DATA SHEET AAT2608A Eight-Channel LDO with DC/DC Converter General Description Features The AAT2608A is a member of Skyworks' Total Power Management IC (TPMICTM) product family. It contains a fully integrated step-down converter and eight low dropout (LDO) regulators, making it ideal for general multiple rails applications. • 1.5MHz Step-Down Converter ▪ 800mA, Externally Adjustable ▪ Synchronous with Integrated Switches ▪ Independent Enable ▪ Independent Input Power and Ground ▪ Operating Input Voltage Range of 2.7V to 5.5V • LDO1, LDO2, LDO3 and LDO4 Regulators Share Same Input as the Step-down Converter • LDO5 and LDO6 are Tied to the Same Input • LDO7 and LDO8 are Tied to the Same Input • LDO1, LDO7 and LDO8 have Adjustable Outputs with External Resistors • LDO2, LDO3, LDO4, LDO5 and LDO6 have Factory Programmed Outputs • All LDOs have: ▪ Independent Enable ▪ 300mA Current Capability ▪ High PSRR (68dB @10KHz) ▪ Low Ground Current (30µA) ▪ Over-Current Protection ▪ Over-Temperature Protection ▪ Operating Input Voltage Range from 2.7V to 5.5V • TQFN44-28 Package The step-down converter is a 800mA synchronous converter which operates at a switching frequency of 1.5MHz, minimizing the size of external components while keeping efficiency greater than 90%. The step-down converter is capable of 1A of peak current and has an integrated compensation network. The input voltage range is 2.7V to 5.5V, and the output can be externally adjusted from 0.6V to 80% of the step-down converter's input voltage. It includes an independent enable to provide a convenient solution to implement any power up or power down sequencing. The AAT2608A has eight high-PSRR LDOs which provides noise immunity to the generated power rails. The LDOs have independent enable pins to meet any power-up or power-down sequencing requirements. Each LDO requires a small output ceramic capacitor for stability. 5 of the LDOs have a fixed output which is programmed during manufacturing; 3 LDOs have adjustable outputs programmable with external resistors. LDOs 1, 2, 3 and 4 share the same input voltage as the step-down converter’s control circuitry. LDO5 shares its input with LDO6; LDO7 shares its input with LDO8. The AAT2608A is available in the small 28-pin 4mm x 4mm TQFN package. Applications • Cellular Application • Handheld Products • Media Players (MP4 Players) • Portable Navigation Devices (PND) Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202207A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • July 25, 2012 1 DATA SHEET AAT2608A Eight-Channel LDO with DC/DC Converter Typical Application 2.7V to 5.5V A CVCC 2.2µF A CVIN56 2.2µF A CVIN78 2.2µF VINBUCK VCC 2.7V to 5.5V P VIN56 AAT2608A CINBUCK 10µF L1 2.2µH LX VBUCK RBUCK RBUCK VIN78 FBBUCK P CBUCK 22µF A VLDO1 RLDO1 FBLDO1 RLDO1 PGND A A VLDO7 A VLDO1 CLDO1 1µF A VLDO2 CLDO2 1µF A VLDO3 CLDO3 1µF A VLDO4 CLDO4 1µF A VLDO5 CLDO5 1µF A VLDO6 CLDO6 1µF A VLDO7 CLDO7 1µF A VLDO8 CLDO8 1µF LDO1 RLDO7 FBLDO7 RLDO7 A LDO2 VLDO8 RLDO8 FBLDO8 RLDO8 LDO3 A ENBUCK ENLD1 LDO4 ENLD2 ENLD3 LDO5 ENLD4 ENLD5 ENLD6 LDO6 ENLD7 ENLD8 P LDO7 AGND LDO8 2 Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202207A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • July 25, 2012 DATA SHEET AAT2608A Eight-Channel LDO with DC/DC Converter Pin Descriptions Pin # Symbol Function 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 ENLD3 ENLD2 ENLD1 AGND VCC LDO1 FBLDO1 LDO2 LDO3 LDO4 LDO5 LDO6 LDO7 FBLDO7 FBLDO8 LDO8 VIN78 VIN56 ENLD8 ENLD7 ENLD6 VINBUCK LX PGND ENLD5 ENLD4 ENBUCK FBBUCK LDO3 enable; active high. LDO2 enable; active high. LDO1 enable; active high. Analog ground. Input to power control circuit for step-down converter, LDO1, LDO2, LDO3 and LDO4. LDO1 output voltage. Feedback pin for LDO1 LDO2 output voltage. LDO3 output voltage. LDO4 output voltage. LDO5 output voltage. LDO6 output voltage. LDO7 output voltage. Feedback pin of LDO7. Feedback pin of LDO8. LDO8 output voltage. Input to LDO7 and LDO8. Input to LDO5 and LDO6. LDO8 enable; active high. LDO7 enable; active high. LDO6 enable; active high. Power input to the step-down converter input. Switching node for step-down converter regulator. Power ground for step-down converter regulator. LDO5 enable; active high. LDO4 enable; active high. Enable for step-down converter; active high. Feedback input for step-down converter regulator. Pin Configuration TQFN44-28 (Top View) VINBUCK LX PGND ENLD5 ENLD4 ENBUCK FBBUCK ENLD3 ENLD2 ENLD1 AGND VCC LDO1 FBLDO1 28 27 26 25 24 23 22 1 21 2 20 3 19 4 18 5 17 6 16 7 15 8 9 10 11 12 13 14 ENLD6 ENLD7 ENLD8 VIN56 VIN78 LDO8 FBLDO8 FBLDO7 LDO7 LDO6 LDO5 LDO4 LDO3 LDO2 Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202207A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • July 25, 2012 3 DATA SHEET AAT2608A Eight-Channel LDO with DC/DC Converter Absolute Maximum Ratings1 Symbol Description VIN, VCC, VIN5/6, VIN7/8, ENBK1, ENLD1, ENLD2, ENLD3, ENLD4, ENLD5, ENLD6, ENLD7, ENLD8, FBLD1, FBLD7 and FBLD8, FB to GND LX to PGND VOUT1, VOUT2, VOUT3, VOUT4 to GND VOUT5, VOUT6 to GND VOUT7, VOUT8 to GND PGND to GND Value Units -0.3 to 6.5 V -0.3 to VVIN + 0.3 -0.3 to VVCC + 0.3 -0.3 to VVIN5/6 + 0.3 -0.3 to VVIN7/8 + 0.3 -0.3 to +0.3 V Value Units 50 2 -40 to 150 -65 to 150 300 °C/W W V V Thermal Information2 Symbol θJA PD TJ TS TLEAD Description Thermal Resistance Maximum Power Dissipation Operating Temperature Range Storage Temperature Range Maximum Soldering Temperature (at leads, 10 sec) °C 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. 4 Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202207A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • July 25, 2012 DATA SHEET AAT2608A Eight-Channel LDO with DC/DC Converter Electrical Characteristics1 VCC = VIN = VIN56 = VIN78 = VINLDO = 5.0V, -40°C ≤ TA ≤ +85°C, unless otherwise noted. Typical values are TA = 25°C. Symbol Description Conditions Logic Control / Protection Input High Threshold VENLDx VENBUCK Input Low Threshold Step-Down Regulator VINBUCK, VCC Input Voltage Range IQ Quiescent Current ISD Shutdown Current VO_STEP-DOWN VREG Output Voltage Accuracy 0°C ≤ TA ≤ 85°C ILIM P-Channel Current Limit TRAMP RDS(ON)H RDS(ON)L ΔVOUT / (VOUT ΔVIN) FOSC UVLO IQ 0.3 V 5.5 V V 70 µA 1 µA 0.6 80% of VIN -3 +3 From device enable to 90% of nominal output voltage Time to ramp output voltage from 10% to 90% V % mA 100 µs 60 µs High-Side Switch On-Resistance Low-Side Switch On-Resistance 260 220 mΩ mΩ Line Regulation 0.2 %/V 1.5 2 2.2 MHz Ramp-Up Time Oscillator Frequency Under-Voltage Lockout Threshold Falling Rising 2.7 LDO Output Voltage ILDO = 1mA to 300mA, OTP per requirement 0.6 LDO Accuracy ILDO = 10mA VINLDO = 5V, added quiescent current when LDO is enabled ILDO = 10mA ILDO = 1mA to 300mA VINx = 5V, VOx = 1.8V, EN = HIGH, F = 10KHz, ILDO = 100mA ILDO = 250mA -3 LDO Quiescent Current Line Regulation Load Regulation PSRR VDO ILDO(LIM) Thermal TSD THYS Units 1000 Low-Dropout Regulators (LDO1-LDO8) VINLDO Input Voltage Range VOUTx Max 2.7 IOUT = 0mA, device switching, all LDOs disabled ENBK1 = GND Using external feedback resistors Startup Time Typ 1.4 Output Voltage Programmable Range TSTARTUP Min Dropout Voltage LDO Current Limit Over-Temperature Shutdown Threshold Over-Temperature Shutdown Hysteresis V 5.5 VINLDO - VDO +3 % 55 µA 30 V 0.1 0.003 %/V %/mA 68 dB 250 300 Rising V 145 25 500 mV mA °C °C 1. Specification over the -40°C to +85°C operating temperature range is assured by design, characterization and correlation with statistical process controls. Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202207A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • July 25, 2012 5 DATA SHEET AAT2608A Eight-Channel LDO with DC/DC Converter Programming Output Voltages via OTP Programmable Output Voltage Range Step-down1 LDO1 LDO2 LDO3 LDO4 LDO5 LDO6 LDO7 LDO8 6 0.6V 0.6V 0.6V 0.6V 0.6V 0.6V 0.6V 0.6V 0.6V 80% of VIN 3.7V 3.7V 3.7V 3.7V 3.7V Resolution Externally Adjustable with 0.6V Internal Externally Adjustable with 0.6V Internal 100mV per OTP bit 100mV per OTP bit 100mV per OTP bit 100mV per OTP bit 100mV per OTP bit Externally Adjustable with 0.6V Internal Externally Adjustable with 0.6V Internal Reference Reference Reference Reference Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202207A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • July 25, 2012 DATA SHEET AAT2608A Eight-Channel LDO with DC/DC Converter Typical Characteristics−Step-Down (Buck) Converter Input Current vs. Input Voltage Efficiency vs. Output Current (Buck VOUT = 1.2V; Switching; All LDOs Disabled) (Buck VOUT = 1.8V) 100 90 90 80 80 Efficiency (%) Input Current (µA) 100 70 60 50 60 50 40 10 2.7 3.1 3.5 3.9 4.3 4.7 5.1 5.5 0 0.1 Input Voltage (V) 0.00 -0.50 VIN = 2.7V VIN = 3.6V VIN = 4.2V VIN = 5.5V -1.00 10 100 Output Voltage (50mV/div) (top) Load Regulation (%) 0.50 1.30 3.5 1.25 3.0 1.20 2.5 1.15 2.0 1.10 1.5 1.05 1.0 1.00 0.5 0.95 0.0 0.90 -0.5 1000 Output Current (mA) Time (100µs/div) Line Regulation 0.0 -0.5 -1.0 -1.5 2.7 3.1 3.5 3.9 4.3 Input Voltage (V) 4.7 5.1 5.5 (Buck VOUT = 1.2V; VIN = 3.6V; IOUT = 100mA) 5 0.7 4 0.6 3 0.5 2 0.4 1 0.3 0 0.2 -1 0.1 -2 0.0 -3 -0.1 Input Current (bottom) (100mA/div) 0.5 IOUT = 1mA IOUT = 10mA IOUT = 200mA IOUT = 400mA IOUT = 800mA Enable Voltage (top) (1V/div) Output Voltage (middle) (1V/div) Soft Start (Buck VOUT = 1.2V) 1.0 1000 Output Current (500mA/div) (bottom) 1.00 1.5 100 (Buck VOUT = 1.2V; VIN = 3.6V; IOUT = 80mA to 800mA) 1.50 1 10 Load Transient Load Regulation -1.50 0.1 1 Output Current (mA) (Buck VOUT = 1.2V; COUT = 22µF) Line Regulation (%) VIN = 2.7V VIN = 3.6V VIN = 4.2V VIN = 5.5V 30 20 40 30 70 Time (100µs/div) Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202207A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • July 25, 2012 7 DATA SHEET AAT2608A Eight-Channel LDO with DC/DC Converter Typical Characteristics−LDO1-LDO8 Input Current vs. Input Voltage Load Regulation (LDO1 VOUT = 1.85V) 40 0.10 38 0.08 Load Regulation (%) Input Current (µA) (Contributed By Each LDO) 36 34 32 30 28 26 24 22 20 2.7 3.1 3.5 3.9 4.3 4.7 5.1 0.06 0.04 0.02 0.00 -0.02 -0.04 -0.06 -0.08 -0.10 0.1 5.5 Input Voltage (V) VIN = 2.7V VIN = 3.6V VIN = 4.2V VIN = 5.5V 1 (LDO2 VOUT = 2.6V) 0.6 0.4 0.8 Line Regulation (%) Load Regulation (%) 1.0 VIN = 3.0V VIN = 3.6V VIN = 4.2V VIN = 5.5V 0.8 0.2 0.0 -0.2 -0.4 -0.6 -0.8 10 100 0.6 0.4 0.2 IOUT = 1mA IOUT = 100mA IOUT = 150mA IOUT = 250mA IOUT = 300mA 0.0 -0.2 -0.4 -0.6 -0.8 -1.0 2.7 1000 Output Current (mA) 3.1 3.5 3.9 4.3 4.7 Input Voltage (V) Line Regulation (LDO2 VOUT = 2.6V) 1.0 Line Regulation (%) 0.8 0.6 0.4 0.2 IOUT = 1mA IOUT = 100mA IOUT = 150mA IOUT = 250mA IOUT = 300mA 0.0 -0.2 -0.4 -0.6 -0.8 -1.0 2.7 3.1 3.5 3.9 4.3 4.7 5.1 5.5 Input Voltage (V) 8 1000 (LDO1 VOUT = 1.85V) 1.0 1 100 Line Regulation Load Regulation -1.0 0.1 10 Output Current (mA) Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202207A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • July 25, 2012 5.1 5.5 DATA SHEET AAT2608A Eight-Channel LDO with DC/DC Converter Typical Characteristics−LDO1-LDO8 (continued) Output Voltage Error vs. Temperature Output Voltage Error vs. Temperature (LDO1 VOUT = 1.85V; VIN = 3.6V) (LDO2 VOUT = 2.6V; VIN = 3.6V) 1.0 0.8 0.6 0.4 0.2 0.0 -0.2 -0.4 -0.6 IOUT = 1mA IOUT = 250mA -0.8 -1.0 -50 -25 0 25 50 75 100 Output Voltage Error (%) Output Voltage Error (%) 1.0 0.6 0.4 0.2 0.0 -0.2 -0.4 -0.6 -0.8 -1.0 -50 Temperature (°C) -25 0 25 50 75 100 Temperature (°C) Load Transient Load Transient (LDO1 VOUT = 1.85V; VIN = 3.6V; IOUT = 30mA to 300mA) (LDO2 VOUT = 2.6V; VIN = 3.6V; IOUT = 30mA to 300mA) 2.66 1.4 1.2 2.64 1.2 1.90 1.0 2.62 1.0 1.85 0.8 2.60 0.8 1.80 0.6 2.58 0.6 1.75 0.4 2.56 0.4 1.70 0.2 2.54 0.2 1.65 0.0 2.52 0.0 1.60 -0.2 2.50 -0.2 Time (200µs/div) Output Voltage (20mV/div) (top) 1.4 1.95 Output Current (200mA/div) (bottom) 2.00 Output Current (200mA/div) (bottom) Output Voltage (50mV/div) (top) IOUT = 1mA IOUT = 250mA 0.8 Time (200µs/div) Power Supply Rejection Ratio (PSRR) (VIN(DC) = 5V; VOUT = 1.85V; IOUT = 100mA) 80 70 PSRR (dB) 60 50 40 30 20 10 0 10 100 1000 10000 100000 1000000 Frequency (Hz) Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202207A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • July 25, 2012 9 DATA SHEET AAT2608A Eight-Channel LDO with DC/DC Converter Functional Block Diagram VCC ENLD1 Bias ENBUCK VCC VCC Bias LDO1 UVLO VCC Vref 4 VINBUCK S OTP P N PGND FBBUCK S Control Logic LX P VCC Feedback Compensation 1.5 MHz Oscillator ENLD8 Bias VIN78 Error Amp OTP S Vref1 S Sawtooth Generator LDO8 PWM Comparator Vref 4 Soft Start S Thermal Shutdown OTP S Functional Description The AAT2608A is a highly integrated voltage regulating power management unit for mobile handsets or other portable devices. It includes a 800mA switch-mode stepdown converter and eight low-noise, high-PSRR lowdropout (LDO) regulators. It operates from an input voltage between 2.7V and 5.5V making it ideal for lithium-ion or 5V regulated power sources. All nine converters have separate enable pins for ease of use. 10 Synchronous StepDown (Buck) Converter The AAT2608A switch-mode step-down converter is a constant frequency peak current mode PWM converter with internal compensation. The input voltage range is 2.7V to 5.5V. The output voltage range is 0.6V to 80% of VIN. The high 1.5MHz switching frequency allows the use of small external inductor and capacitor. Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202207A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • July 25, 2012 DATA SHEET AAT2608A Eight-Channel LDO with DC/DC Converter The step-down converter offers soft-start to limit the current surge seen at the input and eliminate output voltage overshoot. The current across the internal P-channel power switch is sensed and turns off when the current exceeds the current limit. Also, thermal protection completely disables switching if internal dissipation becomes excessive, thus protecting the device from damage. The junction over-temperature threshold is 145°C with 25°C of hysteresis. The Buck converter is designed for a peak continuous output current of 800mA. It was designed to maintain over 80% efficiency at its maximum rated output current load of 800mA with a 1.2V output. Peak efficiency is above 90%. It also has excellent transient response, load and line regulation. Transient response time is typically less than 60ns. LDO Regulators The AAT2608A includes eight LDO regulators. The regulators operate from the 2.7V to 5.5V input voltage to a regulated output voltage. Each LDO regulator has its own independent enable pin. LDO regulators 1, 7 and 8 have adjustable output voltages set by resistors. LDO regulators 2 thru 6 have a fixed output programmed during manufacturing. Each LDO consumes 30µA of quiescent current and is stable with a small 1.0μF ceramic output capacitor. These LDOs offer high power supply rejection, over-current protection and over-temperature protection. Application Information Synchronous StepDown (Buck) Converter 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. Table 1 displays suggested inductor values for various output voltages. Manufacturer’s specifications list both the inductor DC current rating, which is a thermal limitation, and the peak current rating, which is determined by the saturation characteristics. The inductor should not show any appreciable saturation under normal load conditions. Some inductors may meet the peak and average current ratings yet result in excessive losses due to a high DCR. Always consider the losses associated with the DCR and its effect on the total converter efficiency when selecting an inductor. Input Capacitor Select a 4.7μF to 10μF X7R or X5R ceramic capacitor for the input; see Table 3 for suggested capacitor components. To estimate the required input capacitor size, determine the acceptable input ripple level (VPP) and solve for CIN. The calculated value varies with input voltage and is a maximum when VCC is double the output voltage. Feedback Resistor Selection The output voltage of the buck converter and LDOs 1, 7 and 8 is each set with an individual resistor divider feedback network. The voltage output of the buck converter can be set between 0.6V and 80% of VIN. The voltage output of the LDOs can be set between 0.6V and VIN VDO. VOUT is defined by the following equation: R1 VOUT = 0.6V · 1 + R2 To minimize the current consumed by the voltage divider and to isolate the FB pin from noise, the resistor values for R1 and R2 should be beween 5kΩ and 500kΩ. CIN = VO V · 1- O VIN VIN VPP - ESR · FS IO VO V · 1- O VIN VIN CIN(MIN) = = 1 for VIN = 2 · VO 4 1 VPP - ESR · 4 · FS IO Always examine the ceramic capacitor DC voltage coefficient characteristics when selecting the proper value. For example, the capacitance of a 10μF, 6.3V, X5R ceramic capacitor with 5.0V DC applied is actually about 6μF. Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202207A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • July 25, 2012 11 DATA SHEET AAT2608A Eight-Channel LDO with DC/DC Converter The maximum input capacitor RMS current is: VO V · 1- O VIN VIN IRMS = IO · 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. VO V · 1- O VIN VIN = D · (1 - D) = For VIN = 2 * VO IRMS = VO · 1- 0.52 = 1 2 IO 2 VO VIN The term VIN appears in both the input voltage ripple and input capacitor RMS current equations and is a maximum when VO is twice VCC. This is why the input voltage ripple and the input capacitor RMS current ripple are a maximum at 50% duty cycle. The input capacitor provides a low impedance loop for the edges of pulsed current drawn by the AAT2608A step-down switching regulators. Low ESR/ESL X7R and X5R ceramic capacitors are ideal for this function. To minimize stray inductance, the capacitor should be placed as closely as possible to the IC. This keeps the high frequency content of the input current localized, minimizing EMI and input voltage ripple. A laboratory test set-up typically consists of two long wires running from the bench power supply to the evaluation board input voltage pins. The inductance of these wires, along with the low-ESR ceramic input capacitor, can create a high Q network that may affect converter performance. This problem often becomes apparent in the form of excessive ringing in the output voltage during load transients. Errors in the loop phase and gain measurements can also result. Since the inductance of a short PCB trace feeding the input voltage is significantly lower than the power leads from the bench power supply, most applications do not exhibit this problem. 12 In applications where the input power source lead inductance cannot be reduced to a level that does not affect the converter performance, a high ESR tantalum or aluminum electrolytic 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 provides holdup during large load transitions. A 10μF to 22μF X5R or X7R ceramic capacitor typically provides sufficient bulk capacitance to stabilize the output during large load transitions and has the ESR and ESL characteristics necessary for low output ripple; see Table 2 for suggested capacitor components The output voltage droop due to a load transient is dominated by the capacitance of the ceramic output capacitor. During a step increase in load current, the ceramic output capacitor alone supplies the load current until the loop responds. Within several switching cycles, the loop responds and the inductor current increases to match the load current demand. The relationship of the output voltage droop during the several switching cycles to the output capacitance can be estimated by: COUT = 3 · ∆ILOAD VDROOP · FS Once the average inductor current increases to the DC load level, the output voltage recovers. The above equation establishes a limit on the minimum value for the output capacitor with respect to load transients. The internal voltage loop compensation also limits the minimum output capacitor value to 10μF. This is due to its effect on the loop crossover frequency (bandwidth), phase margin, and gain margin. Increased output capacitance will reduce the crossover frequency with greater phase margin. The maximum output capacitor RMS ripple current is given by: IRMS(MAX) = 1 VOUT · (VIN(MAX) - VOUT) L · FS · VIN(MAX) 2· 3 · 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. Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202207A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • July 25, 2012 DATA SHEET AAT2608A Eight-Channel LDO with DC/DC Converter LDO Regulators Input Capacitor PB = IOB2 · (RDS(ON)H · VOB + RDS(ON)L · [VINB1 - VOB1]) VIN Typically, a 1.0μF or larger ceramic capacitor is recommended for CVCC, CIN5/6, and CIN7/8 in most applications. The input capacitor should be located as close to the input (VCC/VIN5/6/VIN7/8) of the device as practically possible. CVCC, CIN5/6, and CIN7/8 values greater than 1.0μF will offer superior input line transient response and will assist in maximizing power supply ripple rejection. PLDO1 = ILDO1 · (VCC - VOL1) Output Capacitor PLDO6 = ILDO6 · (VIN5/6 - VOL6) For proper load voltage regulation and operational stability, a capacitor is required between the LDOx and AGND pins. The COUTx capacitor connection to the LDO regulator ground pin should be made as direct as practically possible for maximum device performance. The AAT2608A's LDO regulators have been specifically designed to function with very low ESR ceramic capacitors. Although the device is intended to operate with these low ESR capacitors, it is stable over a very wide range of capacitor ESR, thus it will also work with higher ESR tantalum or aluminum electrolytic capacitors. However, for best performance, ceramic capacitors are recommended. Typical output capacitor values for maximum output current conditions range from 1μF to 10μF. Thermal Calculations There are three types of losses associated with the AAT2608A total power management solution (one stepdown converter and eight LDO regulators): switching losses, conduction losses, and quiescent current losses. Conduction losses are associated with the RDS(ON) characteristics of the internal power switches/FETs of both of the stepdown regulators and the power loss associated with the voltage difference across the pass switch/FET of the four LDO regulators. 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 losses is given by the following (quiescent and switching losses are ignored, since conduction losses are so dominant): PLDO2 = ILDO2 · (VCC - VOL2) PLDO3 = ILDO3 · (VCC - VOL3) PLDO4 = ILDO4 · (VCC - VOL4) PLDO5 = ILDO5 · (VIN5/6 - VOL5) PLDO7 = ILDO7 · (VIN7/8 - VOL7) PLDO8 = ILDO8 · (VIN7/8 - VOL8) PLDO8 = ILDO8 · (VIN7/8 - VOL8) PTOTAL = PB + PLDO1 + PLDO2 + PLDO3 + PLDO4 + PLDO5 + PLDO6 + PLDO7 + PLL PB: Power dissipation of the DC-DC regulator IOB: Output current of the specific DC-DC regulator RDS(ON)H: Resistance of the internal high-side switch/FET RDS(ON)L: Resistance of the internal low-side switch/FET VOB: Output voltage of the DC-DC regulator VCC: Input voltage of the DC-DC regulator and LDOs 1 to 4 PLDOx: Power dissipation of the specific LDO regulator ILDOx: Output current of the specific LDO regulator VIN5/6: Input voltage of regulators LDO5 and LDO6 VIN7/8: Input voltage of regulators LDO7 and LDO8 VOLx: Output voltage of the specific LDO regulator PTOTAL: Total power dissipation of the AAT2608A Since RDS(ON) and conduction losses all vary with input voltage, the dominant losses should be investigated over the complete input voltage range. Given the total conduction losses, the maximum junction temperature (125°C) can be derived from the θJA for the TQFN44-28 package which is 50°C/W. TJ(MAX) = PTOTAL · θJA + TA TJ(MAX) = PTOTAL · θJA + TA TJ(MAX): Maximum junction temperature PTOTAL: Total conduction losses ΘJA: Thermal impedance of the package TA: Ambient temperature Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202207A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • July 25, 2012 13 DATA SHEET AAT2608A Eight-Channel LDO with DC/DC Converter Layout The suggested PCB layout for the AAT2608A is shown in Figures 4 and 5. The following guidelines should be used to help ensure a proper layout. 1. The input capacitors (C1, C2, C3, C4) should connect as closely as possible to VIN (Pin 22), VIN56 (Pin 18), VIN78 (Pin 17), and VCC (Pin 5), and AGND/PGND (Pins 4 and 24). 2. C13 (the step-down regulator output capacitor) and L1 should be connected as closely as possible. The connection of L1 to the LX pin should be as short as possible. 3. The feedback trace or FBx pin (Pins 7, 14, 15, and 28) should be separate from any power trace and Manufacturer TDK Part Number/ Type Inductance (μH) Rated Current (A) DCR (mΩ) (max) 1.2 1.8 2.2 3.3 1 1.8 2.7 3.3 1.2 1.8 2.2 2.7 3.3 1 1.5 2.2 3.3 4.3 3.6 3.2 2.5 2.6 2.35 2.03 1.8 2.8 2.45 2.35 1.95 1.8 4 3.7 3.2 2.9 25 32 40 60 30 50 60 65 20 25 28 30 35 19 (typ) 22 (typ) 29 (typ) 36 (typ) LTF5022 WE-TPC Type M Wurth Electronik WE-TPC Type MH Murata connect as closely as possible to the load point. Sensing along a high current load trace will degrade DC load regulation. If external feedback resistors are used, they should be placed as closely as possible to the FBx pin (Pins 7, 14, 15, and 23) to minimize the length of the high impedance feedback trace. 4. The resistance of the trace from the load return to the PGND (Pins 24) 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. 5. For good thermal coupling, PCB vias are required from the pad for the TQFN44-28 exposed paddle to the ground plane. LQH55D Size (mm) LxWxH 5x5.2x2.2 4.8x4.8x1.8 4.8x4.8x2.8 5x5.7x4.7 Table 1: Suggested Inductor Components. Manufacturer AVX TDK Murata Taiyo Yuden Part Number Value Voltage 0603ZD105K 0603ZD225K C1608X5R1E105K C1608X5R1C225K C1608X5R1A475K C2012X5R1A106K C3216X5R1A226K GRM188R61C105K GRM188R61A225K GRM219R61A106K GRM31CR71A226K LMK107BJ475KA 1μF 2.2μF 1μF 2.2μF 4.7μF 10μF 22μF 1μF 2.2μF 10μF 22μF 4.7μF 10 10 25 16 10 10 10 16 10 10 10 10 Temp. Co. Case X5R 0603 0603 X5R 0805 1206 X5R X7R X5R Table 2: Suggested Capacitor Components. 14 Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202207A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • July 25, 2012 0603 0805 1206 0603 DATA SHEET AAT2608A Eight-Channel LDO with DC/DC Converter VCC TP1 VCC C4 2.2µF VIN JP1 Enable TP13 VOUT_BUCK C13 22µF TB1 L1 2.2µH R14 VIN TP2 VIN U1 C1 10µF TP3 VIN56 C2 2.2µF TP4 VIN78 C3 2.2µF 7 VIN56 LDO1 6 VIN78 LDO2 8 LDO3 9 22 VINBUCK 18 17 AAT2608A R2 1M R3 1M R4 1M R5 1M R6 1M R7 1M R17 100K LDO1 TP10 LDO3 ENLD1 2 ENLD2 LDO4 10 1 ENLD3 LDO5 11 26 ENLD4 LDO6 12 25 ENLD5 LDO7 13 21 ENLD6 FBLDO7 14 20 ENLD7 LDO8 16 19 ENLD8 PGND AGND FBLDO8 15 24 R1 1M R16 100K 28 3 16 SW1 FBLDO1 ENBUCK VCC 1 LX FBBUCK 23 27 LDO1 R15 AAT2608_QFN44-28 5 VCC C14 LDO7 LDO8 TP5 LDO8 TP6 LDO7 C6 1µF TP7 LDO6 TP8 LDO5 C8 1µF TP9 LDO4 C9 1µF TP11 LDO2 C11 1µF TP12 LDO1 C12 1µF C10 1µF C7 1µF C5 1µF LDO7 4 R8 1M LDO8 R10 100K R12 100K R13 100K R11 100K Figure 1: AAT2608A Evaluation Board Schematic. Figure 2: AAT2608A Evaluation Board Top Side PCB Layout. Figure 3: AAT2608A Evaluation Board Bottom Side PCB Layout. Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202207A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • July 25, 2012 15 DATA SHEET AAT2608A Eight-Channel LDO with DC/DC Converter Ordering Information Package Marking1 Part Number (Tape and Reel)2 TQFN44-28 9RXYY AAT2608AINJ-1-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 Information3 TQFN44-28 Pin 1 Dot by Marking 2.600 ± 0.050 4.000 ± 0.050 Detail "A" C0.3 4.000 ± 0.050 2.600 ± 0.050 Top View Bottom View 0.400 ± 0.050 0.430 ± 0.050 0.750 ± 0.050 Side View 0.230 ± 0.050 0.203 REF 0.050 ± 0.050 Pin 1 Indicator Detail "A" 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 202207A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • July 25, 2012 DATA SHEET AAT2608A Eight-Channel LDO with DC/DC Converter 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. Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202207A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • July 25, 2012 17