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60V low Iq step-down with adjustable grid drive

Views:41Time:2023-03-25
    LTC3892 is a dual-output synchronous step-down controller with a wide input voltage range of 4.5V to 60V and an output voltage of 0.8V to V IN of 99%. The combination of the built-in FET driver and the external FET of the LTC3892 produces high efficiency and high power capacity, with efficiency of up to 97% and output current of more than 60A. Its robust design - the IC operating junction temperature range is – 55 ° C to 150 ° C - can meet the needs of industry, automotive, telecommunications, military, aerospace and distributed systems.
    In battery-powered applications where low idle current must be maintained, low IQ of LTC3892 is essential. It has 29 μ No-load quiescent current of A and 3.9 μ A‘s shutdown current can keep the battery charged for as long as possible. The wide input voltage range of LTC3892 can meet the stringent requirements of industrial and automotive applications, which are characterized by the lack of stable and high-quality voltage sources. For example, in the automotive environment, during cold start and sudden load drop, the range of 12V nominal voltage rail can be from 5V to more than 50V. The LTC3892‘s ability to maintain output in the face of high voltage input eliminates expensive voltage suppressors; When the input voltage drops far below the nominal value, its low input can maintain uninterrupted logic power supply.
    Another key feature of the LTC3892 is its programmable gate voltage, which can be set in the range of 5V to 10V. This is important for many reasons. Designers can choose standard (10V) gate drive level and select switching devices from various MOSFETs provided by multiple suppliers to optimize power efficiency and reduce overall cost. However, if the gate driver loss is important, the logic level (5V) FET can be used. As a compromise, the gate voltage can be programmed to any intermediate value to provide acceptable gate and conduction loss 1. The LTC3892 has programmable undervoltage lockout (UVLO) and programmable EXTV CC through the DRVUV pin.
Circuit description
    Figure 1 shows a single LTC3892, dual-output solution: 12V at 5A and 5V at 8A. LTC3892 controls two power systems, each with a pair of switch MOSFETs, inductors and output filters. This circuit shows the ability to set V OUT1 to a fixed level by programming the V PRG1 pin. In this diagram, it is set to 5V 1; Therefore, V OUT1 is directly connected to FB1 pin. Select the standard gate drive level by connecting the DRVSET pin to the INTV CC pin.
    In the solution in Figure 1, the V IN pins of the two outputs and the drain of the top MOSFET are connected to the same input voltage V IN. However, if necessary, these three ports can be connected to different voltages or power supplies. The designer can bias the LTC3892 through the V IN pin and apply the voltage from different sources to the drain of Q1 or Q3. Figures 2 and 3 show the efficiency of the converter in Figure 1 at various input voltages.
    The factory provides demonstration circuit 2 to show various load capacities. Combined with current mode control, the LTC3892 power supply can be connected as a dual-output power supply, provide 12V/30A two-phase single-output power supply (DC2190A-B), or generate 12V (DC2190A-A) at 60A as a four-phase single-output power supply.
conclusion
    LTC3892 is a general 60V input, dual-output step-down controller, optimized for efficient DC/DC solutions in the automotive, industrial and telecommunications fields. Other notable features include programmable gate voltage, extremely low no-load and turn-off quiescent current, programmable frequency, internal bootstrap diode, and simple current sharing for high-current design.
 












   
      
      
   
   


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