AAT2513 SKYWORKS | Alldatasheet

Document overview

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Technical content

Features

  • V IN Range: 2.7V to 5.5V
  • Output Current: ▪ Channel 1: 600mA ▪ Channel 2: 600mA
  • 96% Efficient Step-Down Converter
  • Low No Load Quiescent Current ▪ 60 μA Total for Both Converters
  • Integrated Power Switches
  • 100% Duty Cycle
  • 1.7MHz Switching Frequency
  • Optional Fixed Frequency or External SYNC
  • Logic Selectable 180° Phase Shift Between the Two Converters
  • Current Limit Protection
  • Automatic Soft-Start
  • Over-Temperature Protection
  • QFN33-16 Package
  • -40°C to +85°C Temperature Range

Applications

  • Cellular Phones / Smart Phones
  • Digital Cameras
  • Handheld Instruments
  • Micro Hard Disc Drives
  • Microprocessor / DSP Core / IO Power
  • PDAs and Handheld Computers Typical Application Input: 2.7V to 5.5V VIN2 LX1 CIN 1μF 4.7μF AAT2513 2μH LX2 FB1 FB2 VOUT2 2μH 4.7μF PGND1AGND VCC EN1 EN2 MODE/SYNC PS PGND2 VIN1 VOUT1

Dual 600mA Step-Down Converter with Synchronization DATA SHEET Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com 202023B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • March 19, 2013 Pin Descriptions Pin # Symbol Function 1P S Phase shift pin. Logic high enables the PS feature which forces the two converters to operate 180° out of phase when both are in forced PWM mode. 2 AGND Analog ground. Return the feedback resistive divider to this ground. See section on PCB layout guidelines and evaluation board layout diagram. 4, 3 FB1, FB2 Feedback input pins. An external resistive divider ties to each and programs the respective out- put voltage to the desired value. 5, 16 VIN1, VIN2 Input supply voltage pins. Must be closely decoupled to the respective PGND. 6, 15 N/C Not connected 7, 14 LX1, LX2 Output switching nodes that connect to the respective output inductor. 8, 13 PGND1, PGND2 Main power ground return. Connect to the input and output capacitor return. See section on PCB layout guidelines and evaluation board layout diagram. 10, 9 EN1, EN2 Converter enable input pins. A logic high enables the converter channel. A logic low forces the channel into shutdown mode, reducing the channel supply current to less than 1μA. This pin should not be left fl oating. When not actively controlled, this pin can be tied directly to VIN and/ or VCC. 11 VCC Control circuit power supply. Connect to the higher voltage of VIN1 or VIN2.

12 MODE/SYNC

Logic low enables automatic light load mode for optimized effi ciency throughout the entire load range. Logic high forces low noise PWM operation under all operating conditions. Connect to an external clock for synchronization (PWM only). EP Exposed paddle (bottom). Use properly sized vias for thermal coupling to the ground plane. See section on PCB layout guidelines. Pin Configuration QFN33-16 (Top View) MODE/SYNC VCC EN1 VIN2 PS AGND FB2 N/CVIN1LX1 PGND1 EN2 PGND2 LX2 N/C FB1

Dual 600mA Step-Down Converter with Synchronization DATA SHEET Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com 202023B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • March 19, 2013 1. Stresses above those listed in Absolute Maximum Ratings may cause permanent damage to the device. Functional operation at co nditions other than the operating conditions specified is not implied. Only one Absolute Maximum Rating should be applied at any one time. Absolute Maximum Ratings1 TA = 25°C unless otherwise noted. Symbol Description Value Units VIN1/2 Input Voltage -0.3 to 6.0 V GND, PGND1/2 Ground Pins -0.3 to +0.3 V EN1/2, SYNC, LX1/2, FB1/2, PS Maximum Rating -0.3 to V CC + 0.3 V TJ Operating Temperature Range -40 to 150 °C TS Storage Temperature Range -65 to 150 °C TLEAD Maximum Soldering Temperature (at leads, 10 sec) 300 °C Thermal Information Symbol Description Value Units JA Thermal Resistance 50 °C/W PD Maximum Power Dissipation 2 W

Dual 600mA Step-Down Converter with Synchronization DATA SHEET Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com 202023B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • March 19, 2013 1. The AAT2513 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. Electrical Characteristics1 VIN = VCC = 3.6V, TA = -40°C to +85°C, unless noted otherwise. Typical values are at T A = 25°C. Symbol Description Conditions Min Typ Max Units Power Supply VCC, VIN1, VIN2 Input Voltage 2.7 5.5 V UVLO Under-Voltage Lockout VCC Rising 2.7 V VCC Falling 2.35 IQ Quiescent Current V EN1 = VEN2 = VCC, No Load 60 120 μA ISHDN Shutdown Current EN1 = EN2 = GND 1.0 μA Each Converter VOUT Output Voltage Range 0.6 V IN V ILX_LEAK LX Reverse Leakage Current (Fixed) V IN Open, VLX = 5.5V, EN = GND 1.0 μA ILX_LEAK LX Leakage Current V IN = 5.5V, VLX = 0 to VIN 1.0 μA IFB Feedback Leakage V FB = 1.0V 0.2 μA ILIM P-Channel Current Limit Each Converter 1.0 A RDS(ON)H High Side Switch On Resistance 0.45  RDS(ON)L Low Side Switch On Resistance 0.40  VOUT/ VOUT/IOUT Load Regulation I LOAD = 0 to 600 mA 0.002 %/mA VOUT/ VOUT/VIN Line Regulation V IN = 2.7 to 5.5V, ILOAD = 100mA 0.125 %/V VFB Feedback Threshold Voltage Accuracy No Load, T A = 25°C 0.591 0.600 0.609 V FOSC Oscillator Frequency 1.7 MHz TS Start-Up Time From Enable to Output Regulation; Both Channels 150 μs Logic TSD Over-Temperature Shutdown Threshold 140 °C THYS Over-Temperature Shutdown Hysteresis 15 °C VIL EN, MODE/SYNC, PS Logic Low Threshold 0.6 V VIH EN, MODE/SYNC, PS Logic High Threshold 1.4 V IEN, IMODE/SYNC, IPS Logic Input Current V IN = VFB = 5.5V -1.0 1.0 μA

Dual 600mA Step-Down Converter with Synchronization DATA SHEET Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com 202023B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • March 19, 2013

Electrical Characteristics

Efficiency vs. Load (VOUT = 3.3V; L = 4.7µH; LL Mode) Output Current (mA) Efficiency (%) 100 0.1 1 10 100 100 VIN = 3.6V VIN = 4.2V VIN = 5.0V DC Regulation (VIN = 5.0V; VOUT = 3.3V; L = 4.7µH; LL Mode) Output Current (mA) Output Error (%) -1.00 -0.75 -0.50 -0.25 0.00 0.25 0.50 0.75 1.00 0.1 1 10 100 1000 Efficiency vs. Load (VOUT = 2.5V; L = 3.3µH; LL Mode) Output Current (mA) Efficiency (%) 100 0.1 1 10 100 1000 VIN = 2.7V VIN = 4.2V VIN = 3.6V VIN = 5.0V DC Regulation (VIN = 3.3V to 5.5V; VOUT = 2.5V; L = 3.3µH; LL Mode) Output Current (mA) Output Error (%) -2.0 -1.5 -1.0 -0.5 0.0 0.5 1.0 1.5 2.0 0.1 1 10 100 1000 Efficiency vs. Load (VOUT = 1.8V; L = 2.2µH; LL Mode) Output Current (mA) Efficiency (%) 100 0.1 1 10 100 1000 VIN = 2.7V VIN = 4.2V VIN = 3.6V VIN = 5.0V DC Regulation (VOUT = 1.8V; L = 2.2µH; LL Mode) Output Current (mA) Output Error (%) -0.8 -1.0 -0.6 -0.4 -0.2 0.2 0.0 0.4 0.6 0.8 1.0 0.1 1 10 100 1000 VIN = 5.0V VIN = 4.2V VIN = 3.3V

Dual 600mA Step-Down Converter with Synchronization DATA SHEET Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com 202023B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • March 19, 2013 Efficiency vs. Load (VOUT = 1.5V; L = 2.2µH; LL Mode) Output Current (mA) Efficiency (%) 100 0.1 1 10 100 1000 VIN = 2.7V VIN = 4.2V VIN = 3.6V DC Regulation (VOUT = 1.5V; L = 2.2µH; LL Mode) Output Current (mA) Output Error (%) -1.0 -0.8 -0.6 -0.4 -0.2 0.0 0.2 0.4 0.6 0.8 1.0 0.1 1 10 100 1000 VIN = 3.3V VIN = 4.2V VIN = 5.0V Switching Frequency vs. Temperature Temperature (°°C) Switching Frequency (MHz)1.55 1.60 1.65 1.70 1.75 1.80 1.85 1.90 -40 -20 0 20 40 60 80 100 120 VIN = 4.2V VIN = 3.6V Switching Frequency vs. Input Voltage (IOUT = 600mA; 25°C) Input Voltage (V) Frequency Variation (%) VIN = 2.5V VOUT = 1.8VVOUT = 1.5V VIN = 3.3V Output Voltage Error Vs. Temperature (VOUT = 2.5V; IOUT = 600mA) Temperature (°°C) Output Voltage Error (%) 0.00 0.05 0.10 0.15 0.20 0.25 0.30 -40 -20 0 20 40 60 80 100 120 VIN = 3.6V VIN = 4.2V No Load Quiescent Current vs. Input Voltage Input Voltage (V) Input Current (µA) 2.5 3 3.5 4 4.5 5 5.5 6 25°C 85°C -40°C

Dual 600mA Step-Down Converter with Synchronization DATA SHEET Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com 202023B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • March 19, 2013 P-Channel RDS(ON) vs. Input Voltage Input Voltage (V) RDS(ON) (mΩΩ) 300 400 500 600 700 800 900 1000 2.5 3 3.5 4 4.5 5 5.5 6 120°C 25°C 100°C 85°C VIH vs. Input Voltage Input Voltage (V) VIH (V) 0.6 0.7 0.8 0.9 1.0 1.1 1.2 1.3 25°C 85°C -40°C VIL vs. Input Voltage Input Voltage (V) VIL (mV) 0.6 0.7 0.8 0.9 1.0 1.1 1.2 25°C 85°C -40°C Soft Start (VIN = 3.6V; VOUT = 1.8V; IOUT = 600mA) Time (50µs/div) Enable Voltage (top) (V) Output Voltage (middle) (V) Inductor Current (bottom) (A) -0.2 0.0 0.2 0.4 0.6 Load Transient (1mA to 450mA; VIN = 3.6V; VOUT = 1.8V; COUT = 4.7µF) Time (20µs/div) Output Voltage (top) (V) Load Current (middle) (A) Inductor Current (bottom) (A) 1.8 2.0 0.5 450mA 1mA Load Transient (1mA to 450mA; VIN = 3.6V; VOUT = 1.8V; COUT = 10µF; CFF = 100pF) Time (20µs/div) Output Voltage (AC) (top) (V) Load Current (middle) (A) Inductor Current (bottom) (A) 1.6 1.8 2.0 -0.5 0.0 0.5 1mA 450mA

Dual 600mA Step-Down Converter with Synchronization DATA SHEET Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com 202023B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • March 19, 2013 (5mA to 600mA; VIN = 3.6V; VOUT = 1.8V; COUT = 4.7µF) Time (40µs/div) Output Voltage (top) (V) Load Current (middle) (A) Inductor Current (bottom) (A) 1.3 1.8 2.3 2.8 -0.5 0.0 0.5 1.0 5mA 600mA Load Transient (1mA to 600mA; VIN = 3.6V; VOUT = 1.8V; COUT = 10µF; CFF = 100pF) Time (40µs/div) Output Voltage (top) (V) Load Current (middle) (A) Inductor Current (bottom) (A) 1.6 1.8 2.0 0.5 600mA 1mA Load Transient (450mA to 600mA; VIN = 3.6V; VOUT = 1.8V; COUT = 4.7µF) Time (20µs/div) Output Voltage (top) (V) Load Current (middle) (A) Inductor Current (bottom) (A) 1.6 1.8 2.0 0.2 0.4 0.6 450mA 600mA Load Transient (450mA to 600mA; VIN = 3.6V; VOUT = 1.8V; COUT = 10µF; CFF = 100pF) Time (20µs/div) Output Voltage (AC) (top) (V) Load Current (middle) (A) Output Current (bottom) (A) 1.7 1.8 1.9 2.0 0.2 0.4 0.6 600mA 450mA Line Transient (VIN = 3.6V to 4.2V; VOUT = 1.8V; IOUT = 600mA; COUT = 4.7µF) Time (40µs/div) Input Voltage (top) (V) Output Voltage (bottom) (V) 1.74 1.76 1.78 1.80 1.82 1.84

Dual 600mA Step-Down Converter with Synchronization DATA SHEET Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com 202023B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • March 19, 2013 (VOUT = 1.8V; L = 2.2µH) Input Voltage (V) Accuracy (%) -2.0 -1.5 -1.0 -0.5 0.0 0.5 1.0 IOUT = 400mA IOUT = 0.1mA to 100mA Line Regulation (VOUT = 1.5V; L = 2.2µH) Input Voltage (V) Accuracy (%) -2.0 -1.5 -1.0 -0.5 0.0 0.5 1.0 1.5 2.0 IOUT = 400mA IOUT = 0.1mA to 100mA Output Voltage Ripple (VOUT = 1.8V; VIN = 3.6V; Load = 1mA) Time (10µs/div) Output Voltage (top) (V) Inductor Current (bottom) (A) 1.75 1.80 1.85 -0.1 0.0 0.1 0.2 Output Voltage Ripple (VOUT = 1.8V; VIN = 3.6V; Load = 600mA) Time (0.2µs/div) Output Voltage (top) (V) Inductor Current (bottom) (A) 1.78 1.80 1.82 0.4 0.5 0.6 0.7 Input Ripple (CIN = 2 x 10µF; VIN = 3.6V; VOUT1 = 1.8V; VOUT2 = 2.5V; IOUT1,2 = 600mA; 0°° Phase Shift; PS = Low) Time (0.2µs/div) Input Voltage (top) (V) Switching Voltage LX1,LX2 (V) 3.59 3.60 3.61 3.62 LX1 LX2 Input Ripple (CIN = 2 x 10µF; VIN = 3.6V; VOUT1 = 1.8V; VOUT2 = 2.5V; IOUT1,2 = 600mA; 180°° Phase Shift) Time (0.2µs/div) Input Voltage (top) (V) Switching Voltage LX1,LX2 (V)3.59 3.60 3.61 LX1 LX2

Dual 600mA Step-Down Converter with Synchronization DATA SHEET Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com 202023B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • March 19, 2013 Functional Description The AAT2513 is a peak current mode pulse width modu- lated (PWM) converter with internal compensation. Each channel has independent input, enable, feedback, and ground pins with a 1.7MHz clock. Both converters oper- ate in either a fixed frequency (PWM) mode or a more efficient light load (LL) mode. A phase shift pin programs the converters to operate in phase or 180° out of phase. The converter can also be synchronized to an external clock during PWM operation. The input voltage range is 2.7V to 5.5V. An external resistive divider as shown in Figure 1 programs the out- put voltage up to the input voltage. The converter MOSFET power stage is sized for 600mA load capability with up to 96% efficiency. Light load efficiency is up to 90% at a 1mA load. Soft Start / Enable The AAT2513 soft start control prevents output voltage overshoot and limits inrush current when either the input power or the enable input is applied. When pulled low, the enable input forces the converter into a low power non- switching state with a bias current of less than 1μA. Low Dropout Operation For conditions where the input voltage drops to the out- put voltage level, the converter duty cycle increases to 100%. As the converter approaches the 100% duty cycle, the minimum off time initially forces the high side on time to exceed the 1.7MHz clock cycle and reduce the effective switching frequency. Once the input drops below the level where the converter can regulate the output, the high side P-channel MOSFET is enabled con- tinuously for 100% duty cycle. At 100% duty cycle the output voltage tracks the input voltage minus the I*R drop of the high side P-channel MOSFET. Functional Block Diagram EN1 LX1 DH DL PGND1 VIN1FB1 EN2 LX2 DH DL PGND2 Comp. Control Logic Control Logic VIN2 FB AGND Voltage Reference Voltage Reference Comp Oscillator PS MODE/SYNC VCC Logic Logic Err. Amp. Err. Amp.

Dual 600mA Step-Down Converter with Synchronization DATA SHEET Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com 202023B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • March 19, 2013 Low Supply UVLO Under-voltage lockout (UVLO) guarantees sufficient V IN bias and proper operation of all internal circuitry prior to activation. Fault Protection For overload conditions, the peak inductor current is lim- ited. Thermal protection disables the converter when the internal dissipation or ambient temperature becomes excessive. The over-temperature threshold for the junc- tion temperature is 140°C with 15°C of hysteresis. PWM/LL Operation For fixed frequency, with minimum ripple under light load conditions, the MODE/SYNC pin should be tied to a logic high. For more efficient operation under light load conditions the MODE/SYNC pin should be tied to a logic low level. Clock Phase and Frequency A logic high on the PS pin while in PWM mode forces both converters to operate 180° out of phase thus reducing the input ripple by roughly half. A logic low on the PS pin synchronizes both converters in phase. Applications Information Inductor Selection The step down converter uses peak current mode control with slope compensation to maintain stability for duty cycles greater than 50%. The output inductor value must be selected so the inductor current down slope meets the internal slope compensation requirements. The internal slope compensation for the adjustable and low voltage fixed versions of the AAT2513 is 0.6A/μsec. This equates to a slope compensation that is 75% of the inductor current down slope for a 1.8V output and 2.2μH inductor. 0.75 · 1.8V 2.2μH A μs In this case a standard 3.3μH value is selected. Table 1 displays the suggested inductor values for the AAT2513. 2.2uH 4.7μF 1.8V 118k 2.2μH 2.5V 59.0k 59.0k 10μF VIN 187k FB1 EN1 LX1 PGND2 LX2 PGND1 AGND VIN1 VIN2 PS FB2 EN2 VCC MODE/SYNC N/C N/C AAT2513 4.7μF Figure 1: AAT2513 Typical Schematic. m 0.75V × VO 0.6 μs A μs A μs A

Dual 600mA Step-Down Converter with Synchronization DATA SHEET Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com 202023B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • March 19, 2013 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 induc- tor’s saturation characteristics. The inductor should not show any appreciable saturation under all 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 effi- ciency when selecting an inductor. The 2.2 μH CDRH2D11 series inductor selected from Sumida has a 98m DCR and a 1.27A DC current rating. At full load the inductor DC loss is 35mW which corre- sponds to a 3.2% loss in efficiency for a 600mA, 1.8V output. Input Capacitor A key feature of the AAT2513 is that the fundamental switching frequency ripple at the input can be reduced by operating the two converters 180° out of phase. This reduces the input ripple by roughly half, reducing the required input capacitance. An X5R ceramic input capac- itor as small as 1 μF is often sufficient. 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 This equation provides an estimate for the input capaci- tor required for a single channel. The equation below solves for the input capacitor size for both channels. It makes the worst case assumption that both converters are operating at 50% duty cycle with in phase synchronization. CIN = 1 VPP IO1 + IO2 Because the AAT2513 channels will generally operate at different duty cycles the actual ripple will vary and be less than the ripple (V PP) used to solve for the input capacitor in the above equation. Always examine the ceramic capacitor DC voltage coef- ficient characteristics when selecting the proper value. For example, the capacitance of a 10μF 6.3V X5R ceram- ic capacitor with 5V DC applied is actually about 6 μF. The maximum input capacitor RMS current is: VO1 VIN VO1 VIN VO2 VIN VO2 VIN The input capacitor RMS ripple current varies with the input and output voltage and will always be less than or equal to half of the total DC load current of both convert- ers combined. IO1(MAX) + IO2(MAX) RMS(MAX)I 2= This equation also makes the worst-case assumption that both converters are operating at 50% duty cycle synchronized. The term VO VIN VO VIN appears in both the input voltage ripple and input capacitor RMS current equations. It is at maximum when V O is twice V IN. This is why the input voltage ripple and the input capacitor RMS current ripple are a maximum at 50% duty cycle. = 0.25⎝⎠ VO VIN VO VIN Confi guration Output Voltage Inductor Slope Compensation 0.6V adjustable with external resistive divider 0.6V-2.0V 2.2 μH 0.6A/μs2.5V 3.3 μH 3.3V 4.7 μH Table 1: Inductor Values.

Dual 600mA Step-Down Converter with Synchronization DATA SHEET Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com 202023B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • March 19, 2013 The input capacitor provides a low impedance loop for the edges of pulsed current drawn by the AAT2513. Low ESR/ESL X7R and X5R ceramic capacitors are ideal for this function. To minimize the stray inductance, the capacitor should be placed as close as possible to the IC. This keeps the high frequency content of the input cur- rent localized, minimizing EMI and input voltage ripple. The proper placement of the input capacitor (C3 and C9) can be seen in the evaluation board layout in Figures 3 and 4. Since decoupling must be as close to the input pins as possible it is necessary to use two decoupling capacitors, one for each converter. A Laboratory test set-up typically consists of two long wires running from the bench power supply to the evalu- ation board input voltage pins. The inductance of these wires along with the low ESR ceramic input capacitor can create a high Q network that may effect the converter performance. This problem often becomes apparent in the form of excessive ringing in the output voltage during load tran- sients. Errors in the loop phase and gain measurements can also result. Since the inductance of a short printed circuit board trace feeding the input voltage is significantly lower than the power leads from the bench power supply, most applications do not exhibit this problem. In applications where the input power source lead induc- tance cannot be reduced to a level that does not effect the converter performance, a high ESR tantalum or alu- minum electrolytic (C10 of Figure 2) 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. As the loop responds the induc- tor current increases to match the load current demand. This typically takes two to three switching cycles and can be estimated by: COUT = 3 · ΔILOAD VDROOP · FS Once the average inductor current increases to the DC load level, the output voltage recovers. The above equa- tion establishes a limit on the minimum value for the output capacitor with respect to load transients. The internal voltage loop compensation also limits the minimum output capacitor value to 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 Resistors R1 through R4 of Figure 1 program the output to regulate at a voltage higher than 0.6V. To limit the bias current required for the external feedback resistor string, the minimum suggested value for R2 and R4 is 59k. Although a larger value will reduce the quiescent current, it will also increase the impedance of the feed- back node, making it more sensitive to external noise and interference. Table 2 summarizes the resistor values for various output voltages with R2 and R4 set to either 59k for good noise immunity or 221k  for reduced no load input current. VOUT VREF 1.5V 0.6V With an external feedforward capacitor (C4 and C5 of Figure 2) the AAT2513 delivers enhanced transient response for extreme pulsed load applications. The addi- tion of the feedforward capacitor typically requires a larger output capacitor (C1 and C2) for stability.

Dual 600mA Step-Down Converter with Synchronization DATA SHEET Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com 202023B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • March 19, 2013 VOUT (V) R2, R4 = 59k R1, R3 (k) R2, R4 = 221k R1, R3 (k) 0.8 19.6 75 0.9 29.4 113 1.0 39.2 150 1.1 49.9 187 1.2 59.0 221 1.3 68.1 261 1.4 78.7 301 1.5 88.7 332 1.8 118 442 1.85 124 464 2.0 137 523 2.5 187 715 3.3 265 1000 Table 2: Feedback Resistor Values. Thermal Calculations There are three types of losses associated with the AAT2513 converter: switching losses, conduction losses, and quiescent current losses. The conduction losses are associated with the R DS(ON) characteristics of the power output switching devices. The switching losses are dom- inated by the gate charge of the power output switching devices. At full load, assuming continuous conduction mode (CCM), a simplified form of the dual converter losses is given by: PTOTAL IO1 2 · (RDSON(HS) · VO1 + RDSON(LS) · [VIN -VO1]) VIN + (tsw · F · [IO1 + IO2] + 2 · IQ) · VIN IO2 2 · (RDSON(HS) · VO2 + RDSON(LS) · [VIN -VO2]) VIN IQ is the AAT2513 quiescent current for one channel and tSW is used to estimate the full load switching losses. For the condition where channel one is in dropout at 100% duty cycle the total device dissipation reduces to: PTOTAL = IO1 2 · RDSON(HS) + (tsw · F · IO2 + 2 · IQ) · VIN IO2 2 · (RDSON(HS) · VO2 + RDSON(LS) · [VIN -VO2]) VIN Since RDS(ON), quiescent current, and switching losses all vary with input voltage, the total losses should be inves- tigated over the complete input voltage range. Given the total losses, the maximum junction tempera- ture can be derived from the  JA for the QFN33-12 pack- age which is 28°C/W to 50°C/W minimum. TJ(MAX) = PTOTAL · ΘJA + TAMB PCB Layout Use the following guidelines to insure a proper layout: 1. Due to the pin placement of V IN for both converters, proper decoupling is not possible with just one input capacitor. The input capacitors C3 and C9 should connect as closely as possible to the respective VIN and GND as shown in Figure 3. 2. Connect the output capacitor and inductor as closely as possible. The connection of the inductor to the LX pin should also be as short as possible. 3. The feedback trace should be separate from any power trace and connect as close as possible to the load point. Sensing along a high-current load trace will degrade DC load regulation. Place the external feedback resistors as close as possible to the FB pin. This prevents noise from being coupled into the high impedance feedback node. 4. Keep the resistance of the trace from the load return to GND to a minimum. This minimizes any error in DC regulation due to potential differences of the internal signal ground and the power ground. 5. For good thermal coupling, PCB vias are required from the pad for the QFN paddle to the ground plane. The via diameter should be 0.3mm to 0.33mm and positioned on a 1.2 mm grid.

Dual 600mA Step-Down Converter with Synchronization DATA SHEET Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com 202023B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • March 19, 2013 Design Example Specifications VO1 2.5V @ 600mA (adjustable using 0.6V version), pulsed load ILOAD = 300mA VO2 1.8V @ 600mA (adjustable using 0.6V version), pulsed load ILOAD = 300mA VIN 2.7V to 4.2V (3.6V nominal) FS 1.7 MHz TAMB 85°C 1.8V VO1 Output Inductor L1 = 1.2 ⋅ VO1 = 1.2 ⋅ 1.8V = 2.2µHµs A µs A (see table 1). For Sumida CDRH2D11 2.2μH DCR = 98m. IPK1 = IO1 + ΔI1 = 0.4A + 0.115A = 0.515A2 PL1 = IO1 2 ⋅ DCR = 0.6A2 ⋅ 123mΩ = 44mW 2.5V VO2 Output Inductor L1 = 1.2 ⋅ VO1 = 1.2 ⋅ 2.5V = 3.3µHµs A µs A (see table 1). For Sumida inductor CDRH2D11 3.3μH DCR = 123m. IPK2 = IO2 + ΔI2 = 0.4A + 0.115A = 0.515A2 PL2 = IO2 2 ⋅ DCR = 0.6A2 ⋅ 123mΩ = 44mW

Dual 600mA Step-Down Converter with Synchronization DATA SHEET Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com 202023B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • March 19, 2013 1.8V Output Capacitor 2.2µH · 1.7MHz · 4.2V 23 RMS(MAX)I L · F · VIN(MAX) 3 · ΔILOAD VDROOP · FS 3 · 0.3A 0.2V · 1.7MHz COUT = = = 4.8µF

  • = 31mArms (VOUT) · (VIN(MAX) - VOUT) = Pesr = esr · IRMS 2 = 5mΩ · (31mA)2 = 4.8µW 2.5V Output Capacitor 3.3µH · 1.7MHz · 4.2V 23 RMS(MAX)I L · F · VIN(MAX) 3 · ΔILOAD VDROOP · FS 3 · 0.3A 0.2V · 1.7MHz COUT = = = 4.8µF
  • = 67mArms (VOUT) · (VIN(MAX) - VOUT) = Pesr = esr · IRMS 2 = 5mΩ · (67mA)2 = 22µW Input Capacitor Input Ripple VPP = 25mV. CIN = = = 10µF 1 VPP IO1 + IO2 25mV 1.2A IO1 + IO2 RMS(MAX)I P = esr · IRMS 2= = 0.6Arms

Dual 600mA Step-Down Converter with Synchronization DATA SHEET Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com 202023B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • March 19, 2013 AAT2513 Losses The maximum dissipation occurs at dropout where VIN = 2.7V. All values assume an 85°C ambient and a 120°C junction temperature. PTOTAL + (tsw · F · IO2 + 2 · IQ) · VIN IO1 2 · (RDSON(HS) · VO1 + RDSON(LS) · (VIN -VO1)) + IO2 2 · (RDSON(HS) · VO2 + RDSON(LS) · (VIN -VO2)) VIN + (5ns · 1.7MHz · 0.6A + 60µA) · 2.7V = 533mW 2.7V TJ(MAX) = TAMB + ΘJA · PLOSS = 85°C + (50°C/W) · 533mW = 111°C TJ(MAX) = TAMB + ΘJA · PLOSS = 85°C + (28°C/W) · 533mW = 100°C

Dual 600mA Step-Down Converter with Synchronization DATA SHEET Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com 202023B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • March 19, 2013 1. For reduced quiescent current, R2 and R4 = 221k . Adjustable Version (0.6V device) VOUT (V) R2, R4 = 59k R1, R3 (k) R2, R4 = 221k1 R1, R3 (k) L1, L2 ( μH) 0.9 29.4 113 1.0 - 1.5 1.0 39.2 150 1.0 - 1.5 1.1 49.9 187 1.0 - 1.5 1.2 59.0 221 1.0 - 1.5 1.3 68.1 261 1.0 - 1.5 1.4 78.7 301 2.2 1.5 88.7 332 2.2 1.8 118 442 2.2 1.85 124 464 2.2 2.0 137 523 3.3 2.5 187 715 3.3 3.3 265 1000 4.7 Fixed Version VOUT (V) R2, R4 not used R1, R3 (k) L1, L2 ( μH) 0.6-3.3V zero 2.2 Table 3: Evaluation Board Component Values. Manufacturer Part Number Inductance (μH) Max DC Current (A) DCR ( ) Size (mm) LxWxH Type 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.

Dual 600mA Step-Down Converter with Synchronization DATA SHEET Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com 202023B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • March 19, 2013 1. XYY = assembly and date code. 2. Sample stock is generally held on part numbers listed in BOLD.

Ordering Information

Marking1 Part Number (Tape and Reel)2Channel 1 Channel 2 QFN33-16 0.6V 0.6V UFXYY AAT2513IVN-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. Legend Voltage Code Adjustable (0.6V) A 1.5 G 1.8 I 1.9 Y 2.5 N 2.6 O 2.7 P 2.8 Q 2.85 R 2.9 S 3.0 T 3.3 W

Dual 600mA Step-Down Converter with Synchronization DATA SHEET Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com 202023B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • March 19, 2013 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 fo r errors or omissions in these materials or the information contained herein. Sky- works may change its documentation, products, services, specifi cations or product descriptions at any time, without notice. Skyworks makes no commitment to update the materials or information and shall have no responsibility whatsoever for confl icts, incompatibilities, or other diffi culties arising from any future changes. No license, whether express, implied, by estoppel or otherwise, is granted to any intellectual property rights by this document. Skyworks assumes no liability for any materials, products or information provided here- under, including the sale, distribution, reproduction or use of Skyworks products, information or materials, except as may be provided in Skyworks Terms and Conditions of Sale. THE MATERIALS, PRODUCTS AND INFORMATION ARE PROVIDED “AS IS” WITHOUT WARRANTY OF ANY KIND, WHETHER EXPRESS, IMPLIED, STATUTORY, OR OTHERWISE, INCLUDING FITNESS FOR A PARTICULAR PURPOSE OR USE, MERCHANTABILITY, PERFORMANCE, QUALITY OR NON-INFRINGEMENT OF ANY INTELLECTUAL PROPERTY RIGHT; ALL SUCH WARRANTIES ARE HEREBY EXPRESSLY DISCLAIMED. SKYWORKS DOES NOT WARRANT THE ACCURACY OR COMPLETENESS OF THE INFORMATION, TEXT, GRAPHICS OR OTHER ITEMS CONTAINED WITHIN THESE MATERIALS. SKYWORKS SHALL NOT BE LIABLE FOR ANY DAMAGES, IN- CLUDING BUT NOT LIMITED TO ANY SPECIAL, INDIRECT, INCIDENTAL, STATUTORY, OR CONSEQUENTIAL DAMAGES, INCLUDING WITHOUT LIMITATION, LOST REVENUES OR LOST PROFITS THAT MAY RESULT FROM THE USE OF THE MATERIALS OR INFORMATION, WHETHER OR NOT THE RECIPIENT OF MATERIALS HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. Skyworks products are not intended for use in medical, lifesaving or life-sustaining applications, or other equipment in which the failure of the Skyworks products could lead to personal injury, death, physical or en- vironmental damage. Skyworks customers using or selling Skyworks products for use in such applications do so at their own risk and agree to fully indemnify Skyworks for any damages resulting from such improper use or sale. Customers are responsible for their products and applications using Skyworks products, which may deviate from published specifi cations as a result of design defects, errors, or operation of products outside of pub- lished parameters or design specifi cations. Customers should include design and operating safeguards to minimize these and other risks. Skyworks assumes no liability for applications assistance, customer product design, or damage to any equipment resulting from the use of Skyworks products outside of stated published specifi cations or parameters. Skyworks, the Skyworks symbol, and “Breakthrough Simplicity” are trademarks or registered trademarks of Skyworks Solutions, Inc., in the United States and other countries. Third-party brands and names are for identifi cation purposes only, and are the property of their respective owners. Additional information, including relevant terms and conditions, posted at www.skyworksinc.com, are incorporated by reference. 1. The leadless package family, which includes QFN, TQFN, DFN, TDFN and STDFN, has exposed copper (unplated) at the end of the lead terminals due to the manufacturing process. A solder fillet at the exposed copper edge cannot be guaranteed and is not required to ensure a proper bottom solder c onnection. Package Information1 QFN33-16 3.000 ± 0.050 Pin 1 Dot By Marking 1.250 ± 0.050 0.400 ± 0.100 1.250 ± 0.0503.000 ± 0.050 0.500 ± 0.050 0.900 ± 0.100 Pin 1 Identification C0.3 0.025 ± 0.025 0.214 ± 0.036 0.230 ± 0.050 Top View Bottom View Side View All dimensions in millimeters.