mA) Figure 15. Switching Frequency 7 www.fairchildsemi.com www.onsemi.com FAN53541 -- 2.4 MHz, 5 A TinyBuckTM Synchronous Buck Regulator Typical Characteristics 60 50 50 40 Input Current (mA) Input Current (A) Unless otherwise specified; VIN=5 V, VOUT=1.2 V, VMODE=0 V, TA=25C, circuit in Figure 1, and components per Table 1. 40 30 20 30 20 10 -40C -40C +25C +25C +85C 10 +85C 0 2.5 3.0 3.5 4.0 4.5 5.0 5.5 2.5 3.0 Input Voltage (V) 4.0 4.5 5.0 5.5 Input Voltage (V) Figure 16. Quiescent Current, Auto Mode, EN=VIN Figure 17. Quiescent Current, PMW Mode, EN=VIN 70 100% 1.2VOUT, 25mA Load 1.2VOUT, 1.0A Load 3.3VOUT, 1.0A Load 60 95% 50 90% Efficiency PSRR (dB) 3.5 40 30 85% 1.2 VOUT, L=SC2511 80% 1.2 VOUT, L=IHLP16 1.8 VOUT, L=SC2511 20 75% 10 70% 1.8 VOUT, L=IHLP16 3.3 VOUT, L=SC2511 10 100 1,000 10,000 100,000 3.3 VOUT, L=IHLP16 0 Frequency (Hz) 1000 2000 3000 4000 5000 Load Current (mA) Figure 18. Power Supply Rejection (PSRR) Figure 19. Inductor Efficiency Comparison, 5.0 VIN Figure 20. Line Transient, 50 Load, tR=tF=10 s Figure 21. Line Transient, ILOAD=1.0 A, tR=tF=10 s (c) 2013 Semiconductor Components Industries, LLC. FAN53541 * Rev. 1.1 8 www.fairchildsemi.com www.onsemi.com FAN53541 -- 2.4 MHz, 5 A TinyBuckTM Synchronous Buck Regulator Typical Characteristics Unless otherwise specified; VIN=5 V, VOUT=1.2 V, VMODE=0 V, TA=25C, circuit in Figure 1, and components per Table 1. Figure 22. Load Transient, 0.1-1.5 A Load, tR=tF=100 ns Figure 23. Load Transient, 0.1-3.0 A Load, tR=tF=100 ns, COUT=2x22 F Figure 24. Startup / Shutdown, No Load Figure 25. Startup / Shutdown, 240 m Load, COUT=2x22 F Figure 26. Overload Protection and Recovery Figure 27. Startup into Overload (c) 2013 Semiconductor Components Industries, LLC. FAN53541 * Rev. 1.1 9 www.fairchildsemi.com www.onsemi.com FAN53541 -- 2.4 MHz, 5 A TinyBuckTM Synchronous Buck Regulator Typical Characteristics The FAN53541 is a step-down switching voltage regulator that delivers an adjustable output from an input voltage supply of 2.7 V to 5.5 V. Using a proprietary architecture with synchronous rectification, the FAN53541 is capable of delivering up to 5 A at over 90% efficiency. The regulator operates at a nominal frequency of 2.4 MHz at full load, which reduces the value of the external components to 470 nH for the output inductor and 20 F for the output capacitor. High efficiency is maintained at light load with single-pulse PFM Mode. limits the COUT capacitance when a heavy load ( ILOAD(SS) ) is applied during the startup. The maximum COUT capacitance for successful starting with a heavy constant-current load is approximately: COUT Under-Voltage Lockout (UVLO) When EN is HIGH, the under-voltage lockout keeps the part from operating until the input supply voltage rises high enough to operate properly. This ensures no misbehavior of the regulator during startup or shutdown. Input Over-Voltage Protection (OVP) For very light loads, the FAN53541 operates in Discontinuous Current (DCM) single-pulse PFM Mode, which produces low output ripple compared with other PFM architectures. Transition between PWM and PFM is seamless, with a glitch of less than 3% of VOUT during the transition between DCM and CCM Modes. When VIN exceeds VSDWN (about 6.1 V), the IC stops switching to protect the circuitry from excessive internal voltage spikes. An internal filter prevents the circuit from shutting down due to VIN noise spikes. Current Limiting PFM Mode is disabled by holding the MODE pin HIGH. The IC synchronizes to the MODE pin frequency. When synchronizing to the MODE pin, PFM Mode is disabled. A heavy load or short circuit on the output causes the current in the inductor to increase until a maximum current threshold is reached in the high-side switch. Upon reaching this point, the high-side switch turns off, preventing high currents from causing damage. 16 consecutive PWM cycles in current limit cause the regulator to shut down and stay off for about 1.6 ms before attempting a restart. Setting Output Voltage The output voltage is set by the R1, R2, and VREF (0.8 V): (1) In the event of a short circuit, the soft-start circuit attempts to restart and produces an over-current fault after 16 consecutive cycles in current limit, which results in a duty cycle of less than 5%, providing current into a short circuit. (2) External Frequency Synchronization R1 must be set at or below 100 K; therefore: R1 0.8 Logic 1 on the MODE pin forces the IC to stay in PWM Mode. Logic 0 allows the IC to automatically switch to PFM during light loads. If the MODE pin is toggled, the converter synchronizes its switching frequency to four times the frequency on the mode pin (fMODE). For example, for VOUT=1.2 V, R1=100 k, R2=200 k. Enable and Soft-Start When the EN pin is LOW, the IC is shut down, all internal circuits are off, and the part draws very little current. Raising EN above its threshold voltage activates the part and starts the soft-start cycle. During soft-start, the modulator's internal reference is ramped slowly to minimize surge currents on the input and prevents overshoot of the output voltage. The MODE pin is internally buffered with a Schmitt trigger, which allows the MODE pin to be driven with slow rise and fall times. An asymmetric duty cycle for frequency synchronization is permitted, provided it is consistent with parametric table limits. If large values of output capacitance are used, the regulator may fail to start. If VOUT fails to achieve regulation within 1.2 ms from the beginning of soft-start, the regulator shuts down and waits 1.6 ms before attempting a restart. If the regulator is in current limit for 16 consecutive PWM cycles, the regulator shuts down before restarting 1.6 ms later. This (c) 2013 Semiconductor Components Industries, LLC. FAN53541 * Rev. 1.1 (3) When EN is LOW, a 150 resistor discharges VOUT. Regulator performance is independent of the output capacitor ESR, allowing for the use of ceramic output capacitors. Although this type of operation normally results in a switching frequency that varies with input voltage and load current, an internal frequency loop holds the switching frequency constant over a large range of input voltages and load currents. VOUT 0.8 800 VOUT Diode Emulation Mode is employed during soft-start, allowing the IC to start into a pre-charged output. Diode emulation prohibits reverse inductor current from flowing through the synchronous rectifier. The FAN53541 uses a proprietary non-linear, fixedfrequency PWM modulator to deliver very fast load transient response, while maintaining a constant switching frequency over a wide range of operating conditions. R2 5.8 ILOAD where COUTMAX is expressed in F and ILOAD is the load current during soft-start, expressed in A. Control Scheme R1 VOUT VREF R2 VREF MAX 10 www.fairchildsemi.com www.onsemi.com FAN53541 -- 2.4 MHz, 5 A TinyBuckTM Synchronous Buck Regulator Operation Description Application Information The PGOOD pin is an open-drain that indicates that the IC is in regulation when its state is open. PGOOD pulls LOW under the following conditions: The IC has operated in cycle-by-cycle current limit for eight consecutive PWM cycles; The circuit is disabled, either after a fault occurs or when EN is LOW; or Selecting the Inductor The output inductor must meet both the required inductance and the energy handling capability of the application. The inductor value affects the average current limit, output voltage ripple, transient response, and efficiency. The ripple current (I) of the regulator is: The IC is performing a soft-start. I Thermal Shutdown When the die temperature increases, due to a high load condition and/or a high ambient temperature, the output switching is disabled until the temperature on the die has fallen sufficiently. The junction temperature at which the thermal shutdown activates is nominally 155C with a 20C hysteresis. IMAX (LOAD) ILIM(PK) (5) I 2 (6) The FAN53541 is optimized for operation with L=470 nH, but is stable with inductances up to 1.2 H (nominal). The inductor should be rated to maintain at least 80% of its value at ILIM(PK). Failure to do so lowers the amount of DC current the IC can deliver. tOFF(MIN) is 45 ns, which constrains the maximum VOUT/VIN that the FAN53541 can provide, while still maintaining a fixed switching frequency in PWM Mode. Regulation is maintained even though the regulator is unable to provide sufficient duty-cycle and operate at 2.4 MHz. Efficiency is affected by the inductor DCR and inductance value. Decreasing the inductor value for a given physical size typically decreases the DCR; but since I increases, the RMS current increases, as do core and skin-effect losses. Switching frequency is the lower of 2.4 MHz or: The maximum average load current, I MAX(LOAD), is related to the peak current limit, ILIM(PK), by the ripple current as: Minimum Off-Time Effect on Switching Frequency VOUT IOUT ROFF fSW (MHz) 22.2 1 V IN IOUT (R OFF R ON ) VOUT VIN VOUT VIN L fSW IRMS (4) IOUT(DC ) 2 I2 12 (7) The increased RMS current produces higher losses through the RDS(ON) of the IC MOSFETs as well as the inductor ESR. where: Increasing the inductor value produces lower RMS currents, but degrades transient response. For a given physical inductor size, increased inductance usually results in an inductor with lower saturation current. IOUT = load current, in A; RON = RDS(ON)_P + DCRL, in Ohms; and ROFF = RDS(ON)_N + DCRL, in Ohms. Table 3 shows the effects on regulator performance of higher inductance than the recommended 470 nH. A result of <0 MHz indicates 100% duty cycle operation. Table 3. Inductor Value and Regulator Performance IMAX(LOAD) VOUT (Eq.(8)) Transient Response Increase Decrease Degraded Inductor Current Rating The FAN53541's current-limit circuit can allow a peak current of about 8.8 A to flow through L1 under worst-case conditions. If it is possible for the load to draw that much continuous current, the inductor should be capable of sustaining that current or failing in a safe manner. For space-constrained applications, a lower current rating for L1 can be used. The FAN53541 may still protect these inductors in the event of a short circuit, but may not be able to protect the inductor from failure if the load is able to draw higher currents than the DC rating of the inductor. (c) 2013 Semiconductor Components Industries, LLC. FAN53541 * Rev. 1.1 11 www.fairchildsemi.com www.onsemi.com FAN53541 -- 2.4 MHz, 5 A TinyBuckTM Synchronous Buck Regulator PGOOD Pin Layout Recommendations Table 1 suggests 0805 capacitors, but 0603 capacitors may be used if space is at a premium. Due to voltage effects, the 0603 capacitors have a lower in-circuit capacitance, which can degrade transient response and output ripple. The layout example below illustrates the recommended component placement and top copper (green) routing. The inductor in this example is the TDK VLC5020T-R47N. To minimize VIN and SW spikes and thereby reduce voltage stress on the IC's power switches, it is critical to minimize the loop length for the VIN bypass capacitors. Increasing COUT has a negligible effect on loop stability and can be increased to reduce output voltage ripple or to improve transient response. Output voltage ripple, VOUT, is: VOUT 1 I ESR 8 C f OUT SW Switching current paths through C IN and COUT should be returned directly to the GND bumps of the IC on the top layer of the printed circuit board (PCB). VOUT and GND connections to the system power and ground planes can be made through multiple vias placed as close as possible to the COUT capacitors. The regulator should be placed as close to its load as possible to minimize trace inductance and capacitance. (8) where COUT is the effective output capacitance. The capacitance of COUT decreases at higher output voltages, which results in higher VOUT. If large values are used for COUT, the regulator may fail to start under load. If an inductor value greater than 1.0 H is used, at least 30 F of COUT should be used to ensure transient response performance. The lowest VOUT is obtained when the IC is in PWM Mode and, therefore, operating at 2.4 MHz. In PFM Mode, fSW is reduced, causing VOUT to increase. ESL Effects The Equivalent Series Inductance (ESL) of the output capacitor network should be kept low to minimize the squarewave component of output ripple that results from the division ratio COUT ESL and the output inductor (LOUT). The squarewave component due to the ESL can be estimated as: VOUT(SQ ) VIN ESLCOUT L1 (9) A good practice to minimize this ripple is to use multiple output capacitors to achieve the desired COUT value. For example, to obtain COUT=20 F, a single 22 F 0805 would produce twice the square wave ripple of two 10 F 0805. Figure 28. Recommended Layout Connect the VOUT pin and R1 directly to COUT using a low impedance path (shown in red in Figure 28. Recommended Layout). A >0.4 mm wide trace is recommended. Avoid routing this trace directly beneath SW unless separated by an internal GND plane. To minimize ESL, try to use capacitors with the lowest ratio of length to width. 0805 s have lower ESL than 1206 s. If very low output ripple is necessary, research vendors that produce 0508 or 0612 capacitors with ultra-low ESL. Placing additional small value capacitors near the load also reduces the high-frequency ripple components. If the MODE function is not required, extend the ground plane through the MODE pin to reduce the loop inductance for the VIN bypass. Input Capacitor The 10 F ceramic input capacitor should be placed as close as possible between the VIN pin and PGND to minimize the parasitic inductance. If a long wire is used to bring power to the IC, additional "bulk" capacitance (electrolytic or tantalum) should be placed between CIN and the power source lead to reduce under-damped ringing that can occur between the inductance of the power source leads and CIN. Thermal Considerations Heat is removed from the IC through the solder bumps to the PCB copper. The junction-to-ambient thermal resistance (JA) is largely a function of the PCB layout (size, copper weight, and trace width) and the temperature rise from junction to ambient (T). The JA is 38C/W when mounted on its four-layer evaluation board in still air, with 2 oz. outer layer copper weight and 1 oz. inner layers. Halving the copper thickness results in an increased JA of 48C/W. The effective CIN capacitance value decreases as VIN increases due to DC bias effects. This has no significant impact on regulator performance. To reduce ringing and overshoot on VIN and SW, an additional bypass capacitor CIN1 is recommended. Because this lower value capacitor has a higher resonant frequency than CIN; CIN1 should be placed closer to the VIN and GND pins of the IC than CIN. (c) 2013 Semiconductor Components Industries, LLC. FAN53541 * Rev. 1.1 For long term reliable operation, the IC's junction temperature (TJ) should be maintained below 125C. Maximum IC power loss is 2.88 W. Figure 29 shows required power dissipation and derating for a FAN53541 mounted on the ON Semiconductor evaluation board in still air (38C/W). 12 www.fairchildsemi.com www.onsemi.com FAN53541 -- 2.4 MHz, 5 A TinyBuckTM Synchronous Buck Regulator Output Capacitor and VOUT Ripple Maximum Power Dissipation (W) 3.0 2.88W, max. 2.5 2.0 1.5 1.0 0.5 E. 0 25 50 75 100 From Eq. (11), DCR<16.4 m Due to the +0.4%/C temperature coefficient of copper, inductor DCR must be further reduced to accommodate the ~50C temperature rise. 0.0 125 Ambient Temperature (C) Figure 29. Power Derating To meet the design requirements, an inductor with a room temperature DCR of <13.6 m is necessary. To calculate maximum operating temperature (<125C) for a specific application: Figure 30 shows the maximum ambient temperature where FAN53541 can be used for a continuous load, at 5.0 VIN: 2. Use efficiency graphs to determine efficiency for the desired VIN, VOUT, and load condition 6 1.2 VOUT Maximum RMS Load Current (A) 1. Calculate IC power dissipation using: 1 PIC VOUT ILOAD 1 (10) where is efficiency from Figure 4 through Figure 9. 3. Compute inductor copper losses using: 2 PL ILOAD DCRL 4. 3 2 1 50 75 100 125 Ambient Temperature (C) (12) Figure 30. Load Current Derating(6) Note: 6. The graph was empirically determined using an ultra-low DCR (2.6 m) inductor. For physically smaller devices with higher DCR, further derating may be necessary. (13) Device temperature (TIC) should not exceed 125C. (c) 2013 Semiconductor Components Industries, LLC. FAN53541 * Rev. 1.1 4 25 Determine device operating temperature: T PD RJA and TIC TAMB T 3.3 VOUT 0 Combine IC (step 2) and inductor losses (step 3) to determine total dissipation: PD PIC PL 5. (11) 1.8 VOUT 5 13 www.fairchildsemi.com www.onsemi.com FAN53541 -- 2.4 MHz, 5 A TinyBuckTM Synchronous Buck Regulator A different approach, shown here as an example, uses the same equations to determine maximum inductor DCR for a specific application: Suppose a design requires a 5.0 VIN, 1.2 VOUT, 4 ARMS, at 75C: A. From Figure 4, is ~82%. B. From Eq. (10), PIC=1,054 mW. C. From Eq. (13), maximum PD=1,316 mW for 50C rise. D. From Eq. (12), PL=262 mW. 3.5 BALL A1 INDEX AREA F A E 1.20 B 1.20 O0.20 A1 Cu Pad 0.03 C 2X 1.60 D O0.215 Cu Pad A1 O0.30 Solder Mask Opening 0.40 O0.315 Solder Mask Opening 0.40 0.03 C 0.40 option 1 2X TOP VIEW option 2 RECOMMENDED LAND PATTERN (NSMD TYPE) 0.06 C 0.625 0.547 0.05 C 0.3780.018 0.2080.021 E C SEATING PLANE SIDE VIEWS D NOTES: 0.005 1.20 A. NO JEDEC REGISTRATION APPLIES. C A B B. DIMENSIONS ARE IN MILLIMETERS. O0.2600.02 20X 0.40 E D C B A 1.60 0.40 C. DIMENSIONS AND TOLERANCE PER ASMEY14.5M, 1994. D. DATUM C IS DEFINED BY THE SPHERICAL CROWNS OF THE BALLS. (Y) 0.018 E. PACKAGE NOMINAL HEIGHT IS 586 MICRONS 39 MICRONS (547-625 MICRONS). F 1 2 3 4 (X) 0.018 F. FOR DIMENSIONS D, E, X, AND Y SEE PRODUCT DATASHEET. BOTTOM VIEW G. DRAWING FILNAME: MKT-UC020AArev3. Figure 31 20-Ball WLCSP, 4x5 Array, 0.4mm Pitch, 250 m Ball Product-Specific Dimensions Product D E X Y FAN53541UCX 1.96 +0.030 1.56 +0.030 0.180 0.180 Package drawings are provided as a service to customers considering ON Semiconductor components. Drawings may change in any manner without notice. Please note the revision and/or date on the drawing and contact a ON Semiconductor representative to verify or obtain the most recent revision. Package specifications do not expand the terms of ON Semiconductor's worldwide terms and conditions, specifically the warranty therein, which covers ON Semiconductor products. (c) 2013 Semiconductor Components Industries, LLC. FAN53541 * Rev. 1.1 14 www.fairchildsemi.com www.onsemi.com FAN53541 -- 2.4 MHz, 5 A TinyBuckTM Synchronous Buck Regulator Physical Dimensions FAN53541 -- 2.4 MHz, 5 A TinyBuckTM Synchronous Buck Regulator ON Semiconductor and the ON Semiconductor logo are trademarks of Semiconductor Components Industries, LLC dba ON Semiconductor or its subsidiaries in the United States and/or other countries. ON Semiconductor owns the rights to a number of patents, trademarks, copyrights, trade secrets, and other intellectual property. A listing of ON Semiconductor's product/patent coverage may be accessed at www.onsemi.com/site/pdf/Patent-Marking.pdf. ON Semiconductor reserves the right to make changes without further notice to any products herein. ON Semiconductor makes no warranty, representation or guarantee regarding the suitability of its products for any particular purpose, nor does ON Semiconductor assume any liability arising out of the application or use of any product or circuit, and specifically disclaims any and all liability, including without limitation special, consequential or incidental damages. Buyer is responsible for its products and applications using ON Semiconductor products, incl uding compliance with all laws, regulations and safety requirements or standards, regardless of any support or applications information provided by ON Semiconductor. "Typical" parameters which may be provided in ON Semiconductor data sheets and/or specifications can and do vary in different applications and actual performance may vary over time. All operating parameters, including "Typicals" must be validated for each customer application by customer's technical experts. ON Semiconductor does not convey any license under its patent rights nor the rights of others. ON Semiconductor products are not designed, intended, or authorized for use as a critical component in life support systems or any FDA Class 3 medical devices or medical devices with a same or similar classification in a foreign juri sdiction or any devices intended for implantation in the human body. Should Buyer purchase or use ON Semiconductor products for any such unintended or unauthorized application, Buyer shall indemnify and hold ON Semiconductor and its officers, employees, subsidiaries, affiliates, and distributors harmless against all claims, costs, damages, and expenses, and reasonable attorney fees arising out of, directly or indirectly, any claim of personal injury or death associated with such unintended or unauthorized use, even if such claim all eges that ON Semiconductor was negligent regarding the design or manufacture of the part. ON Semiconductor is an Equal Opportunity/Affirmative Action Employer. This literature is subject to all applicable copyright laws and is not for resale in any manner. PUBLICATION ORDERING INFORMATION LITERATURE FULFILLMENT: Literature Distribution Center for ON Semiconductor 19521 E. 32nd Pkwy, Aurora, Colorado 80011 USA Phone: 303-675-2175 or 800-344-3860 Toll Free USA/Canada Fax: 303-675-2176 or 800-344-3867 Toll Free USA/Canada Email: orderlit@onsemi.com (c) 2013 Semiconductor Components Industries, LLC. FAN53541 * Rev. 1.1 N. American Technical Support: 800-282-9855 Toll Free USA/Canada. Europe, Middle East and Africa Technical Support: Phone: 421 33 790 2910 Japan Customer Focus Center Phone: 81-3-5817-1050 15 ON Semiconductor Website: www.onsemi.com Order Literature: http://www.onsemi.com/orderlit For additional information, please contact your local Sales Representative www.fairchildsemi.com www.onsemi.com ON Semiconductor and are trademarks of Semiconductor Components Industries, LLC dba ON Semiconductor or its subsidiaries in the United States and/or other countries. ON Semiconductor owns the rights to a number of patents, trademarks, copyrights, trade secrets, and other intellectual property. A listing of ON Semiconductor's product/patent coverage may be accessed at www.onsemi.com/site/pdf/Patent-Marking.pdf. ON Semiconductor reserves the right to make changes without further notice to any products herein. ON Semiconductor makes no warranty, representation or guarantee regarding the suitability of its products for any particular purpose, nor does ON Semiconductor assume any liability arising out of the application or use of any product or circuit, and specifically disclaims any and all liability, including without limitation special, consequential or incidental damages. Buyer is responsible for its products and applications using ON Semiconductor products, including compliance with all laws, regulations and safety requirements or standards, regardless of any support or applications information provided by ON Semiconductor. "Typical" parameters which may be provided in ON Semiconductor data sheets and/or specifications can and do vary in different applications and actual performance may vary over time. All operating parameters, including "Typicals" must be validated for each customer application by customer's technical experts. ON Semiconductor does not convey any license under its patent rights nor the rights of others. ON Semiconductor products are not designed, intended, or authorized for use as a critical component in life support systems or any FDA Class 3 medical devices or medical devices with a same or similar classification in a foreign jurisdiction or any devices intended for implantation in the human body. Should Buyer purchase or use ON Semiconductor products for any such unintended or unauthorized application, Buyer shall indemnify and hold ON Semiconductor and its officers, employees, subsidiaries, affiliates, and distributors harmless against all claims, costs, damages, and expenses, and reasonable attorney fees arising out of, directly or indirectly, any claim of personal injury or death associated with such unintended or unauthorized use, even if such claim alleges that ON Semiconductor was negligent regarding the design or manufacture of the part. ON Semiconductor is an Equal Opportunity/Affirmative Action Employer. This literature is subject to all applicable copyright laws and is not for resale in any manner. PUBLICATION ORDERING INFORMATION LITERATURE FULFILLMENT: Literature Distribution Center for ON Semiconductor 19521 E. 32nd Pkwy, Aurora, Colorado 80011 USA Phone: 303-675-2175 or 800-344-3860 Toll Free USA/Canada Fax: 303-675-2176 or 800-344-3867 Toll Free USA/Canada Email: orderlit@onsemi.com (c) Semiconductor Components Industries, LLC N. American Technical Support: 800-282-9855 Toll Free USA/Canada Europe, Middle East and Africa Technical Support: Phone: 421 33 790 2910 Japan Customer Focus Center Phone: 81-3-5817-1050 www.onsemi.com 1 ON Semiconductor Website: www.onsemi.com Order Literature: http://www.onsemi.com/orderlit For additional information, please contact your local Sales Representative www.onsemi.com