EV-137 AAT3244 EVAL: 300mA Adjustable Dual CMOS Low Voltage LDO Linear Regulator Introduction The AAT3244 evaluation board provides a platform for test and evaluation of the AAT3244 Dual CMOS Low Voltage LDO Linear Regulator. The evaluation board demonstrates suggested size and placement of external components to achieve the best performance. The external components are limited and selected for small size to suit portable devices applications, while the layout has been optimized to achieve low output noise and highest possible power supply ripple rejection performance with the TSOPJW-12 package. The design operates across an input voltage range from 1.8V to 5.5V and provides an ultra-low adjustable output voltage from 3.6V to 0.6V. The AAT3244 Evaluation Board provides dual inputs and outputs at 300mA output current per LDO. Resistors R1, R2 and R3, R4 program the outputs to regulate at a voltage higher than 0.6V. The suggested value for R2 and R4 is 59kΩ. Table 1 summarizes the resistor values for various output voltages. The Power OK open drain outputs are pulled up by 100kΩ resistors R5, R6. Connecting ENA or ENB to INA or INB will turn on the part while connecting ENA or ENB to GND will disable either the A or B channel. Schematic and BOM VCC C3 1uF R6 100K R5 100K 12 POKA POKA TSOPJW-12 VCC OUTA C1 1uF ENA FBA ENA C6 22pF C4 3 2.2uF INA 11 OUTA R1 Adj. POKB 2 (Optional) 1 7 POKB INA 9 R2 59K AAT3244 ON/OFF OUTB INB OUTB R3 Adj. INB FBB C2 (Optional) 6 5 C7 22pF 4 C5 8 ENB ENB 1uF ON/OFF GND 10 2.2uF R4 59K Figure 1: AAT3244 Evaluation Board Schematic (AAT3244 ITP-DB1) Symbol U1 C1, C2, C3 C4, C5 C6, C7 R1, R3 R2, R4 Description AAT3244 TSOPJW-12 1μF 10V 0603 2.2μF 10V 0603 22pF 10V 0603 (Optional) See Table 2; 10V 0603 59kΩ 10V 0603 Table 1: AAT3244 Evaluation Board Bill of Materials (BOM). EV-137.2007.08.1.0 1 EV-137 AAT3244 EVAL: 300mA Adjustable Dual CMOS Low Voltage LDO Linear Regulator VOUT (V) R2 = 59kΩ R1(kΩ) R2 = 221kΩ R1(kΩ) VOUT (V) R2 = 59kΩ R1(kΩ) R2 = 221kΩ R1(kΩ) 0.8 0.9 1.0 1.1 1.2 1.3 1.4 19.6 29.4 39.2 49.9 59.0 68.1 78.7 75 113 150 187 221 261 301 1.5 1.8 1.85 2.0 2.5 3.3 3.6 88.7 118 124 137 187 267 295 332 442 464 523 715 1000 1105 Table 2: AAT3244 Adjustable Resistor Values For LDO Regulator. Test Equipment 1. 2. 3. 4. 5. 6. 7. Unit under test (UUT) is the AAT3244 Evaluation Board. One (1) Keithley 2430 3A source meter or equivalent. Two (2) XT30-2 power supplies or equivalent. Two (2) 10Ω, 100W variable resistors, or two DC electronic loads. Two (2) Fluke 189 DC voltmeters or equivalent. Set to DCV setting. A HP33120A 15MHz function/ arbitrary waveform generator. Set to PWM setting. Oscilloscope: Tektronix TDS3054B or equivalent, three (3) Tek P6139A oscilloscope voltage probes or equivalent, and one Tektronix TCP202 300V 15A peak current probe. 8. Miscellaneous test leads (banana plug to clip lead type is recommended). Setup and Test Test: Line-Load Regulation 1. Configure the specified test equipment as shown in Figure 2. 2. Enable dual LDO by JP1 and JP3 to the ‘ON’ position, as shown in Figure 2. Connect both inputs of UUT to VCC by JP2 and JP4 as shown in Figure 2. 3. Turn on the input power supply and set to desired input voltage based on the DC voltmeter. 4. Vary the output load from 0 to 300mA and vary the input voltage from 1.8V to 5.5V while monitoring the output voltage. 2 EV-137.2007.08.1.0 EV-137 AAT3244 EVAL: 300mA Adjustable Dual CMOS Low Voltage LDO Linear Regulator Figure 2: AAT3244 Evaluation Board Connection Diagram for Line and Load Regulation. EV-137.2007.08.1.0 3 EV-137 AAT3244 EVAL: 300mA Adjustable Dual CMOS Low Voltage LDO Linear Regulator Test: Line Transient Response 1. Configure the specified test equipment as shown in Figure 3. 2. Enable dual LDO by JP1 and JP3 to the ‘ON’ position, as shown in Figure 2. Connect both inputs of UUT to VCC by JP2 and JP4 as shown in Figure 2. 3. Use Line Transient Response board to generate the step input voltage supply by setting the first power supplies to 3.6V and the second one to 4.2V. 4. Toggle the input voltage from 3.6V to 4.2 V by setting the magnitude of the PWM to 5Vpp at 5MHz while monitoring the AC input voltage and the AC output voltage on the oscilloscope. Vin(AC) Vout(AC) Figure 3: AAT3244 Evaluation Board Connection Diagram for Line Transient Response. 4 EV-137.2007.08.1.0 EV-137 AAT3244 EVAL: 300mA Adjustable Dual CMOS Low Voltage LDO Linear Regulator Test: Load Transient Response 1. Configure the specified test equipment as shown in Figure 4. 2. Enable dual LDO by JP1 and JP3 to the ‘ON’ position, as shown in Figure 2. Connect both inputs of UUT to VCC by JP2 and JP4 as shown in Figure 2. 3. Generate the step output load using a PWM (set VPP = 5V at 5KHz), a Power MOSFET, and adjustable resistors (R7, R8). 4. Adjust R7 and R8 to achieve the designed output current while monitoring the step output current and the output voltage response (AC coupling) on the oscilloscope. 5. Repeat step 4 for different step output currents. Iload Vout(AC) Figure 4: AAT3244 Evaluation Board Connection Diagram for Load Transient Response. EV-137.2007.08.1.0 5 EV-137 AAT3244 EVAL: 300mA Adjustable Dual CMOS Low Voltage LDO Linear Regulator Test: Quiescent Current vs. Input Voltage 1. Configure the specified test equipment as shown in Figure 5. 2. Replace the input power supply with a Keithley 2400 3A source meter or equivalent. Set VSRC to the designed input voltage (VSRC = VOUT + 1V), and set the ICOM to 200µA. 3. Remove the output loads (open circuit). 4. Enable dual LDO by JP1 and JP3 to the ‘ON’ position, as shown in Figure 2. Connect both inputs of UUT to VCC by JP2 and JP4 as shown in Figure 2. 5. Turn on the Keithley and read the compliance current (quiescent current). 6. Vary the input voltage VSRS = VOUT + 1V while monitoring the corresponding compliance current. Figure 5: AAT3244 Evaluation Board Connection Diagram for Quiescent Current. 6 EV-137.2007.08.1.0 EV-137 AAT3244 EVAL: 300mA Adjustable Dual CMOS Low Voltage LDO Linear Regulator Test: Dropout Voltage vs. Output Current 1. Configure the specified test equipment as shown in Figure 6. 2. Enable dual LDO by setting JP1 and JP3 to the ‘ON’ position, as shown in Figure 2. Connect both inputs of UUT to VCC by JP2 and JP4 as shown in Figure 2. 3. Set the output current to 1mA, and measure the output voltage. 4. Calculate the nominal output voltage as 98% of the output voltage at 1mA output current. 5. Reduce the input voltage until the output voltage drops to the nominal voltage. 6. Record the dropout voltage between the input and the output pins (as close to the pins as possible). 7. Repeat step #5 and step #6 for different output current levels. Figure 6: AAT3244 Evaluation Board Connection Diagram for Dropout Voltage vs. Output Current. EV-137.2007.08.1.0 7 EV-137 AAT3244 EVAL: 300mA Adjustable Dual CMOS Low Voltage LDO Linear Regulator Test: POK Output Response 1. Configure the specified test equipment as shown in Figure 7. 2. Enable dual LDO by setting JP1 and JP3 to the ‘ON’ position, as shown in Figure 2. Connect both inputs of UUT to VCC by JP2 and JP4 as shown in Figure 2. 3. Use Line Transient Response board to generate the step input voltage supply. 4. Adjust the power supplies while monitoring VIN (AC coupling), VOUT ( AC coupling) and POK (AC coupling) on the oscilloscope. Figure 7: AAT3244 Evaluation Board Connection Diagram for POK Output Response. 8 EV-137.2007.08.1.0 EV-137 AAT3244 EVAL: 300mA Adjustable Dual CMOS Low Voltage LDO Linear Regulator Test: PSRR vs. Frequency 1. Configure the specified test equipment as shown in Figure 8. 2. Enable dual LDO by setting JP1 and JP3 to the ‘ON’ position, as shown in Figure 2. Connect both inputs of UUT to VCC by JP2 and JP4 as shown in Figure 2. 3. Connect the SOURCE OUT, CHA from the Network Analyzer to the input of the LDO, and CHB to the output of the LDO. 4. Set the output load current to 10mA (light load). 5. Sweep the frequency from SOURCE OUT of the Network Analyzer from 10Hz to 1MHz, while monitoring the sine waves from the input and the output of the LDO. ⎛ V (AC)⎞ PSRR(dB) = abs 20 · log OUT ⎝ VIN (AC) ⎠ Figure 8: AAT3244 Evaluation Board Connection Diagram for PSRR. EV-137.2007.08.1.0 9 EV-137 AAT3244 EVAL: 300mA Adjustable Dual CMOS Low Voltage LDO Linear Regulator Printed Circuit Board Figure 9: Top Layer (not to scale). Figure 10: Bottom Layer (not to scale). © 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. 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All other brand and product names appearing in this document are registered trademarks or trademarks of their respective holders. Advanced Analogic Technologies, Inc. 830 E. Arques Avenue, Sunnyvale, CA 94085 Phone (408) 737- 4600 Fax (408) 737- 4611 10 EV-137.2007.08.1.0