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