DATA SHEET AAT2608 Single 800mA Switching Converter and Eight-Channel 300mA LDO Regulator General Description Features The AAT2608 is a member of Skyworks' Total Power Management IC (TPMIC™) product family. It contains an 800mA switching regulator and eight fully integrated 300mA low dropout (LDO) regulators in a small, Pb-free 28-pin 4mmx4mm TQFN package, making it ideal for space-constrained systems. • 2.7V to 5.5V Operating Input Voltage Range • Factory Programmable Outputs from 0.6V to 3.7V • 800mA Monolithic Switching Converter • 1.5MHz Switching Frequency • 90% Efficiency • 70µA Quiescent Current • Independent Input Power and Ground • Independent Enable • ±1% Typical Accuracy • 8 Channel 300mA LDO Regulators • 250mV Dropout Voltage at 250mA • Low 30µA Quiescent Current • High PSRR (68dB @10KHZ) • Independent Enable • ±1% Typical Accuracy • Over-Current Protection • Over-Thermal Protection • 4mmx4mm, 0.4mm Lead Pitch, 28-pin TQFN Package The step-down converter is a monolithic synchronous converter with an integrated compensation network and 90% efficiency. It operates at 1.5MHz and uses a tiny 2.2µH inductor with a small 10µF output capacitor. At no load the switching converter quiescent current is 70µA. The 8 channel 300mA LDO regulator features low power consumption, low dropout, and high noise immunity from the input power supply. Each channel consumes a mere 30µA of current when enabled, features 250mV of dropout at 250mA, and 68dB of power supply rejection at 10kHz. Each channel uses a small 1µF output capacitor and 2.2µF input capacitor. All regulators include a separate enable, providing a convenient solution to implement any power-up and power-down sequencing. All output voltages are factory One Time Programmable (OTP) between 0.6V and 3.7V with 100mV increment and typical regulation accuracy is ±1%. The switcher has a separate input from the linear regulators, permitting post-regulation configuration of the LDO channels from the switcher’s output. Its output is externally programmable with external resistors. LDO1 and LDO2 share the same input voltage, as do LDO3 and LDO4, while LDO5 through LDO8 have their own independent input. Applications • Cellular Application • Handheld Products • Media Players (MP4 Players) • Portable Navigation Devices (PNDs) The AAT2608 is a safe solution which integrates an overcurrent limit for each channel and over-thermal protection. The device is rated over a temperature range of -40°C to 85°C. Typical Application C7 2.2µF VINBUCK VIN34 C1 10µF C2 2.2µF VIN8 C6 2.2µF VCC U1 AAT2608_TQFN44-28 L1 2.2µH VCC ENBUCK LX R11 VINBUCK FBBUCK R12 VIN34 AAT2608 VIN8 LDO1 ENLD1 ENLD0 PGND AGND LDO1 Efficiency vs. Output Current (Buck VOUT = 1.2V) 100 C17 1µF 90 80 C16 10µF Efficiency (%) VCC C15 1µF 70 60 50 40 VIN = 2.7V VIN = 3.6V VIN = 4.2V VIN = 5.5V 30 20 LDO8 LDO8 C8 1µF 10 0 0.1 1 10 100 1000 Output Current (mA) Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202206A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • July 25, 2012 1 DATA SHEET AAT2608 Single 800mA Switching Converter and Eight-Channel 300mA LDO Regulator Pin Descriptions Pin # Symbol 1 2 3 ENLD3 ENLD2 ENLD1 Function LDO3 enable; active high. LDO2 enable; active high. LDO1 enable; active high. 4 AGND Analog ground. 5 VIN34 Input to LDO3 and LDO4. 6 VCC 7 LDO1 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 LDO2 LDO3 LDO4 LDO5 LDO6 LDO7 LDO8 VIN8 VIN7 VIN6 VIN5 ENLD8 ENLD7 ENLD6 VINBUCK LX PGND ENLD5 ENLD4 ENBUCK FBBUCK Input to power control circuitry for step-down converter, bias, and LDO1 and LDO2. This pin is also the power input for LDO1 and LDO2. LDO1 output voltage. LDO2 output voltage. LDO3 output voltage. LDO4 output voltage. LDO5 output voltage. LDO6 output voltage. LDO7 output voltage. LDO8 output voltage. Input to LDO8. Input to LDO7. Input to LDO6. Input to LDO5. LDO8 enable; active high. LDO7 enable; active high. LDO6 enable; active high. Power input to the step-down converter. Switching node for step-down converter. Power ground for step-down converter. LDO5 enable; active high. LDO4 enable; active high. Enable for step-down converter; active high. Feedback input for step-down converter. Pin Configuration TQFN44-28 (Top View) VINBUCK LX PGND ENLD5 ENLD4 ENBUCK FBBUCK ENLD3 ENLD2 ENLD1 AGND VIN34 VCC LDO1 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 VIN5 VIN6 VIN7 VIN8 LDO8 LDO7 LDO6 LDO5 LDO4 LDO3 LDO2 2 Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202206A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • July 25, 2012 DATA SHEET AAT2608 Single 800mA Switching Converter and Eight-Channel 300mA LDO Regulator Absolute Maximum Ratings1 Symbol Description VINBUCK, VCC, VIN34, VIN5, VIN6, VIN7, VIN8, ENBUCK, ENLD1, ENLD2, ENLD3, ENLD4, ENLD5, ENLD6, ENLD7, ENLD8, FBBUCK to AGND LX to PGND LDO1, LDO2 to GND LDO3, LDO4 to GND LDO5 to GND LDO6 to GND LDO7 to GND LDO8 to GND PGND to AGND Value Units -0.3 to 6.5 V -0.3 to VVINBUCK + 0.3 -0.3 to VVCC + 0.3 -0.3 to VVIN34 + 0.3 -0.3 to VVIN5 + 0.3 -0.3 to VVIN6 + 0.3 -0.3 to VVIN7 + 0.3 -0.3 to VVIN8 + 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. Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202206A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • July 25, 2012 3 DATA SHEET AAT2608 Single 800mA Switching Converter and Eight-Channel 300mA LDO Regulator Electrical Characteristics1 VCC = VINBUCK = VIN34 = VIN5 = VIN6 = VIN7 = VIN8 = 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 Converter 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% % mA 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, VOUTx = 1.8V, EN = HIGH, F = 10KHz, ILDO = 100mA ILDO = 250mA -3 LDO Quiescent Current PSRR Dropout Voltage LDO Current Limit Over-Temperature Shutdown Threshold Over-Temperature Shutdown Hysteresis V 5.5 VINLDO - VDO +3 % 55 µA 30 V %/V %/mA 68 dB 250 300 Rising V 0.1 0.003 145 25 1. Specification over the -40°C to +85°C operating temperature range is assured by design, characterization and correlation with statistical process controls. 4 V 100 Line Regulation Load Regulation 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 ENBUCK = 0V Using external feedback resistors Startup Time Typ 1.4 Output Voltage Programmable Range TSTARTUP Min Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202206A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • July 25, 2012 500 mV mA °C °C DATA SHEET AAT2608 Single 800mA Switching Converter and Eight-Channel 300mA LDO Regulator Programming Output Voltages Programmable Output Voltage Range Step-down LDO1 LDO2 LDO3 LDO4 LDO5 LDO6 LDO7 LDO8 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 3.7V 3.7V 3.7V Resolution Externally Adjustable with 0.6V Internal Reference 100mV 100mV 100mV 100mV 100mV 100mV 100mV 100mV Block Diagram AAT2608 VINBUCK Buck1 ENBUCK VCC A LX Control P 2.2µH 10µF PGND 2.2µF FBBUCK Bias, Control, and OTP A LDO 1 LDO1 Output Voltage Trim ENLD2 LDO 2 2.2µF A ENLD3 A LDO 3 A LDO 4 2.2µF A ENLD5 A ENLD6 2.2µF A ENLD7 A ENLD8 LDO5 LDO 6 1µF A LDO6 Output Voltage Trim LDO 7 A LDO 8 1µF LDO7 Output Voltage Trim VIN8 2.2µF 1µF A Output Voltage Trim VIN7 1µF LDO4 LDO 5 VIN6 2.2µF A Output Voltage Trim VIN5 1µF LDO3 Output Voltage Trim ENLD4 1µF LDO2 Output Voltage Trim VIN34 P AGND Output Voltage Trim ENLD1 P 1µF A LDO8 A 1µF Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202206A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • July 25, 2012 5 DATA SHEET AAT2608 Single 800mA Switching Converter and Eight-Channel 300mA LDO Regulator 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 = 1.2V) 100 90 90 80 80 Efficiency (%) Input Current (µA) 100 70 60 50 60 50 40 VIN = 2.7V VIN = 3.6V VIN = 4.2V VIN = 5.5V 30 20 40 30 70 10 2.7 3.1 3.5 3.9 4.3 4.7 5.1 0 0.1 5.5 1 10 Input Voltage (V) 1.5 1.00 1.0 0.50 0.00 -0.50 VIN = 2.7V VIN = 3.6V VIN = 4.2V VIN = 5.5V -1.00 10 100 1000 Line Regulation (%) Load Regulation (%) (Buck VOUT = 1.2V) 1.50 1 IOUT = 1mA IOUT = 10mA IOUT = 200mA IOUT = 400mA IOUT = 800mA 0.5 0.0 -0.5 -1.0 -1.5 2.7 Output Current (mA) 3.9 4.3 4.7 5.1 5.5 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 (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 Time (100µs/div) Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202206A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • July 25, 2012 Input Current (bottom) (100mA/div) 1.30 Output Current (500mA/div) (bottom) Output Voltage (50mV/div) (top) 3.5 Soft Start Enable Voltage (top) (1V/div) Output Voltage (middle) (1V/div) Load Transient 6 3.1 Input Voltage (V) (Buck VOUT = 1.2V; VIN = 3.6V; IOUT = 80mA to 800mA) Time (100µs/div) 1000 Line Regulation Load Regulation (Buck VOUT = 1.2V; COUT = 22µF) -1.50 0.1 100 Output Current (mA) DATA SHEET AAT2608 Single 800mA Switching Converter and Eight-Channel 300mA LDO Regulator Typical Characteristics−LDO1-LDO8 Input Current vs. Input Voltage Load Regulation (LDO1 VOUT = 1.85V) 40 0.5 38 0.4 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 0.3 0.2 0.1 0.0 -0.1 -0.2 -0.3 -0.4 -0.5 0.1 5.5 Input Voltage (V) VIN = 2.7V VIN = 3.6V VIN = 4.2V VIN = 5.5V 1 (VOUT = 3V) 0.5 VIN = 3.3V VIN = 3.6V VIN = 4.2V VIN = 5.5V 0.4 0.3 0.2 0.1 0.0 -0.1 -0.2 -0.3 -0.4 10 100 0.3 0.2 0.1 0.0 -0.1 -0.2 -0.3 -0.4 -0.5 2.7 1000 Output Current (mA) IOUT = 1mA IOUT = 100mA IOUT = 150mA IOUT = 300mA 0.4 Line Regulation (%) Load Regulation (%) 1000 (LDO1 VOUT = 1.85V) 0.5 1 100 Line Regulation Load Regulation -0.5 0.1 10 Output Current (mA) 3.1 3.5 3.9 4.3 4.7 5.1 5.5 Input Voltage (V) Line Regulation (VOUT = 3V) 0.5 IOUT = 1mA IOUT = 100mA IOUT = 150mA IOUT = 300mA Line Regulation (%) 0.4 0.3 0.2 0.1 0.0 -0.1 -0.2 -0.3 -0.4 -0.5 2.7 3.1 3.5 3.9 4.3 4.7 5.1 5.5 Input Voltage (V) Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202206A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • July 25, 2012 7 DATA SHEET AAT2608 Single 800mA Switching Converter and Eight-Channel 300mA LDO Regulator Typical Characteristics−LDO1-LDO8 (continued) Output Voltage Error vs. Temperature Output Voltage Error vs. Temperature (LDO1 VOUT = 1.85V; VIN = 3.6V) IOUT = 1mA IOUT = 250mA 0.8 0.6 0.4 0.2 0.0 -0.2 -0.4 -0.6 -0.8 -1.0 -50 -25 0 25 50 75 1.0 Output Voltage Error (%) Output Voltage Error (%) 1.0 (LDO VOUT = 3V) IOUT = 1mA IOUT = 250mA 0.8 0.6 0.4 0.2 0.0 -0.2 -0.4 -0.6 -0.8 -1.0 -50 100 -25 Temperature (°C) Load Transient 75 100 (VIN(DC) = 5V; VOUT = 1.85V; IOUT = 100mA) 1.4 80 1.95 1.2 70 1.90 1.0 1.85 0.8 1.80 0.6 1.75 0.4 1.70 0.2 1.65 0.0 1.60 -0.2 60 PSRR (dB) Output Voltage (50mV/div) (top) 50 Power Supply Rejection Ratio (PSRR) 2.00 Output Current (200mA/div) (bottom) 8 25 Temperature (°C) (LDO VOUT = 1.85V; VIN = 3.6V; IOUT = 30mA to 300mA) Time (200µs/div) 0 50 40 30 20 10 0 10 100 1000 10000 100000 Frequency (Hz) Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202206A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • July 25, 2012 1000000 DATA SHEET AAT2608 Single 800mA Switching Converter and Eight-Channel 300mA LDO Regulator Functional Block Diagram ENBUCK VCC VCC VCC Bias ENLD1 Bias UVLO VCC LDO1 VINBUCK + A P OTP LX N PGND A Control Logic P VCC Compensation ENLD8 1.5 MHz Oscillator Bias FBBUCK Feedback VIN8 Error Amp Sawtooth Generator + A Soft Start Thermal Shutdown LDO8 PWM Comparator + A OTP A Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202206A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • July 25, 2012 9 DATA SHEET AAT2608 Single 800mA Switching Converter and Eight-Channel 300mA LDO Regulator Functional Description The AAT2608 is a highly integrated voltage regulating power management unit for mobile handsets or other portable devices. It includes an 800mA switch-mode step-down converter and eight low-noise, high-PSRR low-dropout (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. Synchronous StepDown (Buck) Converter The AAT2608 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 VINBUCK. The high 1.5MHz switching frequency allows the use of small external inductor and capacitor. 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 regulation, and line regulation. LDO Regulators The AAT2608 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. All LDOs 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 and provide over-current and over-temperature protection. 10 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. 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 202206A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • July 25, 2012 DATA SHEET AAT2608 Single 800mA Switching Converter and Eight-Channel 300mA LDO Regulator 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 AAT2608 stepdown switching converter. 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. 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 202206A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • July 25, 2012 11 DATA SHEET AAT2608 Single 800mA Switching Converter and Eight-Channel 300mA LDO Regulator LDO Regulators Input Capacitor Typically, a 1.0μF or larger ceramic capacitor is recommended for CVCC, CVINBUCK, CVIN34, CVIN5, CVIN6, CVIN7, and CVIN8 in most applications. The input capacitor should be located as close to the inputs of the device as practically possible. CVCC, CVINBUCK, CVIN34, CVIN5, CVIN6, CVIN7, and CVIN8 values greater than 1.0μF will offer superior input line transient response and will assist in maximizing power supply ripple rejection. Output Capacitor 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 AAT2608'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 AAT2608 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 the stepdown converter and the power loss associated with the voltage difference across the pass switch/FET of the eight 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): 12 PB = IOB2 · (RDS(ON)H · VOB + RDS(ON)L · [VINBUCK - VOB]) VIN PLDO1 = ILDO1 · (VCC - VOL1) PLDO2 = ILDO2 · (VCC - VOL2) PLDO3 = ILDO3 · (VIN34 - VOL3) PLDO4 = ILDO4 · (VIN34 - VOL4) PLDO5 = ILDO5 · (VIN5 - VOL5) PLDO6 = ILDO6 · (VIN6 - VOL6) PLDO7 = ILDO7 · (VIN7 - VOL7) PLDO8 = ILDO8 · (VIN8 - VOL8) PTOTAL = PB + PLDO1 + PLDO2 + PLDO3 + PLDO4 + PLDO5 + PLDO6 + PLDO7 + PLDO8 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, LDO1, and LDO2 PLDOx: Power dissipation of the specific LDO regulator ILDOx: Output current of the specific LDO regulator VINBUCK: Input voltage of the step-down converter. VIN34: Input voltage of LDO3 and LDO4 VIN5: Input voltage of LDO5 VIN6: Input voltage of LDO6 VIN7: Input voltage of LDO7 VIN8: Input voltage of LDO8 VOLx: Output voltage of the specific LDO regulator PTOTAL: Total power dissipation of the AAT2608 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 202206A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • July 25, 2012 DATA SHEET AAT2608 Single 800mA Switching Converter and Eight-Channel 300mA LDO Regulator Layout The suggested PCB layout for the AAT2608 is shown in Figures 2 and 3. The following guidelines should be used to help ensure a proper layout. 1. The input capacitors (C1, C2, C3, C4, C5, C6) should connect as closely as possible to VINBUCK (Pin 22), VIN34 (Pin 5), VIN5 (Pin 18), VIN6 (Pin 17), VIN7 (Pin 16) VIN8 (Pin 15), VCC (Pin 6), and AGND/ PGND (Pins 4 and 24). 2. C13 (the step-down converter 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. 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 3. The feedback trace or FBBUCK pin (Pin 28) should be separated from any power trace and connected 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 FBBUCK pin (Pin 28) to minimize the length of the high impedance feedback trace. 4. The resistance of the trace from the load return to the PGND (Pin 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 0603 0805 1206 0603 Table 2: Suggested Capacitor Components. Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202206A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • July 25, 2012 13 DATA SHEET AAT2608 Single 800mA Switching Converter and Eight-Channel 300mA LDO Regulator VCC TP5 C7 2.2µF VCC JP1 VINBUCK TP1 C1 10µF VINBUCK TB1 Enable L1 2.2µH VINBUCK U1 TP2 VIN34 C2 2.2µF TP3 VIN5 C3 2.2µF 27 TP4 ENBUCK 22 VINBUCK VIN6 C4 2.2µF TP7 5 VIN8 TP6 VIN7 18 C5 2.2µF C6 2.2µF VCC 1 16 SW1 6 VCC R2 1M R3 1M R4 1M R5 1M R6 1M R7 1M 23 FBBUCK 28 R12 VIN5 LDO1 7 17 VIN6 VIN7 LDO2 8 16 15 VIN8 LDO3 9 AAT 2608 TP15 TP14 3 ENLD1 LDO4 10 2 ENLD2 LDO5 11 ENLD3 26 ENLD4 25 ENLD5 21 ENLD6 20 ENLD7 19 ENLD8 LDO6 LDO7 AGND PGND 24 R1 1M LX 4 R8 1M LDO8 C17 1µF R11 AAT2608_TQFN44-28 VIN34 1 TP16 VOUT_BUCK C16 10µF TP12 TP11 TP10 12 LDO6 TP9 13 14 TP8 LDO8 LDO7 LDO5 LDO4 TP13 LDO2 LDO3 C14 1µF LDO1 C15 1µF C13 1µF C12 1µF C11 1µF C10 1µF C9 1µF C8 1µF Figure 1: AAT2608 Evaluation Board Schematic. 14 Figure 2: AAT2608 Evaluation Board Top Side PCB Layout. Figure 3: AAT2608 Evaluation Board Bottom Side PCB Layout. Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202206A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • July 25, 2012 DATA SHEET AAT2608 Single 800mA Switching Converter and Eight-Channel 300mA LDO Regulator Ordering Information Package Marking1 Part Number (Tape and Reel)2 TQFN44-28 9QXYY AAT2608INJ-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. Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202206A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • July 25, 2012 15 DATA SHEET AAT2608 Single 800mA Switching Converter and Eight-Channel 300mA LDO Regulator 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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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 202206A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • July 25, 2012