PRODUCT DATASHEET AAT2503178 SystemPowerTM Adjustable 3-Channel Regulator General Description Features The AAT2503 is a three-channel regulator consisting of a step-down converter with an input voltage range of 2.7V to 5.5V plus two low dropout (LDO) linear regulators. • 800mA Step-Down Converter ▪ VIN Range: 2.7V to 5.5V ▪ VOUT Range: 0.9V to VIN ▪ High Efficiency ▪ 2MHz Switching Frequency • Two 150mA Low Dropout Regulators ▪ LDO Input Voltage Range: 1.62V to 5.5V ▪ VOUT Range: 0.6V to VIN ▪ High Output Accuracy: ±1.5% • 85μA of Total IQ • Independent Enable Pins • Integrated Power MOSFETs • Over-Temperature Protection • QFN34-20 Package • -40°C to +85°C Temperature Range The step-down converter optimizes power efficiency throughout the load range. Pulling the MODE/SYNC pin high enables “PWM Only” mode, maintaining constant frequency and low output ripple across the operating range. Alternatively, the converter may be synchronized to an external clock input to the MODE/SYNC pin. The step-down converter delivers up to 800mA of output current, while consuming 30μA of typical no load quiescent current. The switching frequency is 2MHz, minimizing the size of external components. The two LDOs (LDOA/LDOB) have independent inputs and are capable of delivering up to 150mA each. Ultra low input voltage on the VLDOA and VLDOB pins (down to 1.62V) allows for efficient post-buck regulation. A Power-OK (POK) function provides an open drain output signal when LDOA is within regulation. Both LDOs feature low quiescent current and a low dropout voltage. The output voltages for both LDOs are adjustable to as low as 0.6V. The linear regulators have independent Enable pins. Applications • • • • • Cellular Phones Digital Cameras Handheld Instruments Microprocessor/DSP Core/IO Power PDAs and Handheld Computers The AAT2503 is available in a Pb-free 3x4mm QFN34-20 package and is rated over the -40°C to +85°C temperature range. Typical Application L1 LX AAT2503 VIN VIN VLDOA VLDOB VP MODE/SYNC EN 2503.2008.02.1.4 R1 OUTA R3 100kΩ POK R4 OUTA C2 10μF POK FBA OUTB OUTB R5 FBB ENA ENB VOUT (Buck) FB R8 C6 2.2μF R7 C5 2.2μF R2 PGND AGND www.analogictech.com 1 PRODUCT DATASHEET AAT2503178 SystemPowerTM Adjustable 3-Channel Regulator Pin Descriptions Pin # Symbol 1 FBB 2 ENA 3 ENB 4 MODE/SYNC 5 FB 6 7 AGND PGND 8, 9 LX 10 11, 12 VP N/C 13 VIN 14 EN 15 POK 16 FBA 17 18 19 20 EP OUTA VLDOA VLDOB OUTB 2 Function Feedback input pin for LDOB. This pin is connected to OUTB via an external resistor. It is used to see the output of LDOB to regulate to the desired value via an external resistor divider. For fixed versions, short FBB to OUTB. Enable pin for LDOA. When connected low, LDOA is disabled and consumes less than 1μA of current. When connected high, normal operation. Enable pin for LDOB. When connected low, LDOB is disabled and consumes less than 1μA of current. When connected high, normal operation. Connect to ground for PWM/PFM mode and optimized efficiency throughout the load range. Connect high for low noise PWM operation under all operating conditions. Connect to an external clock for synchronization (PWM only). Feedback input pin for the step-down converter. This pin is connected to the converter output via an external resistor. It is used to see the output of the converter to regulate to the desired value via an external resistor divider. Ground connection pin. Main power ground return pin for the step-down converter. Connect to the output and input capacitor return. Connect inductor to this pin. Switching node internally connected to the drain of both high- and low-side MOSFETs. Input supply voltage for the converter. Must be closely decoupled. Not connected. Bias supply. Supply power for the internal circuitry. Connect to input power via low pass filter with decoupling to AGND. Enable for the step-down converter. A logic low disables the converter and it consumes less than 1μA of current. A logic high enables normal operation. Power-OK pin with open drain output. It is pulled low when the OUTA pin is outside the regulation window. Place a pull-up resistor between POK and OUTA. Feedback input pin for LDOA. This pin is connected to OUTA via an external resistor. It is used to see the output of LDOA to regulate to the desired value via an external resistor divider. For fixed versions, short FBA to OUTA. LDOA output pin; should be closely decoupled with a low-ESR ceramic capacitor. Input voltage pin for linear regulator A; should be closely decoupled. Input voltage pin for linear regulator B; should be closely decoupled. LDOB output pin; should be closely decoupled with a low-ESR ceramic capacitor. Exposed paddle; connect to ground directly beneath the package. www.analogictech.com 2503.2008.02.1.4 PRODUCT DATASHEET AAT2503178 SystemPowerTM Adjustable 3-Channel Regulator Pin Configuration QFN34-20 (Top View) OUTA VLDOA VLDOB OUTB 17 18 19 20 FBB ENA ENB MODE/SYNC FB AGND 1 16 2 15 3 14 4 13 5 12 6 11 FBA POK EN VIN N/C N/C 9 10 8 7 VP LX LX PGND Absolute Maximum Ratings1 Symbol VP, VIN, VLDO VLX VFB VN TJ TLEAD Description Input Voltage and Bias Power to GND LX to GND FB to GND EN, MODE/SYNC to GND Operating Junction Temperature Range Maximum Soldering Temperature (at leads, 10 sec) Value Units 6.0 -0.3 to VP + 0.3 -0.3 to VP + 0.3 -0.3 to 6.0 -40 to 150 300 V V V V °C °C Value Units 2.0 50 W °C/W Thermal Information Symbol PD θJA Description Maximum Power Dissipation (TA = 25°C) Thermal Resistance2 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. 2503.2008.02.1.4 www.analogictech.com 3 PRODUCT DATASHEET AAT2503178 SystemPowerTM Adjustable 3-Channel Regulator Electrical Characteristics1 VIN = 3.6V; TA = -40°C to +85°C, unless otherwise noted. Typical values are TA = 25°C. Symbol Description Conditions Bias Power Supply IQ Quiescent Current ISHDN Shutdown Current LDOA, LDOB; IOUT = 150mA VLDO Input Voltage VOUT VFB VDO ΔVOUT/ VOUT*ΔVIN VEN(L) VEN(H) IOUT ISHT TSD THYS LDOA; IOUT VPOK VPOKHYS VPOK(LO) IPOK Min ENA = ENB = EN = VIN; ILOAD = 0 ENA = ENB = EN = GND IOUT = 1mA to 150mA Output Voltage Tolerance TA = 25°C TA = -40°C to +85°C Feedback Voltage Dropout Voltage2 IOUT = 150mA Line Regulation3 VIN = VOUT + 1 to 5.0V Enable Threshold Low Enable Threshold High Output Current Shutdown Current Over-Temperature Shutdown Threshold Over-Temperature Shutdown Hysteresis = 150mA Power-OK Trip Threshold Power-OK Hysteresis Power-OK Output Voltage Low Power-OK Output Leakage Current 1.62 -1.5 -2.5 0.593 Typ Max Units 85 145 1.0 μA μA 5.5 1.5 2.5 0.607 150 V % V mV 0.09 %/V 0.6 V V mA μA °C °C 0.6 1.4 150 VIN = 5V 1.0 140 15 VOUT Rising, TA = 25°C ISINK = 1mA VPOK <5.5V, VOUT in Regulation 80 90 1.0 98 0.4 1.0 % of VOUT % of VOUT V μA 1. The AAT2503 is guaranteed to meet performance specifications over the -40°C to +85°C operating temperature range and is assured by design, characterization, and correlation with statistical process controls. 2. VDO is defined as VIN - VOUT when VOUT is 98% of nominal. 3. CIN = 10μF. 4 www.analogictech.com 2503.2008.02.1.4 PRODUCT DATASHEET AAT2503178 SystemPowerTM Adjustable 3-Channel Regulator Electrical Characteristics (continued)1 VIN = 3.6V; TA = -40°C to +85°C, unless otherwise noted. Typical values are TA = 25°C. Symbol Description Conditions Min Typ Max Units 5.5 1.8 1.2 400 300 0.5 V V mV V % V V μA μA μA A mΩ mΩ % 0.2 %/V Step-Down Converter; IOUT = 800mA VIN UVLO Under-Voltage Lockout Voltage VOUT VOUT VFB ISHDN Output Voltage Tolerance VOUT Programmable Range Feedback Threshold Voltage Shutdown Current LX Leakage Current Feedback Leakage Current Limit High Side Switch On Resistance Low Side Switch On Resistance Load Regulation ILX_LEAK IFB ILIM RDS(ON)H RDS(ON)L ΔVOUT/VOUT ΔVOUT/ VOUT*ΔVIN FOSC TSD THYS VEN(L) VEN(H) IEN VMODE/SYNC(L) VMODE/SYNC(H) IMODE/SYNC 2.7 Input Voltage VIN Rising Hysteresis VIN Falling IOUT = 0 to 800mA; VIN = 2.7V to 5.5V 250 1.5 -3.0 0.9 0.891 0.9 EN = GND VIN = 5.5, VLX = 0 to VIN VFB = 1.0V ILOAD = 0 to 800mA Line Regulation Oscillator Frequency Over-Temperature Shutdown Threshold Over-Temperature Shutdown Hysteresis Enable Threshold Low Enable Threshold High EN Input Leakage Enable Threshold Low Enable Threshold High Input Low Current 1.6 2.0 140 15 3.0 VIN 0.909 1.0 1.0 0.2 2.4 0.6 VEN = 5V, VIN = 5V 1.4 -1.0 VIN · 0.7 -1.0 1.0 VIN · 0.4 1.0 MHz °C °C V V μA V V μA 1. The AAT2503 is guaranteed to meet performance specifications over the -40°C to +85°C operating temperature range and is assured by design, characterization, and correlation with statistical process controls. 2503.2008.02.1.4 www.analogictech.com 5 PRODUCT DATASHEET AAT2503178 SystemPowerTM Adjustable 3-Channel Regulator Typical Characteristics—Step-Down Converter Efficiency vs. Output Current Efficiency vs. Output Current (VOUT = 1.8V; L = 2.2µH) 90 100 80 90 VIN = 2.7V 60 50 VIN = 3.6V 40 PWM Only Mode VIN = 4.2V 30 20 70 VIN = 2.7V 60 50 PWM Only Mode 40 VIN = 4.2V 30 20 10 10 0 0 0 1 10 100 0 1000 Switching Frequency vs. Temperature (VIN = 3.6V; IOUT = 800mA) 2.4 2.3 Frequency (MHz) VIN = 3.3V 70 60 VIN = 3.6V PWM Only Mode 40 VIN = 4.2V VOUT = 0.9V 2.2 2.1 VOUT = 1.8V 2.0 1.9 1.8 VOUT = 2.5V 1.7 1.6 10 0 0 1 10 100 1000 1.5 -40 -20 0 20 40 60 Load Regulation Soft Start (VOUT = 1.8V; VMODE/SYNC = VIN; L = 2.2µH) (VIN = 3.6V; VOUT = 1.8V; IOUT = 800mA) 6.0 0.9 4.0 0.6 VIN = 4.2V 0.0 -0.3 100 VIN = 3.3V VIN = 3.6V -0.6 -0.9 ENABLE 1.8V 2.0 0.0 VOUT 0V 1.0 0.5 IINDUCTOR Inductor Current (Bottom) (A) ENABLE and VOUT (Top and Middle) (V) 1.2 0.3 80 Temperature (°°C) Output Current (mA) 0.0 -1.2 -0.5 0 1 10 100 1000 Time (100µs/div) Output Current (mA) 6 1000 (VOUT = 2.5V; L = 3.3µH) 20 Accuracy (%) 100 Efficiency vs. Output Current 90 30 10 Output Current (mA) 100 50 1 Output Current (mA) 80 Efficiency (%) VIN = 3.6V 80 70 Efficiency (%) Efficiency (%) (VOUT = 0.9V; L = 1µH) www.analogictech.com 2503.2008.02.1.4 PRODUCT DATASHEET AAT2503178 SystemPowerTM Adjustable 3-Channel Regulator Typical Characteristics—Step-Down Converter Turn Off Line Regulation (VIN = 3.6V; VOUT = 1.8V; IOUT = 800mA) (VOUT = 1.8V; VMODE/SYNC = VIN) 1.2 6.0 ENABLE 2.0 0.0 VOUT (1V/div) 1.8V 1.0 0V IINDUCTOR 0.5 Accuracy (%) 0.9 Inductor Current (Bottom) (A) ENABLE and VOUT (Top and Middle) (V) 4.0 0.6 0.3 IL = 800mA 0.0 -0.3 IL = 10mA 0.0 -0.9 -0.5 -1.2 2.7 3.1 3.5 Time (100µs/div) 4.3 4.7 5.1 Line Regulation No Load Quiescent Current vs. VIN (VOUT = 0.9V; VMODE/SYNC = VIN) (VOUT = 1.8V; L = 2.2µH) 5.5 Quiescent Current (µA) 65 0.9 Accuracy (%) 3.9 Input Voltage (V) 1.2 0.6 IL = 800mA 0.3 0.0 -0.3 IL = 650mA -0.6 -0.9 -1.2 60 55 TA = 85°C 50 45 TA = 25°C 40 35 TA = -40°C 30 25 2.7 3.1 3.5 3.9 4.3 4.7 5.1 5.5 2.7 3.1 3.5 Input Voltage (V) 3.9 4.3 4.7 5.1 5.5 Input Voltage (V) No Load Quiescent Current vs. VIN Output Voltage Error vs. Temperature (VOUT = 0.9V; L = 1µH) (VIN = 3.6V; VOUT = 0.9V; IOUT = 800mA) 50 2.0 Output Voltage Error (%) Quiescent Current (µA) IL = 100mA -0.6 45 TA = 85°C 40 35 TA = 25°C 30 TA = -40°C 25 20 2.7 3.1 3.5 3.9 4.3 4.7 5.1 5.5 1.5 VIN = 2.5V 0.5 0.0 -0.5 -1.0 VOUT = 0.9V -1.5 -2.0 -40 -20 0 20 40 60 80 100 Temperature (°°C) Input Voltage (V) 2503.2008.02.1.4 VIN = 1.8V 1.0 www.analogictech.com 7 PRODUCT DATASHEET AAT2503178 SystemPowerTM Adjustable 3-Channel Regulator Line Transient Load Transient (VOUT = 1.8V; IOUT = 800mA; VIN = 3.6V to 4.2V) (VIN = 3.6V; VOUT = 1.8V; IOUT = 300mA to 650mA) 2.2 2.4 2.0 4.0 2.3 3.5 2.2 3.0 2.1 2.5 2.0 2.0 1.9 1.5 1.8 1.0 1.7 Output Voltage (top) (V) 2.5 4.5 1.8 1.6 VOUT IOUT 300mA 1.2 1.0 0.5 1.6 0.8 0.0 1.5 0.6 0.6 IINDUCTOR Light Load Output Ripple Heavy Load Output Ripple (VIN = 3.6V; VOUT = 1.8V; IOUT = 800mA) 1.0 0 0.8 -10 0.6 -20 0.4 -30 IINDUCTOR -40 0.0 -50 -0.2 -60 1.8 1.6 Inductor Current (Bottom) (A) 10 Time (10µs/div) 8 20 10 VOUT 1.4 0 1.2 -10 1.0 -20 0.8 -30 0.6 0.4 -40 IINDUCTOR -50 0.2 -60 Output Voltage (AC coupled) (Top) (mV) 20 VOUT Output Voltage (AC coupled) (Top) (mV) Inductor Current (Bottom) (A) Time (20µs/div) (VIN = 2.7V; VOUT = 1.8V; IOUT = 1mA) 1.4 0.2 0.3 0.0 Time (20µs/div) 1.2 650mA 1.4 Load and Inductor Current (Bottom) (A) 5.0 Output Voltage (bottom) (V) Input Voltage (top) (V) Typical Characteristics—Step-Down Converter Time (200ms/div) www.analogictech.com 2503.2008.02.1.4 PRODUCT DATASHEET AAT2503178 SystemPowerTM Adjustable 3-Channel Regulator Typical Characteristics—LDO Regulator Dropout Voltage vs. Temperature Dropout Voltage vs. Output Current (VOUT = 2.8V) (VOUT = 2.8V) 100 150mA 100 80 Dropout Voltage (mV) Dropout Voltage (mV) 120 100mA 60 50mA 40 20 90 85°C 80 70 25°C 60 50 40 30 -40°C 20 10 0 0 -40 -20 0 20 40 60 80 100 0 120 20 40 60 80 100 120 140 160 Temperature (°°C) Output Current (mA) Dropout Characteristics LDO Output Voltage vs. LDO Input Voltage Output Voltage (V) 3.0 10mA 2.9 1mA 2.8 150mA 100mA 2.7 2.6 50mA 2.5 2.4 2.7 2.8 2.9 3.0 3.1 3.2 LDO Output Voltage (VOUTA) (V) (IOUTA = 100mA, VIN = VP = 3.6V) 1.90 1.85 1.80 1.75 1.70 1.65 1.60 1.55 1.50 1.45 1.40 1.35 1.30 VOUTA = 1.8V VOUTA = 1.5V 1.6 1.7 2.2 DC Regulation (VIN = 3.6V; VOUT = 1.8V) 2.5 2.0 DC Regulation (%) DC Regulation (%) 2.1 DC Regulation 2.0 1.5 1.0 0.5 IOUT = 50mA 0.0 -0.5 IOUT = 1mA -1.0 IOUT = 100mA -1.5 -2.0 0 20 40 2.3 2.4 2.5 60 1.5 1.0 IOUT = 50mA 0.5 80 100 IOUT = 1mA 0.0 -0.5 -1.0 IOUT = 150mA -1.5 IOUT = 100mA -2.0 IOUT = 150mA -2.5 -2.5 -40 Temperature (°°C) 2503.2008.02.1.4 2.0 (VIN = 3.6V; VOUT = 1.2V) 2.5 -20 1.9 LDO Input Voltage (VLDOA/B) (V) Input Voltage (V) -40 1.8 -20 0 20 40 60 80 100 Temperature (°°C) www.analogictech.com 9 PRODUCT DATASHEET AAT2503178 SystemPowerTM Adjustable 3-Channel Regulator Typical Characteristics—LDO Regulator DC Regulation Quiescent Current vs. Input Voltage (VIN = 3.6V; VOUT = 2.8V) (VLDO = 2.8V) 2.5 35 1.5 1.0 IOUT = 50mA 0.5 0.0 -0.5 IOUT = 1mA -1.0 IOUT = 100mA -1.5 IOUT = 150mA -2.0 -2.5 -40 -20 0 20 40 60 80 100 Ground Current (µA) DC Regulation (%) 2.0 IOUT = 150mA IOUT = 50mA 31 IOUT = 100mA 27 IOUT = 0mA 23 19 15 2.7 3.5 3.9 4.3 4.7 Turn-On Response Time Turn-Off Response Time (VIN = 3.6V; VOUT = 1.8V; IOUT = 150mA) (VIN = 3.6V; VOUT = 1.8V; IOUT = 150mA) 5.1 5.5 6 7 6 4 6 2 5 2 5 0 4 0 4 -2 3 -2 3 -4 2 -4 2 -6 1 -6 1 -8 0 -8 0 -10 -1 -10 -1 ENABLE (Top ) (V) 7 4 Output Voltage (Bottom) (V) 6 Time (10µs/div) Time (50µs/div) Load Transient Load Transient (VIN = 3.6V; VOUT = 1.8V; IOUT = 1mA to 100mA) (VIN = 3.6V; VOUT = 1.8V; IOUT = 50mA to 100mA) 2.2 0.7 0.6 2.0 0.6 1.8 0.5 1.8 0.5 1.6 0.4 1.6 0.4 1.4 0.3 1.4 0.3 1.2 0.2 Output Voltage (Top) (V) 0.7 2.0 1.2 0.2 1.0 0.1 1.0 0.1 0.8 0.0 0.8 0.0 0.6 -0.1 0.6 -0.1 Time (200µs/div) Output Current (Bottom) (A) 2.2 Output Current (Bottom) (A) Output Voltage (top) (V) 3.1 Input Voltage (V) Output Voltage (Bottom) (V) ENABLE (Top ) (V) Temperature (°°C) 10 IOUT = 10mA Time (50µs/div) www.analogictech.com 2503.2008.02.1.4 PRODUCT DATASHEET AAT2503178 SystemPowerTM Adjustable 3-Channel Regulator Typical Characteristics—LDO Regulator 5.0 2.6 5.0 4.5 2.5 4.5 2.4 4.0 2.3 3.5 2.2 3.0 2.1 2.5 2.0 2.0 1.9 Input Voltage (top) (V) VIN 3.5 2.3 3.0 2.2 2.5 2.1 2.0 2.0 1.5 1.9 1.0 1.8 0.5 VOUT 0.0 2.5 2.4 VIN 1.8 1.5 1.0 VOUT 1.7 1.7 0.5 1.6 1.6 0.0 1.5 Time (100µs/div) Time (100µs/div) Line Regulation Load Regulation (VOUT = 1.2V) (VOUT = 1.2V) 2.0 2.0 1.5 1.5 1.0 10mA 1mA 0.5 0.0 50mA -0.5 150mA 100mA -1.0 Output Error (%) Output Error (%) Output Voltage (bottom) (V) 4.0 Input Voltage (top) (V) Line Transient (VOUT = 1.8V; IOUT = 150mA; VIN = 3.6V to 4.2V) Output Voltage (bottom) (V) Line Transient (VOUT = 1.8V; IOUT = 100mA; VIN = 3.6V to 4.2V) 1.0 VIN = 2.7V 0.5 VIN = 3.6V 0.0 -0.5 VIN = 5.5V -1.0 VIN = 4.2V -1.5 -1.5 -2.0 -2.0 2.7 3.1 3.5 3.9 4.3 4.7 5.1 5.5 Input Voltage (V) 0 1 10 100 1000 Output Current (mA) Load Regulation (VOUT = 2.8V) 2.0 Output Error (%) 1.5 1.0 VIN = 3.3V 0.5 VIN = 3.6V 0.0 -0.5 VIN = 5.5V -1.0 VIN = 4.2V -1.5 -2.0 0 1 10 100 1000 Output Current (mA) 2503.2008.02.1.4 www.analogictech.com 11 PRODUCT DATASHEET AAT2503178 SystemPowerTM Adjustable 3-Channel Regulator Functional Block Diagram FB Voltage Reference VIN DH Err. Amp. MODE/SYNC EN VP LX Logic Control Logic DL PGND OUTA VLDOA ENB Err. Amp. VLDOB ENA Err. Amp. Voltage Reference FBA 90% VREF POK OUTB FBB AGND Functional Description Switch-Mode Step-Down Converter The AAT2503 is a high performance power management IC comprised of a step-down converter and two linear regulators. The step-down converter operates in both fixed and variable frequency modes for high efficiency performance. The switching frequency is 2MHz, minimizing the size of the inductor. The converter requires only three external components (CIN, COUT, and L). The LDOs can deliver up to 150mA each. Each regulator has independent input voltage and enable pins and operates with ceramic capacitors. The switching regulator is a monolithic step-down converter operating with input voltage range of 2.7V to 5.5V. Power devices are sized for 800mA current capability and achieve over 95% efficiency. PFM operation maintains high efficiency under light load conditions (typically <50mA). The MODE/SYNC pin allows an optional “PWM Only” mode. This maintains constant frequency and low output ripple across all load conditions. Alternatively, the IC can be synchronized to an external clock via the MODE/SYNC input. External synchronization is main- 12 www.analogictech.com 2503.2008.02.1.4 PRODUCT DATASHEET AAT2503178 SystemPowerTM Adjustable 3-Channel Regulator tained between 1MHz and 3MHz. It consumes 30μA of typical no load quiescent current, making it also ideal for light load applications. The oscillator operates at 2MHz, minimizing the cost and size of external components. A logic low on the EN pin shuts the converter down and makes it consume less than 1μA of current. Soft start increases the inductor current limit point in discrete steps when the input voltage or enable input is applied. It limits the current surge seen at the input and eliminates output voltage overshoot. Soft Start / Enable Soft start limits the current surge seen at the input and eliminates output voltage overshoot in the step-down converter. The step-down converter and the two LDOs have independent enable pins. When pulled low, the enable input forces the LDO into shutdown mode and forces the stepdown converter into a low-power, non-switching state. The input current during shutdown is less than 1μA. For overload conditions, the peak input current is limited. As load impedance decreases and the output voltage falls closer to zero, more power gets internally dissipated, raising the device temperature. Thermal protection completely disables switching when internal dissipation becomes excessive, protecting the device from damage. The junction over-temperature threshold is 140°C with 15°C of hysteresis. Linear Regulators Control Loop LDOA features an integrated Power-OK comparator which indicates when the output is out of regulation. The POK is an open drain output and it is held low when the AAT2503 is in shutdown mode. The AAT2503 includes a peak current mode step-down converter. The current through the P-channel MOSFET (high side) is sensed for current loop control, as well as short-circuit and overload protection. A fixed slope compensation signal is added to the sensed current to maintain stability for duty cycles greater than 50%. The peak current mode loop appears as a voltage-programmed current source in parallel with the output capacitor. The output of the voltage error amplifier programs the current mode loop for the necessary peak switch current to force a constant output voltage for all load and line conditions. Internal loop compensation terminates the transconductance voltage error amplifier output. For fixed voltage versions, the error amplifier reference voltage is internally set to program the converter output voltage. For the adjustable output, the error amplifier reference is fixed at 0.9V. 2503.2008.02.1.4 The two linear regulators are high performance LDOs where each LDO can source up to 150mA of current. For added flexibility, both regulators have independent input voltages operating from 2.8V to 5.5V. An external feedback pin for each LDO allows programming the output voltage from VIN to 0.6V. The regulators have thermal protection in case of adverse operating conditions. Under-Voltage Lockout Internal bias of all circuits is controlled via the VIN pin. Under-voltage lockout guarantees sufficient VIN bias and proper operation of all internal circuits prior to activation. Over-Temperature Protection Thermal protection completely disables switching when internal dissipation becomes excessive. The junction over-temperature threshold is 140°C with 15°C of hysteresis. Once an over-temperature or over-current fault conditions is removed, the output voltage automatically recovers. www.analogictech.com 13 PRODUCT DATASHEET AAT2503178 SystemPowerTM Adjustable 3-Channel Regulator Applications Information CIN = Step-Down Converter Inductor Selection The step-down converter uses peak current mode control with slope compensation to maintain stability for duty cycles greater than 50%. The output inductor value must be selected so the inductor current down slope meets the internal slope compensation requirements. The internal slope compensation for the AAT2503 stepdown converter is 0.51A/μsec. This equates to a slope compensation that is 75% of the inductor current down slope for a 1.5V output and 2.2μH inductor. m= 0.75 ⋅ VO 0.75 ⋅ 1.5V A = = 0.51 L 2.2μH μsec 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. The 2.2μH CDRH2D14 series Sumida inductor has a 94mΩ DCR and a 1.5A DC current rating. At full 800mA load, the inductor DC loss is 17mW which gives a 2.8% loss in efficiency for a 800mA, 1.8V output. Configuration Output Voltage Inductor 0.9V Adjustable With External Feedback 1V, 1.2V 1.5V, 1.8V 2.5V, 3.3V 1.5μH 2.2μH 3.3μH Table 1: Inductor Values. Input Capacitor Select a 4.7μF to 10μF X7R or X5R ceramic capacitor for the input of the step-down converter. 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 VIN is double the output voltage. 14 V ⎞ VO ⎛ · 1- O VIN ⎝ VIN ⎠ ⎛ VPP ⎞ - ESR · FS ⎝ IO ⎠ VO ⎛ V ⎞ 1 · 1 - O = for VIN = 2 · VO VIN ⎝ VIN ⎠ 4 CIN(MIN) = 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. The maximum input capacitor RMS current is: IRMS = IO · VO ⎛ V ⎞ · 1- O VIN ⎝ VIN ⎠ The input capacitor RMS ripple current varies with the input and output voltage and will always be less than or equal to half of the total DC load current. VO ⎛ V ⎞ · 1- O = VIN ⎝ VIN ⎠ D · (1 - D) = 0.52 = 1 2 for VIN = 2 · VO: IRMS(MAX) = VO IO 2 ⎛ V ⎞ · 1- O The term V ⎝ V ⎠ appears in both the input voltage ripple and input capacitor RMS current equations and is a maximum when VO is twice VIN. This is why the input voltage ripple and the input capacitor RMS current ripple are a maximum at 50% duty cycle. IN IN The input capacitor provides a low impedance loop for the edges of pulsed current drawn by the AAT2503. 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. www.analogictech.com 2503.2008.02.1.4 PRODUCT DATASHEET AAT2503178 SystemPowerTM Adjustable 3-Channel Regulator 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. tion establishes a limit on the minimum value for the output capacitor with respect to load transients. 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. Adjustable Output Resistor Selection 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 4.7μF to 10μF X5R or X7R ceramic capacitor typically provides sufficient bulk capacitance to stabilize the output during large load transitions and has the ESR and ESL characteristics necessary for low output ripple. The output voltage droop due to a load transient is dominated by the capacitance of the ceramic output capacitor. During a step increase in load current, the ceramic output capacitor alone supplies the load current until the loop responds. Within two or three 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 three switching cycles to the output capacitance can be estimated by: COUT = 3 · ΔILOAD VDROOP · FS Once the average inductor current increases to the DC load level, the output voltage recovers. The above equa- The internal voltage loop compensation also limits the minimum output capacitor value to 4.7μF. This is due to its effect on the loop crossover frequency (bandwidth), phase margin, and gain margin. Increased output capacitance will reduce the crossover frequency with greater phase margin. The output voltage on the step-down converter is programmed with external resistors R2 and R6. To limit the bias current required for the external feedback resistor string while maintaining good noise immunity, the minimum suggested value for R6 is 59kΩ. Although a larger value will further reduce quiescent current, it will also increase the impedance of the feedback node, making it more sensitive to external noise and interference. Table 2 summarizes the resistor values for various output voltages with R6 set to either 59kΩ for good noise immunity or 221kΩ for reduced no load input current. With enhanced transient response for extreme pulsed load application, an external feed-forward capacitor (C1 in Fig.3) can be added. VOUT (V) R6 = 59kΩ R2 (kΩ) R6 = 221kΩ R2 (kΩ) 0.9* 1.0 1.1 1.2 1.3 1.4 1.5 1.8 1.85 2.0 2.5 2.8 3.0 3.3 0 6.65 13.3 19.6 26.1 32.4 39.2 59.0 61.9 71.5 105 124 137 158 0 24.3 48.7 73.2 97.6 124 147 221 232 274 392 464 511 590 Table 2: Step-Down Converter Resistor Values for Various Output Voltages. * For the 0.9V output, R6 is open. 2503.2008.02.1.4 www.analogictech.com 15 PRODUCT DATASHEET AAT2503178 SystemPowerTM Adjustable 3-Channel Regulator Thermal Calculations There are three types of losses associated with the AAT2503 step-down converter: switching losses, conduction losses, and quiescent current losses. Conduction losses are associated with the RDS(ON) characteristics of the power output switching devices. Switching losses are dominated by the gate charge of the power output switching devices. At full load, assuming continuous conduction mode (CCM), a simplified form of the LDO losses is given by: PTOTAL = IO2 · (RDSON(HS) · VO + RDSON(LS) · [VIN - VO]) VIN + (tsw · F · IO + IQ) · VIN IQ is the step-down converter quiescent current. The term tsw is used to estimate the full load step-down converter switching losses. For the condition where the step-down converter is in dropout at 100% duty cycle, the total device dissipation reduces to: PTOTAL = IO2 · RDSON(HS) + IQ · VIN Since RDS(ON), quiescent current, and switching losses all vary with input voltage, the total losses should be investigated over the complete input voltage range. Given the total losses, the maximum junction temperature can be derived from the θJA for the QFN34-20 package which is 50°C/W. TJ(MAX) = PTOTAL · ΘJA + TAMB LDO Linear Regulator Input Capacitor A 1μF or larger capacitor is typically recommended for CIN in most applications. A CIN capacitor is not required for basic LDO regulator operation; however, if the AAT2503 is physically located more than three centimeters from an input power source, a CIN capacitor will be needed for stable operation. CIN should be located as closely to the device VIN pin as practically possible. CIN values greater than 1μF will offer superior input line transient response and will assist in maximizing the highest possible power supply ripple rejection. Ceramic, tantalum, or aluminum electrolytic capacitors may be selected for CIN. There is no specific capacitor 16 ESR requirement for CIN; however, for 150mA LDO regulator output operation, ceramic capacitors are recommended for CIN due to their inherent capability over tantalum capacitors to withstand input current surges from low impedance sources such as batteries in portable devices. Output Capacitor For proper load voltage regulation and operational stability, a capacitor is required between pins OUTA, OUTB, and GND. The COUT capacitor connection to the LDO regulator ground pin should be made as direct as practically possible for maximum device performance. The AAT2503 has been specifically designed to function with very low ESR ceramic capacitors. For best performance, ceramic capacitors are recommended. Typical output capacitor values for maximum output current conditions range from 1μF to 10μF. Applications utilizing the exceptionally low output noise and optimum power supply ripple rejection characteristics of the AAT2503 should use 2.2μF or greater for COUT. If desired, COUT may be increased without limit. In low output current applications where output load is less than 10mA, the minimum value for COUT can be as low as 0.47μF. Capacitor Characteristics Ceramic composition capacitors are highly recommended over all other types of capacitors for use with the AAT2503. Ceramic capacitors offer many advantages over their tantalum and aluminum electrolytic counterparts. A ceramic capacitor typically has very low ESR, is lower cost, has a smaller PCB footprint, and is nonpolarized. Line and load transient response of the LDO regulator is improved by using low ESR ceramic capacitors. Since ceramic capacitors are non-polarized, they are not prone to incorrect connection damage. Equivalent Series Resistance ESR is a very important characteristic to consider when selecting a capacitor. ESR is the internal series resistance associated with a capacitor that includes lead resistance, internal connections, size and area, material composition, and ambient temperature. Typically, capacitor ESR is measured in milliohms for ceramic capacitors and can range to more than several ohms for tantalum or aluminum electrolytic capacitors. www.analogictech.com 2503.2008.02.1.4 PRODUCT DATASHEET AAT2503178 SystemPowerTM Adjustable 3-Channel Regulator Ceramic Capacitor Materials POK Output Ceramic capacitors less than 0.1μF are typically made from NPO or C0G materials. NPO and C0G materials generally have tight tolerance and are very stable over temperature. Larger capacitor values are usually composed of X7R, X5R, Z5U, or Y5V dielectric materials. These two material types are not recommended for use with LDO regulators since the capacitor tolerance can vary more than ±50% over the operating temperature range of the device. A 2.2μF Y5V capacitor could be reduced to 1μF over temperature; this could cause problems for circuit operation. X7R and X5R dielectrics are much more desirable. The temperature tolerance of X7R dielectric is better than ±15%. Capacitor area is another contributor to ESR. Capacitors which are physically large in size will have a lower ESR when compared to a smaller sized capacitor of an equivalent material and capacitance value. These larger devices can improve circuit transient response when compared to an equal value capacitor in a smaller package size. Consult capacitor vendor datasheets carefully when selecting capacitors for LDO regulators. LDOA of the AAT2503 features an integrated Power OK comparator which can be used as an error flag. The POK open drain output goes low when output voltage is 10% (typ) below its nominal regulation voltage. Additionally, any time LDOA is in shutdown, the POK output is pulled low. Connect a pull-up resistor from POK to OUTA. Adjustable Output Resistor Selection The output voltage on the linear regulator is programmed with external resistors: R4 and R7 for LDOA and R5 and R8 for LDOB. Table 3 summarizes the resistor values for various output voltages with R4 and R5 set to either 59kΩ for good noise immunity or 221kΩ for reduced no load input current. LDO VOUT (V) R7, R8 = 59kΩ R4, R5 (kΩ) R7, R8 = 221kΩ R4, R5 (kΩ) 0.6* 0.8 0.9 1.0 1.1 1.2 1.3 1.4 1.5 1.8 1.85 2.0 2.5 3.3 0 19.6 29.4 39.2 49.9 59.0 68.1 78.7 88.7 118 124 137 187 267 0 75 113 150 187 221 261 301 332 442 464 523 715 1000 Table 3: LDO Linear Regulators Resistor Values for Various Output Voltages. Enable Function The AAT2503 features an LDO regulator enable/disable function. Each LDO has its own dedicated enable pin. These pins (ENA, ENB) are active high and are compatible with CMOS logic. To assure the LDO regulators will switch on, ENA/B must be greater than 1.4V. The LDO regulators will shut down when the voltage on the ENA/B pins falls below 0.6V. In shutdown, the LDO regulators will consume less than 1.0μA of current. If the enable function is not needed in a specific application, it may be tied to VIN to keep the LDO regulator in a continuously on state. Thermal Protection Each of the two LDOs of the AAT2503 has an internal thermal protection circuit which will turn on when the device die temperature exceeds 140°C. The LDO regulator outputs will remain in a shutdown state until the internal die temperature falls back below the ~125°C trip point. No-Load Stability The LDOs in the AAT2503 are designed to maintain output voltage regulation and stability under operational no-load conditions. This is an important characteristic for applications where the output current may drop to zero. Reverse Output-to-Input Voltage Conditions and Protection Under normal operating conditions, a parasitic diode exists between the output and input of the LDO regulator. The input voltage should always remain greater than the output load voltage maintaining a reverse bias on the internal parasitic diode. Conditions where VOUT might exceed VIN should be avoided since this would forward bias the internal parasitic diode and allow excessive current flow into the VOUT pin, possibly damaging the LDO regulator. In applications where there is a possibility of * For the 0.6V output, R7 and R8 are open. 2503.2008.02.1.4 www.analogictech.com 17 PRODUCT DATASHEET AAT2503178 SystemPowerTM Adjustable 3-Channel Regulator VOUT exceeding VIN for brief amounts of time during normal operation, the use of a larger value CIN capacitor is highly recommended. A larger value of CIN with respect to COUT will effect a slower CIN decay rate during shutdown, thus preventing VOUT from exceeding VIN. In applications where there is a greater danger of VOUT exceeding VIN for extended periods of time, it is recommended to place a Schottky diode across VIN to VOUT (connecting the cathode to VIN and anode to VOUT). The Schottky diode forward voltage should be less than 0.45V. The maximum continuous output current for the AAT2503 is a function of the package power dissipation and the input-to-output voltage drop across the LDO regulator. To determine the maximum output current for a given output voltage, refer to the following equation. This calculation accounts for the total power dissipation of the LDO regulator, including that caused by ground current. PD(MAX) = [(VIN - VOUTA)IOUTA + (VIN · IGND)] + [(VIN - VOUTB)IOUTB + (VIN · IGND)] Layout Thermal Considerations and High Output Current Applications The LDOs of the AAT2503 are designed to deliver continuous output load currents of 150mA each under normal operation. This is desirable for circuit applications where there might be a brief high in-rush current during a power-on event. The limiting characteristic for the maximum output load current safe operating area is essentially package power dissipation and the internal preset thermal limit of the device. In order to obtain high operating currents, careful device layout and circuit operating conditions need to be taken into account. The suggested PCB layout for the AAT2503 is shown in Figures 2 and 3. The following guidelines should be used to help ensure a proper layout. 1. 2. 3. The following discussions will assume the LDO regulator is mounted on a printed circuit board utilizing the minimum recommended footprint as stated in the layout considerations section of this document. At any given ambient temperature (TA), the maximum package power dissipation can be determined by the following equation: PD(MAX) = 4. TJ(MAX) - TA θJA Constants for the AAT2503 are TJ(MAX) (the maximum junction temperature for the device, which is 125°C) and θJA = 50°C/W (the package thermal resistance). Typically, maximum conditions are calculated at the maximum operating temperature of TA = 85°C and under normal ambient conditions where TA = 25°C. Given TA = 85°C, the maximum package power dissipation is 800mW. At TA = 25°C, the maximum package power dissipation is 2W. 18 5. The input capacitors (C4, C7, C8, and C9) should connect as closely as possible to VIN and PGND. The output capacitor (C5, and C6) of the LDOs connect as closely as possible to OUT. C2 and L1 should be connected as closely as possible. The connection of L1 to the LX pin should be as short as possible. Do not make the node small by using a narrow trace. The trace should be kept wide, direct, and short. The feedback trace should be separate from any power trace and connect as closely as possible to the load point. Sensing along a high-current load trace will degrade DC load regulation. Feedback resistors should be placed as closely as possible to VOUT to minimize the length of the high impedance feedback trace. If possible, they should also be placed away from the LX (switching node) and inductor to improve noise immunity. The resistance of the trace from the load return to the PGND should be kept to a minimum. This will help to minimize any error in DC regulation due to differences in the potential of the internal signal ground and the power ground. Ensure all ground pins are tied to the ground plane. No pins should be left floating. For maximum power dissipation, it is recommended that the exposed pad must be soldered to a good conductive PCB ground plane layer to further increase local heat dissipation. www.analogictech.com 2503.2008.02.1.4 PRODUCT DATASHEET AAT2503178 SystemPowerTM Adjustable 3-Channel Regulator Figure 1: AAT2503 Evaluation Board Component Side Layout. Figure 2: AAT2503 Evaluation Board Solder Side Layout. SYNC U1 R10 100k 5 AAT2503 FB LX 9 LX L1 4 VIN SYNC LX 2.2μH CDRH2D14 R1 13 VIN OUTA 17 100 3 2 1 C4 0.1μF 18 3 2 1 VINB 19 C9 1μF 1 2 3 1 2 3 3 1 2 3 ENA GND POK VINB FBA 15 2 R12 100k 16 R2 C1 100pF C3 0.01μF R4 OUTA 10 14 ENB VINA C2 10μF R3 100k C8 1μF VINA EN VOUT_BUCK 8 VP EN/SET ENB ENA OUTB FBB PGND AGND 20 OUTB R5 1 7 6 R7 59.0k C7 10μF R8 59.0k C6 2.2μF C5 2.2μF R6 59.0k GND GND POK GND C5, C6 2.2μF, 10V, X5R, 0603 GRM188R61A225KE34 C8, C9 1μF, 6.3V, X5R, 0603 GRM185R60J105KE26 C2, C7 10μF, 6.3V, X5R, 0805 GRM219R60J106KE19 L1 Sumida CDRH2D14 or Coltronics SD3814 U1 AAT2503 QFN34-20 Figure 3: AAT2503 Evaluation Board Schematic. 2503.2008.02.1.4 www.analogictech.com 19 PRODUCT DATASHEET AAT2503178 SystemPowerTM Adjustable 3-Channel Regulator Manufacturer Part Number Value (μF) Voltage Rating Temp. Co. Case Size Murata Murata Murata Murata Murata GRM219R60J106KE19 GRM188R60J475KE19 GRM188R61A225KE34 GRM188R61A105KA61 GRM185R60J105KE26 10 4.7 2.2 1.0 1.0 6.3 6.3 10 10 6.3 X5R X5R X5R X5R X5R 0805 0603 0603 0603 0603 Table 4: Surface Mount Capacitors. Manufacturer Part Number Inductance (μH) Saturated Rated Current (mA) Sumida Sumida Sumida Coiltronics Coiltronics Coiltronics Taiyo Yuden Taiyo Yuden Taiyo Yuden CDRH2D14-1R5 CDRH2D14-2R2 CDRH2D14-3R3 SD3812-1R5 SD3812-2R2 SD3812-3R3 NR3010-1R5 NR3010-2R2 NR3010-3R3 1.5 2.2 3.3 1.5 2.2 3.3 1.5 2.2 3.3 1800 1500 1200 1580 1320 1100 1200 1100 870 DCR (mΩ) Size (mm) LxWxH Type 63 94 125 78 111 159 80 95 140 3.2x3.2x1.55 3.2x3.2x1.55 3.2x3.2x1.55 4.0x4.0x1.2 4.0x4.0x1.2 4.0x4.0x1.2 3.0x3.0x1.0 3.0x3.0x1.0 3.0x3.0x1.0 Shielded Shielded Shielded Shielded Shielded Shielded Shielded Shielded Shielded Table 5: Suggested Inductors and Suppliers. 20 www.analogictech.com 2503.2008.02.1.4 PRODUCT DATASHEET AAT2503178 SystemPowerTM Adjustable 3-Channel Regulator Ordering Information Voltage Package Channel 1 Channel 2 Channel 3 Marking1 Part Number (Tape and Reel)2 QFN34-20 0.9V 0.6V 0.6V TPXYY AAT2503IZL-BAA-T1 All AnalogicTech products are offered in Pb-free packaging. The term “Pb-free” means semiconductor products that are in compliance with current RoHS standards, including the requirement that lead not exceed 0.1% by weight in homogeneous materials. For more information, please visit our website at http://www.analogictech.com/about/quality.aspx. Legend Voltage Code Adjustable (0.6V) 0.9 1.2 1.5 1.8 1.9 2.5 2.6 2.7 2.8 2.85 2.9 3.0 3.3 4.2 A B E G I Y N O P Q R S T W C 1. XYY = assembly and date code. 2. Sample stock is generally held on part numbers listed in BOLD. 2503.2008.02.1.4 www.analogictech.com 21 PRODUCT DATASHEET AAT2503178 SystemPowerTM Adjustable 3-Channel Regulator Package Information1 QFN34-20 Detail "A" Index Area (D/2 x E/2) Detail "B" 4.00 ± 0.05 0.925 ± 0.125 7.5° ± 7.5° 0.025 ± 0.025 0.214 ± 0.036 Side View 3.00 ± 0.05 Top View Bottom View 0.40 ± 0.10 0.075 ± 0.075 Option B: R0.30 (4x) max Round corner 0.50 ± 0.05 Option A: C0.30 (4x) max Chamfered corner 0.24 ± 0.06 Pin 1 indicator (optional) Detail "A" Detail "B" All dimensions in millimeters. 1. The leadless package family, which includes QFN, TQFN, DFN, TDFN and STDFN, has exposed copper (unplated) at the end of the lead terminals due to the manufacturing process. A solder fillet at the exposed copper edge cannot be guaranteed and is not required to ensure a proper bottom solder connection. Advanced Analogic Technologies, Inc. 3230 Scott Boulevard, Santa Clara, CA 95054 Phone (408) 737-4600 Fax (408) 737-4611 © Advanced Analogic Technologies, Inc. AnalogicTech cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in an AnalogicTech product. No circuit patent licenses, copyrights, mask work rights, or other intellectual property rights are implied. AnalogicTech reserves the right to make changes to their products or specifications or to discontinue any product or service without notice. Except as provided in AnalogicTech’s terms and conditions of sale, AnalogicTech assumes no liability whatsoever, and AnalogicTech disclaims any express or implied warranty relating to the sale and/or use of AnalogicTech products including liability or warranties relating to fitness for a particular purpose, merchantability, or infringement of any patent, copyright or other intellectual property right. In order to minimize risks associated with the customer’s applications, adequate design and operating safeguards must be provided by the customer to minimize inherent or procedural hazards. Testing and other quality control techniques are utilized to the extent AnalogicTech deems necessary to support this warranty. Specific testing of all parameters of each device is not necessarily performed. AnalogicTech and the AnalogicTech logo are trademarks of Advanced Analogic Technologies Incorporated. All other brand and product names appearing in this document are registered trademarks or trademarks of their respective holders. 22 www.analogictech.com 2503.2008.02.1.4