DATA SHEET AAT3244 300mA Adjustable Dual CMOS Low Voltage LDO Linear Regulator General Description Features The AAT3244 is a dual, low input voltage, low dropout (LDO) linear regulator. Two integrated regulators provide high power outputs of 300mA from an input voltage range of 1.62V to 5.5V. • Low Input Voltage ▪ 1.62V to 5.5V • Ultra-Low Adjustable Output Voltage ▪ 3.6V to 0.6V • High Output Current ▪ 300mA per LDO • Low Dropout Voltage ▪ Typ 200mV @ 300mA • Low 85µA Quiescent Current (Both LDOs On) • High Output Accuracy: ±1.5% • Independent Input Supply and Enable Pins • Over-Temperature Protection • 12-Pin TSOPJW Package • -40°C to +85°C Temperature Range The AAT3244 has independent voltage inputs and enable pins for increased design flexibility. The device features a very low quiescent current (typically 85µA) and low dropout voltages (200mV at full load), making it ideal for portable applications where battery life is critical. The AAT3244 is available in a space-saving, Pb-free 12-pin TSOPJW package and is capable of operation over the -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 VIN = 3.6V INA Enable A VCC VOUTA = 1.8V OUTA 118k ENA FBA 59k INB OUTB 267k CIN 1µF Enable B FBB ENB GND VOUTB = 3.3V 2.2µF 2.2µF 59k GND Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202260A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • August 10, 2012 1 DATA SHEET AAT3244 300mA Adjustable Dual CMOS Low Voltage LDO Linear Regulator Pin Descriptions Pin # Symbol 1 OUTA 2 INA 3 FBA 4 FBB 5 6 8 9 7, 10, 12 11 INB OUTB ENB VCC GND ENA Function 300mA regulator output pin; should be closely decoupled with a low equivalent series resistance (ESR) ceramic capacitor. Input voltage pin for LDOA; should be closely decoupled. Feedback input pin for LDOA. This pin is connected to OUTA. It is used to see the output of LDOA to regulate to the desired value via an external resistor divider. Feedback input pin for LDOB. This pin is connected to OUTB. It is used to see the output of LDOB to regulate to the desired value via an external resistor divider. Input voltage pin for LDOB; should be closely decoupled. 300mA regulator output pin; should be closely decoupled with a low ESR ceramic capacitor. Enable pin for LDOB. Active high. VEN must be less than or equal to VCC. Input bias supply. Connect to an “always ON” supply voltage between 2.7V and 5.5V. Ground connection pin. Enable pin for LDOA. Active high. VEN must be less than or equal to VCC. Pin Configuration TSOPJW-12 (Top View) 2 OUTA 1 12 GND INA 2 11 ENA FBA 3 10 GND FBB 4 9 VCC INB 5 8 ENB OUTB 6 7 GND Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202260A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • August 10, 2012 DATA SHEET AAT3244 300mA Adjustable Dual CMOS Low Voltage LDO Linear Regulator Absolute Maximum Ratings1 Symbol VCC, VIN VFB VEN TJ TLEAD Description Input Voltage, LDO Input Voltage to GND FB to GND EN to GND Operating Junction Temperature Range Maximum Soldering Temperature (at leads, 10 sec) Value - 0.3 to 6.0 -0.3 to VIN + 0.3 -0.3 to 6.0 -40 to 150 300 Units V °C Thermal Information Symbol PD qJA Description Maximum Power Dissipation (TA = 25°C) Thermal Resistance2 Value Units 625 160 mW °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. 2. Mounted on an FR4 board. Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202260A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • August 10, 2012 3 DATA SHEET AAT3244 300mA Adjustable Dual CMOS Low Voltage LDO Linear Regulator Electrical Characteristics1 VCC = VINA = VINB = 3.6V; TA = -40°C to +85°C, unless otherwise noted. Typical values are TA = 25°C. Symbol Description Bias Power Supply VCC Bias Power Supply Input IQ Quiescent Current ISHDN Shutdown Current UVLO Under-Voltage Lockout Voltage Conditions Min 2.7 VENA = VENB = VIN; ILOAD = 0 VENA = VENB = GND VCC Rising Hysteresis LDOA, LDOB; IOUT = 300mA VIN Input Voltage VOUT VFB VDO DVOUT/ VOUT /DVIN VEN(L) VEN(H) tEN IOUT ISD TSD THYS Output Voltage Tolerance IOUT = 1mA to 300mA TA = 25°C TA = -40°C to +85°C Feedback Voltage Dropout Voltage2 IOUT = 300mA Line Regulation3 VIN = VOUT + 1.0V to 5.0V Enable Threshold Low Enable Threshold High Turn-On Enable Time Output Current Shutdown Current Over-Temperature Shutdown Threshold Over-Temperature Shutdown Hysteresis Typ 85 Max Units 5.5 160 1.0 2.6 V µA µA V mV 5.5 2.0 3.5 0.606 300 V V mV 0.09 %/V 0.6 VCC V V µs mA µA °C °C 200 1.62 -2.0 -3.5 0.594 0.6 200 1.5 100 VIN(MIN) = 2.5V VIN = 5V 300 1.0 140 15 % 1. The AAT3244 is guaranteed to meet performance specifications over the -40°C to +85°C operating temperature range and is assured by design, characterization, and correlation with statistical process controls. 2.VDO is defined as VIN - VOUT when VOUT is 98% of nominal. 3.CIN = 10µF. 4 Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202260A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • August 10, 2012 DATA SHEET AAT3244 300mA Adjustable Dual CMOS Low Voltage LDO Linear Regulator Typical Characteristics Dropout Voltage vs. Temperature Output Voltage vs. Input Voltage (VOUT = 2.5V) 220 2.60 200 2.55 100mA Output Voltage (V) Dropout Voltage (mV) (VOUT = 2.5V; IOUT = 300mA) 180 160 140 120 100 80 60 -40 -15 10 35 60 2.40 2.35 2.25 Output Voltage (V) Output Voltage (V) 1.55 1.70 1.60 1.50 100mA 200mA 300mA 1.30 2.0 2.1 2.2 2.3 2.4 3.0 1.50 1.45 1.40 1.35 100mA 200mA 300mA 1.30 1.25 1.20 1.6 2.5 Input Voltage (V) 1.7 1.8 1.9 2.0 2.1 2.2 2.3 2.4 2.5 Input Voltage (V) Dropout Voltage vs. Output Current Quiescent Current vs. Input Voltage (VOUT = 2.5V) (VOUT = 2.5V) 180 120 Quiescent Current (µA) Dropout Voltage (mV) 2.9 (VOUT = 1.5V; VCC = 3.6V) 1.60 1.40 2.8 Output Voltage vs. Input Voltage 1.80 1.9 2.7 Input Voltage (V) 1.90 1.8 2.6 (VOUT = 1.8V; VCC = 3.6V) 1.7 150mA 2.30 Output Voltage vs. Input Voltage 1.20 1.6 300mA 250mA 200mA 2.45 2.20 2.5 85 Temperature (°C) 50mA 2.50 160 85°C 140 120 25°C 100 80 60 40 -40°C 20 0 110 100 85°C 25°C 90 80 70 60 -40°C 50 40 0 50 100 150 200 Output Current (mA) 250 300 2.7 2.9 3.1 3.3 3.5 3.7 3.9 4.1 4.3 4.5 4.7 4.9 5.1 5.3 5.5 Input Voltage (V) Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202260A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • August 10, 2012 5 DATA SHEET AAT3244 300mA Adjustable Dual CMOS Low Voltage LDO Linear Regulator Typical Characteristics Quiescent Current vs. Temperature Output Voltage vs. Temperature (VOUT = 2.5V) (VIN = 3.6V; VOUT = 2.5V) 2.60 VIN = 3.0V 86 VIN = 3.6V 84 82 2.58 Output Voltage (V) Quiescent Current (µA) 88 VIN = 4.2V 80 78 76 74 72 -40 -15 10 35 60 2.56 2.54 50mA 2.52 300mA 2.50 2.48 2.46 2.44 2.42 -40 85 Temperature (°C) 100mA 200mA -15 2.5 2 2.0 0 1.5 1.0 0.5 0.0 Output Voltage Error (%) Enable (top) (V) 4 2.00 Output Voltage (bottom) (V) 3.0 Time (50µs/div) 1.50 1.00 VIN = 2.7V 0.50 VIN = 3.0V 0.00 -0.50 VIN = 3.6V -1.00 VIN = 4.2V -1.50 -2.00 1 10 100 1000 Output Current (mA) Load Transient Load Transient (1mA–200mA; VOUT = 1.8V) (200mA–300mA; VOUT = 1.8V) 0.1 50 25 0 -25 -50 Output Current (top) (A) 0.2 0.2 0.1 0.0 150 100 50 0 -50 -100 Time (50µs/div) Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202260A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • August 10, 2012 Output Voltage (AC coupled) (bottom) (mV) 0.3 0.3 Output Voltage (AC coupled) (bottom) (mV) 0.4 Output Current (top) (A) 85 (VOUT = 2.5) 6 0 6 60 Load Regulation (VOUT = 1.8V) Time (50µs/div) 35 Temperature (°C) Turn-On Time 0.0 10 DATA SHEET AAT3244 300mA Adjustable Dual CMOS Low Voltage LDO Linear Regulator Typical Characteristics Line Transient Over-Current Protection (3.6V– 4.2V; VOUT = 1.8V) 3.5 3.0 2.5 100 2.0 50 1.5 0 1.0 -50 0.5 -100 Time (50µs/div) 3.5 3.0 2.5 Current (A) Input Voltage (top) (V) 4.0 Output Voltage (AC coupled) (bottom) (mV) 4.5 2.0 1.5 1.0 0.5 0.0 Time (50ms/div) Ground Current vs. Input = 4.2V VINVoltage Enable Threshold Voltage vs.VINInput = 4.2VVoltage VIN = 2.7V 1.4 130 1.3 120 Ground Current (µA) Enable Voltage (V) VIN = 2.7V VIN = 3.6V 1.2 1.1 VIH 1.0 0.9 0.8 0.7 VIL VIN = 3.6V 110 100 IOUT = 300mA IOUT = 100mA 90 80 IOUT = 50mA IOUT = 10mA 70 60 0.6 2.5 2.7 2.9 3.1 3.3 3.5 3.7 3.9 4.1 4.3 4.5 4.7 4.9 5.1 5.3 5.5 Input Voltage (V) 3 3.5 4 4.5 5 5.5 Input Voltage (V) Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202260A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • August 10, 2012 7 DATA SHEET AAT3244 300mA Adjustable Dual CMOS Low Voltage LDO Linear Regulator Functional Block Diagram INA OUTA ENA FBA VCC LDO Bias Voltage Reference FBB ENB INB OUTB GND Functional Description Applications Information The AAT3244 is a high performance, low input voltage, dual LDO linear regulator. Both LDOA and LDOB are capable of delivering 300mA of current within power dissipation limits. The LDOs are designed to operate with low-cost ceramic capacitors. For added flexibility, both regulators have independent input voltages operating from 1.62V to 5.5V, but share a common bias voltage, VCC. The VCC voltage should be tied to the highest system voltage available and should be available at all times. Each regulator has an independent enable pin. An external feedback pin for each LDO allows programming the output voltage from 3.6V to 0.6V. The regulators have thermal protection in case of adverse operating conditions. To assure the maximum possible performance is obtained from the AAT3244, please refer to the following application recommendations. Refer to the Thermal Considerations section of this datasheet for details on device operation at maximum output current loads. Input Capacitor A 1µF or larger capacitor is typically recommended for CIN in most applications. A CIN capacitor is not required for basic LDO regulator operation. However, if the AAT3244 is physically located more than three centimeters from an input power source, a CIN capacitor will be needed for stable operation. CIN should be located as close to the device supply pin as practically possible. CIN values greater than 1µF will offer superior input line transient response and will assist in maximizing the highest possible power supply ripple rejection. Ceramic, tantalum, or aluminum electrolytic capacitors may be selected for CIN. There is no specific capacitor ESR requirement for CIN. However, for 300mA LDO regu- 8 Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202260A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • August 10, 2012 DATA SHEET AAT3244 300mA Adjustable Dual CMOS Low Voltage LDO Linear Regulator lator output operation, ceramic capacitors are recommended due to their inherent capability to withstand input current surges from low impedance sources such as batteries in portable devices, over tantalum capacitors, for CIN. Output Capacitor For proper load voltage regulation and operational stability, a capacitor is required between pins OUT and GND. The COUT capacitor connection to the LDO regulator ground pin should be made as direct as practically possible for maximum device performance. The AAT3244 has been specifically designed to function with very low ESR ceramic capacitors. For best performance, ceramic capacitors are recommended. Typical output capacitor values for maximum output current conditions range from 1µF to 10µF. Applications requiring low output noise and optimum power supply ripple rejection should use 2.2µF or greater for COUT. If desired, COUT may be increased without limit. In low output current applications where output load is less than 10mA, the minimum value for COUT can be as low as 0.47µF. Capacitor Characteristics Ceramic composition capacitors are highly recommended over all other types of capacitors for use with the AAT3244. Ceramic capacitors offer many advantages over their tantalum and aluminum electrolytic counterparts. A ceramic capacitor typically has very low ESR, is lower cost, has a smaller PCB footprint, and is nonpolarized. Line and load transient response of the LDO regulator is improved by using low ESR ceramic capacitors. Since ceramic capacitors are non-polarized, they are not prone to incorrect connection damage. Ceramic Capacitor Materials Ceramic capacitors less than 0.1µF are typically made from NPO or C0G materials. NPO and C0G materials generally have tight tolerance and are very stable over temperature. Larger capacitor values are usually composed of X7R, X5R, Z5U, or Y5V dielectric materials. The last two material types are not recommended for use with LDO regulators since the capacitor tolerance can vary more than ±50% over the operating temperature range of the device. A 2.2µF Y5V capacitor could be reduced to 1µF over temperature; this could cause problems for circuit operation. X7R and X5R dielectrics are much more desirable. The temperature tolerance of X7R dielectric is better than ±15%. Capacitor area is another contributor to ESR. Capacitors which are physically large in size will have a lower ESR when compared to a smaller sized capacitor of an equivalent material and capacitance value. These larger devices can improve circuit transient response when compared to an equal value capacitor in a smaller package size. Consult capacitor vendor datasheets carefully when selecting capacitors for LDO regulators. Enable Function The AAT3244 features an LDO regulator enable/disable function. Each LDO has its own dedicated enable pin. These pins (ENA, ENB) are active high and are compatible with CMOS logic. To assure the LDO regulators will switch on, 1.5V ≤ VEN ≤ VCC In shutdown, the AAT3244 will consume less than 1.0µA of current. If the enable function is not needed in a specific application, it may be tied to VCC to keep the LDO regulator in a continuously on state. Equivalent Series Resistance ESR is a very important characteristic to consider when selecting a capacitor. ESR is the internal series resistance associated with a capacitor that includes lead resistance, internal connections, size and area, material composition, and ambient 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. Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202260A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • August 10, 2012 9 DATA SHEET AAT3244 300mA Adjustable Dual CMOS Low Voltage LDO Linear Regulator Thermal Protection VOUT from exceeding VIN. In applications where there is a greater danger of VOUT exceeding VIN for extended periods of time, it is recommended to place a Schottky diode across INA/B to OUTA/B (connecting the cathode to INA/B and anode to OUTA/B). The Schottky diode forward voltage should be less than 0.45V. The AAT3244 has an internal thermal protection circuit which will activate when the device die temperature exceeds 140°C. The LDO regulator output will remain in a shutdown state until the internal die temperature falls back approximately 15°C below the trip point. Low Voltage Input Bias Considerations No-Load Stability The input voltage of both LDOs is designed to operate down to 1.62V input. However, to operate the LDO to its full potential, the AAT3244 requires a minimum bias voltage (VCC) of 2.7V for all LDO input voltages between 1.62V and 2.7V. In portable systems utilizing single-cell Lithium-ion batteries, the VCC pin may be connected directly to the battery. In non-portable applications, the voltage can be connected to any supply from 2.7V to 5.5V. In the event that one of the input supplies is above 2.7V, this can also be connected to VCC, assuming that the supply will always be available. The AAT3244 is designed to maintain output voltage regulation and stability under operational no-load conditions. This is an important characteristic for applications where the output current may drop to zero. Reverse Output-to-Input Voltage Conditions and Protection Under normal operating conditions, a parasitic diode exists between the output and input of the LDO regulator. The input voltage should always remain greater than the output load voltage, maintaining a reverse bias on the internal parasitic diode. Adjustable Output Resistor Selection Resistors R1, R2 and R3, R4 of Figure 1 program the outputs 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 suggested value for R2 and R4 is 59kW. Decreased resistor values are necessary to maintain noise immunity on the FB pin, resulting in increased quiescent current. Table 1 summarizes the resistor values for various output voltages. Conditions where VOUT might exceed VIN should be avoided since this would forward bias the internal parasitic diode and allow excessive current flow into the OUTA/B pins, possibly damaging the LDO regulator. In applications where there is a possibility of VOUT exceeding VIN for brief amounts of time during normal operation, the use of a larger value CIN capacitor is highly recommended. A larger value of CIN with respect to COUT will result in a slower CIN decay rate during shutdown, thus preventing VCC 9 12 7 INA 2 C1 1uF ENA 11 GND TSOPJW-12 VCC OUTA R1 Adj. GND FBA ENA INB C2 1uF ENB 8 ON/OFF C4 R2 59K AAT3244 FBB GND 10 (Optional) 6 R3 Adj. INB ENB 22pF 2.2uF OUTB 5 OUTA C6 3 INA ON/OFF (Optional) 1 4 OUTB C7 22pF C5 2.2uF R4 59K Figure 1: AAT3244 Schematic. 10 Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202260A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • August 10, 2012 DATA SHEET AAT3244 300mA Adjustable Dual CMOS Low Voltage LDO Linear Regulator VOUT R1 = V - 1 · R2 REF With enhanced transient response for extreme pulsed load application, an external feed-forward capacitor, (C6 and C7 in Figure 1), can be added. VOUT (V) R2 = 59kW R1 (kW) R2 = 221kW R1 (kW) 0.8 0.9 1.0 1.1 1.2 1.3 1.4 1.5 1.8 1.85 2.0 2.5 3.3 3.6 19.6 29.4 39.2 49.9 59.0 68.1 78.7 88.7 118 124 137 187 267 295 75 113 150 187 221 261 301 332 442 464 523 715 1000 1105 Table 1. Adjustable Resistor Values For LDO Regulator. Thermal Considerations and High Output Current Applications The AAT3244 is designed to deliver continuous output load currents of 300mA under normal operating conditions and can supply up to 600mA during circuit start-up conditions. This is desirable for applications where there might be a brief high inrush current during a power-on event. The limiting characteristic for the maximum output load current safe operating area is essentially package power dissipation and the internal preset thermal limit of the device. In order to obtain high operating currents, careful board layout and circuit operating conditions need to be taken into account. The following discussions will assume the LDO regulator is mounted on a printed circuit board utilizing the minimum recommended footprint as stated in the layout considerations section of this document. At any given ambient temperature (TA), the maximum package power dissipation can be determined by the following equation: PD(MAX) = TJ(MAX) - TA θJA Constants for the AAT3244 are TJ(MAX) (the maximum junction temperature for the device, which is 125°C) and qJA = 160°C/W (the package thermal resistance). Typically, maximum conditions are calculated at the maximum operating temperature of TA = 85°C and under normal ambient conditions where TA = 25°C. Given TA = 85°C, the maximum package power dissipation is 250mW. At TA = 25°C, the maximum package power dissipation is 625mW. The maximum continuous output current for the AAT3244 is a function of the package power dissipation and the input-to-output voltage drop across the LDO regulator. To determine the maximum output current for a given output voltage, refer to the following equation. This calculation accounts for the total power dissipation of the LDO regulator, including that caused by ground current. PD(MAX) = [(VIN - VOUTA)IOUTA + (VIN · IGND)] + [(VIN - VOUTB)IOUTB + (VIN · IGND)] This formula can be solved for IOUTA to determine the maximum output current for LDOA: IOUTA(MAX) = PD(MAX) - (2 · VIN · IGND) - (VIN - VOUTB) · IOUTB VIN - VOUTA The following is an example for a 2.5V output: VOUTA = 2.5V VOUTB = 1.5V IOUTB = 150mA VIN = 4.2V IGND = 125µA IOUTA(MAX) = 625mW - (2 · 4.2V · 125µA) - (4.2 - 1.5) · 150mA 4.2 - 2.5 IOUTA(MAX) = 129mA From the discussion above, PD(MAX) was determined to equal 625mW at TA = 25°C. Therefore, with Regulator B delivering 150mA at 1.5V, Regulator A can sustain a constant 2.5V output at a 129mA load current at an ambient temperature of 25°C. Higher input-to-output voltage differentials can be obtained with the AAT3244, while maintaining device functions within the thermal safe operating area. To accomplish this, the device thermal resistance must be reduced by increasing the heat sink area or by operating the LDO regulator in a duty-cycled mode. Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202260A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • August 10, 2012 11 DATA SHEET AAT3244 300mA Adjustable Dual CMOS Low Voltage LDO Linear Regulator For example, an application requires VIN = 4.2V while VOUTA = 1.5V at a 300mA load, VOUTB = 1.5V at a 200mA load, and TA = 25°C. To maintain this high input voltage and output current level, the LDO regulator must be operated in a duty-cycled mode. Refer to the following calculation for duty-cycle operation: IGND = 125μA IOUTA = 300mA IOUTB = 200mA VIN = 4.2V VOUT = 1.5V PD(MAX) is assumed to be 625mW %DC = 100(PD(MAX)) [(VIN - VOUTA)IOUTA + (VIN · IGND)] + [(VIN - VOUTB)IOUTB + (VIN · IGND)] %DC = 100 · 625mW [(4.2V - 1.5V)300mA + (4.2V · 125µA)] + [(4.2V - 1.5V)200mA + (4.2V · 125µA)] %DC = 46.3% %DC = 46.3% For a 300mA output current and a 2.7V drop across the AAT3244 at an ambient temperature of 25°C, the maximum on-time duty cycle for the device would be 46.3%. Under-Voltage Lockout Under-voltage lockout (UVLO) guarantees sufficient VCC bias and proper operation of all internal circuits prior to activation. Printed Circuit Board Layout Recommendations The suggested PCB layout for the AAT3244 in a TSOPJW-12 package is shown in Figures 2 and 3. The following guidelines should be used to help ensure a proper layout. 1. Connect the input capacitors (C1 and C2) connect as close as possible to input pins (Pin 2 and Pin 5) and GND (Pin 10). 2. Separate the output traces of the feedback resistors (R1 and R3) from any power trace and connect as close as possible to the load point. Sensing along a high-current load trace will degrade DC load regulation. Place feedback resistors as close as possible to the FB pin (Pin 3 and Pin 4) to minimize the length of the high impedance feedback trace. 3. Keep the resistance of the trace from the load returns to GND (Pin 10) to a minimum. This will help to minimize any error in DC regulation due to differences in the potential of the internal signal ground and the power ground. 4. The feedback node is connected directly to the noninverting input of the error amplifier, thus any noise or ripple from the divider resistors will be subsequently amplified by the gain of the error amplifier. This effect can increase noise seen on the LDO regulator output, as well as reduce the maximum possible power supply ripple rejection. For low output noise and highest possible power supply ripple rejection performance, it is critical to connect the divider resistors (R2 and R4) and output capacitors (C4 and C5) directly to the LDO regulator ground pin. This method will eliminate any load noise or ripple current feedback through the LDO regulator. Evaluation Board Layout The AAT3244 evaluation layout follows the recommended printed circuit board layout procedures and can be used as an example for good application layouts (see Figures 2 and 3). Note: Board layout shown is not to scale. 12 Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202260A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • August 10, 2012 DATA SHEET AAT3244 300mA Adjustable Dual CMOS Low Voltage LDO Linear Regulator Figure 2: AAT3244 Evaluation Board Top Side Layout. Figure 3: AAT3244 Evaluation Board Bottom Side Layout. Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202260A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • August 10, 2012 13 DATA SHEET AAT3244 300mA Adjustable Dual CMOS Low Voltage LDO Linear Regulator Ordering Information Voltage Package LDO A LDO B Marking1 Part Number (Tape and Reel)2 TSOPJW-12 0.6V 0.6V WTXYY AAT3244ITP-AA-T1 Skyworks Green™ products are compliant with all applicable legislation and are halogen-free. For additional information, refer to Skyworks Definition of Green™, document number SQ04-0074. Package Information TSOPJW-12 2.85 ± 0.20 2.40 ± 0.10 0.20 + 0.10 - 0.05 0.50 BSC 0.50 BSC 0.50 BSC 0.50 BSC 0.50 BSC 7° NOM 0.055 ± 0.045 All dimensions in millimeters. 0.04 REF 0.15 ± 0.05 + 0.10 1.00 - 0.065 0.9625 ± 0.0375 3.00 ± 0.10 4° ± 4° 0.45 ± 0.15 0.010 2.75 ± 0.25 1. XYY = assembly and date code. 2. Sample stock is generally held on part numbers listed in BOLD. Copyright © 2012 Skyworks Solutions, Inc. All Rights Reserved. Information in this document is provided in connection with Skyworks Solutions, Inc. (“Skyworks”) products or services. These materials, including the information contained herein, are provided by Skyworks as a service to its customers and may be used for informational purposes only by the customer. Skyworks assumes no responsibility for errors or omissions in these materials or the information contained herein. Skyworks may change its documentation, products, services, specifications or product descriptions at any time, without notice. Skyworks makes no commitment to update the materials or information and shall have no responsibility whatsoever for conflicts, incompatibilities, or other difficulties arising from any future changes. No license, whether express, implied, by estoppel or otherwise, is granted to any intellectual property rights by this document. 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Customers are responsible for their products and applications using Skyworks products, which may deviate from published specifications as a result of design defects, errors, or operation of products outside of published parameters or design specifications. 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 specifications 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 identification 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. 14 Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202260A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • August 10, 2012