AAT1143

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Document overview

• Manufacturer or author: Provided By ALLDATASHEET.COM(FREE DATASHEET DOWNLOAD SITE)
• PDF pages: 19

Technical content

Features

• V IN Range: 2.7V to 5.5V
• V OUT Adjustable Down to 0.6V ▪ Fixed or Adjustable Version
• 25 μA No Load Quiescent Current
• Up to 95% Efficiency
• 400mA Max Output Current
• 1MHz Switching Frequency
• Soft Start
• Over-Temperature Protection
• Current Limit Protection
• 100% Duty Cycle Low-Dropout Operation
• 0.1 μA Shutdown Current
• SC70JW-8 Package
• Temperature Range: -40°C to +85°C

Applications

• Cellular Phones
• Digital Cameras
• Handheld Instruments
• Microprocessor / DSP Core / IO Power
• PDAs and Handheld Computers
• USB Devices Typical Application (Fixed Output Voltage) 4.7μH 4.7μF 4.7μF EN OUT VIN LX AGND PGND PGND PGND AAT1143 VIN VO Efficiency vs. Load Current (VOUT = 2.5V; VIN = 3.3V) Output Current (mA) Efficiency (%) 100 0.1 1 10 100 1000

1MHz 400mA Step-Down Converter DATA SHEET Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com 201983B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • March 25, 2013 Pin Descriptions Pin # Symbol Function 1 EN Enable pin. 2 OUT Feedback input pin. This pin is connected either directly to the converter output or to an external resis- tive divider for an adjustable output. 3 VIN Input supply voltage for the converter. 4L X Switching node. Connect the inductor to this pin. It is internally connected to the drain of both high- and low-side MOSFETs. 5 AGND Non-power signal ground pin. 6, 7, 8 PGND Main power ground return pin. Connect to the output and input capacitor return. Pin Configuration SC70JW-8 (Top View) OUT VIN LX PGND PGND PGND AGND EN 1

1MHz 400mA Step-Down Converter DATA SHEET Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com 201983B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • March 25, 2013 Absolute Maximum Ratings1 Symbol Description Value Units VIN Input Voltage GND 6.0 V VLX LX to GND -0.3 to VP + 0.3 V VOUT OUT to GND -0.3 to VP + 0.3 V VEN EN to GND -0.3 to 6.0 V TJ Operating Junction Temperature Range -40 to 150 °C TLEAD Maximum Soldering Temperature (at leads, 10 sec) 300 °C Thermal Information Symbol Description Value Units PD Maximum Power Dissipation (SC70JW-8) 625 mW JA Thermal Resistance2 (SC70JW-8) 160 °C/W 1. Stresses above those listed in Absolute Maximum Ratings may cause permanent damage to the device. Functional operation at co nditions other than the operating conditions specified is not implied. Only one Absolute Maximum Rating should be applied at any one time. 2. Mounted on an FR4 board.

1MHz 400mA Step-Down Converter DATA SHEET Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com 201983B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • March 25, 2013 Electrical Characteristics1 TA = -40°C to +85°C, unless otherwise noted. Typical values are T A = 25°C, VIN = 3.6V. Symbol Description Conditions Min Typ Max Units Step-Down Converter VIN Input Voltage 2.7 5.5 V VUVLO UVLO Threshold VIN Rising 2.6 V Hysteresis 100 mV VIN Falling 1.8 V VOUT Output Voltage Tolerance I OUT = 0 to 400mA, VIN = 2.7V to 5.5V -3.0 +3.0 % VOUT Output Voltage Range Fixed Output Version 0.6 4.0 VAdjustable Output Version2 0.6 2.5 IQ Quiescent Current No Load, 0.6V Adjustable Version 25 50 μA ISHDN Shutdown Current EN = AGND = PGND 1.0 μA ILIM P-Channel Current Limit 600 mA RDS(ON)H High Side Switch On Resistance 0.45  RDS(ON)L Low Side Switch On Resistance 0.40  ILXLEAK LX Leakage Current V IN = 5.5V, VLX = 0 to VIN, EN = GND 1 μA VLinereg Line Regulation V IN = 2.7V to 5.5V 0.2 %/V VOUT Out Threshold Voltage Accuracy 0.6V Output, No Load, T A = 25°C 597 600 615 mV IOUT Out Leakage Current 0.6V Output 0.2 μA ROUT Out Impedance >0.6V Output 250 k  FOSC Oscillator Frequency T A = 25°C 0.7 1.0 1.5 MHz TSD Over-Temperature Shutdown Threshold 140 °C THYS Over-Temperature Shutdown Hysteresis 15 °C EN VEN(L) Enable Threshold Low 0.6 V VEN(H) Enable Threshold High 1.4 V IEN Input Low Current V IN = VFB = 5.5V -1.0 1.0 μA 1. The AAT1143 is guaranteed to meet performance specifications over the -40°C to +85°C operating temperature range and is assu red by design, characterization, and correla- tion with statistical process controls. 2. For adjustable version with higher than 2.5V output, please consult your Skyworks representative.

1MHz 400mA Step-Down Converter DATA SHEET Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com 201983B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • March 25, 2013 Typical Characteristics Efficiency vs. Load (VOUT = 2.5V; L = 4.7μμH) Output Current (mA) Efficiency (%) 100 0.1 1 10 100 1000 VIN = 3.3V VIN = 3.6V VIN = 3.0V Load Regulation (VOUT = 2.5V; L = 4.7μμH) Output Current (mA) Output Error (%) -2.0 -1.0 0.0 1.0 2.0 0.1 1 10 100 1000 VIN = 3.0V VIN = 3.3V VIN = 3.6V Efficiency vs. Load (VOUT = 1.8V; L = 4.7μμH) Output Current (mA) Efficiency (%) 100 0.1 1 10 100 1000 VIN = 2.7V VIN = 3.6V VIN = 4.2V DC Regulation (VOUT = 1.8V; L = 4.7μμH) Output Current (mA) Output Error (%) -2.0 -1.0 0.0 1.0 2.0 0.1 1 10 100 1000 VIN = 2.7V VIN = 3.6V VIN = 4.2V Frequency vs. Input Voltage (VOUT = 1.8V) Input Voltage (V) Frequency Variation (%) -2.0 -1.5 -1.0 -0.5 0.0 0.5 1.0 Output Voltage Error vs. Temperature (VIN = 3.6V; VO = 1.5V) Temperature (°°C) Output Error (%) -2.0 -1.0 0.0 1.0 2.0 -40 -20 0 20 40 60 80 100

1MHz 400mA Step-Down Converter DATA SHEET Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com 201983B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • March 25, 2013 Typical Characteristics Switching Frequency vs. Temperature (VIN = 3.6V; VO = 1.5V) Temperature (°°C) Variation (%) -0.20 -0.10 0.00 0.10 0.20 -40 -20 0 20 40 60 80 100 Quiescent Current vs. Input Voltage (VO = 1.8V) Input Voltage (V) Supply Current (μμA) 85°C 25°C -40°C P-Channel RDS(ON) vs. Input Voltage Input Voltage (V) RDS(ON) (mΩΩ) 300 350 400 450 500 550 600 650 700 750 25°C 120°C 100°C 85°C N-Channel RDS(ON) vs. Input Voltage Input Voltage (V) RDS(ON) (mΩΩ) 300 350 400 450 500 550 600 650 700 750 25°C 120°C 100°C 85°C Load Transient Response (30mA to 300mA; VIN = 3.6V; VOUT = 1.8V; C1 = 10μμF) Output Voltage (top) (V) Load and Inductor Current (200mA/div) (bottom) Time (25μs/div) 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2.0 1.4 1.2 1.0 0.8 0.6 0.4 0.2 0.0 -0.2 300mA 30mA Load Transient Response (30mA to 300mA; VIN = 3.6V; VOUT = 1.8V; C1 = 10μμF; C4 = 100pF; see Figure 1) Output Voltage (AC Coupled) (top) (V) Load and Inductor Current (200mA/div) (bottom) Time (25μs/div) -0.7 -0.6 -0.5 -0.4 -0.3 -0.2 -0.1 0.1 0.0 1.2 1.4 0.8 0.6 1.0 0.2 0.4 -0.2 0.0 300mA 30mA

1MHz 400mA Step-Down Converter DATA SHEET Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com 201983B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • March 25, 2013 Typical Characteristics Load Transient Response (30mA to 300mA; VIN = 3.6V; VOUT = 1.8V; C1 = 4.7μμF) Output Voltage (top) (V) Load and Inductor Current (200mA/div) (bottom) Time (25μs/div) 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2.0 1.4 1.2 1.0 0.8 0.6 0.4 0.2 0.0 -0.2 300mA 30mA Line Transient (VOUT = 1.8V @ 400mA) Output Voltage (top) (V) Input Voltage (bottom) (V) Time (25μμs/div) 1.50 1.55 1.60 1.65 1.70 1.75 1.80 1.85 1.90 3.0 3.5 4.0 4.5 5.0 5.5 6.0 6.5 7.0 Line Regulation (VOUT = 1.8V) Input Voltage (V) Accuracy (%) -0.35 -0.3 -0.25 -0.2 -0.15 -0.1 -0.05 0.05 0.1 IOUT = 400mA IOUT = 100mA IOUT = 10mA Soft Start (VIN = 3.6V; VOUT = 1.8V; 400mA) Enable and Output Voltage (top) (V) Inductor Current (bottom) (A) Time (250μμs/div) -4.0 -3.0 -2.0 -1.0 0.0 1.0 2.0 3.0 4.0 -0.5 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5

1MHz 400mA Step-Down Converter DATA SHEET Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com 201983B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • March 25, 2013 Functional Description The AAT1143 is a high performance 400mA 1MHz mono- lithic step-down converter. It has been designed with the goal of minimizing external component size and optimiz- ing efficiency over the complete load range. Apart from the small bypass input capacitor, only a small L-C filter is required at the output. Typically, a 4.7μH inductor and a 4.7μF ceramic capacitor are recommended (see table of values). The fixed output version requires only three external power components (C IN, COUT, and L). The adjustable ver- sion can be programmed with external feedback to any voltage, ranging from 0.6V to the input voltage. An addi- tional feed-forward capacitor can also be added to the external feedback to provide improved transient response (see Figure 1). At dropout, the converter duty cycle increases to 100% and the output voltage tracks the input voltage minus the R DSON drop of the P-channel high-side MOSFET. The input voltage range is 2.7V to 5.5V. The converter efficiency has been optimized for all load conditions, ranging from no load to 400mA. The internal error amplifier and compensation provides excellent transient response, load, and line regulation. Soft start eliminates any output voltage overshoot when the enable or the input voltage is applied. Functional Block Diagram EN LX Err .Amp Logic DH DL PGND VINOUT AGND Voltage Reference INPUT See note Note: For adjustable version, the internal feedback divider is omitted and the FB pin is tied directly to the internal error amplifier.

1MHz 400mA Step-Down Converter DATA SHEET Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com 201983B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • March 25, 2013 L1 CDRH3D16-4R7 4.7μH 10μF 4.7μF U1 AAT1143 SC70JW-8 C2 4.7μF 10V 0805 X5R VOUT =1.8V GND VIN Enable LX EN OUT VIN LX AGND PGND PGND PGND AAT1143 GND2 118k 59k C1 10μF 6.3V 0805 X5R 100pF Figure 1: Enhanced Transient Response Schematic. Control Loop The AAT1143 is a peak current mode step-down con- verter. The current through the P-channel MOSFET (high side) is sensed for current loop control, as well as short circuit and overload protection. A fixed slope compensa- tion signal is added to the sensed current to maintain stability for duty cycles greater than 50%. The peak cur- rent mode loop appears as a voltage-programmed cur- rent source in parallel with the output capacitor. The output of the voltage error amplifier programs the current mode loop for the necessary peak switch current to force a constant output voltage for all load and line conditions. Internal loop compensation terminates the transconductance voltage error amplifier output. For fixed voltage versions, the error amplifier reference volt- age is internally set to program the converter output voltage. For the adjustable output, the error amplifier reference is fixed at 0.6V. Soft Start / Enable Soft start limits the current surge seen at the input and eliminates output voltage overshoot. When pulled low, the enable input forces the AAT1143 into a low-power, non-switching state. The total input current during shut- down is less than 1μA. Current Limit and Over-Temperature Protection For overload conditions, the peak input current is limit- ed. To minimize power dissipation and stresses under current limit and short-circuit conditions, switching is terminated after entering current limit for a series of pulses. Switching is terminated for seven consecutive clock cycles after a current limit has been sensed for a series of four consecutive clock cycles. Thermal protection completely disables switching when internal dissipation becomes excessive. The junction over-temperature threshold is 140°C with 15°C of hys- teresis. Once an over-temperature or over-current fault conditions is removed, the output voltage automatically recovers. Under-Voltage Lockout Internal bias of all circuits is controlled via the VIN input. Under-voltage lockout (UVLO) guarantees sufficient V IN bias and proper operation of all internal circuitry prior to activation.

1MHz 400mA Step-Down Converter DATA SHEET Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com 201983B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • March 25, 2013 Applications Information Inductor Selection The step-down converter uses peak current mode con- trol with slope compensation to maintain stability for duty cycles greater than 50%. The output inductor value must be selected so the inductor current down slope meets the internal slope compensation requirements. The internal slope compensation for the adjustable and low-voltage fixed versions of the AAT1143 is 0.24A/μsec. This equates to a slope compensation that is 75% of the inductor current down slope for a 1.5V output and 4.7μH inductor. 0.75 ⋅ VO m = = = 0.24 L 0.75 ⋅ 1.5V 4.7μH A μsec This is the internal slope compensation for the adjust- able (0.6V) version or low-voltage fixed versions. When externally programming the 0.6V version to 2.5V, the calculated inductance is 7.5μH. 0.75 ⋅ VO L = = ≈ 3 ⋅ VO = 3 ⋅ 2.5V = 7.5μH m 0.75 ⋅ VO 0.24A μsec A μsec A A μsec In this case, a standard 10μH value is selected. For high-voltage fixed versions (2.5V and above), m = 0.48A/μsec. Table 1 displays inductor values for the AAT1143 fixed and adjustable options. Manufacturer’s specifications list both the inductor DC current rating, which is a thermal limitation, and the peak current rating, which is determined by the satura- tion characteristics. The inductor should not show any appreciable saturation under normal load conditions. Some inductors may meet the peak and average current ratings yet result in excessive losses due to a high DCR. Always consider the losses associated with the DCR and its effect on the total converter efficiency when selecting an inductor. The 4.7 μH CDRH3D16 series inductor selected from Sumida has a 105mW DCR and a 900mA DC current rat- ing. At full load, the inductor DC loss is 17mW which gives a 2.8% loss in efficiency for a 400mA, 1.5V output. Input Capacitor Select a 4.7μF to 10μF X7R or X5R ceramic capacitor for the input. To estimate the required input capacitor size, determine the acceptable input ripple level (V PP) and solve for C. The calculated value varies with input voltage and is a maximum when V IN is double the output voltage. VO VIN CIN = VO VIN VPP IO VO VIN VO VIN CIN(MIN) = 1 VPP IO Always examine the ceramic capacitor DC voltage coeffi- cient characteristics when selecting the proper value. For example, the capacitance of a 10 μF, 6.3V, X5R ceramic capacitor with 5.0V DC applied is actually about 6μF. Confi guration Output Voltage Inductor Slope Compensation 0.6V Adjustable With External Resistive Divider 0.6V to 2.0V 4.7μH 0.24A/ μsec 2.5V 10 μH 0.24A/ μsec Fixed Output 0.6V to 2.0V 4.7μH 0.24A/ μsec 2.5V to 3.3V 4.7μH 0.48A/ μsec Table 1: Inductor Values. The maximum input capacitor RMS current is: VO VIN VO VIN The input capacitor RMS ripple current varies with the input and output voltage and will always be less than or equal to half of the total DC load current. VO VIN VO VIN for VIN = 2 · VO

1MHz 400mA Step-Down Converter DATA SHEET Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com 201983B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • March 25, 2013 The term VO VIN VO VIN appears in both the input voltage ripple and input capacitor RMS current equations and is a maximum when V O is twice V IN. This is why the input voltage ripple and the input capacitor RMS current ripple are a maximum at 50% duty cycle. The input capacitor provides a low impedance loop for the edges of pulsed current drawn by the AAT1143. Low ESR/ESL X7R and X5R ceramic capacitors are ideal for this function. To minimize stray inductance, the capacitor should be placed as closely as possible to the IC. This keeps the high frequency content of the input current localized, minimizing EMI and input voltage ripple. The proper placement of the input capacitor (C2) can be seen in the evaluation board layout in Figure 2. A laboratory test set-up typically consists of two long wires running from the bench power supply to the evalu- ation board input voltage pins. The inductance of these wires, along with the low-ESR ceramic input capacitor, can create a high Q network that may affect converter performance. This problem often becomes apparent in the form of excessive ringing in the output voltage dur- ing load transients. Errors in the loop phase and gain measurements can also result. Since the inductance of a short PCB trace feeding the input voltage is significantly lower than the power leads from the bench power supply, most applications do not exhibit this problem. In applications where the input power source lead induc- tance cannot be reduced to a level that does not affect the converter performance, a high ESR tantalum or alu- minum electrolytic should be placed in parallel with the low ESR, ESL bypass ceramic. This dampens the high Q network and stabilizes the system. Output Capacitor The output capacitor limits the output ripple and pro- vides holdup during large load transitions. A 4.7 μF to 10μF X5R or X7R ceramic capacitor typically provides sufficient bulk capacitance to stabilize the output during large load transitions and has the ESR and ESL charac- teristics necessary for low output ripple. The output voltage droop due to a load transient is dominated by the capacitance of the ceramic output capacitor. During a step increase in load current, the ceramic output capacitor alone supplies the load current until the loop responds. Within two or three switching cycles, the loop responds and the inductor current increases to match the load current demand. The rela- tionship of the output voltage droop during the three switching cycles to the output capacitance can be esti- mated by: COUT = 3 · ΔILOAD VDROOP · FS Once the average inductor current increases to the DC load level, the output voltage recovers. The above equa- tion establishes a limit on the minimum value for the output capacitor with respect to load transients. The internal voltage loop compensation also limits the minimum output capacitor value to 4.7μF. This is due to its effect on the loop crossover frequency (bandwidth), phase margin, and gain margin. Increased output capac- itance will reduce the crossover frequency with greater phase margin. The maximum output capacitor RMS ripple current is given by: VOUT · (VIN(MAX) - VOUT) RMS(MAX)I L · FS · VIN(MAX) Dissipation due to the RMS current in the ceramic output capacitor ESR is typically minimal, resulting in less than a few degrees rise in hot-spot temperature.

1MHz 400mA Step-Down Converter DATA SHEET Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com 201983B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • March 25, 2013 L1 CDRH3D16-4R7 4.7μH 10μF 4.7μF U1 AAT1143 SC70JW-8 C2 4.7μF 10V 0805 X5R VOUT =1.8V GND VIN Enable LX EN OUT VIN LX AGND PGND PGND PGND AAT1143 GND2 118k 59k C1 10μF 6.3V 0805 X5R 100pF n/a Figure 5: AAT1143 Adjustable Evaluation Board Schematic. VOUT (V) R2 = 59kΩ R1 (kΩ) R2 = 221kΩ R1 (kΩ) 0.8 19.6 75 0.9 29.4 113 1.0 39.2 150 1.1 49.9 187 1.2 59.0 221 1.3 68.1 261 1.4 78.7 301 1.5 88.7 332 1.8 118 442 1.85 124 464 2.0 137 523 2.5 187 715 Table 2: Adjustable Resistor Values For Use With 0.6V Step-Down Converter. Thermal Calculations There are three types of losses associated with the AAT1143 step-down converter: switching losses, con- duction losses, and quiescent current losses. Conduction losses are associated with the R DS(ON) characteristics of the power output switching devices. Switching losses are dominated by the gate charge of the power output switching devices. At full load, assuming continuous con- duction mode (CCM), a simplified form of the losses is given by: PTOTAL IO 2 · (RDS(ON)H · VO + RDS(ON)L · [VIN - VO]) VIN + (tsw · FS · IO + IQ) · VIN IQ is the step-down converter quiescent current. The term tsw is used to estimate the full load step-down con- verter switching losses.

1MHz 400mA Step-Down Converter DATA SHEET Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com 201983B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • March 25, 2013 For the condition where the step-down converter is in dropout at 100% duty cycle, the total device dissipation reduces to: PTOTAL = IO 2 · RDS(ON)H + IQ · VIN Since RDS(ON), quiescent current, and switching losses all vary with input voltage, the total losses should be inves- tigated over the complete input voltage range. Given the total losses, the maximum junction tempera- ture can be derived from the  JA for the SC70JW-8 pack- age which is 160°C/W. TJ(MAX) = PTOTAL · ΘJA + TAMB Dissipation due to the RMS current in the ceramic output capacitor ESR is typically minimal, resulting in less than a few degrees rise in hot-spot temperature. Layout The suggested PCB layout for the AAT1143 is shown in Figures 2, 3, and 4. The following guidelines should be used to help ensure a proper layout. 1. The input capacitor (C2) should connect as closely as possible to VIN (Pin 3) and PGND (Pins 6 through 8). 2. C1 and L1 should be connected as closely as possi- ble. The connection of L1 to the LX pin should be as short as possible. 3. The feedback trace or OUT pin (Pin 2) should be separate from any power trace and connect as close- ly as possible to the load point. Sensing along a high-current load trace will degrade DC load regula- tion. If external feedback resistors are used, they should be placed as closely as possible to the OUT pin (Pin 2) to minimize the length of the high imped- ance feedback trace. 4. The resistance of the trace from the load return to PGND (Pins 6 through 8) should be kept to a mini- mum. This will help to minimize any error in DC regulation due to differences in the potential of the internal signal ground and the power ground.

1MHz 400mA Step-Down Converter DATA SHEET Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com 201983B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • March 25, 2013 Step-Down Converter Design Example Specifications VO = 1.8V @ 400mA (adjustable using 0.6V version), Pulsed Load ILOAD = 300mA VIN = 2.7V to 4.2V (3.6V nominal) FS = 1.0MHz TAMB = 85°C 1.8V Output Inductor L1 = 3 ⋅ VO2 = 3 ⋅ 1.8V = 5.4μHμsec A μsec A (see Table 1) For Sumida inductor CDRH3D16, 4.7μH, DCR = 105mΩ. IPKL1 = IO + ΔIL1 PL1 = IO 2 ⋅ DCR = 0.4A2 ⋅ 105mΩ = 17mW 1.8V Output Capacitor VDROOP = 0.2V 4.7μH · 1.0MHz · 4.2V 23 RMSI L1 · FS · VIN(MAX) = · 3 · ΔILOAD VDROOP · FS 3 · 0.3A 0.2V · 1MHz COUT = = = 4.5 μF

• = 63mArms (VO) · (VIN(MAX) - VO) = Pesr = esr · IRMS 2 = 5mΩ · (63mA)2 = 20μW Input Capacitor Input Ripple VPP = 25mV CIN = = = 4.75 μF1 VPP IO 25mV 0.4A IO RMSI P = esr · IRMS 2= = 0.2Arms

1MHz 400mA Step-Down Converter DATA SHEET Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com 201983B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • March 25, 2013 AAT1143 Losses PTOTAL + (tsw · FS · IO + IQ) · VIN IO 2 · (RDS(ON)H · VO + RDS(ON)L · [VIN -VO]) VIN + (5ns · 1.0MHz · 0.4A + 50μA) · 4.2V = 122mW 4.2V TJ(MAX) = TAMB + ΘJA · PLOSS = 85°C + (160°C/W) · 122mW = 104.5°C

1MHz 400mA Step-Down Converter DATA SHEET Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com 201983B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • March 25, 2013 VOUT (V) Adjustable Version (0.6V device) R1 (kΩ) R2 = 59kΩ R1 (kΩ) R2 = 221kΩ1 L1 (μH) 0.8 19.6 75.0 4.7 0.9 29.4 113 4.7 1.0 39.2 150 4.7 1.1 49.9 187 4.7 1.2 59.0 221 4.7 1.3 68.1 261 4.7 1.4 78.7 301 4.7 1.5 88.7 332 4.7 1.8 118 442 4.7 1.85 124 464 4.7 2.0 137 523 4.7 or 6.8 2.5 187 715 10 VOUT (V) Fixed Version R1 (k) R2 Not Used L1 ( μH) 0.6-3.3V 0 4.7 Table 3: Evaluation Board Component Values. Manufacturer Part Number Inductance (μH) Max DC Current (A) DCR ( ) Size (mm) LxWxH Type Table 4: Typical Surface Mount Inductors. Manufacturer Part Number Value Voltage Temp. Co. Case Murata GRM21BR61A475KA73L 4.7 μF 10V X5R 0805 Murata GRM18BR60J475KE19D 4.7 μF 6.3V X5R 0603 Murata GRM21BR60J106KE19 10 μF 6.3V X5R 0805 Murata GRM21BR60J226ME39 22 μF 6.3V X5R 0805 Table 5: Surface Mount Capacitors. 1. For reduced quiescent current R2 = 221k .

1MHz 400mA Step-Down Converter DATA SHEET Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com 201983B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • March 25, 2013

Ordering Information

Output Voltage1 Package Marking 2 Part Number (Tape and Reel)3 0.6 SC70JW-8 NUXYY AAT1143IJS-0.6-T1 1.2 SC70JW-8 PBXYY AAT1143IJS-1.2-T1 1.6 SC70JW-8 PYXYY AAT1143IJS-1.6-T1 1.8 SC70JW-8 OKXYY AAT1143IJS-1.8-T1 2.5 SC70JW-8 OYXYY AAT1143IJS-2.5-T1 3.3 SC70JW-8 PLXYY AAT1143IJS-3.3-T1 Skyworks Green™ products are compliant with all applicable legislation and are halogen-free. For additional information, refer to Skyworks Definition of Green™ , document number SQ04-0074.

Package Information

0.225 ± 0.075 0.45 ± 0.10 0.05 ± 0.05 2.10 ± 0.30 2.00 ± 0.20 7° ± 3° 4° ± 4° 0.15 ± 0.05

1.10 MAX

0.100 2.20 ± 0.20 0.048REF 0.50 BSC 0.50 BSC 0.50 BSC All dimensions in millimeters. 1. Contact Sales for other voltage options. 2. XYY = assembly and date code. 3. Sample stock is generally held on part numbers listed in BOLD.

1MHz 400mA Step-Down Converter DATA SHEET Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com 201983B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • March 25, 2013 Copyright © 2012, 2013 Skyworks Solutions, Inc. All Rights Reserved. Information in this document is provided in connection with Skyworks Solutions, Inc. (“Skyworks”) products or services. These materials, including the information contained herein, are provided by Skyworks as a service to its customers and may be used for informational purposes only by the customer. Skyworks assumes no responsibility fo r errors or omissions in these materials or the information contained herein. Sky- works may change its documentation, products, services, specifi cations or product descriptions at any time, without notice. Skyworks makes no commitment to update the materials or information and shall have no responsibility whatsoever for confl icts, incompatibilities, or other diffi culties arising from any future changes. No license, whether express, implied, by estoppel or otherwise, is granted to any intellectual property rights by this document. Skyworks assumes no liability for any materials, products or information provided here- under, including the sale, distribution, reproduction or use of Skyworks products, information or materials, except as may be provided in Skyworks Terms and Conditions of Sale. THE MATERIALS, PRODUCTS AND INFORMATION ARE PROVIDED “AS IS” WITHOUT WARRANTY OF ANY KIND, WHETHER EXPRESS, IMPLIED, STATUTORY, OR OTHERWISE, INCLUDING FITNESS FOR A PARTICULAR PURPOSE OR USE, MERCHANTABILITY, PERFORMANCE, QUALITY OR NON-INFRINGEMENT OF ANY INTELLECTUAL PROPERTY RIGHT; ALL SUCH WARRANTIES ARE HEREBY EXPRESSLY DISCLAIMED. SKYWORKS DOES NOT WARRANT THE ACCURACY OR COMPLETENESS OF THE INFORMATION, TEXT, GRAPHICS OR OTHER ITEMS CONTAINED WITHIN THESE MATERIALS. SKYWORKS SHALL NOT BE LIABLE FOR ANY DAMAGES, IN- CLUDING BUT NOT LIMITED TO ANY SPECIAL, INDIRECT, INCIDENTAL, STATUTORY, OR CONSEQUENTIAL DAMAGES, INCLUDING WITHOUT LIMITATION, LOST REVENUES OR LOST PROFITS THAT MAY RESULT FROM THE USE OF THE MATERIALS OR INFORMATION, WHETHER OR NOT THE RECIPIENT OF MATERIALS HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. Skyworks products are not intended for use in medical, lifesaving or life-sustaining applications, or other equipment in which the failure of the Skyworks products could lead to personal injury, death, physical or en- vironmental damage. Skyworks customers using or selling Skyworks products for use in such applications do so at their own risk and agree to fully indemnify Skyworks for any damages resulting from such improper use or sale. Customers are responsible for their products and applications using Skyworks products, which may deviate from published specifi cations as a result of design defects, errors, or operation of products outside of pub- lished parameters or design specifi cations. Customers should include design and operating safeguards to minimize these and other risks. Skyworks assumes no liability for applications assistance, customer product design, or damage to any equipment resulting from the use of Skyworks products outside of stated published specifi cations or parameters. Skyworks, the Skyworks symbol, and “Breakthrough Simplicity” are trademarks or registered trademarks of Skyworks Solutions, Inc., in the United States and other countries. Third-party brands and names are for identifi cation purposes only, and are the property of their respective owners. Additional information, including relevant terms and conditions, posted at www.skyworksinc.com, are incorporated by reference.