AAT2500MITP-AW-T1

AAT2500M SKYWORKS | Alldatasheet

Document overview

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• PDF pages: 21

Technical content

Features

• V IN Range: 2.7V to 5.5V
• Output Current: ▪ Step-Down Converter: 400mA ▪ LDO: 300mA
• Low Quiescent Current ▪ 130 μA Combined for Both Step-Down Converter plus LDO
• 90% Efficient Step-down Converter (at 100mA)
• Integrated Power Switches
• 100% Duty Cycle
• 1.8MHz Switching Frequency
• Current Limit Protection
• Automatic Soft-Start
• Over Temperature Protection
• TSOPJW-12 Package
• -40°C to +85°C Temperature Range

Applications

• Cellular Phones
• Digital Cameras
• Handheld Instruments
• Micro Hard Disc Drives
• Microprocessor / DSP Core / IO Power
• Optical Storage Devices
• PDAs and Handheld Computers
• Portable Media Players Typical Application 2.7V to 5.5VInput Supply Enable Buck Enable LDO IN_BUCK VOUT_BUCKLX4.7μF 4.7μF AAT2500M 2.2μH OUT_LDO FB_BUCK VOUT(LDO) 2.2μF PGNDAGND IN_LDO EN_BUCK EN_LDO 1μF

400mA Step-Down Converter and 300mA LDO DATA SHEET Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com 202015A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 4, 2012 Pin Descriptions Pin # Symbol Function 1 LX Step-down converter switching node. 2 PGND Power ground for step-down converter. 3 EN_BUCK Enable pin for step-down converter. 4 EN_LDO Enable pin for LDO. 5 FB_BUCK Feedback input pin for step-down converter. Regulated at 0.6V for adjustable version. 6 OUT_LDO LDO power output. 7 IN_LDO Input supply voltage for LDO. 8, 9, 10, 11 AGND Analog signal ground. 12 IN_BUCK Input supply voltage for step-down converter. Pin Configuration TSOPJW-12 (Top View) LX PGND EN_BUCK EN_LDO FB_BUCK OUT_LDO IN_BUCK AGND AGND AGND AGND IN_LDO

400mA Step-Down Converter and 300mA LDO DATA SHEET Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com 202015A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 4, 2012 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. Absolute Maximum Ratings1 Symbol Description Value Units VP Input Voltage -0.3 to 6.0 V AGND, PGND Ground Pins -0.3 to +0.3 V VEN, VFB Enable and Feedback Pins V IN + 0.3 V IOUT Maximum DC Output Current (continuous) 1000 mA TJ Operating Temperature Range -40 to 150 °C TS Storage Temperature Range -65 to 150 °C TLEAD Maximum Soldering Temperature (at leads, 10 sec) 300 °C Thermal Information Symbol Description Value Units JA Thermal Resistance2 110 °C/W PD Maximum Power Dissipation 909 mW

400mA Step-Down Converter and 300mA LDO DATA SHEET Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com 202015A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 4, 2012 1. Specification over the -40°C to +85°C operating temperature ranges is assured by design, characterization and correlation w ith statistical process controls. 2. To calculate the minimum LDO input voltage, use the following equation: VIN(MIN) = VOUT(MAX) + VDO(MAX). 3. VDO is defined as VIN - VOUT when VOUT is 98% of nominal. Electrical Characteristics1 VIN_BUCK = VIN_LDO = 5.0V. TA = -40°C to +85°C unless noted otherwise. Typical values are at T A = +25°C. Symbol Description Conditions Min Typ Max Units Power Supply VINBUCK, VINLDO Input Voltage 2.7 5.5 V VUVLO Under-Voltage Lockout VIN Rising 2.7 V VIN Falling 2.35 V IQ Quiescent Current V EN = VIN, No Load 130 μA ISHDN Shutdown Current V EN = GND 1.0 μA Step-Down Converter VFB Feedback Voltage Tolerance No Load, TA = 25°C 0.591 0.609 V IOUT = 0 to 400mA; VIN = 2.7 to 5.5V -3 +3 % ILXLEAK LX Reverse Leakage Current V IN = 5.5V, VLX = 0 to VIN, VEN = GND -1.0 1.0 μA IFB Feedback Leakage V FB = 1.0V 0.2 μA ILIM P-Channel Current Limit 1.2 A RDS(ON)H High Side Switch On Resistance 0.4  RDS(ON)L Low Side Switch On Resistance 0.25  VOUT/VOUT Load Regulation I LOAD = 0 to 400mA 0.25 % VOUT/VOUT Line Regulation V IN = 2.7V to 5.5V 0.3 % FOSC Oscillator Frequency 1.8 MHz TS Start-Up Time From Enable to Output Regulation 120 μs LDO (VOUT = 3.3V) VOUT Output Voltage Tolerance No Load, 25°C 3.24 3.30 3.36 V VOUT Output Voltage Range I OUT = 0 to 300mA -3 3 % VIN Input Voltage VOUT + VDO2 5.5 V IOUT Output Current 300 mA ILIM Current Limit 1A VDO Dropout Voltage3 IOUT = 300mA 160 240 mV VOUT/VOUT Load Regulation I LOAD = 0 to 300mA 1.2 % VOUT/VOUT Line Regulation V IN = 3.7V to 5.5V 0.6 % TS Start-Up Time From Enable to Output Regulation 100 μs Logic Signals VEN(L) Enable Threshold Low 0.6 V VEN(H) Enable Threshold High 1.5 V IEN(H) Enable Current Consumption -1.0 1.0 μA TSD Over-Temperature Shutdown Threshold 150 C THYS Over-Temperature Shutdown Hysteresis 15 C

400mA Step-Down Converter and 300mA LDO DATA SHEET Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com 202015A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 4, 2012 Typical Characteristics LDO Dropout Voltage vs. Temperature Temperature (°C) Dropout Voltage (mV) 120 150 180 210 -40 -20 0 20 40 60 80 100 IL = 300mA IL = 200mA IL = 100mA IL = 50mA LDO Dropout Characteristics (VOUT = 3.3V) Input Voltage (V) Output Voltage (V) 2.8 2.9 3.0 3.1 3.2 3.3 3.4 3.5 IOUT = 100mA IOUT = 200mA IOUT = 300mA IOUT = 0.1mA IOUT = 10mA IOUT = 50mA LDO Dropout Voltage vs. Output Current Output Current (mA) Dropout Voltage (mV) 100 150 200 250 0 50 100 150 200 250 300 35 85°C 25°C -40°C No Load Quiescent Current vs. Input Voltage (EN_BUCK = EN_LDO = VIN) Input Voltage (V) Input Current (µA) 110 130 150 2.5 3 3.5 4 4.5 5 5.5 6 25°C 85°C -40°C LDO Turn-Off Response Time (VIN = 5V; VOUT = 3.3V; IOUT = 300mA) Time (50ns/div) Enable Voltage (top) (V) Output Voltage (bottom)(V) -1.0 0.0 1.0 2.0 3.0 LDO Turn-On Time From Enable (VIN = 5V; VOUT = 3.3V; IOUT = 300mA) Time (40µs/div) Enable Voltage (top) (V) Output Voltage (bottom)(V)

400mA Step-Down Converter and 300mA LDO DATA SHEET Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com 202015A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 4, 2012 Typical Characteristics LDO Line Transient Response (VIN = 4V to 5V; VOUT = 3.3V; IOUT = 300mA; COUT = 4.7µF) Time (40µs/div) Input Voltage (top) (V) Output Voltage (bottom) (V) 3.1 3.3 3.5 LDO Load Transient Response (1mA to 300mA; VIN = 5V; VOUT = 3.3V; COUT = 4.7µF) Time (100µs/div) Output Voltage (top) (V) Output Current (bottom) (A) 2.9 3.1 3.3 3.5 3.7 -0.2 0.0 0.2 0.4 300mA 1mA LDO VIH and VIL vs. Input Voltage Input Voltage (V) VIH and VIL (V) 0.6 0.7 0.8 0.9 1.0 1.1 1.2 VIH VIL Step-Down Converter Switching Frequency vs. Input Voltage (IOUT = 400mA) Input Voltage (V) Frequency Variation (%) VOUT = 1.2V VOUT = 1.8V Step-Down Converter Switching Frequency vs. Temperature (VIN = 5V; VOUT = 1.8V) Temperature (°C) Switching Frequency (MHz)1.5 1.6 1.7 1.8 1.9 -40 -20 0 20 40 60 80 10

400mA Step-Down Converter and 300mA LDO DATA SHEET Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com 202015A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 4, 2012 Typical Characteristics Step-Down Converter Efficiency vs. Load (VOUT = 1.8V; L = 2.2µH) Output Current (mA) Efficiency (%) 100 0.1 1 10 100 1000 VIN = 2.7V VIN = 3.3V VIN = 5.5V VIN = 4.2V Step-Down Converter DC Regulation (VOUT = 1.8V; L = 2.2µH) Output Current (mA) Output Error (%) -1.0 -0.5 0.0 0.5 1.0 0.1 1 10 100 1000 VIN = 3.3V, 4.2V, 5.5V VIN = 2.7V Step-Down Converter Efficiency vs. Load (VOUT = 1.2V; L = 2.2µH) Output Current (mA) Efficiency (%) 100 0.1 1 10 100 1000 VIN = 2.7V VIN = 3.3V VIN = 4.2V VIN = 5V Step-Down Converter DC Regulation (VOUT = 1.2V; L = 2.2µH) Output Current (mA) Output Error (%) -1.0 -0.5 0.0 0.5 1.0 0.1 1 10 100 1000 VIN = 3.6V to 5.5V VIN = 2.7V Step-Down Converter Output Ripple (VOUT = 1.8V; VIN = 5V; IOUT = 1mA) Time (10µs/div) Output Voltage (top) (V) Inductor Current (bottom) (A) 1.79 1.80 1.81 0.0 0.1 0.2 Step-Down Converter Output Ripple (VOUT = 1.8V; VIN = 5V; IOUT = 400mA) Time (200ns/div) Output Voltage (top) (V) Inductor Current (bottom) (A) 1.79 1.80 1.81 1.82 0.0 0.2 0.4 0.6

400mA Step-Down Converter and 300mA LDO DATA SHEET Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com 202015A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 4, 2012 Typical Characteristics Step-Down Converter Output Voltage Error vs. Temperature (VIN = 5V; VOUT = 1.8V; IOUT = 400mA) Temperature (°C) Output Voltage Error (%)-1.0 -0.5 0.0 0.5 1.0 -50 -25 0 25 50 75 100 Step-Down Converter Output Voltage Error vs. Temperature (VIN = 5V; VOUT = 1.2V; IOUT = 400mA) Temperature (°C) Output Voltage Error (%)-1.0 -0.5 0.0 0.5 1.0 -50 -25 0 25 50 75 100 Step-Down Converter P-Channel RDS(ON)H vs. Input Voltage Input Voltage (V) RDS(ON)H (mΩΩ) 300 400 500 600 700 2.5 3 3.5 4 4.5 5 5.5 6 120°C 85°C 100°C 25°C Step-Down Converter N-Channel RDS(ON)L vs. Input Voltage Input Voltage (V) RDS(ON)L (mΩΩ) 100 200 300 400 500 2.5 3 3.5 4 4.5 5 5.5 6 120°C 85°C100°C 25°C Step-Down Converter Soft Start (VIN = 5V; VOUT = 1.8V; IOUT = 400mA; CFF = Open) Time (50µs/div) Inductor Current (bottom) (A) Enable Voltage (top) (V) Output Voltage (middle) (V) -0.2 0.0 0.2 0.4

400mA Step-Down Converter and 300mA LDO DATA SHEET Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com 202015A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 4, 2012 Typical Characteristics Step-Down Converter Load Transient Response (1mA to 400mA; VIN = 5V; VOUT = 1.8V; COUT = 4.7µF) Time (100µs/div) Output Voltage (top) (V) Output Current (middle) (A) Inductor Current (bottom) (A) 1.8 2.0 -0.2 0.0 0.2 0.4 400mA 1mA Step-Down Converter Load Transient Response (1mA to 400mA; VIN = 5V; VOUT = 1.8V; COUT = 4.7µF; CFF = 100pF) Time (100µs/div) Output Voltage (top) (V) Output Current (middle) (A) Inductor Current (bottom) (A) 1.8 2.0 -0.2 0.0 0.2 0.4 400mA 1mA Step-Down Converter Load Transient Response (1mA to 400mA; VIN = 5V; VOUT = 1.2V; COUT = 4.7µF) Time (100µs/div) Output Voltage (top) (V) Output Current (middle) (A) Inductor Current (bottom) (A) 1.2 1.4 -0.2 0.0 0.2 0.4 400mA 1mA Step-Down Converter Load Transient Response (1mA to 400mA; VIN = 5V; VOUT = 1.2V; COUT = 4.7µF; CFF = 100pF) Time (100µs/div) Output Voltage (top) (V) Output Current (middle) (A) Inductor Current (bottom) (A) 1.2 1.4 -0.2 0.0 0.2 0.4 400mA 1mA Step-Down Converter Line Transient Response (VIN = 4V to 5V; VOUT = 1.8V; IOUT = 400mA; COUT = 4.7µF) Time (40µs/div) Input Voltage (top) (V) Output Voltage (bottom) (V) 1.5 1.6 1.7 1.8 Step-Down Converter Line Regulation (VOUT = 1.2V; L = 2.2µH) Input Voltage (V) Accuracy (%) -1.00 -0.50 0.00 0.50 1.00 IOUT = 0.1mA to 400mA

400mA Step-Down Converter and 300mA LDO DATA SHEET Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com 202015A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 4, 2012 Functional Description The AAT2500M is a high performance power manage- ment IC comprised of a buck converter and a linear regulator. The buck converter is a high efficiency con- verter capable of delivering up to 400mA. Operating at 1.8MHz, the converter requires only three external power components (C IN, COUT, and LX) and is stable with a ceramic output capacitor. The linear regulator delivers 300mA and is also stable with ceramic capacitors. Linear Regulator The advanced circuit design of the linear regulator has been specifically optimized for very fast start-up and shutdown timing. This proprietary LDO has also been tailored for superior transient response characteristics. These traits are particularly important for applications that require fast power supply timing. The high-speed turn-on capability is enabled through implementation of a fast-start control circuit, which accelerates the power-up behavior of fundamental con- trol and feedback circuits within the LDO regulator. Fast turn-off time response is achieved by an active output pull-down circuit, which is enabled when the LDO regu- lator is placed in shutdown mode. This active fast shut- down circuit has no adverse effect on normal device operation. The LDO regulator output has been specifi- cally optimized to function with low-cost, low-ESR ceramic capacitors; however, the design will allow for operation over a wide range of capacitor types. The regulator comes with complete short-circuit and ther- mal protection. The combination of these two internal protection circuits gives a comprehensive safety system to guard against extreme adverse operating conditions. Functional Block Diagram EN_BUCK IN_BUCK LX PGND Bias Oscillator EN_LDO AGND RLDOFB1 VCC RLDOFB2 IN_LDO OUT_LDO FB_BUCK Control Circuit VCC

400mA Step-Down Converter and 300mA LDO DATA SHEET Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com 202015A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 4, 2012 4. 7μH 4.7μF 4. 7μF 10μF AGND AGND AGND AGND PGND FB_BUCK LXVP_BUCK IN_LDO OUT_LDO EN_LDO EN_BUCK AAT2500M VOUT_BUCK VOUT_LDO VIN 4. 7uH 4. 7μF 4. 7μF 10μF 59k 100pF AGND AGND AGND AGND PGND FB_BUCK LXVP_BUCK IN_LDO OUT_LDO EN_LDO EN_BUCK AAT2500M VOUT_BUCK VOUT_LDO VIN Figure 1: AAT2500M Fixed Output. Figure 2: AAT2500M with Adjustable Step-Down Output and Enhanced Transient Response. The regulator features an enable/disable function. This pin (EN_LDO) is active high and is compatible with CMOS logic. To assure the LDO regulator will switch on, the EN_LDO turn-on control level must be greater than 1.5V. The LDO regulator will go into the disable shutdown mode when the voltage on the EN_LDO pin falls below 0.6V. If the enable function is not needed in a specific application, it may be tied to V IN_LDO to keep the LDO regulator in a continuously on state. The IN_LDO input powers the internal reference, oscilla- tor, and bias control blocks. For this reason, the IN_LDO input must be connected to the input power source to provide power to both the LDO and step-down converter functions. When the regulator is in shutdown mode, an internal 1.5k resistor is connected between OUT and GND. This is intended to discharge C OUT when the LDO regulator is disabled. The internal 1.5K  resistor has no adverse impact on device turn-on time. Step-Down Converter The AAT2500M buck is a constant frequency peak cur- rent mode PWM converter with internal compensation. It is designed to operate with an input voltage range of 2.7V to 5.5V. The output voltage ranges from 0.6V to the input voltage. The 0.6V fixed model shown in Figure 1 is also the adjustable version and is externally program- mable with a resistive divider, as shown in Figure 2. The converter MOSFET power stage is sized for 400mA load capability with up to 92% efficiency. Light load efficiency is close to 80% at a 500 μA load. Soft Start The AAT2500M soft-start control prevents output voltage overshoot and limits inrush current when either the input power or the enable input is applied. When pulled low, the enable input forces the converter into a low-power, non- switching state with a bias current of less than 1μA. Low Dropout Operation For conditions where the input voltage drops to the output voltage level, the converter duty cycle increases to 100%. As 100% duty cycle is approached, the minimum off-time initially forces the high side on-time to exceed the 1.8MHz clock cycle and reduce the effective switching frequency. Once the input drops below the level where the output can be regulated, the high side P-channel MOSFET is turned on continuously for 100% duty cycle. At 100% duty cycle, the output voltage tracks the input voltage minus the IR drop of the high side P-channel MOSFET R DS(ON). Low Supply The under-voltage lockout (UVLO) guarantees sufficient V IN bias and proper operation of all internal circuitry prior to activation. Fault Protection For overload conditions, the peak inductor current is lim- ited. Thermal protection disables switching when the internal dissipation or ambient temperature becomes excessive. The junction over-temperature threshold is 150°C with 15°C of hysteresis.

400mA Step-Down Converter and 300mA LDO DATA SHEET Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com 202015A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 4, 2012 Applications Information LDO Regulator Input and Output Capacitors: An input capacitor is not required for basic operation of the linear regulator. However, if the AAT2500M is physically located at a rea- sonable distance from an input power source, an input capacitor (C3) will be needed for stable operation. Typically, a 1μF or larger capacitor is recommended for C3 in most applications. C3 should be located as closely to the input voltage (VIN_LDO) pin as practically possible. An input capacitor greater than 1 μF will offer superior input line transient response and maximize power sup- ply ripple rejection. Ceramic, tantalum, or aluminum electrolytic capacitors may be selected for C3. There is no specific capacitor ESR requirement for C3. However, for 300mA LDO regulator output operation, ceramic capacitors are recommended for C3 due to their inherent capability over tantalum capacitors to withstand input current surges from low impedance sources such as bat- teries in portable devices. For proper load voltage regulation and operational sta- bility, a capacitor is required between the OUT_LDO and AGND pins. The output capacitor (C4) connection to the LDO regulator ground pin should be made as directly as practically possible for maximum device performance. Since the regulator has been designed to function with very low ESR capacitors, ceramic capacitors in the 1.0μF to 10μF range are recommended for best performance. Applications utilizing the exceptionally low output noise and optimum power supply ripple rejection should use 2.2μF or greater for C4. In low output current applica- tions, where output load is less than 10mA, the mini- mum value for C4 can be as low as 0.47 μF. Equivalent Series Resistance: ESR is a very impor- tant characteristic to consider when selecting a capaci- tor. ESR is the internal series resistance associated with a capacitor that includes lead resistance, internal con- nections, size and area, material composition, and ambi- ent temperature. Typically, capacitor ESR is measured in milliohms for ceramic capacitors and can range to more than several ohms for tantalum or aluminum electrolytic capacitors. Step-Down Converter Inductor Selection: The step-down converter uses peak current mode control 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 compensa- tion requirements. The internal slope compensation for the adjustable and low-voltage fixed versions of the AAT2500M is 0.24A/μs. This equates to a slope compen- sation that is 35% of the inductor current down slope for a 1.5V output and 2.2μH inductor. 0.35 ⋅ VO m = = = 0.24 L 0.35 ⋅ 1.5V 2.2µH A µsec This is the internal slope compensation for the adjust- able (V O = 0.6V) version or low output voltage fixed versions. When externally programming the 0.6V ver- sion to 2.5V, the calculated inductance is 3.75μH. m 0.35 ⋅ VO 0.24A µsec A µsec A A µsec In this case, a standard 4.7μH value is selected. For high output voltage fixed versions (2.5V and above), m = 0.48A/ μs. Table 1 displays inductor values for the AAT2500M 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. Confi guration Output Voltage Inductor Slope Compensation 0.6V Adjustable With External Resistive Divider 0.6V to 2.0V 2.2 μH 0.24A/ μs 2.5V 4.7 μH 0.24A/ μs Fixed Output 0.6V to 2.0V 2.2 μH 0.24A/ μs 2.5V to 3.3V 2.2 μH 0.48A/ μs Table 1: Inductor Values.

400mA Step-Down Converter and 300mA LDO DATA SHEET Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com 202015A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 4, 2012 The 2.2 μH CDRH3D16 series inductor selected from Sumida has a 59m DCR and a 1.3A DC current rating. At full load, the inductor DC loss is 9.4mW which gives a 1.5% 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 C2. The calculated value varies with input volt- age and is a maximum when V IN_BUCK is double the output voltage (VO). VO VIN CIN = VO VIN VPP IO VO VIN VO VIN CIN(MIN) = 1 VPP IO Always examine the ceramic capacitor DC voltage coef- ficient characteristics when selecting the proper value. For example, the capacitance of a 10μF, 6.3V, X5R ceram- ic capacitor with 5.0V DC applied is actually about 6μF. 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 (output) current. VO VIN VO VIN for VIN = 2 · VO IO RMS(MAX)I 2= 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 IN_BUCK is twice V OUT_BUCK. This is why the input voltage ripple and the input capacitor RMS cur- rent 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 AAT2500M. 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 3. Figure 3: AAT2500M Evaluation Board Figure 4: AAT2500M Evaluation Board Top Side Layout. Bottom Side Layout.

400mA Step-Down Converter and 300mA LDO DATA SHEET Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com 202015A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 4, 2012 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 capacitor. This dampens the high Q network and stabilizes the system. Output Capacitor The step-down converter output capacitor limits the out- put ripple and provides holdup during large load transi- tions. A 4.7 μF to 10 μF X5R or X7R ceramic capacitor typically provides sufficient bulk capacitance to stabilize the output during large load transitions and has the ESR and ESL characteristics necessary for low output ripple. The output voltage droop due to a load transient is dom- inated 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 relationship of the output volt- age droop during the three switching cycles to the output capacitance can be estimated by: COUT = 3 · ΔILOAD VDROOP · FOSC 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 · FOSC · 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. Adjustable Output Voltage Resistor Selection For applications requiring an adjustable output voltage (VO or V OUT), the 0.6V version can be externally pro- grammed. Resistors R1 and R2 of Figure 5 program the output to regulate at a voltage higher than 0.6V. To limit the bias current required for the external feedback resis- tor string while maintaining good noise immunity, the minimum suggested value for R2 is 59k . Although a larger value will further reduce quiescent current, it will also increase the impedance of the feedback node, mak- ing it more sensitive to external noise and interference. Table 2 summarizes the resistor values for various out- put voltages with R2 set to either 59k  for good noise immunity or 221k for reduced no load input current.

400mA Step-Down Converter and 300mA LDO DATA SHEET Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com 202015A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 4, 2012 4.7μHC1 4.7μF C2 10μF VOUT BUCK VOUT LDO GND VIN1 Buck Enable LX1 GND Table 2 59k LX1 PGND2 EN_BUCK3 EN_LDO4 AGND 9 AGND 10 AGND 11 IN_BUCK 12 FB_BUCK5 OUT_LDO6 AGND 8 IN_LDO 7 AAT2500M 4.7μF 10μF LDO Enable LDO Input 0.01μF n/a n/a Figure 5: AAT2500M Evaluation Board Schematic. VOUT (V) R2 = 59k R1 (k) R2 = 221k R1 (k) 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. VOUT VREF 1.5V 0.6V The adjustable version of the AAT2500M, combined with an external feedforward capacitor (C8 in Figures 2 and 5), delivers enhanced transient response for extreme pulsed load applications. The addition of the feedforward capacitor typically requires a larger output capacitor C1 for stability. Thermal Calculations There are three types of losses associated with the AAT2500M 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

400mA Step-Down Converter and 300mA LDO DATA SHEET Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com 202015A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 4, 2012 switching devices. At full load, assuming continuous con- duction mode (CCM), a simplified form of the step-down converter and LDO losses is given by: PTOTAL IOBUCK 2 · (RDSON(HS) · VOBUCK + RDSON(LS) · [VIN - VOBUCK]) VIN + (tsw · FOSC · IOBUCK + IQBUCK + IQLDO) · VIN + IOLDO · (VIN - VOLDO) IQBUCK is the step-down converter quiescent current and IQLDO is the LDO quiescent current. The term t sw is used to estimate the full load step-down converter switching losses. For the condition where the buck converter is in dropout at 100% duty cycle, the total device dissipation reduces to: PTOTAL = IOBUCK 2 · RDSON(HS) + IOLDO · (VIN - VOLDO) + (IQBUCK + IQLDO) · 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 TSOPJW-12 package which is 110°C/W. TJ(MAX) = PTOTAL · ΘJA + TAMB PCB Layout The following guidelines should be used to ensure a proper layout. 1. The input capacitor C2 should connect as closely as possible to IN_BUCK and PGND, as shown in Figure 2. The output capacitor and inductor should be con- nected as closely as possible. The connection of the inductor to the LX pin should also be as short as pos- sible. 3. The feedback trace should be separate from any power trace and connect as closely as possible to the load point. Sensing along a high-current load trace will degrade DC load regulation. If external feedback resistors are used, they should be placed as closely as possible to the FB_BUCK pin. This prevents noise from being coupled into the high impedance feed- back node. 4. The resistance of the trace from the load return to GND should be kept to a minimum. This will help to minimize any error in DC regulation due to differ- ences in the potential of the internal signal ground and the power ground.

400mA Step-Down Converter and 300mA LDO DATA SHEET Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com 202015A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 4, 2012 Step-Down Converter Design Example Specifications VOBUCK = 1.8V @ 400mA (adjustable using 0.6V version), Pulsed Load ILOAD = 300mA VOLDO = 3.3V @ 300mA VIN = 2.7V to 4.2V (3.6V nominal) FOSC = 1.8MHz TAMB = 85°C 1.8V Buck Output Inductor L1 = 1.5 ⋅ VOBUCK = 1.5 ⋅ 1.8V = 2.7µHµsec A µsec A (see Table 1) For Sumida inductor CDRH3D16, 2.2μH, DCR = 59m. IPKL1 = IOBUCK + ΔIL1 = 0.4A + 0.130A = 0.53A2 PL1 = IOBUCK 2 ⋅ DCR = (0.4A)2 ⋅ 59mΩ = 9.4mW 1.8V Output Capacitor VDROOP = 0.2V 2.2µH · 1.8MHz · 4.2V 23 RMSI L1 · FOSC · VIN(MAX) = · 3 · ΔILOAD VDROOP · FOSC 3 · 0.3A 0.2V · 1.8MHz COUT = = = 2.5µF

• = 75mARMS (VOBUCK) · (VIN(MAX) - VOBUCK) = Pesr = esr · IRMS 2 = 5mΩ · (75mA)2 = 28.1µW

400mA Step-Down Converter and 300mA LDO DATA SHEET Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com 202015A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 4, 2012 Input Capacitor Input Ripple VPP = 25mV CIN = = = 2.42µF 1 VPP IOBUCK 25mV 0.4A IOBUCK RMSI P = esr · IRMS 2= = 0.2A RMS AAT2500M Losses PTOTAL + (tsw · FOSC · IOBUCK + IQBUCK + IQLDO) · VIN + (VIN - VLDO) · ILDO IOBUCK 2 · (RDSON(HS) · VOBUCK + RDSON(LS) · [VIN - VOBUCK]) VIN 4.2V TJ(MAX) = TAMB + ΘJA · PLOSS = 85°C + (110°C/W) · 399mW = 129°C

400mA Step-Down Converter and 300mA LDO DATA SHEET Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com 202015A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 4, 2012 1. For reduced quiescent current R2 = 221k. VOUT (V) Adjustable Version (0.6V device) R1 (kΩ) R2 = 59kΩ R1 (kΩ) R2 = 221kΩ1 L1 (μH) 0.8 19.6 75.0 2.2 0.9 29.4 113 2.2 1.0 39.2 150 2.2 1.1 49.9 187 2.2 1.2 59.0 221 2.2 1.3 68.1 261 2.2 1.4 78.7 301 2.2 1.5 88.7 332 2.2 1.8 118 442 2.2 1.85 124 464 2.2 2.0 137 523 2.2 or 3.3 2.5 187 715 4.7 VOUT (V) Fixed Version R1 (kΩ) R2 Not Used L1 ( μH) 0.6-3.3V 0 2.2 Table 3: Evaluation Board Component Values. Manufacturer Part Number Inductance ( μH) Max DC Current (A) DCR (Ω) 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.

400mA Step-Down Converter and 300mA LDO DATA SHEET Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com 202015A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 4, 2012 1. XYY = assembly and date code. 2. Sample stock is generally held on part numbers listed in BOLD. 3. Contact Sales for availability.

Ordering Information

Marking1 Part Number (Tape and Reel)2Buck Converter LDO TSOPJW-12 Adj ≥ 0.6V 3.3V XLXYY AAT2500MITP-AW-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. Legend Voltage Code Adjustable (0.6V) A 0.9 B 1.2 E 1.5 G 1.8 I 1.9 Y 2.5 N 2.6 O 2.7 P 2.8 Q 2.85 R 2.9 S 3.0 T 3.3 W 4.2 C

400mA Step-Down Converter and 300mA LDO DATA SHEET Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com 202015A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 4, 2012 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 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.

Package Information

0.20 + 0.10 - 0.05 0.055 ± 0.045 0.45 ± 0.15 7° NOM 4° ± 4° 3.00 ± 0.10 2.40 ± 0.10 2.85 ± 0.20 0.15 ± 0.05 0.9625 ± 0.0375 1.00 + 0.10 - 0.065

0.04 REF

0.010 2.75 ± 0.25 All dimensions in millimeters.