AAT2515IWP-AA-T1

AAT2515 ANALOGICTECH | Alldatasheet

Document overview

• Manufacturer or author: Provided By ALLDATASHEET.COM(FREE DATASHEET DOWNLOAD SITE)
• PDF pages: 20

Technical content

Features

• V IN Range: 2.7V to 5.5V
• Output Current: ▪ Channel 1: 600mA ▪ Channel 2: 600mA
• 98% Efficient Step-Down Converter
• Integrated Power Switches
• 100% Duty Cycle
• 1.4MHz Switching Frequency
• Internal Soft Start
• 150 μs Typical Turn-On Time
• Over-Temperature Protection
• Current Limit Protection
• TDFN33-12 Package
• -40°C to +85°C Temperature Range

Applications

• Cellular Phones
• Digital Cameras
• Handheld Instruments
• Microprocessor / DSP Core / IO Power
• PDAs and Handheld Computers Typical Application AAT2515 10μF 10μF GND LX1 FB1 VIN1 VIN2VBAT CIN EN1 EN2 4.7μH 4.7μH COUT 10μF VOUT1 LX2 FB2 VOUT2

Dual 600mA Fast Transient High Frequency Buck ConverterSystemPower TM PRODUCT DATASHEET AAT2515 Dual 600mA Fast Transient High Frequency Buck ConverterSystemPower TM PRODUCT DATASHEET Pin Descriptions Pin # Symbol Function 1 EN1 Enable pin for Channel 1. Active high. When connected low, it disables the channel and consumes less than 1μA of current. 2 FB1 Feedback input pin for Channel 1. This pin is connected to the converter output. It is used to see the output of the converter to regulate to the desired value via an external resistor divider. 3, 6, 7, 10 GND Ground. 4 EN2 Enable pin for Channel 2. Active high. When connected low, it disables the channel and consumes less than 1μA of current. 5 FB2 Feedback input pin for Channel 2. This pin is connected to the converter output. It is used to see the output of the converter to regulate to the desired value via an external resistor divider. 8 LX2 Power switching node for Channel 2. Output switching node that connects to the output inductor. 9 VIN2 Input supply voltage for Channel 2. Must be closely decoupled. 11 LX1 Power switching node for Channel 2. Output switching node that connects to the output inductor. 12 VIN1 Input supply voltage for Channel 1. Must be closely decoupled. Pin Configuration TDFN33-12 (Top View) EN1 FB1 GND EN2 FB2 GND VIN1 LX1 GND VIN2 LX2 GND

Dual 600mA Fast Transient High Frequency Buck ConverterSystemPower TM PRODUCT DATASHEET AAT2515 Dual 600mA Fast Transient High Frequency Buck ConverterSystemPower TM PRODUCT DATASHEET Absolute Maximum Ratings1 Symbol Description Value Units VIN Input Voltages to GND 6.0 V VLX LX to GND -0.3 to VIN + 0.3 V VFB FB1 and FB2 to GND -0.3 to V IN + 0.3 V VEN EN1 and EN2 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 2.0 W θJA Thermal Resistance2 50 °C/W 1. Stresses above those listed in Absolute Maximum Ratings may cause permanent 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. Mounted on an FR4 board.

Dual 600mA Fast Transient High Frequency Buck ConverterSystemPower TM PRODUCT DATASHEET AAT2515 Dual 600mA Fast Transient High Frequency Buck ConverterSystemPower TM PRODUCT DATASHEET Electrical Characteristics1 VIN = 3.6V; TA = -40°C to +85°C, unless otherwise noted. Typical values are T A = 25°C. Symbol Description Conditions Min Typ Max Units VIN Input Voltage 2.7 5.5 V VOUT Output Voltage Tolerance I OUT = 0 to 600mA; VIN = 2.7V to 5.5V -3.0 3.0 % VOUT Output Voltage Range 0.6 V IN V IQ Quiescent Current Per Channel 27 70 μA ISHDN Shutdown Current EN1 = EN2 = GND 1.0 μA ILX_LEAK LX Leakage Current V IN = 5.5V, VLX = 0 to VIN 1.0 μA IFB Feedback Leakage V FB = 1.0V 0.2 μA ILIM P-Channel Current Limit Both Channels 1.2 A RDS(ON)H High Side Switch On Resistance 0.45 Ω RDS(ON)L Low Side Switch On Resistance 0.40 Ω ΔVLINE Line Regulation V IN = 2.7V to 5.5V 0.2 % FOSC Oscillator Frequency 1.4 MHz TS Start-Up Time From Enable to Output Regulation; Both Channels 150 μs TSD Over-Temperature Shutdown Threshold 140 °C THYS Over-Temperature Shutdown Hysteresis 15 °C 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 AAT2515 is guaranteed to meet performance specifications over the -40°C to +85°C operating temperature range and is assured by design, characterization, and correla- tion with statistical process controls.

Dual 600mA Fast Transient High Frequency Buck ConverterSystemPower TM PRODUCT DATASHEET AAT2515 Dual 600mA Fast Transient High Frequency Buck ConverterSystemPower TM PRODUCT DATASHEET Typical Characteristics EN1 = VIN; EN2 = GND. Efficiency vs. Load (VOUT = 1.8V; L = 4.7μμH) Output Current (mA) Efficiency (%) 100 0.1 1 10 100 100 0 VIN = 2.7V VIN = 3.6V VIN = 4.2V DC Regulation (VOUT = 1.8V) Output Current (mA) Output Error (%) -1.0 -0.5 0.0 0.5 1.0 0.1 1 10 100 1000 VIN = 4.2V VIN = 3.6V VIN = 2.7V Efficiency vs. Load (VOUT = 2.5V; L = 6.8μμH) Output Current (mA) Efficiency (%) 100 0.1 1 10 100 1000 VIN = 5.0V VIN = 3.6V VIN = 4.2V VIN = 2.7V DC Regulation (VOUT = 2.5V) Output Current (mA) Output Error (%) -1.0 -0.5 0.0 0.5 1.0 0.1 1 10 100 1000 VIN = 5.0V VIN = 3.6V VIN = 3.0V VIN = 4.2V Efficiency vs. Load (VOUT = 3.3V; L = 6.8μμH) Output Current (mA) Efficiency (%) 100 0.1 1 10 100 1000 VIN = 3.6V VIN = 4.2V VIN = 5.0V DC Regulation (VOUT = 3.3V; L = 6.8µH) Output Current (mA) Output Error (%) -1.0 -0.5 0.0 0.5 1.0 0.1 1 10 100 1000 VIN = 5.0V VIN = 4.2V VIN = 3.6V

Dual 600mA Fast Transient High Frequency Buck ConverterSystemPower TM PRODUCT DATASHEET AAT2515 Dual 600mA Fast Transient High Frequency Buck ConverterSystemPower TM PRODUCT DATASHEET Typical Characteristics EN1 = VIN; EN2 = GND. Soft Start (VIN = 3.6V; VOUT = 1.8V; IOUT = 400mA) Time (100μμs/div) Enable and Output Voltage (top) (V) Inductor Current (bottom) (A) -5.0 -4.0 -3.0 -2.0 -1.0 0.0 1.0 2.0 3.0 4.0 5.0 -0.4 -0.2 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 VEN IL VO Line Regulation (VOUT = 1.8V) Input Voltage (V) Accuracy (%) -0.40 -0.30 -0.20 -0.10 0.00 0.10 0.20 0.30 0.40 IOUT = 10mA IOUT = 400mA IOUT = 1mA Output Voltage Error vs. Temperature (VIN = 3.6V; VO = 1.8V; IOUT = 400mA) Temperature (°°C) Output Error (%) -2.0 -1.0 0.0 1.0 2.0 -40 -20 0 20 40 60 80 100 Switching Frequency vs. Temperature (VIN = 3.6V; VOUT = 1.8V) Temperature (°°C) Variation (%) -15.0 -12.0 -9.0 -6.0 -3.0 0.0 3.0 6.0 9.0 12.0 15.0 -40 -20 0 20 40 60 80 100 Frequency vs. Input Voltage Input Voltage (V) Frequency Variation (%) -4.0 -3.0 -2.0 -1.0 0.0 1.0 2.0 VOUT = 1.8V VOUT = 2.5V VOUT = 3.3V No Load Quiescent Current vs. Input Voltage Input Voltage (V) Supply Current (μμA) 85°C 25°C -40°C

Dual 600mA Fast Transient High Frequency Buck ConverterSystemPower TM PRODUCT DATASHEET AAT2515 Dual 600mA Fast Transient High Frequency Buck ConverterSystemPower TM PRODUCT DATASHEET Typical Characteristics EN1 = VIN; EN2 = GND. 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 (1mA to 300mA; VIN = 3.6V; VOUT = 1.8V; C1 = 10μμF; CFF = 100pF) Output Voltage (top) (V) Load and Inductor Current (200mA/div) (bottom) Time (50μs/div) 1.7 1.8 1.9 2.0 VO 300mA 1mA IO IL Load Transient Response (300mA to 400mA; VIN = 3.6V; VOUT = 1.8V; C1 = 4.7μμF) Output Voltage (top) (V) Load and Inductor Current (200mA/div) (bottom) Time (50μs/div) 1.75 1.80 1.85 1.90 0.1 0.2 0.3 0.4 VO IO IL 400mA 300mA Load Transient Response (300mA to 400mA; VIN = 3.6V; VOUT = 1.8V; C1 = 10μμF) Output Voltage (top) (V) Load and Inductor Current (200mA/div) (bottom) Time (50μs/div) 1.75 1.80 1.85 1.90 0.1 0.2 0.3 0.4 VO IO IL 400mA 300mA Load Transient Response (300mA to 400mA; VIN = 3.6V; VOUT = 1.8V; C1 = 10μμF; C4 = 100pF) Output Voltage (top) (V) Load and Inductor Current (200mA/div) (bottom) Time (50μs/div) 1.775 1.800 1.825 1.850 0.1 0.2 0.3 0.4 VO IO IL 400mA 300mA

Dual 600mA Fast Transient High Frequency Buck ConverterSystemPower TM PRODUCT DATASHEET AAT2515 Dual 600mA Fast Transient High Frequency Buck ConverterSystemPower TM PRODUCT DATASHEET Typical Characteristics EN1 = VIN; EN2 = GND. Line Response (VOUT = 1.8V @ 400mA) Output Voltage (top) (V) Input Voltage (bottom) (V) Time (25μμs/div) 1.76 1.77 1.78 1.79 1.80 1.81 1.82 3.0 3.5 4.0 4.5 5.0 5.5 6.0 Output Ripple (VIN = 3.6V; VOUT = 1.8V; IOUT = 1mA) Time (10µs/div) Output Voltage (AC coupled) (top) (mV) Inductor Current (bottom) (A) -120 -100 -80 -60 -40 -20 -0.10 -0.05 0.00 0.05 0.10 0.15 0.20 0.25 0.30 VO IL Output Ripple (VIN = 3.6V; VOUT = 1.8V; IOUT = 400mA) Time (500ns/div) Output Voltage (AC coupled) (top) (mV) Inductor Current (bottom) (A) -120 -100 -80 -60 -40 -20 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 VO IL

Dual 600mA Fast Transient High Frequency Buck ConverterSystemPower TM PRODUCT DATASHEET Functional Description The AAT2515 is a high performance power management IC comprised of two buck converters. Each channel has independent input voltages and enable pins. Designed to operate at 1.4MHz of switching frequency, the converters require only three external components (C IN, C OUT, and LX), minimizing cost and size of external components. Both converters are designed to operate with an input voltage range of 2.7V to 5.5V. Typical values of the out- put filter are 4.7 μH and 10 μF ceramic capacitor. The output voltage operates to as low as 0.6V and is offered as both fixed and adjustable. Power devices are sized for 600mA current capability while maintaining over 90% efficiency at full load. Light load efficiency is maintained at greater than 80% down to 500 μA of load current. Both channels have excellent transient response, load, and line regulation. Transient response time is typically less than 20μs. The AAT2515 also features soft-start control to limit inrush current. Soft start increases the inductor current limit point in discrete steps when power is applied to the input or when the enable pins are pulled high. It limits the current surge seen at the input and eliminates out- put voltage overshoot. The enable input, when pulled low, forces the converter into a low power, non-switching state consuming less than 1μA of current. For overload conditions, the peak input current is limit- ed. As load impedance decreases and the output voltage falls closer to zero, more power is dissipated internally, raising the device temperature. Thermal protection com- pletely 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. The under-voltage lockout guaran- tees sufficient V IN bias and proper operation of all inter- nal circuits prior to activation. Functional Block Diagram EN1 LX1 Err. Amp. DH DL GND VIN1FB1 GND Voltage Reference Control Logic EN2 LX2 Err. Amp. DH DL GND Comp. Logic Logic Control Logic VIN2 FB2 GND Voltage Reference Comp. See Note See Note Note: Internal resistor divider included for fixed output voltage versions. For low voltage versions, the feedback pin is tied directly to the error amplifier input.

Dual 600mA Fast Transient High Frequency Buck ConverterSystemPower TM PRODUCT DATASHEET 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 AAT2515 is 0.24A/ μs. 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 µs This is the internal slope compensation for the adjust- able (0.6V) version or low-voltage fixed version. When externally programming the 0.6V version to a 2.5V out- put, the calculated inductance would be 7.5 μH. 0.75 ⋅ VO L = = ≈ 3 ⋅ VO = 3 ⋅ 2.5V = 7.5µH m 0.75V 0.24A /µs µs A µs A In this case, a standard 6.8μH value is selected. For high- voltage fixed versions (2.5V and above), m = 0.48A/ μs. Table 1 displays inductor values for the AAT2515 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 105mΩ DCR and a 900mA DC current rat- ing. At full load, the inductor DC loss is 37.8mW which gives a 4.2% loss in efficiency for a 600mA 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 volt- age and is a maximum when V IN is double the output voltage. VO VIN CIN = VO VIN VPP IO This equation provides an estimate for the input capaci- tor required for a single channel. Confi guration Output Voltage Inductor 0.6V Adjustable With External Feedback 1V, 1.2V 2.2 μH 1.5V, 1.8V 4.7 μH 2.5V, 3.3V 6.8 μH Fixed Output 0.6V to 3.3V 4.7 μH Table 1: Inductor Values. The equation below solves for input capacitor size for both channels. It makes the worst-case assumptions that both converters are operating at 50% duty cycle and are synchronized. CIN = 1 VPP IO1 + IO2 Because the AAT2515 channels will generally operate at different duty cycles and are not synchronized, the actual ripple will vary and be less than the ripple (V PP) used to solve for the input capacitor in the equation above. 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 5V DC applied is actually about 6 μF. The maximum input capacitor RMS current is: VO1 VIN VO1 VIN VO2 VIN VO2 VIN

Dual 600mA Fast Transient High Frequency Buck ConverterSystemPower TM PRODUCT DATASHEET 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 of both convert- ers combined. IO1(MAX) + IO2(MAX) RMS(MAX)I 2= This equation also makes the worst-case assumption that both converters are operating at 50% duty cycle and are synchronized. Since the converters are not syn- chronized and are not both operating at 50% duty cycle, the actual RMS current will always be less than this. Losses associated with the input ceramic capacitor are typically minimal. The term VO VIN VO VIN appears in both the input voltage ripple and input capacitor RMS current equations. It is a maximum when V O is twice VIN. 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 AAT2515. Low ESR/ ESL X7R and X5R ceramic capacitors are ideal for this function. To minimize the 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 (C3 and C8) can be seen in the evaluation board layout in Figure 2. Since decoupling must be as close to the input pins as possible, it is necessary to use two decoupling capaci- tors. C3 provides the bulk capacitance required for both converters, while C8 is a high frequency bypass capaci- tor for the second channel (see C3 and C8 placement in Figure 2). A laboratory test set-up typically consists of two long wires running from the bench power supply to the eval- uation 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 during load tran- sients. Errors in the loop phase and gain measurements can also result. Since the inductance of a short printed circuit board 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 converter performance, a high ESR tantalum or alumi- num electrolytic capacitor 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 output capacitor limits the output ripple and pro- vides holdup during large load transitions. A 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 nec- essary 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. As the loop responds, the induc- tor current increases to match the load current demand. This typically takes several switching cycles and can be estimated 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 10 μF. 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 · F · 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.

Dual 600mA Fast Transient High Frequency Buck ConverterSystemPower TM PRODUCT DATASHEET Adjustable Output Resistor Selection For applications requiring an adjustable output voltage, the 0.6V version can be programmed externally. Resistors R1 through R4 of Table 2 program the output to regulate at a voltage higher than 0.6V. To limit the bias current required for the external feedback resistor string, the minimum suggested value for R2 and R4 is 59k Ω. Although a larger value will reduce the quiescent cur- rent, it will also increase the impedance of the feedback node, making it more sensitive to external noise and interference. Table 2 summarizes the resistor values for various output voltages with R2 and R4 set to either 59kΩ for good noise immunity or 221k Ω for reduced no load input current. VOUT VREF 1.5V 0.6V The adjustable version of the AAT2515 in combination with an external feedforward capacitor (C4 and C5 of Figure 1) delivers enhanced transient response for extreme pulsed load applications. The addition of the feedforward capacitor typically requires a larger output capacitor (C1 and C2) for stability. VOUT (V) R2, R4 = 59kΩ R1, R3 (kΩ) R2, R4 = 221kΩ R1, R3 0.8 19.6 75K 0.9 29.4 113K 1.0 39.2 150K 1.1 49.9 187K 1.2 59.0 221K 1.3 68.1 261K 1.4 78.7 301K 1.5 88.7 332K 1.8 118 442K 1.85 124 464K 2.0 137 523K 2.5 187 715K 3.3 267 1.00M Table 2: Adjustable Resistor Values For Use With 0.6V Version. Thermal Calculations There are three types of losses associated with the AAT2515 converter: switching losses, conduction losses, and quiescent current losses. Conduction losses are associated with the R DS(ON) characteristics of the power output switching devices. Switching losses are dominat- ed by the gate charge of the power output switching devices. At full load, assuming continuous conduction mode (CCM), a simplified form of the dual converter losses is given by: PTOTAL IO1 2 · (RDSON(HS) · VO1 + RDSON(LS) · [VIN -VO1]) VIN + (tsw · F · [IO1 + IO2] + 2 · IQ) · VIN IO2 2 · (RDSON(HS) · VO2 + RDSON(LS) · [VIN -VO2]) VIN IQ is the AAT2515 quiescent current for one channel and tsw is used to estimate the full load switching losses. For the condition where channel one is in dropout at 100% duty cycle, the total device dissipation reduces to: PTOTAL = IO1 2 · RDSON(HS) + (tsw · F · IO2 + 2 · IQ) · VIN IO2 2 · (RDSON(HS) · VO2 + RDSON(LS) · [VIN -VO2]) 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 θ JA for the TDFN33-12 pack- age which is 50°C/W. TJ(MAX) = PTOTAL · ΘJA + TAMB

Dual 600mA Fast Transient High Frequency Buck ConverterSystemPower TM PRODUCT DATASHEET PCB Layout The following guidelines should be used to insure a proper layout. 1. Due to the pin placement of V IN for both converters, proper decoupling is not possible with just one input capacitor. The large input capacitor C3 should con- nect as closely as possible to V IN and GND, as shown in Figure 2. The additional input bypass capacitor C8 is necessary for proper high frequency decoupling of the second converter. 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 possible. 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 pin. This prevents noise from being coupled into the high impedance feedback 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. 5. For good thermal coupling, PCB vias are required from the pad for the TDFN paddle to the ground plane. The via diameter should be 0.3mm to 0.33mm and positioned on a 1.2 mm grid.

Dual 600mA Fast Transient High Frequency Buck ConverterSystemPower TM PRODUCT DATASHEET AAT2515 Dual 600mA Fast Transient High Frequency Buck ConverterSystemPower TM PRODUCT DATASHEET Design Example Specifications VO1 = 2.5V @ 600mA (adjustable using 0.6V version), pulsed load ΔILOAD = 300mA VO2 = 1.8V @ 600mA (adjustable using 0.6V version), pulsed load ΔILOAD = 300mA VIN = 2.7V to 4.2V (3.6V nominal) FS = 1.4 MHz TAMB = 85°C 2.5V VO1 Output Inductor L1 = 3 ⋅ VO1 = 3 ⋅ 2.5V = 7.5µHµs A µs A (see Table 1) For Sumida inductor CDRH3D16, 10μH, DCR = 210mΩ. IPK1 = IO1 + ΔI1 = 0.6A + 0.036A = 0.64A2 PL1 = IO1 2 ⋅ DCR = 0.6A2 ⋅ 210mΩ = 75.6mW 1.8V VO2 Output Inductor L2 = 3 ⋅ VO2 = 3 ⋅ 1.8V = 5.4µHµs A µs A (see Table 1) For Sumida inductor CDRH3D16, 4.7μH, DCR = 105mΩ. IPK2 = IO2 + ΔI2 = 0.6A + 0.078A = 0.68A2 PL2 = IO2 2 ⋅ DCR = 0.6A2 ⋅ 105mΩ = 37.8mW

Dual 600mA Fast Transient High Frequency Buck ConverterSystemPower TM PRODUCT DATASHEET AAT2515 Dual 600mA Fast Transient High Frequency Buck ConverterSystemPower TM PRODUCT DATASHEET 2.5V Output Capacitor 10µH · 1.4MHz · 4.2V 23 RMS(MAX)I L · F · VIN(MAX) 3 · ΔILOAD VDROOP · FS 3 · 0.3A 0.1V · 1.4MHz COUT = = = 6.4µF; use 10µF

• = 21mArms (VOUT) · (VIN(MAX) - VOUT) = Pesr = esr · IRMS 2 = 5mΩ · (21mA)2 = 2.2µW 1.8V Output Capacitor 4.7µH · 1.4MHz · 4.2V 23 RMS(MAX)I L · F · VIN(MAX) 3 · ΔILOAD VDROOP · FS 3 · 0.3A 0.1V · 1.4MHz COUT = = = 6.4µF; use 10µF
• = 45mArms (VOUT) · (VIN(MAX) - VOUT) = Pesr = esr · IRMS 2 = 5mΩ · (45mA)2 = 10µW Input Capacitor Input Ripple VPP = 25mV. CIN = = = 11.3µF; use 10µF1 VPP IO1 + IO2 25mV 1.2A IO1 + IO2 RMS(MAX)I P = esr · IRMS 2= = 0.6Arms

Dual 600mA Fast Transient High Frequency Buck ConverterSystemPower TM PRODUCT DATASHEET AAT2515 Dual 600mA Fast Transient High Frequency Buck ConverterSystemPower TM PRODUCT DATASHEET AAT2515 Losses The maximum dissipation occurs at dropout where VIN = 2.7V. All values assume an ambient temperature of 85°C and a junction temperature of 120°C. PTOTAL + (tsw · F · IO2 + 2 · IQ) · VIN IO1 2 · (RDSON(HS) · VO1 + RDSON(LS) · (VIN -VO1)) + IO2 2 · (RDSON(HS) · VO2 + RDSON(LS) · (VIN -VO2)) VIN + 5ns · 1.4MHz · 0.6A + 60μA) · 2.7V = 530mW 2.7V TJ(MAX) = TAMB + ΘJA · PLOSS = 85°C + (50°C/W) · 530mW = 111°C see Table 3 10μF C21 VO1 GND see Table 3 59.0k C41 FB1 EN1 LX1 GND LX2 GND GND VIN1 VIN2 GND FB2 EN2 AAT2515 10μF see Table 3 VO2 GND LX2 see Table 3 59.0k 10μF C11 LX1 123 Output 1 Enable 321 Output 2 Enable VIN 0.01μF 0.01μF 0.1μF Figure 1: AAT2515 Evaluation Board Schematic. 1. For enhanced transient configuration C5, C4 = 100pF.

Dual 600mA Fast Transient High Frequency Buck ConverterSystemPower TM PRODUCT DATASHEET AAT2515 Dual 600mA Fast Transient High Frequency Buck ConverterSystemPower TM PRODUCT DATASHEET Adjustable Version (0.6V device) VOUT (V) R2, R4 = 59kΩ R2, R4 = 221kΩ1 L1, L2 (μH)R1, R3 (kΩ) R1, R3 (k Ω) 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 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 6.8 2.5 187 715 6.8 3.3 267 1000 6.8 Fixed Version VOUT (V) R2, R4 Not Used R1, R3 (kΩ) L1, L2 ( μH) 0.6-3.3V 0 4.7 Table 3: Evaluation Board Component Values. Figure 2: AAT2515 Evaluation Board Top Side. Figure 3: AAT2515 Evaluation Board Bottom Side. 1. For reduced quiescent current, R2 and R4 = 221k Ω.

Dual 600mA Fast Transient High Frequency Buck ConverterSystemPower TM PRODUCT DATASHEET AAT2515 Dual 600mA Fast Transient High Frequency Buck ConverterSystemPower TM PRODUCT DATASHEET 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 Temp. Co. Case Murata GRM219R61A475KE19 4.7 μF X5R 0805 Murata GRM21BR60J106KE19 10uF X5R 0805 Murata GRM21BR60J226ME39 22uF X5R 0805 Table 5: Surface Mount Capacitors.

Dual 600mA Fast Transient High Frequency Buck ConverterSystemPower TM PRODUCT DATASHEET AAT2515 Dual 600mA Fast Transient High Frequency Buck ConverterSystemPower TM PRODUCT DATASHEET

Ordering Information

Marking1 Part Number (Tape and Reel)2Channel 1 Channel 2 TDFN33-12 0.6V 0.6V 2XXYY AAT2515IWP-AA-T1 All AnalogicTech products are offered in Pb-free packaging. The term “Pb-free” means semiconductor products that are in compliance with current RoHS standards, including the requirement that lead not exceed 0.1% by weight in homogeneous materials. For more information, please visit our website at http://www.analogictech.com/pbfree. 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 1. XYY = assembly and date code. 2. Sample stock is generally held on part numbers listed in BOLD.

Dual 600mA Fast Transient High Frequency Buck ConverterSystemPower TM PRODUCT DATASHEET AAT2515 Dual 600mA Fast Transient High Frequency Buck ConverterSystemPower TM PRODUCT DATASHEET Advanced Analogic Technologies, Inc.

3230 Scott Boulevard, Santa Clara, CA 95054

Phone (408) 737-4600 Fax (408) 737-4611 © Advanced Analogic Technologies, Inc. AnalogicTech cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in an AnalogicTech pr oduct. No circuit patent licenses, copyrights, mask work rights, or other intellectual property rights are implied. AnalogicTech reserves the right to make changes to their products or specifi cations or to discontinue any product or service without notice. Except as provided in AnalogicTech’s terms and conditions of sale, AnalogicTech assumes no liability whatsoever, and AnalogicTech disclaims any express or implied warranty relating to the sale and/or use of AnalogicTech products including liability or warranties relating to fi tness for a particular purpose, merchantability, or infringement of any patent, copyright or other intellectual property right. In order to minimize risks associated with the customer’s applications, adequate design and operating safeguards must be provided by the customer to minimize inherent or procedural hazards. Testing and other quality control techniques are utilized to the extent AnalogicTech deems necessary to support this warranty. Specifi c testing of all parameters of each device is not necessarily performed. AnalogicTech and the AnalogicTech logo are trademarks of Advanced Analogic Technologies Incorporated. All other brand and product names appearing in this document are registered trademarks or trademarks of their respective holders.

Package Information

Detail "A" Side View 3.00 ± 0.05 Index Area Detail "A" 1.70 ± 0.05 3.00 ± 0.05 0.05 ± 0.05 0.23 ± 0.05 0.75 ± 0.05 2.40 ± 0.05 0.43 ± 0.05

0.1 REF

(optional) C0.3 All dimensions in millimeters. 1. 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.