Analog Devices LTC3896 | Demoboard DC2447A

Description

Demonstration circuit 2447A is a high voltage, high efficiencysynchronous inverting converter featuring theLTC®3896. This demo board has a wide input voltagerange from 7V to 72V and produces a –12V output voltage.The DC2447A is capable of delivering up to 5A of outputcurrent. Note that the thermal stress increases at lowerinput voltages due to increased input current.This demo board supports four operation modes consistingof fixed-frequency modulation, pulse skipping, BurstMode® Operation (default mode) and adjustable Burst Modeoperation. During a light load condition, fixed-frequencymode reduces output voltage ripple and yields the lowestnoise spectrum. Burst mode operation employs a variablefrequency algorithm that minimizes the no-load quiescentcurrent and improves light load efficiency.The DC2447A consumes less than 12µA of current inshutdown and consumes only 100µA of quiescent currentwhen the output is in regulation, unloaded and configuredfor Burst Mode operation which helps extend the run-timein battery powered applications. This demo board operatesat a 300kHz switching frequency and can easily beadjusted from 50kHz to 900kHz.To prevent high on-chip power dissipation in high inputvoltage applications, the LTC3896 includes an onboardPerformance Summarydriver to drive the gate of an external N-channel MOSFETwhich acts as a linear regulator to power the IC.The LTC3896 can support a wide output voltage rangefrom –0.8V to –60V. However, the voltage differencebetween the input voltage and output voltage should notexceed the maximum voltage of the switching semiconductors(100V for DC2447A) and shown by the equation|–VOUT| + VIN < VDS.The DC2447A is set to provide a 10V gate drive voltage(DRVCC) for the switching MOSFETs. It has an UVLO of7.5V rising and 6.7V falling. However, the gate drive voltageand UVLO voltages can be adjusted lowered. See theLTC3896 data sheet for details.The DC2447A was designed to support multiple footprintsof input and output capacitors, and inductors to accommodatea variety of applications.The LTC3896 data sheet gives a complete description ofthe part, contains operating and application information,and must be read in conjunction with this data sheet

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