DATA SHEET AAT1219 High Current Step-Up Converter with Adjustable Current Limit General Description Features The AAT1219 is a high current synchronous boost converter with programmable low side MOSFET peak current limit of 500mA to 2.5A. It is ideal for preventing input current from overloading system power in PCI-E card applications based on WCDMA/Edge/GPRS/TD-SCDMA PCI-E card GSM high load pulse applications. With a suitable UltraCap or SuperCap, the AAT1219 ensures that output voltage meets load power requirements when large load pulses are applied. It is also ideal for CDMA/ Evdo-A/Evdo-B and other industry modem continuous load current applications. • VIN Range: 2.4V to VOUT + 0.25V • VOUT Range ▪ Adjustable and Fixed Voltage Versions ▪ Adjustable: 3.0V to 5.0V • Programmable NMOS Peak Current Limit: 500mA to 2.5A • Startup Inrush Current Limit: 500mA • Reverse Current Blocking • True Load Disconnect when Shutdown • Up to 95% Efficiency • 1.2MHz Switching Frequency • Low RDS(ON) • Synchronous Boost Rectification and Internal Compensation • Output Ready Indicator • Fault Protection ▪ Programmable Over-Voltage Protection ▪ Short-Circuit Protection ▪ Over-Temperature Protection • Low-profile TDFN33-12 Package The output voltage of the adjustable version of the AAT1219 is programmed from 3.0V to 5.0V by an external resistive divider; the FB pin is left floating in the fixed output voltage version. Optimized internal compensation provides fast transient response with no external components. Light load switching frequency modulation and low quiescent current maintain high efficiency performance for light load mode conditions. The low-side power MOSFET peak current limit of 500mA to 2.5A is set via an external resistor to protect the system power from overload. The high-side current limit operates in a linear mode to limit inrush current to 500mA. Reverse blocking is integrated to prevent current from flowing back to the input. The AAT1219's true load disconnect function isolates the output from the input when the device is disabled. Output over-voltage, short-circuit, and over-temperature protection are also integrated to protect the AAT1219 from these fault conditions. Applications • PC Cards (PCMCIA) Modems • PCI-E Modem Cards ▪ WCDMA/Edge/GPRS/TD-SCDMA ▪ CDMA/Evdo-A/Evdo-B ▪ Industry Modems • USB Modems The AAT1219 is available in a Pb-free, 12-pin, low-profile TDFN33 package and is rated over the -40°C to 85°C temperature range. Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202052A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 12, 2012 1 DATA SHEET AAT1219 High Current Step-Up Converter with Adjustable Current Limit Typical Application 2.4V to VOUT +0.25V L1 4.7μH LX VIN CIN 10μF VOUT 3.8V High Load Pulse OUT R1 316kΩ AAT1219 R3 100kΩ FB R2 59kΩ RDY COUT1 22μF COUT2 UltraCap or SuperCap EN ISET OVP PGND AGND RSET 2.4V to VOUT +0.25V L1 4.7μH LX CIN 10μF VIN R1 287kΩ AAT1219 R3 100kΩ VOUT 3.5V Continuous Load OUT COUT1 22μF FB R2 59kΩ RDY EN ISET AGND OVP PGND RSET 40.2kΩ Pin Descriptions 2 Pin # Symbol 4 IN 1,2 LX 8 FB 10 OUT 11, 12 7 3 6 PGND AGND EN RDY 9 ISET 5 OVP Description Battery input voltage. Supplies the IC at startup. Switching node tied to drain of internal N-channel MOSFET and source of internal P-channel MOSFET. Connect this pin to the external power inductor. Feedback input pin.This pin is connected to an external resistor divider which programs the output voltage for adjustable version with feedback voltage of 0.6V. Boost converter output voltage; connects to the P-channel synchronous MOSFET source. Bypass with ceramic capacitor to GND. Power ground. Non-power signal ground pin. Input enable pin. Logic high to enable the boost. Logic low to disable the IC. System ready pin. Open drain, active low, initiated when the output capacitor is 95% charged. Peak current limit programmable input. An external resistor from ISET to ground is adopted to program the low-side MOSFET peak current limit between 500mA and 2.5A. Over voltage protection pin.This pin is connected to an external resistor divider to set the over voltage threshold.To disable the over voltage feature, short this pin to ground. Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202052A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 12, 2012 DATA SHEET AAT1219 High Current Step-Up Converter with Adjustable Current Limit Pin Configuration TDFN33-12 (Top View) LX LX EN IN OVP RDY 1 12 2 11 3 10 4 9 5 8 6 7 PGND PGND OUT ISET FB AGND Absolute Maximum Ratings1 Symbol Description LX, VIN, EN, RDY, FB Voltage to PGND PGND Voltage to GND Operating Junction Temperature Range Storage Temperature Range Maximum Soldering Temperature (at leads, 10 sec) TJ TS TLEAD Value Units -0.3 to 6.0 -0.3 to 0.3 -40 to 150 -65 to150 300 V V C C C Value Units 2 50 W C/W Thermal Information Symbol PD JA Description Maximum Power Dissipation2 Maximum Thermal Resistance3 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 1.6mm thick FR4 circuit board. 3. Derate 25mW/C above 25 C ambient temperature. Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202052A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 12, 2012 3 DATA SHEET AAT1219 High Current Step-Up Converter with Adjustable Current Limit Electrical Characteristics VIN = 3.3V, CIN = 10μF, COUT = 22μF, L = 4.7μH, TA = 25°C unless otherwise noted. Symbol VIN VOUT_RANGE VOP Input Operating Voltage Range 2.4 IQ ISHDN Quiescent Supply Current Shutdown Current VOVP ILIMIT,P ILIMIT,N FOSC DTYMAX Logic VEN(L) VEN(H) IEN VRDY Thermal TSD TSD(HYS) Min 3.0 UVLO Threshold ∆VOUT/ ∆IOUT ∆VOUT/ ∆VOUT RDS(ON)_N RDS(ON)_P Conditions Minimum Start-Up Voltage Output Voltage Range VUVLO VFB_ACC 4 Description Feedback Voltage Accuracy VIN Rising Hysteresis No Load, No Switching EN = 0V, VIN = 5.5V TA = 25°C, VFB = 600mV TA = -40°C to +85°C, VFB = 600mV Load Regulation 0A to 1.2A, VOUT = 3.8V Line Regulation NMOS Switch On Resistance PMOS Switch On Resistance Over-Voltage Protection Threshold PMOS Current Limit NMOS Current Limit Switching Frequency Maximum Duty Cycle Logic Input Low Threshold for EN Logic Input High Threshold for EN Enable Input Low Current RDY Threshold Over-Temperature Shutdown Threshold Over-Temperature Shutdown Hysteresis Typ Max Units 2.3 2.4 5.0 VOUT + 0.25 2.3 V V 2.1 100 58 0.01 -2 -3 80 1 2 3 V V mV μA μA % % 0.5 % VIN = 2.4V to VOUT 0.2 %/V VOUT = 3.8V VOUT = 3.8V VOVP Rising, TA = 25°C VOVP Hysteresis VOUT = 0V RSET = 100kΩ 250 300 600 20 500 1.0 1.2 90 mΩ mΩ mV mV mA A MHz % 570 0.8 630 1.2 0.4 VIN = VOUT = 5.5V VOUT Rising VOUT Hysteresis 1.4 -1.0 1.0 95 10 140 15 Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202052A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 12, 2012 V V μA % VOUT % VOUT C C o o DATA SHEET AAT1219 High Current Step-Up Converter with Adjustable Current Limit Typical Characteristics L = 4.7μH, COUT = 22μF. Input Current vs. Input Voltage Input Current vs. Input Voltage (VOUT = 3.8V) (VOUT = 5V) 150 110 145 108 140 Input Current (μA) Input Current (μA) 112 106 104 102 100 98 96 94 135 130 125 120 115 110 92 105 90 100 2.4 2.6 2.8 2.4 2.6 2.8 3.0 3.2 3.4 3.6 3.8 3.0 3.2 3.4 3.6 3.8 Quiescent Current vs. Temperature Efficiency vs. Output Current (Measured from VOUT) (VOUT = 3.3V) 100 100 90 90 80 60 50 40 30 VOUT = 5.5V VOUT = 4.2V VOUT = 3.3V VOUT = 2.4V 20 10 -20 0 20 40 60 80 70 60 50 40 30 VIN = 2.4V VIN = 2.7V VIN = 3.0V 20 10 0 0.01 100 0.1 1 Efficiency vs. Output Current 100 1000 10000 Efficiency vs. Output Current (VOUT = 3.8V) (VOUT = 5.0V) 100 100 90 90 80 Efficiency (%) 80 Efficiency (%) 10 Output Current (mA) Temperature (°C) 70 60 50 VIN = 2.4V VIN = 2.6V VIN = 2.8V VIN = 3.0V VIN = 3.3V 40 30 20 10 0 0.01 4.8 5.0 80 70 0 -40 4.6 Input Voltage (V) Efficiency (%) Quiescent Current (μA) Input Voltage (V) 4.0 4.2 4.4 0.1 1 10 100 Output Current (mA) 1000 70 60 VIN = 2.4V VIN = 2.8V VIN = 3.0V VIN = 3.3V VIN = 3.6V VIN = 4.0V VIN = 4.2V 50 40 30 20 10 10000 0 0.01 0.1 1 10 100 1000 10000 Output Current (mA) Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202052A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 12, 2012 5 DATA SHEET AAT1219 High Current Step-Up Converter with Adjustable Current Limit Typical Characteristics L = 4.7μH, COUT = 22μF. Load Regulation vs. Output Current Load Regulation vs. Output Current (VOUT = 3.8V) (VOUT = 5.0V) 1.0 VIN = 2.4V VIN = 2.6V VIN = 2.8V VIN = 3.0V VIN = 3.3V 0.8 0.6 0.4 0.2 Load Regulation (%) Load Regulation (%) 1.0 0.0 -0.2 -0.4 -0.6 -0.8 VIN = 2.4V VIN = 2.8V VIN = 3.0V VIN = 3.3V VIN = 3.6V VIN = 4.0V VIN = 4.2V 0.8 0.6 0.4 0.2 0.0 -0.2 -0.4 -0.6 -0.8 -1.0 0.01 0.1 1 10 100 1000 -1.0 0.01 10000 0.1 1 Output Current (mA) Feedback Voltage Error(%) Feedback Voltage (V) 601.5 601.0 600.5 600.0 599.5 599.0 598.5 3.5 4.0 4.5 5.0 5.5 0.20 0.00 -0.20 -0.40 -40 -20 0 40 60 VEN(H) vs. Temperature VEN(L) vs. Temperature (VIN = 3.6V; VOUT = 5V) (VIN = 3.6V; VOUT = 5V) 1.05 1.05 1 1 0.95 0.95 VEN(L) (V) VEN(H) (V) 20 80 100 Temperature (°C) 0.9 0.85 0.8 0.9 0.85 0.8 -15 10 35 Temperature (°C) 6 10000 0.40 Input Voltage (V) 0.75 -40 1000 Feedback Voltage Error vs. Temperature 602.0 3.0 100 Output Current (mA) Feedback Voltage vs. Input Voltage 598.0 2.5 10 60 85 0.75 -40 -15 10 35 60 Temperature (°C) Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202052A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 12, 2012 85 DATA SHEET AAT1219 High Current Step-Up Converter with Adjustable Current Limit Typical Characteristics L = 4.7μH, COUT = 22μF. RDS(ON)_P vs. Input Voltage RDS(ON)_N vs. Input Voltage 330 390 85°C 25°C -40°C 85°C 25°C -40°C 300 RDS(ON)_N (mΩ) RDS(ON)_P (mΩ) 360 330 300 270 240 270 240 210 180 150 210 180 2.7 3.1 3.5 3.9 4.3 4.7 5.1 120 2.7 5.5 3.1 3.5 Input Voltage (V) 3.9 4.3 4.7 5.1 5.5 Input Voltage (V) Enable Threshold vs. Input Voltage Switching Frequency vs. Temperature Enable Threshold (V) 1.15 1.05 0.95 0.85 0.75 0.65 2.5 VEN(H) VEN(L) 3.0 3.5 4.0 4.5 5.0 5.5 Switching Frequency (MHz) (VIN = 3.6V; VOUT = 5V) 1.30 1.26 1.22 1.18 1.14 1.10 -40 -15 10 35 60 Line Transient Load Transient (VIN = 2.4V to 3.3V; VOUT = 3.8V; IOUT = 200mA; CFF = 0pF) (VIN = 3.3V; VOUT = 3.8V; CFF = 47pF) VIN (0.5V/div) VOUT (200mV/div) 2.4 85 Temperature (°C) Input Voltage (V) 3.8 500mA VOUT (100mV/div) ILOAD (0.25A/div) 3.8 50mA 0A Time (40μs/div) Time (100μs/div) Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202052A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 12, 2012 7 DATA SHEET AAT1219 High Current Step-Up Converter with Adjustable Current Limit Typical Characteristics L = 4.7μH, COUT = 22μF. VIN (4V/div) 0 VOUT (5V/div) 0 IIN (0.2A/div) 0 Soft Start Output Ripple (VIN = 3.6V; VOUT = 5V; IOUT = 100mA) (VIN = 3.3V; VOUT = 3.8V; IOUT = 1mA) ILX (0.1A/div) 0A VOUT (20mV/div) 3.8V Time (200μs/div) Time (100μs/div) Output Ripple Maximum Output Current vs. Input Voltage ILX (0.1A/div) 0.55A VOUT (20mV/div) 3.8V Time (0.8μs/div) 8 (VOUT = 3.8V; CFF = 0F) Maximum Output Current (mA) (VIN = 3.3V; VOUT = 3.8V; IOUT = 500mA) 2000 1800 1600 1400 1200 1000 800 2.4 2.6 2.8 3.0 3.2 3.4 Input Voltage (V) Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202052A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 12, 2012 3.6 3.8 DATA SHEET AAT1219 High Current Step-Up Converter with Adjustable Current Limit Functional Block Diagram OUT IN UVLO Over-Temperature Protection Internal Power Select Control Logic DH Reverse Current Block True Load Disconnect Start-up PMOS Current Control Mode Control OVP EN NMOS Current Control ISET PMOS Comp OVP LX 0.575V RDY 0.6V NMOS DL Slope Compensation PGND Functional Description The AAT1219 synchronous step-up converter is targeted for PC card GSM/GPRS/3G and WiMax modem card applications. It includes two current limits to ensure fast, controlled startup and continuous operation with the PCMCIA specifications. The high 1.2MHz switching frequency of the AAT1219 facilitates output filter component size reduction for improved power density and reduced overall footprint. It also provides greater bandwidth and improved transient Error Amp. FB AGND response over other lower frequency step-up converters. The compensation and feedback is integrated with only three external components (CIN, COUT, L). Low RDS(ON) synchronous power switches provide high efficiency for heavy load conditions. Switching frequency modulation and low quiescent current maintains this high efficiency for light load mode condition. In addition to the improved efficiency, the synchronous rectifier has the added performance advantage of true load disconnect during shutdown (<1μA shutdown current), reverse current blocking, inrush current limit, and short-circuit protection. Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202052A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 12, 2012 9 DATA SHEET AAT1219 High Current Step-Up Converter with Adjustable Current Limit PWM/Light Load Control True Load Disconnect and Shutdown The AAT1219 is a fixed frequency PWM peak current mode control step-up converter. For light load condition (70 to 80mA and below), the converter remains in variable frequency (Light Load) mode to reduce the dominant switching losses. In addition to Light Load operation, a zero current comparator blocks reverse current in the P-channel synchronous MOSFET and no noise control removes the EMI effect caused by inductor current ring. These controls, along with very low quiescent current, help to maintain high efficiency over the complete load range without increased output voltage ripple during light load conditions. A typical synchronous step-up (boost) converter has a conduction path from the input to the output via the parasitic body diode of the P-channel MOSFET when the converter shuts down. The AAT1219 design uses a special power selection for the substrate to keep the parasitic body diode in off-state during shutdown and startup. This enables the AAT1219 to provide true load disconnect during shutdown and inrush current limit at startup. Start-up and Inrush Current Limit When the AAT1219's output voltage is less than the input voltage at start-up, the device operates the limited P-channel power MOSFET in a linear status to charge large output capacitive loads. The fixed current limit of the PMOS controls the maximum input inrush current to 500mA until output voltage is above input voltage. After VOUT exceeds VIN, the converter enters step-up status with internal circuitry power changed from VIN to VOUT. Programmable NMOS Peak Current Limit When the output voltage of the AAT1219 is in boost mode with the output voltage greater than the input voltage, the NMOS peak current limit takes over.During the inductor charge cycle, the current through the NMOS device is sensed. When this current reaches the value set by the RSET resistor, the low-side NMOS switch is turned off.The NMOS current limit is an instantaneous peak current measurement and should be set high enough to allow the desired average current.The applications section discusses proper selection of RSET resistor values. 10 When EN is set to logic low, the step-up converter is forced into shutdown state with less than 1μA input current. Short-Circuit Protection When a short-circuit fault occurs and the AAT1219 detects that the VOUT voltage is lower than VIN minus 400mV, the internal control circuit changes the device operation status from normal PWM regulation to startup status with startup current limit active to limit the input current. When the fault is removed, AAT1219 recovers to normal operation automatically. Over-Temperature Protection An over-temperature event occurs when the AAT1219's junction temperature exceeds the over-temperature protection threshold. In the case, the AAT1219's over-temperature protection circuitry completely disables switching and the PMOS current limit serves to control the current level to avoid damage to the step-up converter. When the over-temperature fault condition is removed, the boost recovers regulation automatically. Power Ready Indicator (RDY) To indicate output voltage OK, an open-drain output RDY pin is designed to pull down when the output voltage increases to 95% of the nominal voltage level. The pin will be pulled up when the output voltage drops below 87% of the nominal output level. Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202052A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 12, 2012 DATA SHEET AAT1219 High Current Step-Up Converter with Adjustable Current Limit Application Information RSET Selection for Current Limit Programming The current limit of the internal low-side NMOS power switch is programmable from 500mA to 2.5A by an external resistor connected from ISET to ground. The resistor value can be calculated using the following formula: RSET = R2 = 59kΩ R1 (kΩ) 3.3 3.6 3.7 3.8 4.0 4.2 5.0 267 294 309 316 340 353 432 Table 2: 1% Standard Resistor Examples for Different Output Voltages. 105 ILIM When the inductor's peak current reaches the current limit, the RDY indicator is pulled high. Table 1 gives standard 1% standard metal film resistor example values for NMOS current limit programming. NMOS Peak Current Limit (A) RSET (kΩ) 0.5 0.6 0.7 0.8 0.9 1.0 1.25 1.5 1.75 2.0 2.25 2.5 200 165 143 124 110 100 78.7 66.5 56.2 49.9 44.2 40.2 Table 1: 1% Standard RSET Value Examples for NMOS Current Limit Programming Output Voltage Programming The output voltage of the AAT1219 adjustable version may be programmed from 3.0V to 5.5V with an external resistor divider. Resistors R1 and R2 in Figure 2 program the output voltage as shown by the following equation: R1 = VOUT (V) R2 · VOUT - R2 0.6 0.6V is the feedback reference voltage. To limit the bias current required for the external feedback resistor string while maintaining good noise immunity, the suggested value for R2 is 59kΩ. Table 2 summarizes the resistor values with R2 set to 59kΩ for good noise immunity and 6μA increased load current and gives some 1% standard metal film resistor values for R1 at different output voltage settings. Over-Voltage Protection The AAT1219’s over-voltage protection function prevents the output voltage from exceeding the programmed over-voltage point via an external resistor divider when output voltage has the possible risk of over-shoot. Resistors R3 and R4 in Figure 2 program the over-voltage trip point. 100kΩ is a good resistance for R4 with good noise immunity and reduced no load input current. Calculate the value of R3 using the following formula: R3 = R4 · VOUT_OVP - R4 0.6 As an example, for a 5.5V OVP setting, R3 is 820kΩ when R4 is 100kΩ. If the over-voltage protection function is not used, connect the OVP pin to ground. Inductor Selection The AAT1219 is designed to operate with a 4.7μH inductor for all input/output voltage combinations. For high efficiency, choose a ferrite inductor with a high frequency core material to reduce core loses. The inductor should have low ESR (equivalent series resistance) to reduce the I2R losses, and must be able to handle the peak inductor current without saturating. To minimize radiated noise, use a shielded inductor. Input Capacitor Select a low ESR ceramic capacitor with a value of at least 10μF as the input capacitor. The input capacitor should be placed as close to the VIN and PGND pins as possible in order to minimize the stray resistance from the converter to the input power source. Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202052A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 12, 2012 11 DATA SHEET AAT1219 High Current Step-Up Converter with Adjustable Current Limit Output Capacitor The output capacitor provides energy to the load when the high-side MOSFET is switched off. The output capacitance together with the boost switching frequency, duty cycle, and load current value determine the output voltage ripple when the boost operation is in the continuous PWM state. ∆VOUT = IOUT · D COUT · fSW D is the duty ratio of low-side MOSFET turn-on time divided by the switching period. It is calculated using the equation D=1- VIN VOUT The output capacitor’s ESR increases the output ripple by IOUT · ESR. The total output ripple is: ∆VOUT = IOUT · D COUT · fSW + IOUT · ESR So the minimum output capacitor value is: COUT_MIN = (∆VOUT - IOUT · ESR) · fSW D · IOUT High Load Pulse Application Together with a large value output capacitor or supercap, the AAT1219 can support a higher load pulse in lower input current limited applications such as GSM burst mode in WCDMA, Edge, GPRS and TD-SCDMA applications. The large capacitance is determined by NMOS peak current limit, inductor current ripple, VIN, VOUT, load pulse high current level and elapsed time. It can be calculated as follows: First calculate the AAT1219's load current from on the expected ILIM based on an approximation of input current equaling ILIM because the inductor current ripple is low enough when compared to the input current: IOUT_BOOST = 12 Second, calculate the maximum current the large capacitor COUT should provide: ICOUT = ILOAD_PEAK - IOUT_BOOST Finally, derive the COUT at a certain load on period TON: COUT = ICOUT · TON ∆VOUT To consider the real tantalum capacitor having 20% tolerance, the selected capacitance should be 20% higher than the calculated value. Example: A 2A, 217Hz 12.5% duty cycle load pulse is applied on 3.8V VOUT at 3.3V VIN. An input peak current limit of 1.1A and a VOUT drop of less than 450mV are required. Under these conditions, with 89% efficiency, the AAT1219's output current is IOUT_BOOST = 3.3 · 1 · 89% = 0.85A 3.8 The maximum current necessary for the large capacitor value is: ICOUT = 2 - 0.85 = 1.15A TON is 577μs for a 217Hz 12.5% duty cycle load pulse. Considering 20% capacitance tolerance, the minimum capacitance should be 1843μF. Figure 1 shows the AAT1219 operating waveform under a 2A 577μs load pulse with 6x330μF tantalum capacitor as COUT, as well as a 22μF ceramic capacitor to closely filter the output voltage. Supercapacitors have large capacitance and can also be used in this application. One supercapacitor has a maximum voltage of 1V or 2.5V depending on its electrode material types (aqueous or organic). For higher voltage applications, supercapacitors are connected in series. To prevent any cell from charging over-voltage, a balance resistor is required on a string of more than three cells. VIN · ILIM · η VOUT Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202052A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 12, 2012 DATA SHEET AAT1219 High Current Step-Up Converter with Adjustable Current Limit VIN 1V/div IIN 1A/div VOUT 2V/div IOUT 2A/div RDY 2V/div 3.3V Layout Guidance 3.8V For best performance of the AAT1219, the following guidelines should be followed when designing the PCB layout: 1. 0V 2. Time (1ms/div) Figure 1: AAT1219 Operation Waveform When 2A 577μs Load Pulse is Applied. 3. Make the power trace as short and wide as possible, including the input/output power lines and switching node, etc. Connect the analog and power grounds together with a single short line and connect all low current loop grounds to analog ground to decrease the power ground noise on the analog ground and achieve better load regulation. For good power dissipation, the exposed pad under the package should be connected to the top and bottom ground planes by PCB vias. Evaluation Board Schematic LX VIN 4 L1 C1 10μF VOUT U1 AAT1219 1 4.7μH 2 VIN GND 3 JP1 RSET 40.2K 9 OUT 10 LX RDY 6 EN FB IN R5 100k VIN LX ISET OVP 8 5 RDY R1 316k FB C3 R3 C21 C22 22μF C23 C24 C25 R2 59k AGND EP PGND PGND 7 12 11 R4 0 Figure 2: AAT1219 Evaluation Board Schematic. Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202052A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 12, 2012 13 DATA SHEET AAT1219 High Current Step-Up Converter with Adjustable Current Limit Evaluation Board Layout Figure 3: AAT1219 Evaluation Board Top Side Layout. Figure 4: AAT1219 Evaluation Board Bottom Side Layout Component Part Number Description Manufacturer U1 R1 R2 R4 R5 RSET C1 C21 L1 R3, C3, C22, C23, C24, C25 AAT1219IWP-1-1.2 RC0603FR-07316KL RC0603FR-0759KL RC0603FR-070RL RC0603FR-07100KL RC0603FR-0740K2L GRM21BR61C106K GRM21BR60J226M SD53-4R7 High Current Step-Up Converter with Adjustable Current Limit Res 316kΩ 1/10W 1% 0603 SMD Res 59kΩ 1/10W 1% 0603 SMD Res 0Ω 1/10W 1% 0603 SMD Res 100kΩ 1/10W 1% 0603 SMD Res 40.2kΩ 1/10W 1% 0603 SMD Cap Ceramic 10μF 0805 X5R 16V 10% Cap Ceramic 22μF 0805 X5R 6.3V 20% Inductor 4.7μH 2.1A SMD Skyworks Yageo Murata Coiltronics Not Populated Table 3: AAT1219 Evaluation Board Bill of Materials. Manufacturer Coiltronics Sumida Coilcraft Part Number L (μH) Max DCR (mΩ) Saturation Current (A) Size WxLxH (mm) SD3118 SD53 SD8328 CDRH4D14HPNP CDRH4D22 CDRH8D28 LPS4018 LPS5030 4.7 4.7 4.7 4.7 4.7 4.7 4.7 4.7 162 45 24.7 140 82.6 19 125 83 1.31 2.1 3.6 1.4 2.2 3.4 1.9 2.0 3.1x3.1x1.8 5.2x5.2x3.0 8.3x9.5x3.0 4.6x4.6x1.5 5.0x5.0x2.4 8.3x8.3x3.0 4.0x4.0x1.7 4.8x4.8x2.9 Table 4: Surface Mount Inductors. 14 Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202052A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 12, 2012 DATA SHEET AAT1219 High Current Step-Up Converter with Adjustable Current Limit Manufacturer Part Number Value (μF) Voltage Tolerance Temp. Co. ESR (mΩ) Case Murata GRM21BR60J226ME39 TAJD337M006R TPSD337M006R0150 TAJD477M006R TPSD477M006R0150 TAJD687M006R TPSD687M006R0100 T491D337M006AT T495D337M006ATE100 T491D477M006AT T495D477M006ATE150 T491D687M006ZT T495D687M006ZTE150 22 330 330 470 470 680 680 330 330 470 470 680 680 6.3 6.3 6.3 6.3 6.3 6.3 6.3 6.3 6.3 6.3 6.3 6.3 6.3 20% 20% 20% 20% 20% 20% 20% 20% 20% 20% 20% 20% 20% X5R X5R X5R X5R X5R X5R X5R X5R X5R X5R X5R X5R X5R 26 400 150 400 150 500 100 400 100 400 150 500 150 0805 7343 7343 7343 7343 7343 7343 7343 7343 7343 7343 7343 7343 AVX KEMET Table 5: Surface Mount Capacitors. Manufacturer Part Number Capacitance (mF) Rated Voltage (V) ESR (mΩ) Size WxLxH (mm) Cap-xx http://www.cap-xx.com/ GZ 215F HS 203F HS 211F HS 206F HW 207F 75 250 370 600 450 4.5 5.5 5.5 5.5 5.5 150 70 55 70 100 20x15x2.6 39x17x2.15 39x17x2.9 39x17x2.4 28.5x17x2.9 Table 6: Supercapacitors. Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202052A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 12, 2012 15 DATA SHEET AAT1219 High Current Step-Up Converter with Adjustable Current Limit Ordering Information Package Output Voltage Feedback Voltage Marking1 Part Number (Tape and Reel)2 TDFN33-12 Adjustable 0.6V 8VXYY AAT1219IWP-1-1.2-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 TDFN33-123 Index Area 0.40 ± 0.05 Detail "A" C0.3 0.45 ± 0.05 2.40 ± 0.05 3.00 ± 0.05 0.1 REF 3.00 ± 0.05 1.70 ± 0.05 Top View Bottom View 0.23 ± 0.05 Pin 1 Indicator (optional) 0.05 ± 0.05 0.23 ± 0.05 0.75 ± 0.05 Detail "A" Side View All dimensions in millimeters. 1. XYY = assembly and date code. 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. 16 Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202052A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 12, 2012 DATA SHEET AAT1219 High Current Step-Up Converter with Adjustable Current Limit Copyright © 2012 Skyworks Solutions, Inc. All Rights Reserved. Information in this document is provided in connection with Skyworks Solutions, Inc. (“Skyworks”) products or services. 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Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202052A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 12, 2012 17