DC830A Analog Devices

QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 830 48VIN TO 3.3V, 40A ISOLATEDQUARTER BRIC TELECOM DC/DC CONVERTER LT1952 DESCRIPTION Demonstration circuit 830 is an isolated input to high The DC830 circuit features soft-start which prevents current output Brick footprint converter featuring output voltage overshoot on startup or when recover- the LT 1952 switching controller. The DC830 con- ing from an overload condition. verts isolated 36V to 75V input to 3.3V output and The DC830 has a precise over-current protection cir- provides over 40A of output current. The converter cuit that allows for continuous operation under short operates at 300kHz with efficiency greater than 92%. circuit conditions. The low power dissipation under The DC830 can easily be modified to generate output short circuit conditions insures high reliability even voltages in the range from 0.6V to 28V. The output during short circuits. currents are limited by total output power of up to The LT1952 can be synchronized to an external clock 200W. of up to 400kHz. Please refer to the LT1952 data Demonstration circuit 830 can generate output cur- sheet for design details and applications information. rents as high as 55A. The output voltage can also be Design files for this circuit board are available. Call changed to any value between 0.6V and 28V by the LTC factory. changing the MOSFETs, power transformer, output inductor and output capacitors. Please consult LTC LT is a trademark of Linear Technology Corporation factory for details. Table 1. Performance Summary PARAMETER CONDITION VALUE Minimum Input Voltage 36V Maximum Input Voltage 75V V V = 36V to 72V, I = 0A to 40A 3.3V 3% OUT IN OUT Typical Output Ripple V V = 36V to 72V, I = 0A to 40A 50mV OUT IN OUT PP Nominal Switching Frequency 300kHz QUICK START PROCEDURE Demonstration circuit 830 is easy to set up to evalu- 1. With power off, connect the input power supply to ate the performance of the LT1952. Refer to Figure 1. Vin and GND. Make sure that the input power sup- for proper measurement equipment setup and follow ply has sufficient current rating at minimum input the procedure below: voltage for the required output load. NOTE: When measuring the input or output voltage 2. Turn on the power at the input. ripple, care must be taken to avoid a long ground lead NOTE: Make sure that the input voltage does not ex- on the oscilloscope probe. Measure the input or out- ceed 75V. put voltage ripple by touching the probe tip directly 3. Check for the proper output voltage. across the Vin or Vout and GND terminals. See Figure Vout = 3.3V. 2. for proper scope probe technique. If there is no output, temporarily disconnect the load to make sure that the load is not set too high. 1 QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 830 48VIN TO 3.3V, 40A ISOLATEDQUARTER BRIC TELECOM DC/DC CONVERTER 4. Once the proper output voltage is established, ad- just the load within the operating range and ob- serve the output voltage regulation, ripple voltage, efficiency and other parameters. 5. The DC830 is equipped with an output capacitor CSYS (470uF) that approximates typical system rail capacitance. If system board already has ca- pacitance of similar value CSYS can be removed. Figure 1. Proper Measurement Equipment Setup Figure 2. Scope Probe Placement for Measuring Input or Output Ripple 2