DEMO MANUAL DC2111A-A/B LTC3774EUHE 4-Phase High Current Step-Down Converter with Very Low DCR Inductor Description Demonstration circuit DC2111A features the LTC 3774 in but the ideal diodes will prevent the bottom FETs from a 4-phase, high output current step-down converter with pulling down the output once an overvoltage is detected. sub-m DCR sensing. This high performance converter The external OVP comparator will also provide overvolt- operates at a switching frequency of 400kHz over an input age protection in case the voltage sense lines are shorted voltage range of 10V to 14V. The 5mm 5mm DrMOS or reversed. and 0.33H/0.325m inductor provide high efficiency For a 12V input, the A assembly provides a full load ef- while supplying 30A per phase. The board comes in two ficiency of 89.3% and a peak efficiency of 90.6% which assembly types. The A assembly provides a 1.2V/90A occurs around 50% load. converter with N+1 MOSFET failure protection and the B assembly provides a high efficiency 1.2V/120A converter. 1.2V/120A High Efficiency Converter The B assembly is a high efficiency 1.2V/120A 4-phase 1.2V/90A Converter with N+1 MOSFET Failure converter. Given that it does not have the MOSFET failure Protection protection and redundancy of the A assembly, it provides The A assembly is intended for high reliability applica- higher efficiency and more output current. For a 12V input tions which have a very low tolerance for down-time or it provides a full load efficiency of 90.6% and a peak ef- which operate in rugged environments. Each phase of the ficiency of 93.1% which occurs at 55% load. 1.2V/90A converter is protected by its own LTC4226-1 hot swap circuit on the input and an LTC4352 ideal diode More Features on its output. If an internal DrMOS MOSFET fails, then Both assembly types provide many features. These include: that phase will be isolated from the rest of the circuit and the converter will continue to operate with only a small Remote sensing perturbation on the output and will provide the full rated CLKIN and CLKOUT pins 90A load. Once a fault is detected, the PWM signal for that phase will be floated. This in turn will signal the DrMOS to PGOOD, RUN and TRACK/SS pins pull its TG and BG signals low. Examples of the converters Dynamic load circuit response to MOSFET failures can be seen in Figure 2 and Optional phase shedding circuit Figure 3. Further protection is provided by a dedicated 5V bias supply for each phase. If the 5V bias for a given phase The LTC3774 data sheet provide a complete description is pulled down due to a DrMOS failure or other fault, the of the IC operation and application information. The data 5V bias for the other phases will not be affected. sheet must be read in conjunction with the quick start guide. In case of an overvoltage event, an external overvoltage Design files for this circuit board are available at protection circuit will pull down the output. The LTC3774 DEMO MANUAL DC2111A-A/-B p erformance s Specifications are at T = 25C A Table 1. A Converter (T = 25C, No Airflow) A PARAMETER CONDITION VALUE Minimum Input Voltage 10V Maximum Input Voltage 14V Output Voltage V I = 0A to 90A, V = 10V to 14V 1.2V 1.5% OUT OUT IN I V = 10V to 14V 90A OUT(MAX) IN Nominal Switching Frequency 400kHz Efficiency, See Figure 6 V = 1.2V, I = 90A, V = 12V 89.3% Typical OUT OUT IN Table 2. B Converter (T = 25C, No Airflow) A PARAMETER CONDITION VALUE Minimum Input Voltage 10V Maximum Input Voltage 14V Output Voltage V I = 0A to 120A, V = 10V to 14V 1.2V 1.5% OUT OUT IN I V = 10V to 14V 120A OUT(MAX) IN Nominal Switching Frequency 400kHz Efficiency, See Figure 7 V = 1.2V, I = 120A, V = 12V 90.6% Typical OUT OUT IN dc2111aabf 2 ummary