DATA SHEET AAT1185 High Voltage Step-Down Controller General Description Features The AAT1185 is a single output step-down (Buck) regulator controller with an input range of 6V to 24V. The output range is adjustable from 0.8V to 5.5V. The device provides high and low-side pins to drive external n-channel MOSFETs; allowing fully synchronous operation for maximum efficiency and performance. Alternately, the low-side MOSFET may be replaced with a Schottky rectifier. Both high and low-side drive pins are compatible with a wide range of external MOSFETs making the device the ideal control solution for low power and high power configurations. Voltage mode control allows for optimum performance across the entire output voltage and load range. The 490kHz fixed switching frequency allows wide range of L/C filtering components, achieving smallest size and maximum efficiency. External compensation allows the designer to optimize the transient response. The controller includes programmable over-current, integrated soft-start and over-temperature protection. The AAT1185 is available in the Pb-free, 14-pin TSOPJW package. The rated operating temperature range is -40°C to 85°C. VIN = 6.0V to 24.0V VOUT Adjustable from 0.8V to 5.5V IOUT from <1A up to 10A Small Solution Size Ultra-small External L/C Synchronous or Non-Synchronous Shutdown Current <30μA High Switching Frequency Voltage Mode Control PWM Fixed Frequency for Lowest Noise ▪ Programmable Over-Current Protection Over-Temperature Protection Internal Soft Start 2.85x3mm TSOPJW-14 Package -40°C to 85°C Temperature Range Applications • • • • DSL and Cable Modems Notebook Computers Satellite Set Top Boxes Wireless LAN Systems Typical Application U1 D1 BAS16 VIN 6V - 24V C7 2.2μF C8 0.1μF BST VCC Q1 DH AAT1185 HV LX EN DL R1 3.32 Q2 R2 3.32 C3 470μF 25V C5 10μF 25V RS PGND OS COMP FB VOUT 3.3V/10A L1 3.9μH R3 1.74K C9 0.47μF R5 1K R6 27.4K C12 680pF C13, C14 2×47μF C10 33pF TSOPJW-14 R4 20K C11 680pF R7 6.04k Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202001A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • May 31, 2012 1 DATA SHEET AAT1185 High Voltage Step-Down Controller Pin Descriptions Pin # Symbol Function 1 RS I 2 OS I 3 EN I 4 BST I 5 DH O 6 LX O 7 PGND GND 8 DL O 9, 11 VL I/O 10 12 IN GND I GND 13 FB I 14 COMP I Description Output sense voltage pin. Connect to the output capacitor to enable over-current sense for step-down converter. Output current sense pin. Connect a small signal resistor from this pin to small signal resistor which is tied to switching node (LX) to enable over-current sense for stepdown converter. The current limit threshold varies with inductor parasitic winding resistance (RDC(L)); see the Applications Information section of this datasheet for details. Step-down regulator enable input pin. Active high or tied to high voltage input (IN) enables internal linear regulator and output. Step-down regulator boost drive input pin. Connect the cathode of fast rectifier from this pin and connect a 100nF capacitor from this pin to the switching node (LX) to provide drive to external hi-side MOSFET gate. High side driver for external high side n-channel MOSFET. Connect this pin to gate of external high side n-channel MOSFET device. Step-down converter switching pin. Connect output inductor to this pin. Power ground pin for step-down regulator. When using synchronous option, tie to PCB ground plane near source pins of external low-side MOSFET(s). Low side driver for external low side n-channel MOSFET. When using synchronous option, connect this pin to gate of external low side n-channel MOSFET device. Otherwise, leave pin open. Internal linear regulator for step-down converter. Connect a 2.2μF/6.3V capacitor from this pin to GND. High voltage input pin. Ground pin for step-down regulator. Tie to PCB ground plane. Feedback input pin for step-down converter. Connect an external resistor divider to this pin to program the output voltage to the desired value. Compensation pin for step-down converter. Connect a resistor, capacitor network to compensate the voltage mode control loop. Pin Configuration TSOPJW-14 (Top View) RS OS EN BST DH LX PGND 2 1 14 2 13 3 12 4 11 5 10 6 9 7 8 COMP FB GND VL IN VL DL Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202001A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • May 31, 2012 DATA SHEET AAT1185 High Voltage Step-Down Controller Absolute Maximum Ratings1 TA = 25OC unless otherwise noted. Symbol Description VIN(HI), VEN VIN(LO) VBST-LX VCONTROL TJ TLEAD IN, LX, EN to GND VL to GND BST to LX DH, DL, FB, COMP, RS, OS to PGND, GND Operating Junction Temperature Range Maximum Soldering Temperature (at leads, 10 sec) Value Units -0.3 to 30.0 -0.3 to 6.0 -0.3 to 6.0 -0.3 to VIN(LO) + 0.3 -40 to 150 300 V V V V C C Value Units Thermal Information2 Symbol ΘJA PD Description Thermal Resistance3 Maximum Power Dissipation 140 0.7 O 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. Only one Absolute Maximum Rating should be applied at any one time. 2. Mounted on an FR4 board. 3. Derate 7mW/°C above 25°C. Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202001A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • May 31, 2012 3 DATA SHEET AAT1185 High Voltage Step-Down Controller Electrical Characteristics1 VIN1 = 12.0V; TA = -40°C to 85°C unless otherwise noted. Typical values are at TA = 25°C. Symbol Description VIN Input Voltage VUVLO VOUT VFB IQ ISHDN VOCP ILX DMAX TON(MIN) UVLO Threshold Output Voltage Range Feedback Pin Voltage Quiescent Current Shutdown Current Over-Current Offset Voltage LX1 Pin Leakage Current Maximum Duty Cycle Minimum On-Time RDH High Side Drive Source Resistance RDL Low Side Drive Source Resistance FOSC FFOLDBACK TS TSD VEN(L) VEN(H) IEN Oscillator Frequency Short Circuit Foldback Frequency Start-Up Time Over-Temperature Shutdown Threshold Over-Temperature Shutdown Hysteresis Enable Threshold Low Enable Threshold High Input Low Current Conditions Min Typ 6.0 VIN Rising VIN Hysteresis VIN Falling VEN = High, No load VEN = Low, VL = 0V VEN = High, VIN = 6.0V to 24.0V, TA = 25°C VIN = 24.0V, VEN = Low Max Units 24.0 5.0 V V mV V V V mA μA mV μA % ns 300 3.0 0.8 0.591 70 -1.0 VIN = 6.0V to 24.0V Pull-Up Pull-Down Pull-Up Pull-Down 350 Current Limit Triggered From Enable to Output Regulation 0.600 1.0 100 85 100 5.0 1.7 5.0 1.7 490 100 2.5 135 15 5.5 0.609 30 130 1.0 Ω Ω 650 0.6 2.5 -1.0 1.0 kHz kHz ms °C °C V V μA 1. The AAT1185 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. 4 Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202001A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • May 31, 2012 DATA SHEET AAT1185 High Voltage Step-Down Controller Typical Characteristics Circuit of Figure 4, unless otherwise specified. Step-Down Controller Efficiency vs. Load Step-Down Controller DC Regulation (VOUT = 3.3V; L = 3.9µH) (VOUT = 3.3V; L = 3.9µH) 100 2.0 90 1.5 Output Error (%) Efficiency (%) 80 70 60 50 VIN = 6V VIN = 8V VIN = 12V VIN = 18V VIN = 24V 40 30 20 10 0 0.1 1 10 100 1000 1.0 0.5 0.0 VIN = 6V VIN = 8V VIN = 12V VIN = 18V VIN = 24V -0.5 -1.0 -1.5 -2.0 0.1 10000 1 Output Current (mA) Step-Down Controller Line Regulation 1000 10000 IOUT = 0.1mA IOUT = 100mA IOUT = 1A IOUT = 5A IOUT = 8A IOUT = 10A 2.0 1.5 1.0 0.5 0.0 -0.5 -1.0 -1.5 -2.0 Output Voltage Error (%) (VIN = 12V; VOUT = 3.3V) 2.5 Accuracy (%) 100 Step-Down Controller Output Voltage Error vs. Temperature (VOUT = 3.3V; L = 3.9µH) -2.5 6 8 10 12 14 16 18 20 22 1.0 IOUT = 0.1mA IOUT = 100mA IOUT = 1A IOUT = 5A IOUT = 8A IOUT = 10A 0.8 0.6 0.4 0.2 0.0 -0.2 -0.4 -0.6 -0.8 -1.0 -50 24 Input Voltage (V) -25 0 25 50 75 100 Temperature (°C) Step-Down Controller Output Ripple (VIN = 12V; VOUT = 3.3V; IOUT = 1mA) (VIN = 12V; VOUT = 3.3V; IOUT = 10A) 0V 3.31 3.30 3.29 1 0 -1 Time (1µs/div) 12V 0V 3.32 3.30 3.28 12 10 8 LX Voltage (top) (V) Inductor Current (bottom) (A) 12V Output Voltage (middle) (V) Step-Down Controller Output Ripple LX Voltage (top) (V) Inductor Current (bottom) (A) Output Voltage (middle) (V) 10 Output Current (mA) Time (1µs/div) Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202001A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • May 31, 2012 5 DATA SHEET AAT1185 High Voltage Step-Down Controller Typical Characteristics Circuit of Figure 4, unless otherwise specified. (VIN = 12V; IOUT = 5A to 10A; COUT = 2x47µF) 15 5 1A 0 3.7 3.5 3.3 3.1 2.9 15 10A 5 0 3.5 3.4 3.3 3.2 3.1 Time (100µs/div) Time (100µs/div) Step-Down Controller Soft Start (VIN = 12V; IOUT = 7.5A to 10A; COUT = 2x47µF) (VIN = 12V; VOUT = 3.3V; IOUT = 10A) 8 6 3.4 3.3 3.2 3.1 15 10 5 0 15 10 5 Inductor Current (bottom) (A) 7.5A 10 Enable Voltage (top) (V) Output Voltage (middle) (V) 12 Output Current (top) (A) Output Voltage (bottom) (V) Step-Down Controller Load Transient Response 10A 10 5A Output Current (top) (A) 10 Output Current (top) (A) 10A Output Voltage (bottom) (V) Step-Down Controller Load Transient Response (VIN = 12V; IOUT = 1A to 10A; COUT = 2x47µF) Output Voltage (bottom) (V) Step-Down Controller Load Transient Response 0 Time (100µs/div) Time (500µs/div) Step-Down Controller Line Transient Response Step-Down Controller Line Transient Response (VIN = 8V to 12V; VOUT = 3.3V; IOUT = 5A) (VIN = 8V to 12V; VOUT = 3.3V; IOUT = 10A) 8 6 3.33 3.30 3.27 3.24 Time (200µs/div) 6 Input Voltage (top) (V) Input Voltage (top) (V) 10 14 12 10 8 6 3.35 3.30 3.25 3.20 Time (200µs/div) Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202001A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • May 31, 2012 Output Voltage (bottom) (V) 12 Output Voltage (bottom) (V) 14 DATA SHEET AAT1185 High Voltage Step-Down Controller Typical Characteristics Circuit of Figure 4, unless otherwise specified. Step-Down Controller Switching Frequency vs. Input Voltage Switching Frequency (kHz) Frequency Variation (%) (VOUT = 3.3V; IOUT = 10A) 5 4 3 2 1 0 -1 -2 -3 -4 -5 6 8 10 12 14 16 18 Step-Down Controller Switching Frequency vs. Temperature 20 22 24 (VIN = 12V; VOUT = 3.3V; IOUT = 10A) 510 500 490 480 470 -40 -20 Input Voltage (V) 20 40 60 (VIN = 12V; VOUT = 3.3V; L = 3.9µH) Output Voltage (top) (V) 0.55 0.50 0.45 0.40 85°C 25°C -40°C 0.35 2 0 12V 20 10 0 0.30 12 15 18 Input Voltage (V) 21 LX Voltage (middle) (V) Inductor Current (bottom) (A) 4 0.60 9 100 Step-Down Controller Current Limit (VEN = VIN) 6 80 Temperature (°C) No Load Step-Down Controller Input Current vs. Input Voltage Input Current (mA) 0 24 Time (400µs/div) Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202001A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • May 31, 2012 7 DATA SHEET AAT1185 High Voltage Step-Down Controller Functional Block Diagram VINT Reg. VL IN OT FB Error Amp OSC Comp. Comp. COMP BST DH Logic LX Control Logic EN DL Voltage Ref EN PGND RS OS Comp VOCP = 0.1V Applications Information The AAT1185 is a single output step-down (Buck) regulator controller with an input range of 6V to 24V. The output range is adjustable from 0.8V to 5.5V. The device provides high and low-side pins to drive external n-channel MOSFETs; allowing fully synchronous operation for maximum efficiency and performance. Alternatively, the low-side MOSFET may be replaced with a Schottky rectifier and the DL pin left open. Both high and low-side drive pins are compatible with a wide range of external MOSFETs making the device the ideal control solution for low power and high power configurations. Voltage mode control allows for optimum performance across the entire output voltage and load range. 490kHz fixed switching frequency allows wide range of L/C filtering components, achieving smallest size and maximum efficiency. External compensation allows the designer to optimize the transient response components. 8 The controller includes programmable over-current, integrated soft-start and over-temperature protection. The AAT1185 is available in the Pb-free, 14-pin TSOPJW package. The rated operating temperature range is -40°C to 85°C. Regulator Output Capacitor Selection Two 47μF ceramic output capacitors are required to filter the inductor current ripple and supply the load transient current for IOUT = 10A. The 1210 package with 10V minimum voltage rating is recommended for the output capacitors to maintain a minimum capacitance drop with DC bias. Output Inductor Selection The step-down converter utilizes constant frequency (PWM-mode) voltage mode control. A 3.9μH to 4.7μH inductor value with appropriate DCR is selected to maintain the desired output current ripple and minimize the Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202001A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • May 31, 2012 DATA SHEET AAT1185 High Voltage Step-Down Controller converter’s response time to load transients. The peak switch current should not exceed the inductor saturation current of the MOSFETs. The DCR of the inductor sets the designed current limit in the following formula: ILIM = as possible to the input pins (Pins 9 and 11) for high frequency decoupling. Feedback and Compensation Networks 100mV DCR C10 C11 For 10A output load, the selected DCR should be less than 10m to avoid the peak inductor current triggers the current limit. C12 R4 The QG affects the turn-on/turn-off time of the synchronous MOSFET; the longer the turn-on/turn-off time, the more likely the step-down converter will have “shootthrough” current issues. “Shoot-through” current occurs when the high-side MOSFET and the low-side MOSFET are conducting current at the same time. This will result in a low impedance path to ground from the input voltage through the two MOSFETs, and the current may exceed the maximum current rating of the MOSFETs. Exceeding the maximum current ratings will lead to the destructive derating of the MOSFETs. The critical parameter recommendations for the external minimum 25V MOSFET are as follows: QG (Total Gate Charge): 5nC to 15nC (max) (VGS: 4.5V to 5V) RDS(ON): 10mΩ to 30mΩ (max) (VGS: 4.5V to 5V) Input Capacitor Selection For low-cost applications, a 470μF/25V electrolytic capacitor is selected to control the voltage overshoot across the high side MOSFET. A 10μF/25V ceramic capacitor with a voltage rating at least 1.05 times greater than the maximum input voltage is connected as close VOUT COMP R6 FB MOSFET Selection The step-down (buck) converter utilizes synchronous rectification (Q1) for constant frequency (PWM mode) voltage mode control. The synchronous rectifier is selected based on the desired RDS(ON) value and QG (total gate charge), these two critical parameters are weighed against each other. To get a low RDS(ON) value, the MOSFET must be very large; a larger MOSFET will have a large QG. Conversely, to get a low QG, the MOSFET must be small and thus have a large RDS(ON) value. In addition to the trade off between RDS(ON) and QG, the maximum voltage rating for the external synchronous MOSFET must exceed the maximum application input voltage value (VDS [max] > VIN [max]). R5 R7 REF Figure 1: AAT1185 Feedback and Compensation Networks for Type III Voltage-Mode Control Loop. The transfer function of the error amplifier is dominated by DC gain and the L COUT output filter of the regulator. This output filter and its equivalent series resistance (ESR) create a double pole at FLC and a zero at FESR in the following equations: Eq. 1: FLC = Eq. 2: FESR = 1 2 · π · L · COUT 1 2 · π · ESR · COUT The feedback and compensation networks provide a closed loop transfer function with the highest 0dB crossing frequency and adequate phase margin for system stability. Equations 3, 4, 5 and 6 relate the compensation network’s poles and zeros to the components R4, R5, R6, C10, C11, and C12: Eq. 3: FZ1 = Eq. 4: FZ2 = 1 2 · π · R4 · C11 1 2 · π · (R5 + R6) · C12 1 Eq. 5: FP1 = 2 · π · R4 · Eq. 6: FP2 = C10 · C11 C10 + C11 1 2 · π · R5 · C12 Components of the feedback, feed-forward, and compensation networks need to be adjusted to maintain the system's stability for different input and output voltages applications as shown in Table 1. Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202001A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • May 31, 2012 9 DATA SHEET AAT1185 High Voltage Step-Down Controller Network Components VOUT =3.3V VIN = 6V-24V VOUT = 5.0V VIN = 6V-24V R6 R7 C12 R5 C10 C11 R4 27.4k 6.04k 680pF 1k 33pF 680pF 20k 1.96k 14.3k 2.2nF 453Ω 2.2nF 150pF 3.92k Feedback Feed-forward Compensation Table 1: AAT1185 Feedback and Compensation Components for VOUT =3.3V and VOUT = 5.0V. Over-Current Protection V OUT 5.0V/10A The controller provides true-load DC output current sensing which protects the load and limits component stresses. The output current is sensed through the DC resistance in the output inductor (DCR). The controller reduces the operating frequency when an over-current condition is detected; limiting stresses and preventing inductor saturation. This allows the smallest possible inductor for a given output load. A small resistor divider may be necessary to adjust the over-current threshold and compensate for variation in inductor DCR. The preset current limit threshold is triggered when the differential voltage from RS to OS exceeds 100mV (nominal). VOUT 5V/10A LX L1 3.9μH R3 1.74k LX R3 1.74k RS R9 OS R10 C9 0.47μF RS R8 R9 OS Figure 3: Resistor Network to Adjust the Current Limit Greater than the Pre-Set Over-Current Threshold (Add R8, R9). L1 (μH) C9 0.47μF L1 3.9μH R3 (kΩ) C9 (μF) 3.9 1.74 0.47 4.2 2 0.47 4.7 1.47 0.47 Part Number B82559A0392A013, 3.9μH, Epcos, ISAT = 12A, DCR = 4.8mΩ RLF12560T-4R2N100, 4.2μH, TDK, ISAT = 10.2A, DCR = 7.4mΩ SER2013-472ML, 4.7μH, Coilcraft, ISAT = 18A, DCR = 1.7mΩ Table 2: Current Limit Network vs. Inductor DCR. Figure 2: Resistor Network to Adjust the Current Limit Less than the Pre-Set Over-Current Threshold (Add R9, R10). 10 Thermal Protection The AAT1185 has an internal thermal protection circuit which will turn on when the device die temperature exceeds 135°C. The internal thermal protection circuit will actively turn off the high side regulator output device to prevent the possibility of over temperature damage. Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202001A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • May 31, 2012 DATA SHEET AAT1185 High Voltage Step-Down Controller Layout Considerations The Buck regulator output will remain in a shutdown state until the internal die temperature falls back below the 135°C trip point. The combination and interaction between the short circuit and thermal protection systems allows the Buck regulator to withstand indefinite short-circuit conditions without sustaining permanent damage. The suggested PCB layout for the AAT1185 is shown in Figures 5, 6, 7, and 8. The following guidelines should be used to help ensure a proper layout. Thermal Calculations 2. There are three types of losses associated with the AAT1185 step-down converter: 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, assuming continuous conduction mode (CCM), a simplified form of the synchronous step-down converter and LDO losses is given by: PTOTAL = 1. 3. 4. IOUT2 · (RDS(ON)H · VOUT + RDS(ON)L · [VIN - VOUT]) VIN + (tSW · FS · IOUT + IQ) · VIN IQ1 is the step-down converter quiescent currents. The term tSW is used to estimate the full load step-down converter switching losses. The power dissipation that relates to the RDS(ON) occurs in the external high side and low side MOSFETs. Therefore, the total package losses for AAT1185 reduce to the following equation: 5. 6. 7. PTOTAL = (tSW · FS · IOUT + IQ1) · VIN1 Since 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 TSOPJW-14 package, which is 140°C/W. 8. The power input capacitors (C3 and C5) should be connected as closely as possible to the high voltage input pin (IN) and power ground. C5, L1, Q1, C13, and C14 should be placed as closely as possible to each other to minimize any parasitic inductance in the switched current path, which generates a large voltage spike during the switching interval. The connection of inductor to switching node should be as short as possible. The feedback trace or FB pin should be separated from any power trace and connected as closely as possible to the load point. Sensing along a highcurrent load trace will degrade DC load regulation. The resistance of the trace from the load returns to PGND should be kept 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 unused signal pins to ground to avoid unwanted noise coupling. The critical small signal components, include feedback components and compensation components, should be placed close to the FB1 and COMP1 pins. The feedback resistors should be located as close as possible to the FB1 pin with its ground tied straight to the signal ground plane, which is separated from the power ground plane. C9 and R3 should be connected as closely as possible to the RS1 and OS1 pins and placed on the bottom side of the layout to avoid noise coupling from the inductor. For good thermal coupling, a 4-layer PCB layout is recommended and PCB vias are required from the exposed pad (EP) for the MOSFETs paddle to the middle plane and bottom plane. TJ(MAX) = PTOTAL · θJA + TAMB Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202001A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • May 31, 2012 11 DATA SHEET AAT1185 High Voltage Step-Down Controller U1 11 D1 VCC BST 4 C8 0.1μF BAS16 9 C7 2.2μF VIN 6V - 24V VCC DH 5 R1 3.32 10 LX 3 EN DL VOUT 3.3V/10A L1 6 3.9μH AAT1185 3 2 HV Q1 Si7326DN 8 R2 Q2 3.32 1 Si7326DN R3 1.74K R5 1k EN 12 C1, C2, C4, C6 open C3 470μF 25V C5 10μF 25V 7 14 GND RS PGND OS 2 COMP FB 13 TSOPJW-14 U1 C3 C5 C7 C8 C9 C10, C11, C12 C13, C14 R1-R7 D1 Q1, Q2 L1 L1 L1 R6 27.4K 1 C9 0.47μF R4 C10 20K 33pF C11 680pF C12 680pF C13, C14 C15, C16 2x47μF open R7 6.04k AAT1185 Skyworks, Hi-Voltage Buck Controller, TSOPJW-14 Cap, MLC, 470μF/25V, Electrolytic Cap, MLC, 10μF/25V, 1210 Cap, MLC, 2.2μF/6.3V, 0603 Cap, MLC, 0.1μF/6.3V, 0603 Cap, MLC, 0.47μF/6.3V, 0603 Cap, MLC, misc, 0402 Cap, MLC, 47μF/10V, 1210 Carbon film resistor, 0402 BAS16, Generic, Rectifier, 0.2A/85V, Ultrafast, SOT23 Si7326DN, Vishay, N-Channel, 30V, 10A, PAK 1212-8 B82559A0392A013, 3.9μH, Epcos, ISAT = 12A, DCR = 4.8mΩ RLF12560T-4R2N100, 4.2μH, TDK, ISAT = 10.2A, DCR = 7.4mΩ SER2013-472ML, 4.7μH, Coicraft, ISAT = 18A, DCR = 1.7mΩ Figure 4: AAT1185ITO Evaluation Board Schematic for VIN = 6V-24V and VOUT = 3.3V. 12 Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202001A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • May 31, 2012 DATA SHEET AAT1185 High Voltage Step-Down Controller Figure 5: AAT1185ITO Evaluation Board Top Layer. Figure 6: AAT1185ITO Evaluation Board MID1 Layer. Figure 7: AAT1185ITO Evaluation Board MID2 Layer. Figure 8: AAT1185ITO Evaluation Board Bottom Layer Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202001A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • May 31, 2012 13 DATA SHEET AAT1185 High Voltage Step-Down Controller AAT1185 Design Example Specifications VO = 3.3V @ 10A, Pulsed Load ILOAD = 10A VIN = 12V FS = 490kHz TAMB = 85°C in TSOPJW-14 Package Output Inductor For Epcos inductor B82559A0392A013, 3.9μH, DCR = 4.8m max. ΔI = VOUT VOUT 3.3V 3.3V · 1= · 1= 1.25A L1 · FS VIN 3.9μH · 490kHz 12V IPK1 = IOUT1 + ΔI = 10A + 0.6A = 10.6A 2 PL1 = IOUT12 · DCR = 10.6A2 · 4.8mΩ = 539mW Output Capacitor VDROOP = 0.6V COUT = 3 · ΔILOAD 3 · 10A = = 102μF; use 2x47μF 0.6V · 490kHz VDROOP · FS IRMS(MAX) = 1 2· 3 · VOUT · (VIN(MAX) - VOUT) 1 3.3V · (24V - 3.3V) · = 430mARMS = 3.9μH · 490kHz · 24V L · FS · VIN(MAX) 2· 3 PRMS = ESR · IRMS2 = 5mΩ · (430mA)2 = 0.9mW Input Capacitor Input Ripple VPP = 60mV CIN = 1 VPP - ESR · 4 · FS IOUT = 1 60mV - 5mΩ · 4 · 490kHz 10A = 510μF For low cost applications, a 470μF/25V electrolytic capacitor in parallel with a 10μF/25V ceramic capacitor is used to reduce the ESR. IRMS = IOUT1 = 5A 2 P = ESR · (IRMS)2 = 5mΩ · (5A)2 = 125mW 14 Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202001A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • May 31, 2012 DATA SHEET AAT1185 High Voltage Step-Down Controller Current Limit Over-current offset voltage VOCP = 100mV Total trace parasitic resistor and inductor DCR is 6m ILIMIT = VS 100mV = = 17A DCR 6mΩ In order to sense the inductor current correctly during dynamic operation the R-C network time constant R3 *C9 should match the inductor time constant L1/DCR: L1 = R3 · C 9 DCR Choose C3 = 0.47μF R3 = L1 3.9μH = = 1.74kΩ DCR · C9 4.8mΩ · 0.47μF AAT1185 Losses All values assume 25°C ambient temperature and thermal resistance of 140°C/W in the TSOPJW-12 package. PTOTAL = (tSW · FS · IOUT1 + IQ) · VIN PTOTAL = (5ns · 490kHz · 10A + 70μA) · 12V PTOTAL = 295mW TJ(MAX) = TAMB + ΘJA · PLOSS = 85°C + (140°C/W) · 0.295mW = 126.3°C Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202001A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • May 31, 2012 15 DATA SHEET AAT1185 High Voltage Step-Down Controller Ordering Information Package Voltage Marking1 Part Number (Tape and Reel)2 TSOPJW-14 Adj (0.6V) 4UXYY AAT1185ITO-0.6-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-14 2.85 ± 0.20 2.40 ± 0.10 0.20 +- 0.10 0.05 0.40 BSC Top View 0.04 REF 0.05 +- 0.05 0.04 All dimensions in millimeters. Side View 0.15 ± 0.05 + 0.05 1.05 - 0.00 + 0.000 1.00 - 0.075 3.05 +- 0.05 0.10 4° ± 4° 0.45 ± 0.15 2.75 ± 0.25 End View 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. 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. 16 Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202001A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • May 31, 2012