SEMTECH SC220

SC220 ™ 20MHz, 650mA, X-EMI -Enabled Synchronous Step-Down Regulator POWER MANAGEMENT Features Description TM (1)  Patented X-EMI Inductor Technology The SC220 is a 20MHz X-EMI™ -enabled step-down regu-  Enables Trace Inductors in PC Board Material lator optimized for powering low voltage rails from 2.7 to  Excellent EMI Performance 5.5V input voltage. X-EMI™ inductor technology enables  Effi ciency up to 90% inductors to be drawn directly on the PC board. This tech-  19μA Quiescent Current under Very Light-load nology meets or exceeds the EMI performance of chip  Wide Input Voltage Range — 2.7V to 5.5V inductors and eliminates the need for discrete inductors.  Adjustable Output Voltage Down to 1.0V  Output DC Current — up to 650mA The SC220 uses a unique constant frequency, self-oscil-  High Light-load Effi ciency via Automatic PSAVE Mode lating control loop architecture to provide excellent  Ultra-fast Transient Response — <1μs transient performance. Under light load condition, the  Temperature Range — -40 to +85°C device operates in Power Save Mode (PSAVE) and main-  Shutdown Current — 0.1μA (typical) tains a typical quiescent current of 19μA. At moderate to  Requires Tiny 220nH Inductor heavy loads, this part operates in PWM mode with a con-  Requires Only 1μF of Output Capacitance stant switching frequency of 20MHz. This high switching  External Switching Frequency Synchronization frequency off ers the advantages of using small and low  Protection Features Including cost external components like a 1μF external capacitor TM  Over-Current Protection and a small 220nH inductor (including X-EMI PCB trace  Output Short-Circuit Protection inductors).  Thermal Shutdown Protection The device provides adjustable output voltages down to  Off ered in SOIC 8 Lead Package 1.0V and an output current up to 650mA. An EN pin can  Lead-free, Halogen-free, and RoHS/WEEE Compliant be used to synchronize to an external source and includes Applications de-glitching to reduce noise sensitivity.  HDTV, Set Top Boxes, Gaming Consoles The SC220 is available in SOIC 8 lead package.  POL Applications  White Goods  Automotive (EMI sensitive console applications) TM Note 1: Purchase of SC220 includes royalty-free rights to use X-EMI inductor technology with no additional cost. Typical Application Circuit V OUT=1.8V V L, 220nH IN up to 650m A PVIN SW 2.7~5.5V AVIN VOUT C IN 1 μF C OUT R 1 SC220 1 μF EN FB Enable PGND R 2 AGND January 25, 2012 1 SC220 Pin Confi guration Ordering Information Device Package (1)(2) SC220STRT SOIC 8 Lead SW 1 8 PGND SC220EVB Evaluation Board PVIN 2 7 AGND 3 6 AVIN VOUT Notes: FB 4 5 EN (1) Available in tape and reel only. A reel contains 2,500 devices. (2) Device is lead-free, halogen-free, and RoHS/WEEE compliant. SOIC 8 Lead, θ = 38 °C/W JA Marking Information nnnnn = Part Number yyww = Date Code xxxxx = Semtech Lot Number 2 SC220 (1) Absolute Maximum Ratings Recommended Operating Conditions AVIN, PVIN (V) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6.0 Input Voltage Range (V) . . . . . . . . . . . . . . . . . . . . . +2.7 to +5.5 VOUT, FB, EN, SW (V) . . . . . . . . . . . . . . . . . . . . .-0.3 to (V +0.3) Output DC Current (mA). . . . . . . . . . . . . . . . . . . . . up to 650 IN AGND (V) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .-0.3 to +0.3 Operating Temperature Range (°C) . . . . . . . . . . -40 to +85 (2) ESD Protection Level . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3kV Thermal Information (3) Thermal Resistance, Junction to Ambient (°C/W)....38 Junction Temperature Range (°C) . . . . . . . . . . -40 to +150 Storage Temperature Range (°C) . . . . . . . . . . . . -65 to +150 Peak IR Refl ow Temperature (10s to 30s) (°C) . . . . . . . . . 260 Exceeding the above specifi cations may result in permanent damage to the device or device malfunction. Operation outside of the parameters specifi ed in the Electrical Characteristics section is not recommended. Notes: (1) All voltage values in this section are with respect to PGND pin voltage. (2) Tested according to JEDEC standard JESD22-A114-B. (3) Calculated from package in still air, mounted to 3 x 4.5 (in), 4 layer FR4 PCB with thermal vias under the exposed pad per JESD51 standards. Electrical Characteristics Unless otherwise specifi ed: AVIN = PVIN = EN = 3.6V, C = C = 1.0μF, L = 220nH. T = 25°C for typical values, -40°C < T = T < 85°C for minimum IN OUT A A J and maximum values. Parameter Symbol Condition Min Typ Max Units POWER SUPPLY Input Voltage V 2.7 5.5 V IN Input Quiescent Current I No load, no switching 19 40 μA VIN_Q Shutdown Current I EN = 0V 1.0 μA VIN_SD POWER SWITCH PMOS On Resistance 400 mΩ NMOS On Resistance 360 mΩ OSCILLATOR Switching Frequency f PWM Mode 16 20 24 MHz OSC REGULATION (1) Output Voltage Tolerance V -4.0 4.0 % OUT_TOL Current Limit I 850 1300 mA LIMIT (1) Soft-Start t EN pin low to high 40 μs SS Feedback Voltage V 2.7V ≤ VIN ≤ 5.5V 0.97 1.00 1.03 V FB 3 SC220 Electrical Characteristics (continued) Unless otherwise specifi ed: AVIN = PVIN = EN = 3.6V, C = C = 1.0μF, L = 220nH. T = 25°C for typical values, -40°C < T = T < 85°C for minimum IN OUT A A J and maximum values. Parameter Symbol Condition Min Typ Max Units Feedback Leakage Current I 1μA FB ENABLE EN Input High Voltage Threshold V 1.2 V ENH EN Input “Low” Voltage Threshold V 0.4 V ENL EN Input High Current I V = V -1.0 1.0 μA ENH EN IN EN Input Low Current I V = AGND -1.0 1.0 μA ENL EN Minimum Synchronization Frequency f Square wave applied at EN pin 3 MHz SYN_MIN PROTECTION (1) Over Temp Thermal Shutdown T 150 °C OT (1) Thermal Shutdown Hysteresis T 15 °C HYST Notes (1) Guaranteed by design. Not tested in production. 4 SC220 Pin Descriptions Pin # Pin Name Pin Function 1 SW Switching output node — connect to the output LC fi lter. 2 PVIN Power input supply voltage (2.7V to 5.5V). 3 VOUT Input for sensing the output of LC fi lter. Input for regulation of output LC fi lter — Using R and R to set the output voltage, V = V x (1+ R /R ). (Please refer 1 2 OUT FB 1 2 4FB to the typical application circuit diagram on page 1). Enable Input — when low, circuit draws <1μA. Apply a square wave clock at EN to synchronize the switching frequency 5EN with an external clock. It is recommended that the externally applied clock frequency should not be above 20MHz. 6AVIN Input supply voltage. 7 AGND Analog ground. 8 PGND Power ground. Block Diagram AVIN PVIN 7 3 1.0V REF EN 8 OSC Soft-Start 20 M H z Therm al Shutdow n CLIM Frequency Control External Freq . Synchronization 1.0V + C ontrol Logic E rror Driver 4 SW + Amp FB 1 - Comp - ZC D C om pensator 2 VOUT 6 5 AGND PGND 5 SC220 Typical Characteristics Effi ciency vs. Load Current Effi ciency vs. V IN V = 1.8V V = 1.8V OUT OUT I = 300mA 100 % 100 % OUT V = 2.7V IN V = 3.7V 90 % 90 % IN 80 % 80 % 70 % 70 % I = 50mA 60 % 60 % OUT V = 4.2V IN 50 % 50 % I = 1mA OUT 40 % 40 % 30 % 30 % 20 % 20 % 10 % 10 % 0 0 0.001 0.01 0.1 1 2.5 3.0 3.5 4.0 4.5 5.0 Load Current (A) Input Voltage (V) Effi ciency vs. Load Current Load Regulation TM (Chip Inductor vs. X-EMI Inductor) Nominal V = 1.8V V = 1.8V OUT OUT 100 % 1.80 V = 3.7V V = 2.7V IN IN 90 % V = 5.0V 80 % IN 70 % 1.79 60 % V = 4.2V IN 50 % V = 4.2V IN 40 % 1.78 V = 2.7V IN V = 3.7V 30 % IN 20 % TM Dashed Lines: Effi ciency with X-EMI Inductor 10 % Solid Lines: Effi ciency with chip Inductor 1.77 0 0.01 0.001 0.1 1 0.001 0.01 0.1 1 Load Current (A) Load Current (A) Switching Frequency vs. V Switching Frequency vs. V IN IN V = 1.0V V = 1.8V OUT OUT 22.5 22.5 I = 200mA OUT 20.0 20.0 I = 200mA OUT 17.5 17.5 I = 300mA OUT 15.0 15.0 I = 650mA OUT I = 450mA OUT 12.5 12.5 I = 300mA OUT 10.0 10.0 7.5 7.5 I = 450mA OUT 5.0 5.0 2.5 2.5 I = 650mA OUT 0 0 2.5 3.0 2.5 3.0 3.5 4.0 4.5 5.5 3.5 4.0 4.5 5.0 5.5 5.0 Input Voltage (V) Input Voltage (V) 6 Switching Frequency (MHz) Effi ciency Effi ciency Output Voltage (V) Effi ciency Switching Frequency (MHz) SC220 Typical Characteristics (Continuous) Load Transient Response Load Transient Response V = 3.7V, V = 2.0V, I = 0mA - 650mA V = 3.7V, V = 2.0V, I = 200mA - 500mA IN OUT OUT IN OUT OUT V (ac coupled) OUT V (ac coupled) OUT 100mV/div. 50mV/div. I I OUT OUT 200mA/div. 200mA/div. Time (1μs/div) Time (1μs/div) Steady State Operation (I = 300mA) Steady State Operation (I = 50mA) OUT OUT V = 3.6V, V = 1.8V, I = 50mA V = 3.6V, V = 1.8V, I = 300mA IN OUT OUT IN OUT OUT I OUT 50mA/div. I OUT 200mA/div. I L 200mA/div. I L 200mA/div. V SW V SW 2V/div. 2V/div. Time (200ns/div) Time (50ns/div) Output Hard Short Input Quiescent Current vs. Temperature V = 5.5V, EN = High, FB = High V = 5.0V, V = 1.8V, I = 650mA IN IN OUT OUT 20.0 V OUT 19.5 1V/div. 19.0 I L 500mA/div. 18.5 I OUT 500mA/div. 18 Time (500ns/div) -40 -20 020 40 80 100 60 Temperature (°C) 7 Quiescent Current (μA) SC220 Typical Characteristics (Continuous) Disable Operation Start-up Operation V = 3.7V, V = 1.8V, I = 10mA V = 3.7V, V = 1.8V, I = 10mA IN OUT OUT IN OUT OUT EN EN 5V/div. 5V/div. V V IN IN 2V/div. 2V/div. V V OUT OUT 1V/div. 1V/div. I I OUT OUT 10mA/div. 10mA/div. Time (20μs/div) Time (100μs/div) Disable Operation Start-up Operation V = 3.7V, V = 1.8V, I = 650mA V = 3.7V, V = 1.8V, I = 650mA IN OUT OUT IN OUT OUT EN EN 5V/div. 5V/div. V V IN IN 2V/div. 2V/div. V V OUT OUT 1V/div. 1V/div. I I OUT OUT 500mA/div. 500mA/div. Time (20μs/div) Time (20μs/div) 8 SC220 typically occurs in the range of 100-200mA, depending A Applica pplications Inf tions Informa ormation tion on the input and output voltages. Under very light load General Description condition, the SC220 maintains high effi ciency by shut- ting down all but the most essential circuit blocks, The SC220 is a step-down regulator capable of delivering maintaining a typical quiescent current of about 19μA. In a lower voltage from an input supply voltage of 2.7V to this mode, some circuitry used to control absolute DC 5.5V with high effi ciency. Using a unique control architec- accuracy is turned off . In that case, there may be a small ture, the SC220 is capable of delivering a peak effi ciency DC shift (tens of millivolts) between normal operation of 90%, while maintaining effi ciency over 80% during light and this “no-load” state. However, in the case of a load load condition. The converter operates at 20MHz switch- transient, the system will turn on the high-side FET within ing frequency with Pulse Width Modulation (PWM) with nanoseconds as a discontinuous pulse is issued. The tran- moderate to heavy output load current of up to 650mA, sition to PWM mode can occur within that nominal which is referred as PWM mode. Under light-load condi- on-time, giving superior no load to full load transient tion, the converter operates in Power Save (PSAVE) response. mode. The transition from PWM mode to PSAVE mode is con- Control Scheme trolled by sensing the minimum value of the ripple current. When it drops below a threshold level for 32 The SC220 operates with a self-oscillating control method consecutive cycles, the transition to PSAVE mode is initi- based on the output voltage ripple. This control loop com- ated. Once in PSAVE mode, the regulation is maintained pares the output voltage to an internal 1V reference to by modulating the time between fi xed current pulses. regulate the output voltage directly, adjusting the turn-on When a new pulse is required by the loop before the and turn-off time of the power switches such that the existing pulse has terminated, the loop determines that output voltage is held at a precise value. This architecture the load cannot be maintained in PSAVE mode. This gives a single-cycle response to transient events. prompts an instantaneous switch from PSAVE mode back to PWM mode. To maintain constant frequency, a phase locked loop (PLL) is included to synchronize the switching with an internal Enable and Start-up clock. This PLL adjusts the effective upper and lower thresholds of the comparator, thus maintaining a constant The SC220 is enabled by applying a voltage higher than frequency. Under transient conditions the voltage control 1.2V on the EN pin, and it is disabled when the applied loop determines the required switching pattern to best voltaga is pulled below the logic low threshold. The EN maintain the output voltage. After a short transient, the pin can also be used to set the switching frequency: if a PLL will bring the switching frequency back to normal. At digital clock is fed to EN, the SC220 will sense this as a extreme duty cycles, where the frequency control loop valid enable signal and the external clock will be used may not be able to maintain frequency lock even under rather than the internal 20MHz oscillator. steady-state conditions, frequency may fall, but the output voltage regulation will be maintained by the main voltage The SC220 has an internal soft start circuit that limits the control loop. This unique architecture helps to achieve the inrush current during start-up with a stepped current excellent line and load transient response. limit. Over the course of about 40μs, the SC220 is stepped in increments of one quarter of the nominal current limit Operating Modes to full current limit, thereby reducing the worst-case surge current that might otherwise be refl ected to the The SC220 operates in two modes over a wide range of input current. load currents. Under moderate to heavy load conditions, it operates in PWM mode with the switching frequency Current Limit held constant. Under light-load condition, the converter enters PSAVE mode automatically. With the typical 220nH The SC220 integrates a current limit feature to protect inductor, the transition between PWM and PSAVE mode itself and the external components under overload con- 9 SC220 energy of the inductors in series. This approach uses mul- Applications Information (Cont.) tiple air core inductors implemented using printed circuit traces. Because these traces may be located on internal dition. When the current fl owing through the high-side layers of the PCB, inductors can be designed with almost PMOS switch exceeds the current limit, the PMOS switch no impact on the available PCB area for components on is turned off . The high-side switch is then held off for a the surface of the board. (See the effi ciency curves using period suffi cient to allow inductor current to decay. When X-EMI™ inductor technology on page 6). the output voltage is close to the nominal regulation point, this will look similar to constant current limiting. As the output voltage falls, the imposed off -time is such that the frequency will drop, thus the inductor will have appro- priate time to reset. This may cause the average current to reduce, giving a mild ‘fold-back’ characteristic to the current limit, where the average load current drops as the output voltage collapses (although the peak current maintains its nominal value). In a short-circuit condition, the system runs continuously at this reduced frequency. Figure 1. Top view of an evaluation board with X-EMI inductor Load Transient Response The SC220 features excellent regulation during line and External Components load transients. This is due to the nature of the proprietary control method and the high di/dt allowed by the use of a The input and output capacitors used for the operation of small inductor. This allows for best performance while the SC220 should be multilayer ceramic capacitors, prefer- providing the benefit of using a small low cost output ably with X7R or X5R dielectric. The SC220 is optimized to capacitor. V shows only tens of millivolts of ripple operate with typical 1μF input and output capacitance. In OUT voltage during a load current step change from less than practice, the self-resonant frequency of surface mount 1mA to 650mA within hundreds of nanoseconds, using capacitors of this type is well below the 20MHz ripple fre- typical a 1μF output capacitor. (See the typical perfor- quency, so eff orts to minimize output ripple may best be mance curves on page 7). focused on minimizing the inductance of the output capacitor and the length of the circuit path to ground X-EMI™ Inductor Technology rather than on increasing the capacitance value of the output capacitor. The SC220 is the industry’s fi rst buck regulator that enables designers to draw their own inductors directly on the PC The inductor should be a high current inductor rated for board. This patented technology is called X-EMI™ inductor currents at least up to 1A. Typical power inductors may be technology and is diff erent from conventional PCB trace too lossy at 20MHz unless specifi cally designed for high inductors. Conventional PCB trace inductors can be used frequency operation. For inductor value of 220nH, it may with high-frequency switchers, but they exhibit signifi cant be preferred to use wire-wound RF chokes, many of which EMI issues. X-EMI™ inductor technology solves these EMI are rated for appropriate currents. problems and can meet or exceed the EMI performance of conventional chip inductors. Some Recommended External Components Value Manufacturer Part Number Package TM X-EMI technology works by placing two small air-core 0.22μH Coilcraft XFL2005-221ME 2x2mm inductors adjacent to each other in anti-phase position, L 0.24μH Coilcraft 0603LS-241XJL 0603 where the magnetic fi elds of each air-core inductor par- C 1μF Murata GRM155R61C105KA12 0402 IN tially cancel one another to reduce EMI. The net fl ux from C 1μF Murata GRM155R61C105KA12 0402 OUT the two inductors, partially cancels the wide leakage paths caused by the wide geometry, but is still able to store the 10 SC220 the pickup of high frequency switching edges to Applications Information (Cont.) other parts of the circuit. The output capacitor, C OUT and the inductor should be put as close as possible to PCB Layout Considerations the related pins of the IC, and connected as close as possible between the SW and ground pins. PCB Layout is important in designing a switching regula- 3. Route the output voltage feedback/sense path tor. A few fundamental layout considerations will help to from the output capacitor path, and away from the achieve the specified performance. Poor layout can inductor and SW node to minimize the possible noise degrade the performance of the switching regulator and and magnetic interference to the output feedback/ may contribute to EMI problems, ground bounce, and sense path. possibly poor regulation and instability. 4. Use a ground plane referenced to the PGND pin, and the ground connection of the input and output The following guidelines are recommended when devel- capacitors should be put on this plane and close to oping a PCB layout: each other if possible, and as close to the PGND pin as possible. Use several vias to connect to the component 1. The input capacitor, C should be placed as close to IN side ground to further reduce noise and interference the PVIN and PGND pins as possible. This capacitor on sensitive circuit nodes. provides a low impedance loop for the pulsed 5. If possible, minimize the resistance from the VOUT currents present at the buck converter’s input. Use and AGND pins to the load. This will reduce the short wide traces to connect this capacitor as close voltage drop on the ground plane and improve the to the IC as possible. This will minimize EMI and input load regulation. And it will also improve the overall voltage ripple by localizing the high frequency current effi ciency by reducing the copper losses on the output pulses. and ground planes. 2. Keep the SW pin traces as short as possible to minimize 11 SC220 Outline Drawing — SOIC 8 Lead DIMENSIONS INCHES MILLIMETERS A DIM MIN NOM MAX MIN NOM MAX D e - - A .053 .069 1.35 1.75 N - - A1 .004 .010 0.10 0.25 - - A2 .049 .065 1.25 1.65 - - 2X E/2 b .012 .020 0.31 0.51 c - - .007 .010 0.17 0.25 D .189 .193 .197 4.80 4.90 5.00 E1 E E1 .150 .154 .157 3.80 3.90 4.00 E .236 BSC 6.00 BSC e .050 BSC 1.27 BSC 12 - - h .010 .020 0.25 0.50 ccc C L .016 .028 .041 0.40 0.72 1.04 2X N/2 TIPS (.041) (1.04) e/2 L1 N 8 8 B - - 01 0° 8° 0° 8° aaa .004 0.10 bbb .010 0.25 D ccc .008 0.20 aaa C h A2 A SEATING PLANE h C A1 H bxN bbb C A-B D c GAGE PLANE 0.25 L 01 (L1) SEE DETAIL A DETAIL A SIDE VIEW NOTES: 1. CO NTRO LLING DIM ENSIO NS ARE IN M ILLIM ETERS (ANGLES IN DEGREES). 2. DATUM S A -A- ND T -B- O BE DETERM INED AT DATUM PLANE -H- 3. DIM ENSIONS "E1" AND "D" DO NO T INCLUDE M O LD FLASH, PROTRUSIONS O R G ATE BURRS. 4. REFERENCE JEDEC STD M S-012, VARIATION AA. 12 SC220 Land Pattern —SOIC 8 Lead X DIMENSIONS DIM INCHES MILLIMETERS (.205) (5.20) C G .118 3.00 (C) G Z P .050 1.27 X .024 0.60 Y .087 2.20 Y Z .291 7.40 P NOTES: 1. THIS LAND PATTERN IS FO R REFERENCE PURPOSES O NLY. CONSULT YOUR M ANUFACTURING GROUP TO ENSURE YOUR COM PANY'S M ANUFACTURING G UIDELINES ARE M ET. 2. REFERENCE IPC-SM -782A, RLP NO . 300A. 13 SC220 © Semtech 2012 All rights reserved. Reproduction in whole or in part is prohibited without the prior written consent of the copyright owner. The information presented in this document does not form part of any quotation or contract, is believed to be accurate and reliable and may be changed without notice. No liability will be accepted by the publisher for any conse- quence of its use. Publication thereof does not convey nor imply any license under patent or other industrial or intellectual property rights. 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