DATA SHEET AAT2614 Step-Down DC/DC Converter with Quad High PSRR LDOs General Description Features The AAT2614 is a multiple rail power management IC. It integrates a 600mA high-frequency switching-converter and four 300mA linear regulators. The switching power supply is a highly-integrated monolithic step-down converter operating at 1.7MHz, achieving high efficiency with small external components. The four linear regulators are high PSRR low dropout regulators (LDOs) providing accurate regulation and excellent transient response. • Current Mode Control DC/DC Converter: ▪ Fixed Factory Programmable Output Up to 600mA ▪ 1.7MHz Switching Frequency ▪ Up to 90% Efficiency ▪ Integrated Switching Power FETS ▪ Integrated Compensation Network ▪ Internal Current Limit •4 Low Dropout Regulators with Separate Enable Pins: ▪ 300mA per Channel ▪ High PSRR ▪ Factory Programmable Output •Integrated Soft-Start •Over-Current Protection •Over-Thermal Protection •TQFN33-20 and WLCSP-16 Packages The step-down converter and the four LDOs are all fixed voltage outputs of seven combinations for 1V, 1.2V, 1.3V, 1.8V, 2.8V, 3.0V and 3.3V. Integrated over-current or over-temperature protection circuitry becomes active when overload or over-temperature fault occurs and the AAT2614 recovers automatically when the fault is removed. The AAT2614 is available in a Pb-free, thermally enhanced 20-pin TQFN33 package and a 16-bump 0.4 pitch CSP package. Applications • • • • • Cellular Phones I/O Power Memory Power Processor Core Power Smart Handheld Devices Typical Application 2.5V to 5.5V 2.2μF INL1 2.5V to 5.5V 2.2μF INL2 OUTL1 1μF OUTL2 1μF AAT2614-2 ENL1 ENL2 ENL3 ENL4 OUTL3 OUTL4 2.5V to 5.5V 4.7μF INB LX OUTB AGND PGND 2.8V 300mA 2.8V 1μF 300mA 2.8V 300mA 1μF 2.2μH ENB 1.8V 300mA 1.2V, 600mA 10μF Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202209B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • March 20, 2013 1 DATA SHEET AAT2614 Step-Down DC/DC Converter with Quad High PSRR LDOs Pin Descriptions Pin Number TQFN33-20 WLCSP-16 Symbol Function 1 C3 INL1 I/O 2 D3 ENL1 I 3 B2 ENL2 I 4 C2 INB I 5 D2 LX I/O 6,8,10 7 D1 C1 PGND ENB I/O I 9 B1 OUTB O 11 A1 ENL3 I 12 A2 ENL4 I 13,17 14 15 B4 A3 B3 AGND OUTL4 OUTL3 I/O O O 16 A4 INL2 I/O 18 19 20 EP N/C C4 D4 N/C N/C OUTL1 OUTL2 GND O O Description Power input for LDO1/2. Connect a 2.2μF capacitor between this pin and ground. Active high enable pin. When pulled high, LDO1 regulates its output to the programmed voltage value. Active high enable pin. When pulled high, LDO2 regulates its output to the programmed voltage value. Power input pin for the switching converter. Connect a 4.7μF capacitor between ground and INB. DC/DC step-down converter switching node. Connect LX to the terminal of the inductor. DC/DC converter power ground. Active high step-down DC/DC converter enable pin. DC/DC converter output pin. Connect OUTB to a 10μF capacitor connected to ground. Active high enable pin. When pulled high, LDO3 regulates its output to the programmed voltage value. Active high enable pin. When pulled high, LDO4 regulates its output to the programmed voltage value. Analog ground. LDO4 output. Connect a 1μF capacitor between the pin and ground. LDO3 output. Connect a 1μF capacitor between the pin and ground. Power input for LDO3/4. Connect a 2.2μF capacitor between the pin and ground. Not connected. LDO1 output. Connect a 1μF capacitor between the pin and ground. LDO2 output. Connect a 1μF capacitor between the pin and ground. Exposed pad. Pin Configuration TQFN33-20 (Top View) WLCSP-16 (Top View) INL2 AGND N/C OUTL1 OUTL2 20 INL1 ENL1 ENL2 INB LX 19 18 17 15 2 14 3 13 4 12 5 11 7 8 9 3 4 A OUTL2 OUTL1 AGND INL2 OUTL3 OUTL4 AGND ENL4 ENL3 B ENL1 INL1 OUTL3 OUTL4 C LX INB ENL2 ENL4 D PGND ENB OUTB ENL3 10 PGND OUTB PGND ENB PGND 2 2 16 1 6 1 Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202209B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • March 20, 2013 DATA SHEET AAT2614 Step-Down DC/DC Converter with Quad High PSRR LDOs Absolute Maximum Ratings1 Symbol Description Value INL1, INL2, INB, OUTL1, OUTL2, OUTL3, OUTL4 ENL1, ENL2, ENL3, ENL4 ENB, OUTB LX to PGND PGND to AGND, AGND to AGND Operating Temperature Range Storage Temperature Range Maximum Soldering Temperature (at leads, 10 sec.) TA TS TLEAD -0.3 to 6.0 -0.3 to 6.0 -0.3 to VINB -0.3 to VINB -0.3 to +0.3 -40 to 150 -65 to 150 300 Units V °C Thermal Information3 Symbol Description ΘJA Thermal Resistance4 PD Maximum Power Dissipation Value TQFN33-20 WLCSP-16 TQFN33-20 WLCSP-16 50 90.4 2 1.1 Units °C/W 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. Based on long-term current density limitation. 3. Mounted on an FR4 board. 4. Thermal Resistance measured with the device on multi-layer evaluation board in a thermal oven. The amount of power dissipation which will cause the thermal shutdown to activate will depend on the ambient temperature and the PC board layout ability to dissipate the heat. De-rate 30mW/°C above 70°C. Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202209B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • March 20, 2013 3 DATA SHEET AAT2614 Step-Down DC/DC Converter with Quad High PSRR LDOs Electrical Characteristics1 VINB = VINL1 = VINL2 = 3.6V, L = 2.2μH, CINL1, 2 = 2.2μF, CINB = 4.7μF, COUTB = 10μF, VINLx = VOUTLx +0.7V, VENLx = VINLx , COUL1, o 2, 3, 4 = 1μF, TA= 25 C unless otherwise noted. Symbol Description Conditions Min PMU Operation VIN Input Voltage UVLO TSD Under-Voltage Lockout Thermal Shutdown Quiescent Current IQ Logic Control VIH Input Logic High Threshold VIL Input Logic Low Threshold DC-DC Step-Down Converter Shutdown Current from INB Pin ISHDN IQ Quiescent Current ILIM P-Channel Current Limit VOUT_ACC Output Voltage Accuracy FSW Operating Switching Frequency RDS(ON)H High-Side Switch On Resistance RDS(ON)L Low-Side Switch On Resistance LDO ISHDN ILIM VDROP VOUTL_ACC ΔVOUTL/ IOUTL VOUTL/ VINL 2.5 Rising Hysteresis Threshold Hysteresis VENB > 1.5V, VENL1,2,3,4 >1.5V, no load IOUTB IOUTB IOUTB IOUTB = = = = 4 800 -3 200mA 200mA, VINB = 2.5V 200mA 200mA, VINB = 2.5V VENB = VENL < 0.4V RLOAD = 1Ω IOUTL = 300mA TA = -40°C to 85°C, 1mA load Load Regulation 1mA < IOUTL < 300mA Line Regulation VINL1 = VINL2 = 2.7V to 5.5V Output Voltage Temperature Coefficient 0.1 120 COUT1,2,3,4 = 1μF, VINL = VOUTL1,2,3,4 + 1V Max Units 5.5 420 V V mV °C °C μA VINB 0.4 V V 1 280 μA μA mA % MHz 3 1.7 230 280 180 220 500 -3 0.3 f = 1kHz f = 10kHz VOUTL_TC 1.5 VENB < 0.4V, VENL 1, 2, 3, 4 < 0.4V VENL 1, 2, 3, 4 < 0.4V , VENB >1.5V , IOUTB = 0mA VINB = 2.7V to 5.5V TA = -40°C to 85°C, 20mA load Shutdown Current Output Current Limit Dropout Voltage Output Voltage Accuracy Power Supply Rejection Ratio 1.9 100 140 15 260 ENL1, ENL2, ENL3, ENL4, ENB ENL1, ENL2, ENL3, ENL4, ENB f = 100Hz PSRR Typ IOUT = 10mA IOUT = 150mA IOUT = 10mA IOUT = 150mA IOUT = 10mA IOUT = 150mA mΩ mΩ 1 600 500 3 μA mA mV % 0.6 % 0.2 %/V 75 75 70 70 50 50 dB 100 ppm/°C Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202209B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • March 20, 2013 DATA SHEET AAT2614 Step-Down DC/DC Converter with Quad High PSRR LDOs Supply Current vs. Supply Voltage Buck Quiescent Current vs. Supply Voltage (VENB, VENL > 1.5V) (VOUTB = 1.2V, VENB > 1.5V, VENL < 0.4V) 300 140 280 130 260 120 IQ (µA) Supply Current (µA) Typical Characteristics−Step-Down (Buck) Converter 240 85°C 25°C -40°C 220 110 85°C 25°C -40°C 100 90 200 2.5 3.0 3.5 4.0 4.5 5.0 5.5 2.5 3.0 3.5 Supply Voltage (V) Switching Frequency vs. Temperature Switching Frequency (MHz) Switching Frequency (MHz) 1.72 1.70 1.68 1.66 1.64 1.62 10 5.0 5.5 (VOUTB = 1.2V, IOUTB = 600mA) 1.74 -15 4.5 Switching Frequency vs. Input Voltage (VINB = 3.6V, IOUT = 600mA) 1.60 -40 4.0 Supply Voltage (V) 35 60 85 1.74 1.72 1.70 1.68 1.66 1.64 2.5 3.0 Temperature (°C) 3.5 4.0 4.5 5.0 5.5 Input Voltage (V) Buck Efficiency vs. Output Current UVLO Voltage vs. Temperature (VOUT = 1.2V; L = 2.2µH) 100 1.95 90 1.91 70 60 50 40 VIN = 2.5V VIN = 3.6V VIN = 4.2V VIN = 5.0V VIN = 5.5V 30 20 10 0 0.1 1 10 100 Output Current (mA) 1000 VEOC (V) Efficiency (%) 80 1.87 1.83 1.79 1.75 -40 UVLO_H UVLO_L -15 10 35 60 85 Temperature (°C) Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202209B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • March 20, 2013 5 DATA SHEET AAT2614 Step-Down DC/DC Converter with Quad High PSRR LDOs Typical Characteristics−Step-Down (Buck) Converter Buck Output Voltage vs. Temperature Buck Line Regulation (VINB = 3.6V, IOUT = 600mA) (VOUTB = 1.2V, L = 2.2µH) 1 1.0 IOUTB = 10mA IOUTB = 100mA IOUTB = 300mA IOUTB = 600mA Output Error (%/V) 0.8 VOUT Error (%) 0.6 0.2 -0.2 -0.6 0.6 0.4 0.2 0 -0.2 -0.4 -0.6 -0.8 -1.0 -40 -15 10 35 60 -1 2.5 85 3.0 Temperature (°C) 3.5 4.0 4.5 5.0 5.5 Input Voltage (V) Buck Load Regulation EN VIH vs. Supply Voltage (VINB = 3.6V; VOUTB = 1.2V; L = 2.2µH) 1 1.20 1.10 0.6 0.4 EN VIH (V) Output Error (%) 0.8 0.2 0 -0.2 -0.4 1.00 0.90 85°C 25°C -40°C 0.80 -0.6 -0.8 -1 10 70 130 190 250 310 370 430 490 550 610 0.70 2.5 3.0 Output Current (mA) 3.5 4.0 4.5 5.0 Supply Voltage (V) Soft Start EN VIL vs. Supply Voltage (VINB = 3.6V; VOUTB = 1.2V; IOUTB = 600mA) 1.2 EN VIL (V) 1.1 VENB (2V/div) 1.0 0 0.9 VOUTB (1V/div) 0 0.8 85°C 25°C -40°C 0.7 0.6 2.5 3.0 3.5 4.0 4.5 Supply Voltage (V) 6 5.0 IINB (0.2A/div) 0 5.5 Time (40µs/div) Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202209B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • March 20, 2013 5.5 DATA SHEET AAT2614 Step-Down DC/DC Converter with Quad High PSRR LDOs Typical Characteristics−Step-Down (Buck) Converter Buck Load Transient Buck Line Transient (VIN = 3.6V; VOUTB = 1.2V; CINB = 10µF; COUTB = 10µF) (VINB = 4V to 5V; CINB = 10µF; IOUTB = 600mA) VOUTB (200mV/div) 1.2 600mA IOUTB (200mA/div) VINB (1V/div) 4 VOUTB (100mV/div) 1.2 400mA 0A Time (40µs/div) Time (40µs/div) Output Ripple (VIN = 3.6V; VOUT = 1.2V; IOUT = 600mA; CINB = 4.7µF) VOUT1.2 (20mV/div) VLX (2V/div) 0 Time (0.4µs/div) Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202209B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • March 20, 2013 7 DATA SHEET AAT2614 Step-Down DC/DC Converter with Quad High PSRR LDOs Typical Characteristics−LDO Regulators LDO Output Voltage vs. Temperature LDO Quiescent Current vs. Supply Voltage (Single Channel) 34 0.6 LDO1 LDO2 LDO3 LDO4 0.2 32 IQ (µA) VOUT Error (%) 0.4 0.0 30 28 -0.2 85°C 25°C -40°C 26 -0.4 -0.6 -40 -15 10 35 60 24 2.5 85 3.0 3.5 4.5 LDO Line Regulation 5.5 Dropout Voltage vs. Load Current (VOUTL = 1.8V) (VOUT = 2.8V) 350 0.2 Dropout Voltage (mV) 0.16 0.12 0.08 0.04 0 -0.04 IOUTB = 10mA IOUTB = 100mA IOUTB = 300mA IOUTB = 600mA -0.08 -0.12 -0.16 -0.2 2.5 3.0 3.5 4.0 4.5 5.0 5.5 300 250 200 150 100 85°C 25°C -40°C 50 0 20 60 Input Voltage (V) 100 140 180 220 260 Load Current (mA) LDO Load Transient LDO Line Transient (VIN = 3.6V; VOUTL = 1.8V; CINL = 2.2µF; COUTL = 1µF) (VINB = 4V to 5V; IOUTL = 300mA) VOUTL (200mV/div) 1.8 VINL (1V/div) 4 VOUTL (100mV/div) 1.2 300mA IOUTL (200mA/div) 0A 10mA Time (100µs/div) 8 5.0 Supply Voltage (V) Temperature (°C) Output Error (%/V) 4.0 Time (40µs/div) Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202209B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • March 20, 2013 300 DATA SHEET AAT2614 Step-Down DC/DC Converter with Quad High PSRR LDOs Typical Characteristics−LDO Regulators LDO Power Supply Rejection Ratio, PSRR (IOUT1 = 10mA, BW = 100~100KHz) 100 Magnitude (dB) 90 80 70 60 50 40 30 20 10 0 1.00E+02 1.00E+03 1.00E+04 1.00E+05 Frequency (Hz) Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202209B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • March 20, 2013 9 DATA SHEET AAT2614 Step-Down DC/DC Converter with Quad High PSRR LDOs Block Diagram INB 4.7μF Buck ENB INL2 2.2μH 1.2V, 600mA P LX Control 10μF PGND 2.2μF P A P OUTB INL1 2.2μF A ENL4 Bias, Control, and OTP Thermal Shutdown LDO 4 1.8V 300mA 1μF OUTL4 A ENL3 LDO 3 2.8V 300mA 1μF OUTL3 A ENL2 LDO 2 2.8V 300mA 1μF OUTL 2 A LDO 1 2.8V 300mA 1μF OUTL 1 ENL1 A AGND Functional Description The AAT2614 is a compact power management solution. It integrates a step-down converter with four high PSRR low-dropout regulators to provide power from a wall adapter, USB port, or a single-cell Lithium Ion/Polymer battery or dual cell alkaline battery. The AAT2614 uses fixed-frequency peak current control architecture. Light load mode is used to enhance light load efficiency. Compensation is integrated to reduce the 10 number of external components and achieve excellent transient response and load and line regulation. The ideal 1.7MHz switching frequency allows the use of smaller output filter components for improved power density, reduced external component size, and optimized output voltage ripple. The AAT2614 has five separate enable pins to control buck converter and four LDO regulator outputs’ startup. Also see the “Enable Function” section in the Applications Information section of this datasheet. Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202209B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • March 20, 2013 DATA SHEET AAT2614 Step-Down DC/DC Converter with Quad High PSRR LDOs Synchronous Step-Down Converter Soft-Start The AAT2614 contains one high performance 600mA, 1.7MHz synchronous step-down converter. The stepdown converter operates to ensure high efficiency performance over all load conditions. Soft start increases the inductor current limit point linearly when the input voltage or enable input is applied. It limits the current surge seen at the input and eliminates output voltage overshoot. The input voltage range is from 2.5V to 5.5V, and the output voltage is fixed and can be trimmed as shown in the Ordering Information section of this datasheet. Power devices are sized for 600mA current capability while maintaining over 85% efficiency at full load. High efficiency is maintained at lower currents Current Limit and Over-Temperature Protection A high DC gain error amplifier with internal compensation controls the output. It provides excellent transient response and load/line regulation. The converter has soft start control to limit inrush current. Apart from the input capacitor, only a small L-C filter is required at the output side for the step-down converter to operate properly. Typically, a 2.2μH inductor and a 10μF ceramic capacitor are recommended for low output voltage ripple and small component size. Control Loop The converter is a peak current mode step-down converter. The inner, wide bandwidth loop controls the inductor peak current. The inductor current is sensed through the P-channel MOSFET (high side) and is also used for short circuit and overload protection. A fixed slope compensation signal is added to the sensed current to maintain stability for duty cycles greater than 50%. The peak current mode loop appears as a voltage programmed current source in parallel with the output capacitor. The output of the voltage error amplifier programs the current mode loop for the necessary peak inductor current to force a constant output voltage for all load and line conditions. The voltage feedback resistive divider is internal and the error amplifier reference voltage is 0.6V. The voltage loop has a high DC gain making for excellent DC load and line regulation. The internal voltage loop compensation is located at the output of the transconductance voltage error amplifier. For overload conditions the peak input current is limited. As load impedance decreases and the output voltage falls closer to zero, more power is dissipated internally, raising the device temperature. Thermal protection completely disables switching when internal dissipation becomes excessive, protecting the device from damage. The junction over-temperature threshold is 140°C with 15°C of hysteresis. LDO Regulator The advanced circuit design of the linear regulator is specifically optimized for very fast start-up and shutdown timing. This proprietary LDO is also tailored for superior transient response characteristics. These traits are particularly important for applications which require fast power supply timing. The high-speed turn-on capability is enabled through the implementation of a fast start control circuit, which accelerates the power up behavior of fundamental control 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 regulator is placed in the shutdown mode. This active fast shutdown circuit has no adverse effect on normal device operation. The LDO regulator output has been specifically 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 thermal protection. The combination of these two internal protection circuits gives a comprehensive safety system to guard against extreme adverse operating conditions. Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202209B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • March 20, 2013 11 DATA SHEET AAT2614 Step-Down DC/DC Converter with Quad High PSRR LDOs Application Information Step-down Converter Input Capacitor Select a 4.7uF to 10uF X7R or X5R ceramic capacitor for the input. To estimate the required input capacitor size, determine the acceptable input ripple voltage level (Vpp) and solve for C. The calculated value varies with input voltage and is a maximum when VIN is double the output voltage. CIN = V VO · 1- O VIN VIN VPP - ESR · fS IO VO D= V IN CIN(MIN) = 1 VPP - ESR · 4 · fS IO Where CIN is the input capacitance, VIN is the input voltage, VO is the output voltage, fS is the switching frequency, IO is the output current, ESR is the equivalent series resistor of output capacitor, and D is the duty cycle. The maximum input capacitor RMS current is: IRMS = IO · VO V · 1- O VIN 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. IRMS = IO 2 The maximum input voltage ripple also appears at 50% duty cycle. The input capacitor provides a low impedance loop for the edges of pulsed current drawn by the AAT2614. Low ESR/ ESL X7R and X5R ceramic capacitors are ideal for this function. To minimize parasitic inductances, 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. 12 The proper placement of the input capacitors (C1, C2, and C3) is shown in the evaluation board layout in Figure 2. A laboratory test set-up typically consists of two long wires running from the bench power supply to the evaluation 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 transients. Errors can also result in the loop phase and gain measurements. 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 inductance cannot be reduced to a level that does not affect the converter performance, a high ESR tantalum or aluminum 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 provides holdup during large load transitions. A typical 4.7μF 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 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 relationship of the output voltage droop during the three switching cycles to the output capacitance 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 equation establishes a limit on the minimum value for the output capacitor with respect to load transients. Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202209B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • March 20, 2013 DATA SHEET AAT2614 Step-Down DC/DC Converter with Quad High PSRR LDOs Output Inductor For most designs, the AAT2614 operates with inductor values of 1.0μH to 4.7μH. Inductors with low inductance values are physically smaller but generate higher inductor current ripple leading to higher output voltage ripple. The inductor value can be derived from the following equation: L= VOUT · (VIN - VOUT) VIN · ∆IL · fOSC Where ΔIL is inductor ripple current. Large value inductors result in lower ripple current and small value inductors result in high ripple current. Choose inductor ripple current approximately 30% of the maximum load current 0.6A, or ∆IL = 180mA Manufacturer’s specifications list both the inductor DC current rating, which is a thermal limitation, and the peak current rating, which is determined by the saturation characteristics. The inductor should not show any appreciable saturation under normal load conditions. The DC current rating of the inductor should be at least equal to the maximum load current plus half the inductor ripple current to prevent core saturation (0.6A + 180mA). 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. Thermal Calculations There are three types of losses associated with the AAT2614 step-down converters: switching losses, conduction losses, and quiescent current losses. Conduction losses are associated with the RDS(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, with continuous conduction mode (CCM), a simplified form of the losses is given by: VO VO PBUCK = IO2 · RDS(ON)P · V + RDS(ON)N · 1 - V IN IN + tSW · fS · IO · VIN + IQ · VIN Where IQ is the step-down converter quiescent current, tsw is the switching time, RDS(ON)P and RDS(ON)N are the high side and low side switching MOSFETs’ on-resistance. VIN, VO and IO are the input voltage, the output voltage and the load current. Since RDS(ON), quiescent current and switching losses all vary with input voltage, the total losses should be investigated over the complete input voltage range. Given the total losses, the maximum junction temperature can be derived from the θJA for the package. TJ(MAX) = PTOTAL · θJA + TA Enable Function The AAT2614 features one buck output enable/disable function for buck converter. This pin (ENB) is active high and is compatible with CMOS logic. To assure the buck output will switch on, the ENB turn-on control level must be greater than 2.4V. The buck converter will go into the disable shutdown mode when the voltage on the ENB pin falls below 0.6V. If the enable function is not needed in a specific application, it may be tied to VIN to keep the buck output in a continuously on state. Low Dropout Regulator Input Capacitor Typically, a 2.2μF or larger capacitor is recommended for CIN in most applications. A CIN capacitor is not required for basic LDO regulator operation. However, if the LDO is physically located any distance more than one or two centimeters from the input power source, a CIN capacitor will be needed for stable operation. CIN should be located as closely to the device VINL pin as practically possible. CIN values greater than 1μF will offer superior input line transient response and will assist in maximizing the power supply ripple rejection. Ceramic, tantalum, or aluminum electrolytic capacitors may be selected for CIN as there is no specific capacitor ESR requirement. For better performance, ceramic capacitors are recommended for CIN due to their inherent capability over tantalum capacitors to withstand input current surges from low impedance sources such as batteries in portable devices. Output Capacitor For proper load voltage regulation and operational stability, a capacitor is required between pins VOUT 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 AAT2614 Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202209B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • March 20, 2013 13 DATA SHEET AAT2614 Step-Down DC/DC Converter with Quad High PSRR LDOs LDOs have been specifically designed to function with very low ESR ceramic capacitors. Although the device is intended to operate with these low ESR capacitors, it is stable over a very wide range of capacitor ESR, thus it will also work with some higher ESR tantalum or aluminum electrolytic capacitors. However, for best performance, ceramic capacitors are recommended. No-Load Stability The value of COUT typically ranges from 1μF to 10μF; however, 1μF is sufficient for most operating conditions. The AAT2614 LDO 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. An output capacitor is required for stability under no-load operating conditions. Refer to the Output Capacitor section of this datasheet for recommended typical output capacitor values. Enable Function Internal Power Supply The AAT2614 features four LDO regulator enable/disable function for LDO1/2/3/4 respectively. These pins (ENL1, ENL2, ENL3, and ENL4) are active high and are compatible with CMOS logic. To assure the LDO regulator will switch on, the EN turn-on control level must be greater than 2.4V. The LDO regulator will go into the disable shutdown mode when the voltage on the EN pin falls below 0.6V. If the enable function is not needed in a specific application, it may be tied to VIN to keep the LDO regulator in a continuously on state. The AAT2614 internal circuitry uses INL1 as the internal power supply. The buck output OUTB will have no output when INL1 is not connected to power. Layout Considerations The suggested PCB layout for the AAT2614 is shown in Figures 2(a) - 2(d). The following guidelines are recommended to ensure a proper layout: 1. Short-circuit and Thermal Protection The AAT2614 LDOs are protected by both current-limiting and over-temperature protection circuitry. The internal short-circuit current limiting circuit is designed to activate when the output load demand exceeds the maximum rated output. If a short-circuit condition were to continually draw more than the current limit threshold, the LDO regulator’s output voltage would drop to a level necessary to supply the current demanded by the load. Under shortcircuit or other over-current operating conditions, the output voltage would drop and the AAT2614’s die temperature would rapidly increase. Once the regulator’s power dissipation capacity has been exceeded and the internal die temperature reaches approximately 140°C, the system thermal protection circuit will become active. The internal thermal protection circuit will actively turn off the LDO regulator output pass device to prevent the possibility of over-temperature damage. The LDO regulator output will remain in a shutdown state until the internal die temperature falls back below the 140°C trip point. The interaction between the short-circuit and thermal protection systems allows the LDO regulator to withstand indefinite short-circuit conditions without sustaining permanent damage. 2. 3. 4. 5. 6. 7. 14 Connect the input capacitors (C1, C2, C3) and output capacitors (C4, C5, C6, C7, C8 ) as close as possible to the pins (VIN, VOUT) and power ground (PGND) to minimize any parasitic inductance in the switched current path which generates a large voltage spike during the switching interval. Keep the power traces (GND, LX, and INB) short, direct, and wide to allow large current flow. Place sufficient multiple-layer pads when needed to change the trace layer. Connect the output capacitor C8 and inductor L1 as close as possible to the device. Keep the connection of L1 to the LX pins as short as possible and route no signal lines under the inductor. Separate the feedback traces or OUTB pins (Pin 9) 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. Keep the resistance of the trace from the load returns to PGND 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. Connect the ground pin of the exposed pad to AGND internal plane with multiple vias to decrease the effect of large power ground PGND noise on the analog ground. Connect the ground pins of LDO output capacitors to AGND. Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202209B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • March 20, 2013 DATA SHEET AAT2614 Step-Down DC/DC Converter with Quad High PSRR LDOs U1 AAT2614IDG-2 1 VIN 2.5V to 5.5V 19 INL1 LDO1 1.8V 300mA OUTL1 C1 2.2μF C4 1μF 16 20 INL2 LDO2 2.8V 300mA OUTL2 C5 1μF C2 2.2μF 4 15 INB LDO3 2.8V 300mA OUTL3 C3 10μF C6 1μF 7 ENB ENL1 ENL2 ENL3 ENB 14 ENL1 C7 1μF 3 ENL2 11 ENL3 5 LX 12 ENL4 ENL4 LDO4 2.8V 300mA OUTL4 2 9 L1 OUTB 17 6 AGND EP BO1 1.2V 600mA 2.2μH PGND C8 10μF Figure 1: AAT2614IDG-2 Evaluation Board Schematic. Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202209B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • March 20, 2013 15 DATA SHEET AAT2614 Step-Down DC/DC Converter with Quad High PSRR LDOs a: Top Side b: Internal Plane 1 (AGND) c: Internal Plane 2 (PGND) d: Bottom Side Figure 2: AAT2614IDG-2 Evaluation Board Layout. 16 Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202209B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • March 20, 2013 DATA SHEET AAT2614 Step-Down DC/DC Converter with Quad High PSRR LDOs U1 AAT2614IUN-2 VINL1 2.5V to 5.5V C3 INL1 OUTL1 C4 C1 2.2μF C4 1μF A4 INL2 OUTL2 D4 C2 INB OUTL3 B3 C3 4.7μF ENL1 ENL2 ENL3 LDO3 2.8V 300mA C6 1μF C1 ENB LDO2 2.8V 300mA C5 1μF C2 2.2μF VINB 2.5V to 5.5V LDO1 1.8V 300mA D3 B2 A1 A2 ENL4 ENB OUTL4 ENL1 LDO4 2.8V 300mA C7 1μF ENL2 ENL3 LX ENL4 OUTB B4 A3 AGND PGND D2 B1 L1 BO1 1.2V 600mA 2.2μH D1 C8 10μF Figure 3: AAT2614IUN-2 Evaluation Board Schematic. Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202209B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • March 20, 2013 17 DATA SHEET AAT2614 Step-Down DC/DC Converter with Quad High PSRR LDOs a: Top Side b: Internal Plane 1 c: Internal Plane 2 d: Bottom Side Figure 4: AAT2614IUN-2 Evaluation Board Layout. 18 Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202209B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • March 20, 2013 DATA SHEET AAT2614 Step-Down DC/DC Converter with Quad High PSRR LDOs Component Part Number Description Manufacturer U1 C1, C2 C3,C8 C4, C5, C6, C7 L1 AAT2614IDG-2/IUN-2 GRM188R71A225KE15 GRM188R60J106ME47 GRM188R70J105KA12 LQH3NPN2R2MM0 Step-Down DC/DC Converter with Quad High PSRR LDOs Cap Ceramic 2.2μF 0603 X7R 10V 10% Cap Ceramic 10μF 0603 X5R 6.3V 10% Cap Ceramic 1μF 0603 X7R 6.3V 10% 2.2μH, 73mΩ, 1.25A, 20% Skyworks Murata Table 1: AAT2614IDG-2/IUN-2 Evaluation Board Bill of Materials (BOM). Manufacturer Murata Coilcraft Part Number L (μH) Max DCR (mΩ) Saturation Current (A) LQH3NP1R5NG0 LQH3NP2R2NG0 LQH3NP3R3NG0 LQH3NP4R7NG0 LPA3015-152MLC LPA3015-222MLC LPA3015-332MLC LPA3015-472MLC 1.5 2.2 3.3 4.7 1.5 2.2 3.3 4.7 100 140 180 260 100 110 130 200 1.47 1.27 0.85 0.8 1.3 1.1 1.1 0.9 Size WxLxH (mm) 3.0x3.0x0.9 3.1x3.1x1.5 Table 2: Surface Mount Inductors. Manufacturer Murata AVX KEMET Part Number Value (μF) Voltage (V) Tolerance Temp. Co. Case GRM188R70J105K GRM188R70J106K GRM188R71A225K GRM188R71A475K 06036C105KAT 06036C106KAT 0603ZC225KAT 0603ZC475KAT C0603C105K9RAC C0603C106K9RAC C0603C225K8RAC C0603C475K8RAC 1 10 2.2 4.7 1 10 2.2 4.7 1 10 2.2 4.7 6.3 6.3 10 10 6.3 6.3 10 10 6.3 6.3 10 10 10% 10% 10% 10% 10% 10% 10% 10% 10% 10% 10% 10% X7R X7R X7R X7R X7R X7R X7R X7R X7R X7R X7R X7R 0603 0603 0603 0603 0603 0603 0603 0603 0603 0603 0603 0603 Table 3: Surface Mount Capacitors. *Default option. Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202209B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • March 20, 2013 19 DATA SHEET AAT2614 Step-Down DC/DC Converter with Quad High PSRR LDOs Ordering Information DC-DC StepDown (V) LDO1 (V) LDO2 (V) LDO3 (V) LDO4 (V) Part Marking1 Part Number (Tape and Reel)2 1 1.2 1.3 1.3 1.3 1.2 1.2 1 1.8 1.8 1.8 1.8 2.8 1.8 2.6 2.8 2.8 2.8 2.8 2.8 2.8 3.0 2.8 2.8 2.8 2.8 1.8 2.8 3.3 2.8 2.8 3.0 3.3 1.8 3.0 L2AYW H3AYW L4AYW L6AYW L8AYW M2AYW M4AYW AAT2614IDG-1-T1 AAT2614IDG-2-T1 AAT2614IDG-3-T1 AAT2614IDG-4-T1 AAT2614IDG-5-T1 AAT2614IDG-6-T1 AAT2614IDG-7-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 TQFN33-203 3.00 ± 0.05 1.700 ± 0.050 Index Area 0.400 BSC 1.700 ± 0.050 Detail "A" 0.400 ± 0.050 3.00 ± 0.05 R(5x) Top View (Saw Type) Bottom View 0.210 ± 0.040 0.75 ± 0.05 Detail "A" 0 + 0.10 -0.00 0.203 REF Side View (Saw Type) All dimensions in millimeters. 1. A = assembly house code, Y = year, W = week. 2. Sample stock is generally held on part numbers listed in BOLD. 3. The leadless package family, which includes QFN, TQFN, DFN, TDFN and STDFN, has exposed copper (unplated) at the end of the lead terminals due to the manufacturing process. A solder fillet at the exposed copper edge cannot be guaranteed and is not required to ensure a proper bottom solder connection. 20 Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202209B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • March 20, 2013 DATA SHEET AAT2614 Step-Down DC/DC Converter with Quad High PSRR LDOs WLCSP-16 0.300 0.100 0.100 Line 2 Top View 0.620 ± 0.085 0.205 ± 0.025 0.300 0.400 BSC 0.200 BSC 1.200 BSC 1.645 ± 0.035 0.170 ± 0.025 0.380 ± 0.025 0.070 ± 0.035 Line 1 Bottom View Side View Copyright © 2012, 2013 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. Skyworks assumes no liability for any materials, products or information provided hereunder, 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, INCLUDING 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 environmental 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 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. Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202209B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • March 20, 2013 21