QUICK START GUIDE FOR DC679 DUAL OUTPUT CONVERTER LT3463EDD DESCRIPTION Demonstration circuit 679 features the LT3463EDD in two circuits. One circuit is optimized for small size and the other for high performance. Both circuits are dual output ±20V voltage regulators. The positive regulator is a boost converter and the negative rail is an inverting charge pump. Refer to Tables 1 and 2 for details on performance. The intended application of the DC679 is portable applications where reduced parts count, small circuit size and high efficiency is important. The Burst Mode operation of the LT3463EDD allows for high efficiency over a broad range of loads and low quiescent current. Parts count is reduced by the integrated schottky diodes and the low current limit and low off time allows small inductors and capacitors to be used. Design files for this circuit board are available. Call the LTC factory. Table 1. Performance Summary for the Small Size Circuit (TA = 25°C) PARAMETER CONDITION Input voltage range |VOUT | (both rails) VALUE 2.7V to 6.0V 0mA to IOUT(MAX) 20V ±4% VIN = 2.7V 5mA VIN = 3.6V 7mA VIN = 5.0V 9mA Typical Output Ripple (+20V) VIN = 3.6V, IOUT = 7mA 130mV P-P Typical Output Ripple (-20V) VIN = 3.6V, IOUT = 7mA 140mV P-P Typical Efficiency (+20V) VIN = 3.6V, IOUT = 7mA, -20V rail not enabled 74% Typical Efficiency (-20V) VIN = 3.6V, IOUT = 7mA, +20V rail not enabled 74% Typical no load input current (both rails) VIN = 3.6V 140uA IOUT(MAX) (both rails) Table 2. Performance Summary for the High Performance Circuit (TA = 25°C) PARAMETER CONDITION Input voltage range |VOUT | (both rails) VALUE 2.7V to 6.0V 0mA to IOUT(MAX) 20V ±4% VIN = 2.7V 7mA VIN = 3.6V 9mA VIN = 5.0V 13mA Typical Output Ripple (+20V) VIN = 3.6V, IOUT = 9mA 105mV P-P Typical Output Ripple (-20V) VIN = 3.6V, IOUT = 9mA 105mV P-P Typical Efficiency (+20V) VIN = 3.6V, IOUT = 9mA, -20V rail not enabled 76% Typical Efficiency (-20V) VIN = 3.6V, IOUT = 9mA, +20V rail not enabled 76% Typical no load input current (both rails) VIN = 3.6V 140uA IOUT(MAX) (both rails) 1 QUICK START GUIDE FOR DC679 DUAL OUTPUT CONVERTER QUICK START PROCEDURE Demonstration circuit 679 is easy to set up to evaluate the performance of the LT3463EDD. Refer to Figure 1 for proper measurement equipment setup and follow the procedure below: 4. Apply the full rated load to the outputs for an input voltage of 3.6V. For the small size circuit this is 7mA and for the high performance circuit this is 9mA. The rails should still be within regulation. NOTE: When measuring the input or output voltage ripple, care must be taken to avoid a long ground lead on the oscilloscope probe. Measure the input or output voltage ripple by touching the probe tip directly across the Vin or Vout and GND terminals. See Figure 2 for proper scope probe technique. 5. With full rated load applied and with the input voltage still at 3.6V, measure the input current. For the small size circuit, the input current should be less than 140mA and for the high performance circuit, the input current should be less than 150mA. 6. Once the proper output voltages are established, adjust the loads within the operating range and observe the output voltage regulation, ripple voltage and other parameters. 1. Make sure the SHDN pins are in the ON position. 2. Turn on the input voltage source and set it to 3.6V. 3. Monitor the output voltage. |VOUT| for both the positive and negative rails of the small size and high performance circuits should be 20V ± 4%. 2 QUICK START GUIDE FOR DC679 DUAL OUTPUT CONVERTER Figure 1. Proper Measurement Equipment Setup 3 QUICK START GUIDE FOR DC679 DUAL OUTPUT CONVERTER GND VIN Figure 2. Measuring Input or Output Ripple 4 QUICK START GUIDE FOR DC679 DUAL OUTPUT CONVERTER 5