Introduction The AAT4282A evaluation board provides a platform for test and evaluation of the AAT4282A Dual Slew Rate Controlled Load Switch. 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 optimum thermal characteristics with the TDFN22-8 package and low inductive output ringing with the fast slew rate setting. The design operates across an input voltage range from 1.5 to 6.5V. The AAT4282A Evaluation Board provides independent dual inputs and outputs with either a 0.1ms or 1ms turnon slew rate. The desired turn-on slew rate time is determined by setting the logic level of the FAST pin. Connecting the FAST pin to Logic high (VIN) sets the output to fast turn-on slew rate while logic low (GND) sets the output to slow turn-on slew rate. Connecting ENA or ENB to logic "1" enables the switch and initiates the turn-on slew rate features while connecting ENA or ENB to GND will disable either A or B channel respectively. This document provides details on the operation and test of the AAT4282A Evaluation Board with a single or separate input power supplies by using the JP1 jumper. Operating Specification, Schematic and BOM INA TDFN22-8 JP1 1 INA OUTA 8 OUTA INB 4 INB OUTB 5 OUTB ENA C1 C2 2 ENA AAT4282A C3 0.1μF C4 0.1μF 1μF 1μF FAST 7 FAST ENB 3 ENB GND 8,9,10,11 Figure 1: AAT4282A Evaluation Board Schematic (AAT4282A-IPS-3-DB1). EV-140.2007.08.1.0 1
Symbol Description U1 AAT4282A TDFN22-8 C1 1μF 10V 0603 C2 1μF 10V 0603 C3 0.1μF 10V 0603 C4 0.1μF 10V 0603 Table 1: AAT4282A Evaluation Board Bill of Materials. Test Equipment 1. Unit under test (UUT) is the AAT4252A Evaluation Board. 2. One (1) Keithley 2430 3A source meter or equivalent. 3. Two (2) XT30-2 power supplies or equivalent. 4. Two (2) 10Ω, 100W variable resistors, or two DC electronic loads. 5. Two (2) Fluke 189 DC voltmeters or equivalent. Set to DCV setting. 6. A HP33120A 15MHz Function/ Arbitrary waveform generator. Set to PWM setting. 7. 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). 2 EV-140.2007.08.1.0
Setup and Test Test: R DS(ON) over V IN using Keithley V/I source 2430 1. Configure the specified test equipment as shown in Figure 2 2. Connect a floating Kelvin pulse from Keithley V/I source between INA and OUTA (with V IN as positive side,) set the voltage pulse to 1V with 5ms pulse width, the compliance set to 100mA (the two sensing output wires need to connect as close as possible to the INA and OUTA pins.) 3. Remove JP1 jumper to disconnect INA and INB; enable ENA and FAST; disable ENB by setting JP3 to GND. 4. Turn on the input power supply and set to desired input voltage based on the DC voltmeter. 5. Power up the Keithley V/I source and read the voltage (V DS ) and the current (I DS ) measurements on the Keithley V/I source. 6. R DS(ON) = VDS I DS Vary the input voltage from 1.8V to 6.5V to observe R DS(ON) at different input voltages. 7. Repeat steps 1 though 6 with different compliance current from 100mA to 2A. Figure 2: AAT4282A Evaluation Board Connection Diagram for R DS(ON) Test. EV-140.2007.08.1.0 3
Test: Slew Rate Controlled Turn On Response 1. Configure the specified test equipment as shown in Figure 3 2. Enable channel A and B by a PWM Function Generator (Note: using the jumper to connect ENA or ENB to INA or INB will force the outputs follow the inputs). Connect the FAST pin to INA or INB for FAST turnon slew rate, and connect it to GND using for SLOW turn-on slew rate. A. INA and INB in parallel: 1. Use JP1 jumper to connect inputs A and B together, set input voltage to 3.6V (use only one power supply) and output current loads to 1A for each output. 2. Toggle the FAST pin between VIN and GND while observing the FAST and SLOW turn-on and turn-off slew rate from the outputs on the oscilloscope. 3. Repeat steps 1 and 2 for different output current loads and input voltages. B. INA and INB independently: 1. Remove JP1 to separate INA and INB, set INA to 3.0V and INB to 4.2V, set output current loads to 1A for each output. 2. Toggle the FAST pin between VIN and GND while observing the FAST and SLOW turn-on and turn-off slew rate from the output on the oscilloscope. 3. Repeat steps 1 and 2 for different output current loads and input voltages. Figure 3: AAT4282A Evaluation Board Connection Diagram for Slew Rate Test. 4 EV-140.2007.08.1.0
Test: Enable Behavior 1. Configure the specified test equipment as shown in Figure 4. 2. Disconnect INB to power supply, set INA to designed input voltage, ENA to 0.4 V, and FAST to GND. 3. Connect OUTA through 100Ω resistor to GND. 4. Ramp up the ENA voltage until OUTA on the oscilloscope flips over (from 0V to V IN ) and record ENA voltage at this pin as V IL 5. Ramp down the ENA voltage until OUTA on the oscilloscope flips over (from V IN to 0V) and record ENA voltage at this pin as V IH. V IL and V IH should be in the range from 0.4 V to 1.4 V. 6. Repeat for different V IN and I OUT. 7. Repeat steps 1 through 6 for channel B. Figure 4: AAT4282A Evaluation Board Connection Diagram Enable Test. EV-140.2007.08.1.0 5
Test: Output Pull Down Impedance at Shutdown as Shown in Figure 3. 1. Remove JP1 jumper, set INA to 5V, set ENA and ENB to 0V to disable both channels. 2. Connect Keithley V/I source between OUTA and GND, set the voltage pulse to 1V with 5ms pulse width, the compliance set to 100mA (the two sensing output wires need to connect as close as possible to the OUTA and GND pins.) 3. Determine the output pull down impedance of channel A by taking the ratio of OUTA voltage and the sinking current 100mA,. R DS(ON) = VDS I DS 4. Repeat the above steps for channel B output pull down impedance. Figure 5: AAT4282A Evaluation Board Connection Diagram for Output Impedance Test. 6 EV-140.2007.08.1.0
Printed Circuit Board Figure 6: AAT4282A Evaluation Board Top Layer (not to scale). Figure 7: AAT4282A Evaluation Board Bottom Layer (not to scale). EV-140.2007.08.1.0 7
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