AAT1141IGV-3.3-T1

AAT1141_08 ANALOGICTECH | Alldatasheet

Document overview

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• PDF pages: 21

Technical content

Features

• V IN Range: 2.7V to 5.5V
• V OUT Fixed or Adjustable from 0.6V to V IN
• 35 μA No Load Quiescent Current
• Up to 98% Efficiency
• 600mA Max Output Current
• 2MHz Switching Frequency
• 150 μs Soft Start
• Fast Load Transient
• Over-Temperature Protection
• Current Limit Protection
• 100% Duty Cycle Low-Dropout Operation
• <1 μA Shutdown Current
• SOT23-5 Package
• Temperature Range: -40°C to +85°C

Applications

• Cellular Phones
• Digital Cameras
• Handheld Instruments
• Microprocessor / DSP Core / IO Power
• PDAs and Handheld Computers
• USB Devices Typical Application (Fixed Output Voltage) 4.7µH 4.7µF 4.7µF C2 EN OUT IN LX GND AAT1141 VIN VOUT

Fast Transient 600mA Step-Down ConverterSwitchReg TM PRODUCT DATASHEET AAT1141 Fast Transient 600mA Step-Down ConverterSwitchReg TM PRODUCT DATASHEET Pin Descriptions Pin # Symbol Function 1 IN Input supply voltage for the converter. 2 GND Ground pin. Connect to the output and input capacitor return. 3 EN Enable pin. 4 OUT Feedback input pin. This pin is connected either directly to the converter output or to an external resistive divider for an adjustable output. 5L X Switching node. Connect the inductor to this pin. It is internally connected to the drains of both high- and low-side MOSFETs. Pin Configuration SOT23-5 (Top View) GND LX OUTEN IN 1 3 4

Fast Transient 600mA Step-Down ConverterSwitchReg TM PRODUCT DATASHEET AAT1141 Fast Transient 600mA Step-Down ConverterSwitchReg TM PRODUCT DATASHEET Absolute Maximum Ratings1 Symbol Description Value Units VIN Input Voltage to GND 6.0 V VLX LX to GND -0.3 to VIN + 0.3 V VOUT OUT to GND -0.3 to VIN + 0.3 V VEN EN to GND -0.3 to 6.0 V TJ Operating Junction 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 PD Maximum Power Dissipation2, 3 667 mW θJA Thermal Resistance2 150 °C/W 1. Stresses above those listed in Absolute Maximum Ratings may cause permanent damage to the device. Functional operation at c onditions 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. 3. Derate 6.67mW/°C above 25°C.

Fast Transient 600mA Step-Down ConverterSwitchReg TM PRODUCT DATASHEET AAT1141 Fast Transient 600mA Step-Down ConverterSwitchReg TM PRODUCT DATASHEET Electrical Characteristics1 TA = -40°C to +85°C, unless otherwise noted. Typical values are T A = 25°C, VIN = 3.6V. Symbol Description Conditions Min Typ Max Units Step-Down Converter VIN Input Voltage 2.7 5.5 V VUVLO UVLO Threshold VIN Rising 2.7 V Hysteresis 100 mV VIN Falling 1.8 V VOUT Output Voltage Tolerance I OUT = 0 to 600mA, VIN = 2.7V to 5.5V -3.5 +3.5 % VOUT Output Voltage Range 0.6 V IN V IQ Quiescent Current No Load, 0.6V Adjustable Version 35 70 μA ISHDN Shutdown Current EN = AGND = PGND 1.0 μA ILIM P-Channel Current Limit 800 mA RDS(ON)H High Side Switch On Resistance 0.35 Ω RDS(ON)L Low Side Switch On Resistance 0.30 Ω ILXLEAK LX Leakage Current V IN = 5.5V, VLX = 0 to VIN, EN = GND 1 μA ΔVLinereg Line Regulation V IN = 2.7V to 5.5V 0.1 %/V VOUT Out Threshold Voltage Accuracy 0.6V Output, No Load, T A = 25°C 588 600 612 mV IOUT Out Leakage Current 0.6V Output 0.2 μA ROUT Out Impedance >0.6V Output 250 k Ω TS Start-Up Time From Enable to Output Regulation 150 μs FOSC Oscillator Frequency T A = 25°C 1.2 2.0 2.6 MHz TSD Over-Temperature Shutdown Threshold 140 °C THYS Over-Temperature Shutdown Hysteresis 15 °C EN VEN(L) Enable Threshold Low 0.6 V VEN(H) Enable Threshold High 1.4 V IEN Input Low Current V IN = VOUT = 5.5V -1.0 1.0 μA 1. The AAT1141 is guaranteed to meet performance specifications over the -40°C to +85°C operating temperature range and is assu red by design, characterization, and correla- tion with statistical process controls.

Fast Transient 600mA Step-Down ConverterSwitchReg TM PRODUCT DATASHEET AAT1141 Fast Transient 600mA Step-Down ConverterSwitchReg TM PRODUCT DATASHEET Typical Characteristics 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 (%) -3.0 -2.0 -1.0 0.0 1.0 2.0 3.0 0 100 200 300 400 500 60 0 VIN = 4.2V VIN = 5.0V VIN = 5.5V 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; L = 6.8µH) Output Current (mA) Output Error (%) -3.0 -2.0 -1.0 0.0 1.0 2.0 3.0 0 100 200 300 400 500 600 VIN = 3.0V VIN = 3.6V VIN = 4.2V VIN = 5.0V 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; L = 4.7μH) Output Current (mA) Output Error (%) -3.0 -2.0 -1.0 0.0 1.0 2.0 3.0 0 100 200 300 400 500 60 0 VIN = 2.7V VIN = 3.6V VIN = 4.2V

Fast Transient 600mA Step-Down ConverterSwitchReg TM PRODUCT DATASHEET AAT1141 Fast Transient 600mA Step-Down ConverterSwitchReg TM PRODUCT DATASHEET Typical Characteristics Soft Start (VIN = 3.6V; VOUT = 1.8V; Load = 3Ω; CFF = 100pF) Time (100μs/div) VOUT (2V/div) EN (2V/div) IIN (200mA/div) 0mA Line Regulation (VOUT = 1.8V) Input Voltage (V) Output Voltage (V) -0.5 -0.4 -0.3 -0.2 -0.1 0.0 0.1 0.2 0.3 0.4 0.5 IOUT = 10mA IOUT = 600mA Output Voltage Error vs. Temperature (VIN = 3.6V; VO = 1.8V; IOUT = 400mA) Temperature (°°C) -2.0 -1.0 0.0 1.0 2.0 -40 -20 0 20 40 60 80 100 Output Error (%) Switching Frequency vs. Temperature (VIN = 3.6V; VOUT = 1.8V) Temperature (°°C) Frequency Variation (%) -40 -20 0 20 40 60 80 100 -10.00 -8.00 -6.00 -4.00 -2.00 0.00 2.00 4.00 6.00 8.00 10.00 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 (VOUT = 3.0V, L = 6.8µH) Input Voltage (V) Supply Current (µA) TA = 85°C TA = 25°C TA = -40°C

Fast Transient 600mA Step-Down ConverterSwitchReg TM PRODUCT DATASHEET AAT1141 Fast Transient 600mA Step-Down ConverterSwitchReg TM PRODUCT DATASHEET Typical Characteristics No Load Quiescent Current vs. Input Voltage (VOUT = 1.8V, L = 4.7µH) Input Voltage (V) Supply Current (mA) 0.020 0.025 0.030 0.035 0.040 0.045 0.050 0.055 0.060 TA = 85°C TA = 25°C TA = -40°C No Load Quiescent Current vs. Input Voltage (VOUT = 1.2V, L = 2.2µH) Input Voltage (V) Supply Current (mA) 0.020 0.025 0.030 0.035 0.040 0.045 0.050 0.055 0.060 TA = 85°C TA = -40°C TA = 25°C P-Channel RDS(ON) vs. Input Voltage Input Voltage (V) RDS(ON)H (mΩΩ) 100 200 300 400 500 600 700 85°C 25°C -40°C N-Channel RDS(ON) vs. Input Voltage Input Voltage (V) RDS(ON)L (mΩΩ) 100 150 200 250 300 350 400 450 500 550 600 85°C 25°C -40°C Step-Down Converter Load Transient Response (1mA to 300mA; VIN = 3.6V; VOUT = 1.8V; COUT = 4.7µF; CFF = 100pF) Time (40µs/div) VOUT (100mV/div) IOUT (100mA/div) 300mA 1mA 1.8V Step-Down Converter Load Transient Response (300mA to 400mA; VIN = 3.6V; VOUT = 1.8V; COUT = 4.7µF; CFF = 100pF) Time (40µs/div) VOUT (50mV/div) IOUT (100mA/div) 400mA 300mA 1.8V

Fast Transient 600mA Step-Down ConverterSwitchReg TM PRODUCT DATASHEET AAT1141 Fast Transient 600mA Step-Down ConverterSwitchReg TM PRODUCT DATASHEET Typical Characteristics Step-Down Converter Load Transient Response (1mA to 300mA; VIN = 3.6V; VOUT = 1.0V; COUT = 10µF; CFF = 0pF) Time (40µs/div) VOUT (100mV/div) IOUT (100mA/div) 300mA 1.0V 1mA Step-Down Converter Load Transient Response (300mA to 400mA; VIN = 3.6V; VOUT = 1.0V; COUT = 10µF; CFF = 0pF) Time (40µs/div) VOUT (50mV/div) IOUT (100mA/div) 400mA 1.0V 300mA 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 Step-Down Converter Output Ripple (VOUT = 1.8V; VIN = 3.6V; IOUT = 1mA; L = 4.7µH; CFF = 100pF; COUT = 4.7µF) Time (10µs/div) Output Ripple (20mV/div) LX (2V/div) Inductor Current (100mA/div) 0mA 1.8V 1.8V Step-Down Converter Output Ripple (VOUT = 1.8V; VIN = 3.6V; IOUT = 600mA; L = 4.7µH; CFF = 100pF; COUT = 4.7µF) Time (0.5µs/div) Output Ripple (20mV/div) LX (2V/div) Inductor Current (100mA/div) 600mA 1.8V

Fast Transient 600mA Step-Down ConverterSwitchReg TM PRODUCT DATASHEET Functional Description The AAT1141 is a high performance 600mA 2MHz mono- lithic step-down converter. It has been designed with the goal of minimizing external component size and optimiz- ing efficiency over the complete load range. Apart from the small bypass input capacitor, only a small L-C filter is required at the output. Typically, a 4.7μH inductor and a 4.7μF ceramic capacitor are recommended (see table of values). The fixed output version requires only three external power components (C IN, COUT, and L). The adjustable ver- sion can be programmed with external feedback to any voltage, ranging from 0.6V to the input voltage. An addi- tional feed-forward capacitor can also be added to the external feedback to provide improved transient response (see Figure 1). At dropout, the converter duty cycle increases to 100% and the output voltage tracks the input voltage minus the R DS(ON) drop of the P-channel high-side MOSFET. The input voltage range is 2.7V to 5.5V. The converter efficiency has been optimized for all load conditions, ranging from no load to 600mA. The internal error amplifier and compensation provides excellent transient response, load, and line regulation. Soft start eliminates any output voltage overshoot when the enable or the input voltage is applied. Functional Block Diagram EN LX Err .Amp Logic DH DL GND INOUT Voltage Reference INPUT See note Note: For adjustable version, the internal feedback divider is omitted and the OUT pin is tied directly to the internal error amplifier.

Fast Transient 600mA Step-Down ConverterSwitchReg TM PRODUCT DATASHEET Control Loop The AAT1141 is a peak current mode step-down con- verter. The current through the P-channel MOSFET (high side) is sensed for current loop control, as well as short circuit and overload protection. A fixed slope compensa- tion signal is added to the sensed current to maintain stability for duty cycles greater than 50%. The peak cur- rent mode loop appears as a voltage-programmed cur- rent source in parallel with the output capacitor. The output of the voltage error amplifier programs the current mode loop for the necessary peak switch current to force a constant output voltage for all load and line conditions. Internal loop compensation terminates the transconductance voltage error amplifier output. For fixed voltage versions, the error amplifier reference volt- age is internally set to program the converter output voltage. For the adjustable output, the error amplifier reference is fixed at 0.6V. Soft Start / Enable Soft start limits the current surge seen at the input and eliminates output voltage overshoot. When pulled low, the enable input forces the AAT1141 into a low-power, non-switching state. The total input current during shut- down is less than 1μA. Current Limit and Over-Temperature Protection For overload conditions, the peak input current is limit- ed. To minimize power dissipation and stresses under current limit and short-circuit conditions, switching is terminated after entering current limit for a series of pulses. Switching is terminated for seven consecutive clock cycles after a current limit has been sensed for a series of four consecutive clock cycles. Thermal protection completely disables switching when internal dissipation becomes excessive. The junction over-temperature threshold is 140°C with 15°C of hys- teresis. Once an over-temperature or over-current fault condition is removed, the output voltage automatically recovers. Under-Voltage Lockout Internal bias of all circuits is controlled via the IN input. Under-voltage lockout (UVLO) guarantees sufficient V IN bias and proper operation of all internal circuitry prior to activation. IN LX GND EN OUT 4.7μF 4.7μH SW VOUT AAT1141 4.7μF 100pF R1 118k 59k VIN Enable Figure 1: Enhanced Transient Response Schematic.

Fast Transient 600mA Step-Down ConverterSwitchReg 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 AAT1141 is 0.24A/μsec. This equates to a slope compensation that is 75% of the inductor current down slope for a 1.5V output and 4.7μH inductor. 0.75 · VO m = = = 0.24 L 0.75 · 1.5V 4.7μH A μs This is the internal slope compensation for the adjust- able (0.6V) version or low-voltage fixed versions. When externally programming the 0.6V version to 2.5V, the calculated inductance is 7.5μH. 0.75 · VO L = = ≈ 3 · VO = 3 · 2.5V = 7.5μH m 0.75 · VO 0.24 μs A μs A A μs In this case, a standard 6.8μH value is selected. For high-voltage fixed versions ( ≥2.5V), m = 0.48A/ μsec. Table 1 displays inductor values for the AAT1141 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 CDRH2D14 series inductor selected from Sumida has a 135m Ω typical DCR and a 1A DC current rating. At full load, the inductor DC loss is 48mW which gives a 4.5% loss in efficiency for a 600mA, 1.8V output. Output Voltage (V) Inductor ( μH) Output Capacitor (μF) 1, 1.2 2.2 10 1.5, 1.8 4.7 4.7 2.5, 3.3 6.8 4.7 Table 1: Inductor and Output Capacitor Values. Input Capacitor Select a 4.7μF to 10μF X7R or X5R ceramic capacitor for the input. To estimate the required input capacitor size, determine the acceptable input ripple level (V PP) and solve for C. The calculated value varies with input voltage and is a maximum when V IN is double the output voltage. VO VIN CIN = VO VIN VPP IO VO VIN VO VIN CIN(MIN) = 1 VPP IO Always examine the ceramic capacitor DC voltage coeffi- cient characteristics when selecting the proper value. For example, the capacitance of a 10 μF, 6.3V, X5R ceramic capacitor with 5.0V DC applied is actually about 6 μF. The maximum input capacitor RMS current is: VO VIN VO VIN The input capacitor RMS ripple current varies with the input and output voltage and will always be less than or equal to half of the total DC load current. VO VIN VO VIN for VIN = 2 · VO 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

Fast Transient 600mA Step-Down ConverterSwitchReg TM PRODUCT DATASHEET Since the inductance of a short PCB trace feeding the input voltage is significantly lower than the power leads from the bench power supply, most applications do not exhibit this problem. In applications where the input power source lead induc- tance cannot be reduced to a level that does not affect the converter performance, a high ESR tantalum or alu- minum electrolytic should be placed in parallel with the low ESR, ESL bypass ceramic. This dampens the high Q network and stabilizes the system. Output Capacitor The output capacitor limits the output ripple and pro- vides holdup during large load transitions. A 4.7 μF to 10μF X5R or X7R ceramic capacitor typically provides sufficient bulk capacitance to stabilize the output during large load transitions and has the ESR and ESL charac- teristics necessary for low output ripple. The output voltage droop due to a load transient is dominated by the capacitance of the ceramic output capacitor. During a step increase in load current, the ceramic output capacitor alone supplies the load current until the loop responds. Within two or three switching cycles, the loop responds and the inductor current increases to match the load current demand. The rela- tionship of the output voltage droop during the three switching cycles to the output capacitance can be esti- mated by: COUT = 3 · ΔILOAD VDROOP · FS Once the average inductor current increases to the DC load level, the output voltage recovers. The above equa- tion establishes a limit on the minimum value for the output capacitor with respect to load transients. The internal voltage loop compensation also limits the minimum output capacitor value to 4.7μF. This is due to its effect on the loop crossover frequency (bandwidth), phase margin, and gain margin. Increased output capac- itance will reduce the crossover frequency with greater phase margin. The maximum output capacitor RMS ripple current is given by: VOUT · (VIN(MAX) - VOUT) RMS(MAX)I L · 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. Adjustable Output Resistor Selection For applications requiring an adjustable output voltage, the 0.6V version can be externally programmed. 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 resistor string while maintaining good noise immunity, the minimum sug- gested value for R2 is 59kΩ. Although a larger value will further reduce quiescent current, it will also increase the impedance of the feedback node, making it more sensi- tive to external noise and interference. Table 2 summa- rizes the resistor values for various output voltages with R2 set to either 59kΩ for good noise immunity or 316kΩ for reduced no load input current. VOUT VREF 1.5V 0.6V The adjustable version of the AAT1141, combined with an external feedforward capacitor (C3 in Figure 1), delivers enhanced transient response for extreme pulsed load applications. The addition of the feedforward capac- itor typically requires a larger output capacitor C1 for stability. VOUT (V) High Noise Immunity R2 = 59kΩ R1 (kΩ) Low Input Current (Without Load) R2 = 316kΩ R1 (kΩ) 0.8 19.6 105 0.9 29.4 158 1.0 39.2 210 1.1 49.9 267 1.2 59.0 316 1.3 68.1 365 1.4 78.7 422 1.5 88.7 475 1.8 88.7 634 2.0 137 732 2.5 187 1000 3.0 237 1270 3.3 267 1430 Table 2: Adjustable Resistor Values For Use With 0.6V Step-Down Converter.

Fast Transient 600mA Step-Down ConverterSwitchReg TM PRODUCT DATASHEET Thermal Calculations There are three types of losses associated with the AAT1141 step-down converter: switching losses, con- duction losses, and quiescent current losses. Conduction losses are associated with the R DS(ON) characteristics of the power output switching devices. Switching losses are dominated by the gate charge of the power output switching devices. At full load, assuming continuous con- duction mode (CCM), a simplified form of the LDO losses is given by: PTOTAL IO 2 · (RDSON(HS) · VO + RDSON(LS) · [VIN - VO]) VIN + (tsw · F · IO + IQ) · VIN IQ is the step-down converter quiescent current. The term tsw is used to estimate the full load step-down con- verter switching losses. For the condition where the step-down converter is in dropout at 100% duty cycle, the total device dissipation reduces to: PTOTAL = IO 2 · RDSON(HS) + IQ · VIN Since RDS(ON), quiescent current, and switching losses all vary with input voltage, the total losses should be inves- tigated over the complete input voltage range. Given the total losses, the maximum junction tempera- ture can be derived from the θ JA for the SOT23-5 pack- age which is 150°C/W. TJ(MAX) = PTOTAL · ΘJA + TAMB Output Dropout At dropout, the duty cycle of AAT1141 switching is 100%. The minimum dropout voltage is determined by R DS(ON)H and the inductor copper loss resistor. AAT1141 has 0.35Ω RDS(ON)H. The inductor copper loss resistor var- ies with different inductor values and manufacturer. The safe dropout voltage is 0.5V for a 600mA load. For example, when load current is 600mA, the voltage dropped across R DS(ON)H is 0.21V; if the inductor copper loss resistor is 135m Ω, the voltage drop across the inductor is 0.08V. So the total voltage drop is 0.29V. Considering manufacturer’s tolerances, the inductor cop- per loss resistor and R DS(ON)H will vary from part to part, a 0.4V dropout window is safe. IN LX GND EN OUT 4.7μF 4.7μH SW V = 1.8VOUT AAT1141 4.7μF 100pF R1 634k 316k VIN Enable Figure 5: AAT1141 Adjustable Evaluation Board Schematic.

Fast Transient 600mA Step-Down ConverterSwitchReg TM PRODUCT DATASHEET Efficiency Besides the AAT1141 device losses including switching losses, conduction losses, and quiescent current losses, the inductor copper loss also affects the efficiency of the buck converter. To the buck converter, the average cur- rent of the inductor is equal to output current I O. So the loss in the inductor is: PLOSS_L = IO 2 · RL Table 4 shows some recommended inductors. A larger size inductor usually has smaller DCR. As a example: if select- ing CDRH2D14 4.7μH for 1.8V output, the P Loss_L is 48.6mW when output current is 600mA, so the inductor loses 4.5% power; if selecting CDRH3D23 4.7μH, the P Loss_L should be 19.8mW, and the inductor losing power ratio is only 1.8%. The inductor size and the buck converter efficiency is always a trade-off in the real application. Layout The suggested 2-layer PCB layout for the AAT1141 is shown in Figures 2, 3 and 4. The following guide lines should be used to help ensure a proper layout. 1. The power traces (GND, LX, VIN) should be kept short, direct, and wide to allow large current flow. Place sufficient multiple-layer pads when needed to change the trace layer. 2. The input capacitor (C1) should connect as closely as possible to IN and GND. 3. The output capacitor C2 and L1 should be connected as closely as possible. The connection of L1 to the LX pin should be as short as possible and there should not be any signal lines under the inductor. The feedback trace or OUT pin should be separate from any power trace and connect as closely as pos- sible 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 OUT pin to minimize the length of the high impedance feedback trace. 5. 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.

Fast Transient 600mA Step-Down ConverterSwitchReg TM PRODUCT DATASHEET AAT1141 Fast Transient 600mA Step-Down ConverterSwitchReg TM PRODUCT DATASHEET Step-Down Converter Design Example Specifications VO = 1.8V @ 600mA (adjustable using 0.6V version), Pulsed Load ΔILOAD = 300mA VIN = 2.7V to 4.2V (3.6V nominal) FS = 2MHz TAMB = 85°C 1.8V Output Inductor L1 = 3 · VO2 = 3 · 1.8V = 5.4µHµs A µs A (use 4.7μH; see Table 1) For Sumida inductor CDRH3D16, 4.7μH, DCR = 105mΩ. IPKL1 = IO + ΔIL1 = 0.6A + 0.055A = 0.655A2 PL1 = IO 2 · DCR = 0.6A2 · 105mΩ = 38mW 1.8V Output Capacitor VDROOP = 0.1V 4.7µH · 2MHz · 4.2V 23 RMSI L1 · F · VIN(MAX) = · 3 · ΔILOAD VDROOP · FS 3 · 0.3A 0.1V · 2MHz COUT = = = 4.48µF; use 10µF

• = 31.5mArms (VO) · (VIN(MAX) - VO) = Pesr = esr · IRMS 2 = 5mΩ · (31.5mA)2 = 5µW Input Capacitor Input Ripple VPP = 25mV CIN = = = 3.4µF; use 4.7µF1 - ESR · 4 · FS VPP IO - 5mW · 4 · 2MHz25mV 0.6A IO RMSI P = esr · IRMS 2= = 0.3Arms

Fast Transient 600mA Step-Down ConverterSwitchReg TM PRODUCT DATASHEET AAT1141 Fast Transient 600mA Step-Down ConverterSwitchReg TM PRODUCT DATASHEET AAT1141 Losses PTOTAL + (tsw · F · IO + IQ) · VIN IO 2 · (RDSON(HS) · VO + RDSON(LS) · [VIN -VO]) VIN + (5ns · 2MHz · 0.6A + 70μA) · 4.2V = 141mW 4.2V TJ(MAX) = TAMB + ΘJA · PLOSS = 85°C + (150°C/W) · 141mW = 106.2°C

Fast Transient 600mA Step-Down ConverterSwitchReg TM PRODUCT DATASHEET AAT1141 Fast Transient 600mA Step-Down ConverterSwitchReg TM PRODUCT DATASHEET Adjustable Version (0.6V device) VOUT (V) R2 = 59kΩ R1 (kΩ) R2 = 316kΩ1 R1 (kΩ) L1 ( μH) 0.8 19.6 105 2.2 0.9 29.4 158 2.2 1.0 39.2 210 2.2 1.1 49.9 267 2.2 1.2 59.0 316 2.2 1.3 68.1 365 2.2 1.4 78.7 422 4.7 1.5 88.7 475 4.7 1.8 118 634 4.7 1.85 124 732 4.7 2.0 137 1000 6.8 2.5 187 1270 6.8 3.3 267 1430 6.8 Fixed Version VOUT (V) R2 Not Used R1 (kΩ) L1 ( μH) 0.6-3.3V 0 4.7 Table 3: Evaluation Board Component Values. Manufacturer Part Number Inductance ( μH) Max DC Current (A) DCR ( Ω) Size (mm) LxWxH Type Sumida CDRH2D14 2.2 1.5 75 6.8 0.85 170 Table 4: Typical Surface Mount Inductors. Manufacturer Part Number Value Voltage Temp. Co. Case Murata GRM219R61A475KE19 4.7 μF 10V X5R 0805 Murata GRM21BR60J106KE19 10 μF 6.3V X5R 0805 Murata GRM21BR60J226ME39 22 μF 6.3V X5R 0805 Table 5: Surface Mount Capacitors. 1. For reduced quiescent current, R2 = 316k Ω.

Fast Transient 600mA Step-Down ConverterSwitchReg TM PRODUCT DATASHEET AAT1141 Fast Transient 600mA Step-Down ConverterSwitchReg TM PRODUCT DATASHEET

Ordering Information

Output Voltage1 Package Marking 2 Part Number (Tape and Reel)3 Adj 0.6 to VIN TSOT23-5 YJXYY AAT1141ICB-0.6-T1 Adj 0.6 to VIN SOT23-5 1AXYY AAT1141IGV-0.6-T1 1.0 SOT23-5 5AXYY AAT1141IGV-1.0-T1 1.2 SOT23-5 4VXYY AAT1141IGV-1.2-T1 1.5 SOT23-5 5BXYY AAT1141IGV-1.5-T1 1.8 SOT23-5 ZEXYY AAT1141IGV-1.8-T1 3.0 SOT23-5 5CXYY AAT1141IGV-3.0-T1 3.3 SOT23-5 5DXYY AAT1141IGV-3.3-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/about/quality.aspx.

Package Information

SOT23-54° ± 4° 0.15 ± 0.07 0.45 ± 0.15 0.10 BSC 1.20 ± 0.25 1.575 ± 0.125 2.80 ± 0.20 0.40 ± 0.10 0.60 REF 2.85 ± 0.15

1.90 BSC

0.95 BSC 1.10 ± 0.20 10° ± 5° GAUGE PLANE 0.075 ± 0.075

0.60 REF

All dimensions in millimeters. 1. Contact Sales for other voltage options. 2. XYY = assembly and date code. 3. Sample stock is generally held on part numbers listed in BOLD.

Fast Transient 600mA Step-Down ConverterSwitchReg TM PRODUCT DATASHEET AAT1141 Fast Transient 600mA Step-Down ConverterSwitchReg 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. TSOT23-5 0.450 ± 0.150 0.950 BSC

1.600 BSC

0.450 ± 0.150

0.127 BSC

Detail "A"

2.800 BSC

1.900 BSC

0° +10° -0° Top View End View Detail "A"Side View 0.950 ± 0.150 0.050 ± 0.050

2.900 BSC

All dimensions in millimeters.

Disposition / Action to be done: New Document Filename: Date: Posted by: DCC admin. Date: Form#: FM-QA-001 Rev. 01