DATA SHEET AAT1157 1MHz 1.2A Buck DC/DC Converter General Description Features The AAT1157 SwitchReg™ is a step-down switching converter, ideal for applications where fixed frequency and low ripple are required over the full range of load conditions. The 2.7V to 5.5V input voltage range makes the AAT1157 ideal for single-cell lithium-ion/polymer battery applications. Capable of up to 1.2A with internal MOSFETs, the current-mode controlled IC provides high efficiency over a wide operating range. Fully integrated compensation simplifies system design and lowers external parts count. The device operates at a fixed 1MHz switching frequency across all load conditions. • • • • • • • • • • • • • • • • The AAT1157 is available in the Pb-free, 16-pin 3x3mm QFN package and is rated over the -40°C to +85°C temperature range. VIN Range: 2.7V to 5.5V Up to 95% Efficiency 110 m RDS(ON) Internal Switches <1μA Shutdown Current 1MHz Buck Switching Frequency Fixed or Adjustable VOUT ≥ 0.8V Integrated Power Switches Current Mode Operation Internal Compensation Stable with Ceramic Capacitors Constant PWM Operation for Low Output Ripple Internal Soft Start Over-Temperature Protection Current Limit Protection 16-Pin QFN 3x3mm Package -40°C to +85°C Temperature Range Applications • • • • • • • HDD MP3 Players Notebook Computers PDAs Point-of-Load Regulation Set Top Boxes Smart Phones Wireless Notebook Adapters Typical Application U1 AAT1157 3.3V 12 R1 100 C1 10μF 11 10 7 9 6 C2 0.1μF 8 5 VP FB VP LX VP LX EN VCC LX N/C N/C PGND N/C PGND SGND PGND 2.5V 4 R3 187k 15 14 13 L1 3.0μH 16 3 R4 59k C3-C4 2x 22μF 2 1 Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 201995A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • May 29, 2012 1 DATA SHEET AAT1157 1MHz 1.2A Buck DC/DC Converter Pin Descriptions Pin # Symbol 1, 2, 3 PGND 4 FB 5 SGND 7 EN 6, 8, 16 N/C 9 VCC 10, 11, 12 VP 13, 14, 15 LX EP Function Main power ground return pin. Connect to the output and input capacitor return. (See board layout rules.) Feedback input pin. This pin is connected to the converter output. It is used to set the output of the converter to regulate to the desired value via an internal resistive divider. For an adjustable output, an external resistive divider is connected to this pin. Signal ground. Connect the return of all small signal components to this pin. (See board layout rules.) Enable input pin. A logic high enables the converter; a logic low forces the AAT1157 into shutdown mode reducing the supply current to less than 1μA. The pin should not be left floating. Not internally connected. Bias supply. Supplies power for the internal circuitry. Connect to input power via low pass filter with decoupling to SGND. Input supply voltage for the converter power stage. Must be closely decoupled to PGND. Connect inductor to these pins. Switching node internally connected to the drain of both high- and low-side MOSFETs. Exposed paddle (bottom); connect to PGND directly beneath package. Pin Configuration QFN33-16 (Top View) LX LX LX N/C 13 14 15 16 PGND PGND PGND FB 1 12 2 11 3 10 4 9 VP VP VP VCC 8 7 6 5 N/C EN N/C SGND 2 Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 201995A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • May 29, 2012 DATA SHEET AAT1157 1MHz 1.2A Buck DC/DC Converter Absolute Maximum Ratings1 Symbol VCC, VP VLX VFB VEN TJ VESD Description VCC, VP to GND LX to GND FB to GND EN to GND Operating Junction Temperature Range ESD Rating2 - HBM Value Units 6 -0.3 to VP + 0.3 -0.3 to VCC + 0.3 -0.3 to -6 -40 to150 3000 V V V V °C V Value Units 50 4.2 2.0 °C/W °C/W W Value Units -40 to 85 °C Thermal Characteristics Symbol JA JC PD Description Maximum Thermal Resistance (QFN33-16)3 Maximum Thermal Resistance (QFN33-16) Maximum Power Dissipation (QFN33-16) (TA = 25°C)3, 4 Recommended Operating Conditions Symbol T Description Ambient Temperature Range 1. Stresses above those listed in Absolute Maximum Ratings may cause damage to the device. Functional operation at conditions other than the operating conditions specified is not implied. Only one Absolute Maximum Rating should be applied at any one time. 2. Human body model is 100pF capacitor discharged through a 1.5k resistor into each pin. 3. Mounted on a demo board (FR4, in still air). Exposed pad must be mounted to PCB. 4. Derate 20mW/°C above 25°C. Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 201995A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • May 29, 2012 3 DATA SHEET AAT1157 1MHz 1.2A Buck DC/DC Converter Electrical Characteristics1 VIN = VCC = VP = 5V, TA = -40°C to +85°C, unless otherwise noted. Typical values are at TA = 25°C. Symbol VIN VOUT VOUT/VOUT VOUT (VOUT*VIN) IQ ISHDN ILIM VUVLO VUVLO(HYS) VIL VIH IIL IIH RDS(ON)H RDS(ON)L Description Conditions Input Voltage Range Output Voltage Tolerance Load Regulation VIN = VOUT + 0.2 to 5.5V, IOUT = 0 to 1.2A VIN = 4.2V, ILOAD = 0 to 1.2A Line Regulation Quiescent Supply Current Shutdown Current Current Limit Under-Voltage Lockout Under-Voltage Lockout Hysteresis Input Low Voltage Input High Voltage Input Low Current Input High Current High Side Switch On Resistance Low Side Switch On Resistance FOSC Oscillator Frequency TSD THYS Over-Temperature Shutdown Threshold Over-Temperature Shutdown Hysteresis Min Typ Max Units 5.5 +4 ±2.5 V % % VIN =2.7 to 5.5V ±0.1 %/V No Load VEN = 0V, VIN = 5.5V TA = 25°C VIN Rising, VEN = VCC VIN Falling, VEN = VCC 160 2.7 -4 300 1.0 1.7 2.5 1.2 250 0.6 1.4 VIN = VFB = 5.5V VIN = VFB = 0V TA = 25°C TA = 25°C TA = 25°C, Adjustable Version TA = 25°C, 3.3V Version 750 600 110 100 1000 850 140 15 1.0 1.0 150 150 1250 1200 μA μA A V mV V V μA μA m m kHz °C °C 1. The AAT1157 is guaranteed to meet performance specifications over the -40°C to +85°C operating temperature range and is assured by design, characterization, and correlation with statistical process controls. 4 Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 201995A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • May 29, 2012 DATA SHEET AAT1157 1MHz 1.2A Buck DC/DC Converter Typical Characteristics No Load Supply Current vs. Input Voltage DC Regulation (VOUT = 2.5V) 2.0 85°C 250 200 150 25°C -40°C 100 50 0 2.5 VIN = 3.0V 0.0 VIN = 3.3V -1.0 -2.0 -3.0 -4.0 3 3.5 4 4.5 5 1 5.5 10 100 10000 Output Current (mA) P-Channel RDSON vs. Input Voltage N-Channel RDSON vs. Input Voltage 200 180 100°C 160 180 120°C 160 RDSON (mΩ Ω) 140 120 100 85°C 80 25°C 60 100°C 140 120°C 120 100 80 85°C 60 40 40 20 20 0 2.5 25°C 0 3 3.5 4 4.5 5 5.5 2.5 3 3.5 4 4.5 5 Input Voltage (V) Input Voltage (V) Output Voltage vs. Temperature Frequency vs. Input Voltage (VIN = 3.6V; VOUT = 2.5V; IOUT = 1.0A) 5.5 (VOUT = 1.8V) 0.1 1.3 0 Frequency (MHz) Output Voltage Error (%) 1000 Input Voltage (V) 200 RDSON (mΩ Ω) VIN = 3.6V 1.0 Output Error (%) Supply Current (μ μA) 300 -0.1 -0.2 -0.3 -0.4 -0.5 -0.6 -0.7 -40 -20 0 20 40 Temperature (°°C) 60 80 100 1.28 1.26 1.24 1.22 1.2 2.7 3.1 3.5 3.9 4.3 4.7 5.1 5.5 Input Voltage (V) Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 201995A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • May 29, 2012 5 DATA SHEET AAT1157 1MHz 1.2A Buck DC/DC Converter Output Ripple (VOUT = 2.5V; IOUT = 1.2A; VIN = 3.6V) 3.5 4.0 3.0 2.0 2.5 0.0 2.0 -2.0 1.5 -4.0 1.0 -6.0 0.5 -8.0 0.0 -10.0 -0.5 0.02 0.01 2 -0.01 1.5 -0.02 -0.03 1 -0.04 0.5 -0.05 -0.06 0 Time (500ns/div) Load Transient Response (400mA-1.2A; VIN = 3.3V; VOUT = 2.5V) 0.24 4.2 0.20 4.0 0.16 3.8 0.12 3.6 0.08 3.4 0.04 3.2 0.00 3.0 -0.04 -0.08 2.8 Time (25μ μs/div) 0.08 4.0 0.05 3.5 0.02 3.0 -0.01 2.5 -0.04 2.0 -0.07 1.2A 1.5 -0.10 -0.13 1.0 400mA -0.16 0.5 0.0 Time (20μ μs/div) Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 201995A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • May 29, 2012 Load Current (A) (bottom) 4.4 Output Voltage (AC Coupled) (V) (top) Line Transient (IOUT = 1.2A; VO = 2.5V) Output Voltage (AC coupled) (bottom) (V) Input Voltage (top) (V) 2.5 0 Time (250μ μs/div) 6 3 Inductor Current (bottom) (A) 6.0 Output Voltage (AC coupled) (top) (V) Soft Start (VOUT = 2.5V; IOUT = 1.2A; VIN = 3.6V) Inductor Current (bottom) (A) Enable and Output Voltage (top) (V) Typical Characteristics DATA SHEET AAT1157 1MHz 1.2A Buck DC/DC Converter Functional Block Diagram VCC VP = 2.7V to 5.5V 1.0V REF FB OP. AMP CMP DH LOGIC 1MΩ LX DL Temp. Sensing OSC SGND Applications Information Control Loop EN PGND nents while providing sufficient DC loop gain for good load regulation. The voltage loop crossover frequency and phase margin are set by the output capacitor. The AAT1157 is a peak current mode buck converter. The inner wide bandwidth loop controls the inductor peak current. The inductor current is sensed through the P-channel MOSFET (high side) and is also used for shortcircuit and overload protection. A fixed slope compensation signal is added to the sensed current to maintain stability for duty cycles greater than 50%. The loop appears as a voltage-programmed current source in parallel with the output capacitor. Soft Start/Enable The voltage error amplifier output programs the current loop for the necessary inductor current to force a constant output voltage for all load and line conditions. The voltage feedback resistive divider (external for adjustable output voltage; internal for fixed output voltage) divides the output voltage to the error amplifier reference voltage of 0.6V. The low-DC gain voltage error amplifier eliminates the need for external compensation compo- Power and Signal Source Soft start increases the inductor current limit point in discrete steps once the input voltage or enable input is applied. It limits the current surge seen at the input and eliminates output voltage overshoot. When pulled low, the enable input forces the AAT1157 into a non-switching shutdown state. The total input current during shutdown is less than 1μA. Separate small signal ground and power supply pins isolate the internal control circuitry from the noise associated with the output power MOSFET switching. The low-pass filter R1 and C2 shown in the Figure 1 schematic filters the input noise associated with the power switching. Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 201995A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • May 29, 2012 7 DATA SHEET AAT1157 1MHz 1.2A Buck DC/DC Converter LX Enable 12 R1 100 R2 C1 10μF 100K C2 0.1μF 11 10 7 9 6 8 5 GND VOUT+ U1 AAT1157 VIN+ VP FB VP LX VP LX EN LX VCC N/C N/C PGND N/C PGND SGND PGND 4 R3 15 14 13 L1 3.0μH 16 3 R4 59.0k C3-C4 2x 22μF 2 1 VOUT(V) 0.8 0.9 1.0 1.1 1.2 1.3 1.4 1.5 1.8 2.0 2.5 3.3 R3 (kΩ) 19.6 29.4 39.2 49.9 59.0 68.1 78.7 88.7 118 137 187 267 GND C1 Murata 10μF 6.3V X5R GRM42-6X5R106K6.3 C3,C4 MuRata 22μF 6.3V GRM21BR60J226ME39L X5R 0805 L1 Sumida CDRH5D28-3R0NC Figure 1: AAT1157 Evaluation Board Schematic Lithium-Ion to 2.5V Converter. Current Limit and Over-Temperature Protection For overload conditions, the peak input current sensed through the high-side P-channel MOSFET is limited. Thermal protection completely disables switching when internal dissipation becomes excessive, protecting the device from damage. The junction over-temperature threshold is 140°C with 15°C of hysteresis. Once the over-temperature or over-current fault is removed, the AAT1157 automatically recovers. Inductor L= = ⎛ VOUT VOUT ⎞ ⋅1ΔIPP ⋅ F ⎝ VIN(MAX)⎠ 2.5V ⎛ 2.5V ⎞ ⋅ 10.33A ⋅ 1MHz ⎝ 4.2V ⎠ = 3.07μH The output inductor should limit the ripple current to 330mA at the maximum input voltage. This matches the inductor current downslope with the fixed internal slope compensation. For a 2.5V output and the ripple set to a maximum input voltage of 4.2V, the inductance value required to limit the ripple current to 330mA is 3.0μH. From this calculated value, a standard value can be selected. 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 saturation characteristics. The inductor should not show any 8 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. For a maximum ripple current of 330mA, the peak switch and inductor current at 1.2A is 1.365A. A standard value of 3.0μH can be used in this example. The 3.0μH Sumida series CDRH5D28 inductor has a 24m maximum DCR and a 2.4A DC current rating. Input Capacitor The primary function of the input capacitor is to provide a low impedance loop for the edges of pulsed current drawn by the AAT1157. A low ESR/ESL ceramic capacitor is ideal for this function. To minimize stray inductance, the capacitor should be placed as closely as possible to Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 201995A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • May 29, 2012 DATA SHEET AAT1157 1MHz 1.2A Buck DC/DC Converter the IC. This keeps the high frequency content of the input current localized, minimizing radiated and conducted EMI while facilitating optimum performance of the AAT1157. Ceramic X5R or X7R capacitors are ideal for this function. The size required will vary depending on the load, output voltage, and input voltage source impedance characteristics. Values range from 1μF to 10μF. The input capacitor RMS current varies with the input voltage and the output voltage. The equation for the RMS current in the input capacitor is: VO ⎛ VO ⎞ ⋅ 1VIN ⎝ VIN ⎠ IRMS = IO ⋅ The input capacitor RMS ripple current reaches a maximum when VIN is two times the output voltage where it is approximately one half of the load current. Losses associated with the input ceramic capacitor are typically minimal and are not an issue. The proper placement of the input capacitor can be seen in the evaluation board layout (C1 in Figure 2). For an X7R or X5R ceramic capacitor, the ESR is very low and the dissipation due to the RMS current of the capacitor is not a concern. Tantalum capacitors with sufficiently low ESR to meet output voltage ripple requirements also have an RMS current rating well beyond that actually seen in this application. Layout The suggested PCB layout for the AAT1157 is shown in Figures 2 and 3. The following guidelines should be used to help insure a proper layout. 1. 2. 3. Output Capacitor Since there are no external compensation components, the output capacitor has a strong effect on loop stability. Larger output capacitance reduces the crossover frequency while increasing the phase margin. For the 2.5V 1.2A design using the 3.0μH inductor, a 40μF capacitor provides a stable output. Table 1 provides a list of suggested output capacitor values for various output voltages. In addition to assisting in stability, the output capacitor limits the output ripple and provides holdup during large load transitions. The output capacitor RMS ripple current is given by: IRMS = 1 2⋅ 3 ⋅ VOUT ⋅ (VIN - VOUT) L ⋅ F ⋅ VIN 4. 5. 6. The input capacitor (C1) should connect as closely as possible to VP (Pins 10, 11, and 12) and PGND (Pins 1, 2, and 3). C3-C4 and L1 should be connected as closely as possible. The connection from L1 to the LX node should be as short as possible. The trace connecting the FB pin to resistors R3 and R4 should be as short as possible by placing R3 and R4 immediately next to the AAT1157. The sense trace connection R3 to the output voltage should be separate from any power trace and connect as closely as possible to the load point. Sensing along a highcurrent load trace will degrade DC load regulation. The resistance of the trace from the load return to the PGND (Pins 1, 2, and 3) and SGND (Pin 5) should be kept to a minimum. 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. SGND (Pin 5) can also be used to remotely sense the output ground at the point of load to improve regulation. A low pass filter (R1 and C2) provides a cleaner bias source for the AAT1157 active circuitry. C2 should be placed as closely as possible to SGND (Pin 5) and VCC (Pin 9). For good heat transfer, four 15 mil vias spaced on a 26 mil grid connect the QFN central paddle to the bottom side ground plane, as shown in Figures 2 and 3. Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 201995A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • May 29, 2012 9 DATA SHEET AAT1157 1MHz 1.2A Buck DC/DC Converter Figure 2: AAT1157 Evaluation Board Top Side. Figure 3: AAT1157 Evaluation Board Bottom Side. Thermal Calculations Adjustable Output There are three types of losses associated with the AAT1157: MOSFET switching losses, conduction losses, and quiescent current losses. The conduction losses are due to the RDSON characteristics of the internal P- and N-channel MOSFET power devices. At full load, assuming continuous conduction mode (CCM), a simplified form of the total losses is given by: Resistors R3 and R4, as shown in Figure 1, force the output to regulate higher than the 0.6V reference voltage level. The optimum value for R4 is 59k. Values higher than this can cause stability problems, while lower values can degrade light load efficiency. For a 2.5V output with R4 set to 59k, R3 is 187k. P= 2 O I ⋅ (RDSON(HS) ⋅ VO + RDSON(LS) ⋅ (VIN - VO)) VIN + (tsw ⋅ F ⋅ IO ⋅ VIN + IQ) ⋅ VIN Where IQ is the AAT1157 quiescent current. Once the total losses have been determined, the junction temperature can be derived from the JA for the QFN package. Close attention should be paid to the proper layout for the QFN package. Proper size and placement of thermal routing vias below the central paddle is necessary for good heat transfer to other PCB layers and their ground planes. The JA for the QFN package with no connection to the central paddle is 50°C/W. The actual JA will vary with the number and type of vias. The PCB board size, number of board layers, and ground plane characteristics also influence the JA. A good thermal connection from the paddle to the PCB ground plane layers can significantly reduce JA. TJ = P • ΘJA + TAMB 10 ⎛ VO ⎞ ⎛ 2.5V ⎞ R3 = V -1 · R4 = 0.6V - 1 · 59kΩ = 187kΩ ⎝ REF ⎠ ⎝ ⎠ Output Voltage (V) 0.8 1.0 1.2 1.5 1.8 2.5 3.3 L1 (μH) 1.5 1.5 2.2 2.2 3.0 3.0 2.2 - Output Capacitor (C3-C4) (μF) R3 for R4 = 59kΩ (kΩ) 3x 22 2x 22 2x 22 2x 22 2x 22 2x 22 22 19.6 39.2 59 88.7 118 187 267 2.6 3.3 3.3 4.7 4.7 4.7 4.7 Table 1: Suggested Component Values. Buck-Boost Output Figure 4 shows how to configure the AAT1157 in a buck boost configuration with an external MOSFET and Schottky diode. The converter has a 3.3V 600mA output with an input voltage ranging from 2.7V to 5.5V. Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 201995A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • May 29, 2012 DATA SHEET AAT1157 1MHz 1.2A Buck DC/DC Converter VIN 2.7V to 5.5V U1 AAT1157 R1 100 C1 22μF C2 0.1μF R2 267k 12 VP OUT 11 VP LX 15 10 VP LX 14 7 EN LX 13 9 VCC N/C 16 6 N/C PGND 8 N/C PGND 5 SGND PGND VO 3.3V/600mA 4 3 L1 3.0μH D1 MBRM120L Q1 Si2302ADS R3 59.0k C3,C4 2x 22μF 2 1 L1 Sumida CDRH5D28-3R0 C1 Murata 22μF 10V X7R 1210 GRM32ER71A226KE20L C3,C4 MuRata 22μF 6.3V X5R 0805 GRM21BR60J226ME39L Figure 4: AAT1157 Buck Boost Converter. Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 201995A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • May 29, 2012 11 DATA SHEET AAT1157 1MHz 1.2A Buck DC/DC Converter Design Example Specifications IOUT = 1.2A IRIPPLE = 330mA VOUT = 2.5V VIN = 3.0V to 4.2V FS = 1MHz TAMB = 85°C Maximum Input Capacitor Ripple IRMS = I O · VO ⎛ V ⎞ · 1 - O = 0.59Arms VIN ⎝ VIN ⎠ P = esr · IRMS2 = 5mΩ · 0.592 A = 1.7mW Inductor Selection L= ⎛ V ⎞ VOUT 2.5V 2.5V⎞ ⎛ ⋅ 1 - OUT = ⋅ 1= 3.07μH ΔIPP ⋅ F ⎝ VIN ⎠ 0.33A ⋅ 1MHz ⎝ 4.2V⎠ Select Sumida inductor CDRH5D28 3.0μH. ΔI = ⎛ 2.5V⎞ VO ⎛ V ⎞ 2.5V ⋅ 1- O = ⋅ 1= 340mA L ⋅ F ⎝ VIN ⎠ 3.0μH ⋅ 1MHz ⎝ 4.2V⎠ IPK = IOUT + ΔI = 1.2A + 0.17A = 1.37A 2 P = IO2 ⋅ DCR = (1.2A)2 ⋅ 31mΩ = 45mW Output Capacitor Ripple Current IRMS = 1 2· 3 · (VOUT) · (VIN - VOUT) 1 2.5V · (4.2V - 2.5V) · = 97.4mArms = L · F · VIN 2 · 3 3.0μH · 1MHz · 4.2V Pesr = esr · IRMS2 = 5mΩ · (97.4mA)2 = 47.4μW 12 Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 201995A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • May 29, 2012 DATA SHEET AAT1157 1MHz 1.2A Buck DC/DC Converter AAT1157 Dissipation and Junction Temperature Estimate PTOTAL = = IO2 • (RDSON(HS) • VO + RDSON(LS) • (VIN -VO)) VIN + (tsw • F • IO + IQ) • VIN 1.2A2 • (0.17Ω • 2.5V + 0.16Ω • (4.2V - 2.5V)) 4.2V + (20nsec • 1MHz • 1.2A + 275μA) • 4.2V = 341mW TJ(MAX) = TAMB + ΘJA • PTOTAL = 85°C + 50°C/W • 0.341W = 102°C Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 201995A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • May 29, 2012 13 DATA SHEET AAT1157 1MHz 1.2A Buck DC/DC Converter Manufacturer Part Number Value (μH) Max DC Current (A) DCR (mΩ) Size (mm) LxWxH Type Sumida Sumida Sumida Taiyo Yuden Sumida Sumida Sumida Sumida Sumida Sumida Murata Murata CDRH5D28-2R6 CDRH5D28-3R0 CDRH5D28-4R2 NPO5DB4R7M CDRH4D28-2R2 CDRH4D28-2R7 CDRH4D28-3R3 CDRH5D18-4R1 CDRH3D16/HP-2R2 CDRH3D16/HP-3R3 LQH55DN4R7M03 LQH66SN4R7M03 2.6 3.0 4.2 4.7 2.2 2.7 3.3 4.1 2.2 3.3 4.7 4.7 2.6 2.4 2.2 1.4 2.04 1.6 1.57 1.95 2.3 1.8 2.7 2.2 18 24 31 38 31 43 49 57 59 85 41 25 5.7x5.7x3.0 5.7x5.7x3.0 5.7x5.7x3.0 5.9x6.1x2.8 5.0x5.0x3.0 5.0x5.0x3.0 5.0x5.0x3.0 5.7x5.7x2.0 4.0x4.0x1.8 4.0x4.0x1.8 5.0x5.0x4.7 6.3x6.3x4.7 Shielded Shielded Shielded Shielded Shielded Shielded Shielded Shielded Shielded Shielded Non-Shielded Shielded Table 2: Surface Mount Inductors. Manufacturer Part Number Value (μF) Voltage (V) Temp. Co. Case Murata Murata Murata GRM21BR60J106ME01L GRM21BR60J226ME01L GRM31CR60J106KA01L 10 22 10 6.3 6.3 6.3 X5R X5R X5R 0805 0805 1206 Table 3: Surface Mount Capacitors. 14 Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 201995A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • May 29, 2012 DATA SHEET AAT1157 1MHz 1.2A Buck DC/DC Converter Ordering Information Output Voltage Package Marking1 Part Number (Tape and Reel)2 FB = 0.6V, Adjustable ≥ 0.8V 3.3V QFN33-16 QFN33-16 OEXYY OZXYY AAT1157IVN-T1 AAT1157IVN-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 Information3 QFN33-16 Pin 1 Dot By Marking 0.230 ± 0.050 Pin 1 Identification 0.500 ± 0.050 1.250 ± 0.050 5 C0.3 13 9 1.250 ± 0.050 Top View 0.025 ± 0.025 Bottom View 0.214 ± 0.036 0.900 ± 0.100 3.000 ± 0.050 0.400 ± 0.100 3.000 ± 0.050 1 Side View All dimensions in millimeters. 1. XYY = assembly and date code. 2. Sample stock is generally held on part numbers listed in BOLD. 3. The leadless package family, which includes QFN, TQFN, DFN, TDFN and STDFN, has exposed copper (unplated) at the end of the lead terminals due to the manufacturing process. A solder fillet at the exposed copper edge cannot be guaranteed and is not required to ensure a proper bottom solder connection. Copyright © 2012 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 for errors or omissions in these materials or the information contained herein. Skyworks may change its documentation, products, services, specifications 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 conflicts, incompatibilities, or other difficulties arising from any future changes. No license, whether express, implied, by estoppel or otherwise, is granted to any intellectual property rights by this document. 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Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 201995A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • May 29, 2012 15