FAN53600 / FAN53610 3 MHz, 600 mA / 1A Synchronous Buck Regulator Features Description The FAN53600/10 is a 3 MHz step-down switching voltage regulator, available in 600 mA or 1 A options, that delivers a fixed output from an input voltage supply of 2.5 V to 5.5 V. Using a proprietary architecture with synchronous rectification, the FAN53600/10 is capable of delivering a peak efficiency of 92%, while maintaining efficiency over 80% at load currents as low as 1 mA. 600 mA or 1 A Output Current Capability 26 µA Typical Quiescent Current 3 MHz Fixed-Frequency Operation Best-in-Class Load Transient Response Best-in-Class Efficiency The regulator operates at a nominal fixed frequency of 3 MHz, which reduces the value of the external components to as low as 1 µH for the output inductor and 4.7 µF for the output capacitor. In addition, the Pulse-Width Modulation (PWM) modulator can be synchronized to an external frequency source. 2.3 V to 5.5 V Input Voltage Range 2.5 V to 3.3 V Fixed Output Voltage Low Ripple Light-Load PFM Mode Forced PWM and External Clock Synchronization Internal Soft-Start Input Under-Voltage Lockout (UVLO) Thermal Shutdown and Overload Protection Optional Output Discharge 6-Bump WLCSP, 0.4 mm Pitch Applications 3G, 4G, WiFi®, WiMAX™, and WiBro® Data Cards Tablets 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 26 µA. 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 3 MHz. In Shutdown Mode, the supply current drops below 1 µA, reducing power consumption. For applications that require minimum ripple or fixed frequency, PFM Mode can be disabled using the MODE pin. The FAN53600/10 is available in 6-bump, 0.4 mm pitch, Wafer-Level Chip-Scale Package (WLCSP). DSC, DVC Netbooks®, Ultra-Mobile PCs All trademarks are the property of their respective owners. Figure 1. Typical Application Ordering Information Output Voltage(1) Max. Output Current Active Discharge(2) FAN53610AUC29X 2.9 V 1A Yes FAN53610AUC30X 3.0 V 1A Yes FAN53600AUC33X 3.3 V 600 mA Yes Part Number Package Temperature Range Packing WLCSP-6, 0.4 mm Pitch –40 to +85°C Tape and Reel Notes: 1. 2. Other voltage options available on request. Contact a Fairchild representative. All voltage and output current options are available with or without active discharge. Contact a Fairchild representative. © 2010 Fairchild Semiconductor Corporation FAN53600 / FAN53610 • Rev. 1.0.2 www.fairchildsemi.com FAN53600 / FAN53610 — 3MHz, 600mA / 1A Synchronous Buck Regulator March 2013 Figure 2. Bumps Facing Down Figure 3. Bumps Facing Up Pin Definitions Pin # Name Description A1 MODE MODE. Logic 1 on this pin forces the IC to stay in PWM Mode. Logic 0 allows the IC to automatically switch to PFM Mode during light loads. The regulator also synchronizes its switching frequency to two times the frequency provided on this pin. Do not leave this pin floating. B1 SW Switching Node. Connect to output inductor. C1 FB Feedback. Connect to output voltage. C2 GND B2 EN Enable. The device is in Shutdown Mode when voltage to this pin is <0.4 V and enabled when >1.2 V. Do not leave this pin floating. A2 VIN Input Voltage. Connect to input power source. Ground. Power and IC ground. All signals are referenced to this pin. © 2010 Fairchild Semiconductor Corporation FAN53600 / FAN53610 • Rev. 1.0.2 www.fairchildsemi.com 2 FAN53600 / FAN53610 — 3 MHz, 600 mA / 1 A Synchronous Buck Regulator Pin Configurations 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 VIN VSW VCTRL Parameter Input Voltage Min. Max. –0.3 7.0 Unit V (3) Voltage on SW Pin –0.3 VIN + 0.3 V EN and MODE Pin Voltage –0.3 VIN + 0.3(3) V –0.3 (3) V Other Pins VIN + 0.3 Human Body Model per JESD22-A114 3.5 Charged Device Model per JESD22-C101 1.5 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 kV Note: 3. 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. Fairchild does not recommend exceeding them or designing to Absolute Maximum Ratings. Symbol Parameter VCC Supply Voltage Range IOUT Output Current L CIN COUT Min. Max. Unit 2.3 5.5 V FAN53600 0 600 mA FAN53610 0 1 A Inductor Input Capacitor Output Capacitor VOUT<2.7 V 1.6 VOUT ≥2.7 V Typ. 1 µH 2.2 µF 4.7 12.0 µF 10 TA Operating Ambient Temperature –40 +85 °C TJ Operating Junction Temperature –40 +125 °C Thermal Properties Junction-to-ambient thermal resistance is a function of application and board layout. This data is measured with two-layer 1s2p boards in accordance to JEDEC standard JESD51. Special attention must be paid not to exceed junction temperature TJ(max) at a given ambient temperature TA. Symbol θJA Parameter Junction-to-Ambient Thermal Resistance © 2010 Fairchild Semiconductor Corporation FAN53600 / FAN53610 • Rev. 1.0.2 Typical Unit 150 °C/W www.fairchildsemi.com 3 FAN53600 / FAN53610 — 3 MHz, 600 mA / 1 A Synchronous Buck Regulator Absolute Maximum Ratings Minimum and maximum values are at VIN = VEN = 2.3 V to 5.5 V, VMODE = 0 V (AUTO Mode), and TA = -40°C to +85°C; circuit of Figure 1, unless otherwise noted. Typical values are at TA = 25°C, VIN = VEN = 3.6 V, VOUT=2.9 V. Symbol Parameter Conditions Min. Typ. Max. Unit Power Supplies IQ I(SD) VUVLO Quiescent Current No Load, Not Switching 26 µA PWM Mode 3 mA Shutdown Supply Current VIN = 3.6 V, EN = GND 0.25 1.00 µA Under-Voltage Lockout Threshold Rising VIN 2.15 2.27 V VUVHYST Under-Voltage Lockout Hysteresis 200 mV Logic Inputs: EN and MODE Pins VIH Enable HIGH-Level Input Voltage VIL Enable LOW-Level Input Voltage VLHYST Logic Input Hysteresis Voltage IIN Enable Input Leakage Current 1.2 V 0.4 100 Pin to VIN or GND V mV 0.01 1.00 µA Switching and Synchronization fSW fSYNC Switching Frequency(4) VIN = 3.6 V, TA = 25°C 2.7 3.0 3.3 MHz MODE Synchronization Range(4) Square Wave at MODE Input 1.3 1.5 1.7 MHz ILOAD = 0 to 400 mA, VIN ≥ VOUT + 150 mV -5 +3 % ILOAD = 0 to 600 mA, VIN ≥ VOUT + 300 mV -3 +3 % ILOAD = 0 to 1000 mA, VIN =3.6V -4 +3 % ILOAD = 0 to 600 mA, VIN ≥ VOUT + 300 mV -3 +3 % ILOAD = 0 to 1000 mA, VIN =5.0 V -4 +3 % 300 µs Regulation 2.500 V to 2.900 V VO Output Voltage Accuracy 2.900 V to 3.300 V tSS Soft-Start From EN Rising Edge 180 PMOS On Resistance VIN = VGS = 3.6 V 175 mΩ NMOS On Resistance VIN = VGS = 3.6 V 165 mΩ Output Driver RDS(on) ILIM(OL) PMOS Peak Current Limit Open-Loop for FAN53600 900 1100 1250 mA Open-Loop for FAN53610 1500 1750 2000 mA RDIS Output Discharge Resistance EN = GND 230 Ω TTSD Thermal Shutdown CCM Only 150 °C THYS Thermal Shutdown Hysteresis 15 °C Notes: 4. Limited by the effect of tOFF minimum (see Operation Description section). 5. The Electrical Characteristics table reflects open-loop data. © 2010 Fairchild Semiconductor Corporation FAN53600 / FAN53610 • Rev. 1.0.2 www.fairchildsemi.com 4 FAN53600 / FAN53610 — 3 MHz, 600 mA / 1 A Synchronous Buck Regulator Electrical Characteristics 98% 100% 95% 95% 92% 90% Efficiency Efficiency Unless otherwise noted, VIN = VEN = 3.6 V, VMODE = 0 V (AUTO Mode), and TA = 25°C. 89% 86% 85% 80% 3.6 4.2 5.0 5.5 83% 80% 0 200 400 600 800 VIN VIN VIN VIN - 40C, AUTO +25C, AUTO +85C, AUTO - 40C, PWM +25C, PWM +85C, PWM 75% 70% 1000 0 200 Load Current (mA) 600 95% 95% 92% 90% Efficiency 100% 89% 86% 85% 80% 3.2 VIN 3.6 VIN 4.2 VIN 5.0 VIN 83% 80% 200 400 600 800 - 40C, AUTO +25C, AUTO +85C, AUTO - 40C, PWM +25C, PWM +85C, PWM 75% 70% 0 1000 Load Current (mA) 200 400 600 800 1000 Load Current (mA) Figure 6. Efficiency vs. Load Current and Input Voltage, VOUT=2.9 V, Dotted for Decreasing Load © 2010 Fairchild Semiconductor Corporation FAN53600 / FAN53610 • Rev. 1.0.2 1000 Figure 5. Efficiency vs. Load Current and Temperature VIN=5 V, VOUT=3.3 V, Dotted for FPWM 98% 0 800 Load Current (mA) Figure 4. Efficiency vs. Load Current and Input Voltage, VOUT=3.3 V, Dotted for Decreasing Load Efficiency 400 Figure 7. Efficiency vs. Load Current and Temperature, VOUT=2.9 V, Dotted for FPWM www.fairchildsemi.com 5 FAN53600 / FAN53610 — 3 MHz, 600 mA / 1 A Synchronous Buck Regulator Typical Performance Characteristics Unless otherwise noted, VIN = VEN = 3.6 V, VMODE = 0 V (AUTO Mode), and TA = 25°C. 3 1 3.6VIN, AUTO 4.2VIN, AUTO 5.0VIN, AUTO 5.5VIN, AUTO 3.6VIN, PWM 4.2VIN, PWM 5.0VIN, PWM 5.5VIN, PWM 2 Output Regulation (%) 2 Output Regulation (%) 3 3.2VIN, AUTO 3.6VIN, AUTO 4.2VIN, AUTO 5.0VIN, AUTO 3.2VIN, PWM 3.6VIN, PWM 4.2VIN, PWM 5.0VIN, PWM 0 -1 1 0 -1 -2 -2 -3 -3 0 200 400 600 800 0 1000 200 500 500 400 400 300 200 100 PFM 100% d.c. 0 4.4 4.9 300 200 PWM PFM 100% d.c. 0 5.4 3.3 3.8 Input Voltage (V) 4.3 4.8 5.3 Input Voltage (V) Figure 10. PFM / PWM /100% Duty Cycle Boundary vs. Input Voltage, VOUT=2.9 V Figure 11. PFM / PWM /100% Duty Cycle Boundary vs. Input Voltage, VOUT=3.3 V 40 25 35 20 Input Current (mA) Input Current (μA) 1000 100 PWM 3.9 800 Figure 9. ∆VOUT (%) vs. Load Current and Input Voltage, VOUT=3.3 V, Normalized to 3.6 VIN, 500 mA Load, FPWM, Dotted for Auto Mode Load Current (mA) Load Current (mA) Figure 8. ∆VOUT (%) vs. Load Current and Input Voltage, VOUT=2.9 V, Normalized to 3.6 VIN, 500 mA Load, FPWM, Dotted for Auto Mode 3.4 600 Load Current (mA) Load Current (mA) 2.9 400 30 25 20 - 40C, EN=VIN +25C, EN=VIN +85C, EN=VIN - 40C, EN=1.8V +25C, EN=1.8V +85C, EN=1.8V 15 10 2.5 3.0 3.5 4.0 4.5 5.0 10 5 - 40C +25C +85C 0 5.5 2.5 Input Voltage (V) 3.0 3.5 4.0 4.5 5.0 5.5 Input Voltage (V) Figure 12. Quiescent Current vs. Input Voltage and Temperature, VOUT=2.9 V, EN=VIN Solid, Dotted for EN=1.8 V © 2010 Fairchild Semiconductor Corporation FAN53600 / FAN53610 • Rev. 1.0.2 15 Figure 13. Quiescent Current vs. Input Voltage and Temperature, VOUT=2.9 V, Mode=EN=VIN (FPWM) www.fairchildsemi.com 6 FAN53600 / FAN53610 — 3 MHz, 600 mA / 1 A Synchronous Buck Regulator Typical Performance Characteristics (Continued) Unless otherwise noted, VIN = VEN = 3.6 V, VMODE = 0 V (AUTO Mode), and TA = 25°C. 100 100 3.2VIN, AUTO 3.6VIN, AUTO 4.2VIN, AUTO 3.6VIN, AUTO 5.0VIN, AUTO 3.2VIN, PWM Output Ripple (mVpp) Output Ripple (mVpp) 80 3.6VIN, PWM 5.0VIN, PWM 60 5.0VIN, AUTO 80 40 20 3.6VIN, PWM 4.2VIN, PWM 5.0VIN, PWM 60 40 20 0 0 200 400 600 800 0 1000 0 200 Load Current (mA) 3,500 3,000 3,000 Switching Frequency (KHz) Switching Frequency (KHz) 3,500 2,500 3.2VIN, AUTO 3.6VIN, AUTO 1,500 5.0VIN, AUTO 3.2VIN, PWM 1,000 600 800 1000 Figure 15. Output Ripple vs. Load Current and Input Voltage, VOUT=3.3 V, FPWM, Dotted for Auto Mode Figure 14. Output Ripple vs. Load Current and Input Voltage, VOUT=2.9 V, FPWM, Dotted for Auto Mode 2,000 400 Load Current (mA) 3.6VIN, PWM 5.0VIN, PWM 500 2,500 3.6VIN, AUTO 3.6VIN, AUTO 2,000 5.0VIN, AUTO 3.6VIN, PWM 1,500 4.2VIN, PWM 5.0VIN, PWM 1,000 500 0 0 200 400 600 800 0 1000 0 Load Current (mA) 200 400 600 800 1000 Load Current (mA) Figure 16. Frequency vs. Load Current and Input Voltage, VOUT=2.9 V, Auto Mode, Dotted for FPWM Figure 17. Frequency vs. Load Current and Input Voltage, VOUT=3.3 V, Auto Mode, Dotted for FPWM Figure 18. Load Transient, VIN=5 V, VOUT=3.3 V, 10-200-10 mA, 100 ns Edge Figure 19. Load Transient, VIN=5 V, VOUT=3.3 V, 200800-200 mA, 100 ns Edge © 2010 Fairchild Semiconductor Corporation FAN53600 / FAN53610 • Rev. 1.0.2 www.fairchildsemi.com 7 FAN53600 / FAN53610 — 3 MHz, 600 mA / 1 A Synchronous Buck Regulator Typical Performance Characteristics (Continued) Unless otherwise noted, VIN = VEN = 3.6 V, VMODE = 0 V (AUTO Mode), and TA = 25°C. Figure 20. Load Transient, VIN=5 V, VOUT=2.9 V, 10-200-10 mA, 100 ns Edge Figure 21. Load Transient, VIN=5 V, VOUT=2.9 V, 200-800-200 mA, 100 ns Edge Figure 22. Line Transient, 3.3-3.9-3.3 VIN, 10 µs Edge, VOUT=2.9 V, 58 mA Load Figure 23. Line Transient, 3.3-3.9-3.3 VIN, 10 µs Edge, VOUT=2.9 V, 600 mA Load Figure 24. Combined Line / Load Transient, VOUT=2.9 V, 3.9-3.3-3.9 VIN, 10 µs Edge, 58-500-58 mA Load, 100 ns Edge Figure 25. Startup, VOUT=2.9 V, 50 Ω Load © 2010 Fairchild Semiconductor Corporation FAN53600 / FAN53610 • Rev. 1.0.2 www.fairchildsemi.com 8 FAN53600 / FAN53610 — 3 MHz, 600 mA / 1 A Synchronous Buck Regulator Typical Performance Characteristics (Continued) Unless otherwise noted, VIN = VEN = 3.6 V, VMODE = 0 V (AUTO Mode), and TA = 25°C. Figure 26. Startup, VOUT=2.9 V, 4.7 Ω Load Figure 27. Over-Current, Load Increasing Past Current Limit, VOUT=2.9 V, FAN53600 Figure 28. 250 mΩ Fault, Rapid Fault, VOUT=2.9 V, FAN53600 © 2010 Fairchild Semiconductor Corporation FAN53600 / FAN53610 • Rev. 1.0.2 www.fairchildsemi.com 9 FAN53600 / FAN53610 — 3 MHz, 600 mA / 1 A Synchronous Buck Regulator Typical Performance Characteristics (Continued) The FAN53600/10 is a 3 MHz, step-down switching voltage regulator, available in 600 mA or 1 A options, that delivers a fixed output from an input voltage supply of 2.3 V to 5.5 V. Using a proprietary architecture with synchronous rectification, the FAN53600/10 is capable of delivering a peak efficiency of 92%, while maintaining efficiency over 80% at load currents as low as 1 mA. All voltage options can be ordered with a feature that actively discharges FB to ground through a 230 Ω path when EN is LOW. Raising EN above its threshold voltage activates the part and starts the soft-start cycle. During soft-start, the internal reference is ramped using an exponential RC shape to prevent overshoot of the output voltage. Current limiting minimizes inrush during soft-start. The regulator operates at a nominal fixed frequency of 3 MHz, which reduces the value of the external components to as low as 1 µH for the output inductor and 4.7 µF for the output capacitor. In addition, the PWM modulator can be synchronized to an external frequency source. The IC may fail to start if heavy load is applied during startup and/or if excessive COUT is used. This is due to the currentlimit fault response, which protects the IC in the event of an over-current condition present during soft-start. The current required to charge COUT during soft-start, commonly referred to as “displacement current,” is given as: Control Scheme dV (2) dt dV term refers to the soft-start slew rate above. where the dt The FAN53600/10 uses a proprietary, non-linear, fixedfrequency PWM modulator to deliver a fast load transient response, while maintaining a constant switching frequency over a wide range of operating conditions. The regulator performance is independent of the output capacitor ESR, allowing 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. IDISP = COUT • To prevent shutdown during soft-start, the following condition must be met: IDISP + ILOAD < IMAX ( DC ) where IMAX(DC) is the maximum load current the IC is guaranteed to support. For very light loads, the FAN53600/10 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 18 mV at VOUT during the transition between DCM and CCM modes. Startup into Large COUT Multiple soft-start cycles are required for no-load startup if COUT is greater than 15 μF. Large COUT requires light initial load to ensure the FAN53600/10 starts appropriately. The IC shuts down for 1.3 ms when IDISP exceeds ILIMIT for more than 210 μs of current limit. The IC then begins a new softstart cycle. Since COUT retains its charge when the IC is off, the IC reaches regulation after multiple soft-start attempts. Combined with exceptional transient response characteristics, the very low quiescent current of the controller (26 µA) maintains high efficiency, even at very light loads, while preserving fast transient response for applications requiring tight output regulation. MODE Pin 100% Duty Cycle Operation Logic 1 on this 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, with a frequency between 1.3 MHz and 1.7 MHz, the converter synchronizes its switching frequency to two times the frequency on the MODE pin (fMODE). When VIN approaches VOUT, the regulator increases its duty cycle until 100% duty cycle is reached. As the duty cycle approaches 100%, the switching frequency declines due to the minimum off-time (tOFF(MIN)) of about 50 ns imposed by the control circuit. When 100% duty cycle is reached, VOUT follows VIN with a drop-out voltage (VDROPOUT) determined by the total resistance between VIN and VOUT as calculated by: ( VDROPOUT = ILOAD • PMOS R DS(ON) + DCR L (3) ) 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 also permitted as long as the minimum time below VIL(MAX) or above VIH(MAX) is 100 ns. (1) Enable and Soft-Start When EN is LOW, all circuits are off and the IC draws ~50 nA of current. When EN is HIGH and VIN is above its UVLO threshold, the regulator begins a soft-start cycle. The output ramp during soft-start is a fixed slew rate of 50 mV/μs from 0 to 1 VOUT, then 12.5 mV/μs until the output reaches its setpoint. Regardless of the state of the MODE pin, PFM Mode is enabled to prevent current from being discharged from COUT if soft-start begins when COUT is charged. © 2010 Fairchild Semiconductor Corporation FAN53600 / FAN53610 • Rev. 1.0.2 www.fairchildsemi.com 10 FAN53600 / FAN53610 — 3 MHz, 600 mA / 1 A Synchronous Buck Regulator Operation Description Minimum Off-Time and Switching Frequency 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. The regulator continues to limit the current cycle by cycle. After 16 cycles of current limit, the regulator triggers an over-current fault, causing the regulator to shut down for about 1.3 ms before attempting a restart. tOFF(MIN) is 50 ns. This imposes constraints on the maximum VOUT that the FAN53600/10 can provide, or the maximum VIN output voltage it can provide at low VIN while maintaining a fixed switching frequency in PWM Mode. When VIN is LOW, fixed switching frequency is maintained as long as: If the fault was caused by short circuit, the soft-start circuit attempts to restart and produces an over-current fault after about 250 μs, which results in a duty cycle of less than 0%, limiting power dissipation. VOUT ≤ 1 − tOFF ( MIN ) • fSW ≈ 0.85 . VIN The switching frequency drops when the regulator cannot provide sufficient duty cycle at 3 MHz to maintain regulation. This occurs when VOUT >0.85 VIN at high load currents. The calculation for switching frequency is given by: The closed-loop peak-current limit, ILIM(PK), is not the same as the open-loop tested current limit, ILIM(OL), in the Electrical Characteristics table. This is primarily due to the effect of propagation delays of the IC current-limit comparator. 1 , 3MHz fSW = min tSW ( MAX ) 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 properly operate. This ensures no misbehavior of the regulator during startup or shutdown. where: VOUT + IOUT • ROFF t SW ( MAX ) = 50ns • 1 + V IN − IOUT • RON − VOUT Thermal Shutdown (TSD) (5) where: 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 150°C with a 15°C hysteresis. © 2010 Fairchild Semiconductor Corporation FAN53600 / FAN53610 • Rev. 1.0.2 (4) ROFF RON = RDSON _ N + DCRL = RDSON _ P + DCRL . www.fairchildsemi.com 11 FAN53600 / FAN53610 — 3 MHz, 600 mA / 1 A Synchronous Buck Regulator Current Limit, Fault Shutdown, and Restart The increased RMS current produces higher losses through the RDS(ON) of the IC MOSFETs, as well as the inductor DCR. Selecting the Inductor The output inductor must meet both the required inductance and the energy handling capability of the application. The inductor value affects average current limit, the PWM-toPFM transition point, output voltage ripple, and efficiency. 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 and higher DCR. The ripple current (∆I) of the regulator is: V − VOUT V ΔI ≈ OUT • IN VIN L • fSW Table 1 shows the effects of inductance higher or lower than the recommended 1 μH on regulator performance. (6) Output Capacitor The maximum average load current, IMAX(LOAD), is related to the peak current limit, ILIM(PK), by the ripple current, given by: I MAX ( LOAD ) = I LIM ( PK ) − ΔI 2 Table 2 suggests 0402 capacitors. 0603 capacitors may further improve performance in that the effective capacitance is higher. This improves transient response and output ripple. (7) Increasing COUT has no effect on loop stability and can therefore be increased to reduce output voltage ripple or to improve transient response. Output voltage ripple, ∆VOUT, is: The transition between PFM and PWM operation is determined by the point at which the inductor valley current crosses zero. The regulator DC current when the inductor current crosses zero, IDCM, is: IDCM = ΔI 2 f ⋅C ⋅ ESR2 1 ΔVOUT = ΔIL SW OUT + ( ) ⋅ ⋅ − ⋅ ⋅ 2 D 1 D 8 f C SW OUT (8) Input Capacitor The 2.2 μF ceramic input capacitor should be placed as close as possible between the VIN pin and GND to minimize 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 ringing that can occur between the inductance of the power source leads and CIN. The FAN53600/10 is optimized for operation with L = 1 μH, but is stable with inductances up to 2.2 μH (nominal). The inductor should be rated to maintain at least 80% of its value at ILIM(PK). Efficiency is affected by inductor DCR and inductance value. Decreasing the inductor value for a given physical size typically decreases DCR; but since ∆I increases, the RMS current increases, as do the core and skin effect losses: IRMS = Table 1. 2 IOUT(DC ) + ΔI2 12 The effective capacitance value decreases as VIN increases due to DC bias effects. (9) Effects of Changes in Inductor Value (470 nH Recommended Value) on Regulator Performance Inductor Value Table 2. (10) IMAX(LOAD) ∆VOUT Transient Response Increase Increase Decrease Degraded Decrease Decrease Increase Improved Recommended Passive Components and Variation Due to DC Bias Component Description Vendor 1 μH, 2012, 190 mΩ, 0.8 A Murata LQM21PN1R0MC0 1 μH Not recommended for 1 A load 1 μH, 1.4 A, 85 mΩ, 2016 Murata LQM2MPN1R0M 1 μH Utilized to generate graphs, Figure 4 — Figure 28 CIN 2.2 μF, 6.3 V, X5R, 0402 Murata or Equivalent GRM155R60J225ME15 GRM188R60J225KE19D 1.0 μF 2.2 μF Decrease primarily due to DC bias (VIN) and elevated temperature COUT 4.7 μF, X5R 0603 Murata or Equivalent GRM188R60G106ME47D 1.6 μF 4.7 μF Decrease primarily due to DC bias (VOUT) and elevated temperature L1 © 2010 Fairchild Semiconductor Corporation FAN53600 / FAN53610 • Rev. 1.0.2 Min. Typ. Comment www.fairchildsemi.com 12 FAN53600 / FAN53610 — 3 MHz, 600 mA / 1 A Synchronous Buck Regulator Applications Information There are only three external components: the inductor and the input and output capacitors. For any buck switcher IC, including the FAN53600/10, it is important to place a low-ESR input capacitor very close to the IC, as shown in Figure 29. The input capacitor ensures good input decoupling, which helps reduce noise at the output terminals and ensures that the control sections of the IC do not behave erratically due to Figure 29. © 2010 Fairchild Semiconductor Corporation FAN53600 / FAN53610 • Rev. 1.0.2 excessive noise. This reduces switching cycle jitter and ensures good overall performance. It is important to place the common GND of CIN and COUT as close as possible to the C2 terminal. There is some flexibility in moving the inductor further away from the IC; in that case, VOUT should be considered at the COUT terminal. 3 MHz PCB Layout Guidance www.fairchildsemi.com 13 FAN53600 / FAN53610 — 3 MHz, 600 mA / 1 A Synchronous Buck Regulator PCB Layout Guidelines FAN53600 / FAN53610 — 3 MHz, 600 mA / 1 A Synchronous Buck Regulator Physical Dimensions Figure 30. 6-Bump WLCSP, 0.4 mm Pitch Product-Specific Dimensions Product D E X Y FAN53610AUC29X 1.160 ±0.030 0.860 ±0.030 0.230 0.180 FAN53610AUC30X 1.160 ±0.030 0.860 ±0.030 0.230 0.180 FAN53610UC33X 1.160 ±0.030 0.860 ±0.030 0.230 0.180 Package drawings are provided as a service to customers considering Fairchild components. Drawings may change in any manner without notice. Please note the revision and/or date on the drawing and contact a Fairchild Semiconductor representative to verify or obtain the most recent revision. Package specifications do not expand the terms of Fairchild’s worldwide terms and conditions, specifically the warranty therein, which covers Fairchild products. Always visit Fairchild Semiconductor’s online packaging area for the most recent package drawings: http://www.fairchildsemi.com/packaging/. © 2010 Fairchild Semiconductor Corporation FAN53600 / FAN53610 • Rev. 1.0.2 www.fairchildsemi.com 14 FAN53600 / FAN53610 — 3 MHz, 600 mA / 1 A Synchronous Buck Regulator © 2010 Fairchild Semiconductor Corporation FAN53600 / FAN53610 • Rev. 1.0.2 www.fairchildsemi.com 15