DC543A Analog Devices

QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 543 LTC2920 WITH DUAL DC TO DC CONVERTER LTC2920-2 DESCRIPTION Demonstration circuit 543 is an LTC 2920-2 Dual tween margined and un-margined voltages can be Voltage Margining Controller integrated with an demonstrated. The total PCB footprint used by the LTC1628 Dual High Efficiency, 2-Phase Synchronous LTC2920-2 and all of its associated components is Step-Down Switching Regulator. Two 3-position less than .05 in. switches are provided to demonstrate both high and Design files for this circuit board are available. Call low voltage margining. The switches margin the 5.0V the LTC factory. and 3.3V outputs to 10% of their nominal values. LTC is a Registered trademark of Linear Technology Corporation By changing jumpers a slower raise and fall time be- Table 1. Performance Summary PARAMETER CONDITION MIN TYP MAX UNITS Input Voltage Range 7 24 V Output Voltage V 5 V OUT1 Output Voltage V 3.3 V OUT2 Voltage Margining 10 % Output Current I 10 12 A OUT QUICK START PROCEDURE The circuit is very simple as far as the basic input and board, additional low impedance electrolytic capaci- output connections are concerned, see Figure 1. tors at the output of the lab supply are recommended. However, due to the high current nature of this de- This is particularly important for transient load test- sign, care must be exercised or unreliable results will ing, especially at low input voltages. be obtained. The first consideration is the wire gauge Connect a resistive load to the output terminals of the for input and output power connections. The load DC543. For the 5V supply, connect a load resistor be- current of 12A will require at least 3 strands of AWG tween the two output terminals with a value between 18 wire or equivalent for the output power and 0.5 ohms and 50 ohms. For the 3.3V supply, connect ground connections. The input wire size is 1 to 3 a load resistor between the two output terminals with strands of AWG 18 or equivalent, depending on the a value between 0.33 ohms and 33 ohms. Be sure to input voltage. There is one pair of connector termi- calculate the power dissipation in each resistor and nals for the inputs of the DC543 and one pair for each select resistors with a high enough constant power output. It is important that all these connections be rating. The demo board is shipped with the following tightened and secured before applying power to the settings: circuit. JP1 (FCB) INTVcc The lab supply used for the input source of DC543 JP2 (STBYMD) 0 must be capable of supplying a current estimated at 1.2 x (VO1 x IO1 + VO2 x IO2)/VIN. Use a lab power JP3 (FLTCPL) INTVcc supply with a voltage between 7 and 24 Volts. To pre- JP6 (RUN1) 1 vent interaction between the lab supply and the demo 1 QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 543 LTC2920 WITH DUAL DC TO DC CONVERTER JP7 (RUN2) 1 tion will cause the associated output voltage to be 10% lower than the nominal voltage. JP8 (Damped) Normal JP9 (Damped) Normal Attach the voltmeters directly to the input and output connectors to measure the input voltage and output voltage, respectively. Place the two 3 position switches, SW1 and SW2 in the middle position. Turn on the power supply connected to the Vin terminals and verify the nominal voltages at the Vin terminals and both sets of output terminals. SW2 controls the 5 Volt output, SW1 controls the 3.3 Volt output. Moving a switch to the 0 position will cause the associated output voltage to be 10% higher than nominal voltage. Moving a switch to the 1 posi- 2