LTC3890 Step-Down Switching Regulator DC/DC Controller Data Sheet and Application Circuit

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Probe current voltage pin 420*4450 head diameter 5.0 over current current and voltage pin

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description

The LTC3890 is a high performance, dual, step-down switching regulator DC/DC controller for driving all N-channel synchronous power MOSFET stages. The device utilizes a constant frequency current mode architecture to provide a phase-lockable frequency of up to 850kHz. By operating the two controller output stages out of phase, power loss and power supply noise due to the ESR of the input capacitor are minimized.

The 50μA no-load quiescent current extends the operating life in battery-powered systems. The use of OPTI-LOOP compensation allows for transient response optimization over a wide range of output capacitance and ESR values. The LTC3890 features a precision 0.8V reference and power good output indicator. The 4V to 60V input supply range includes numerous intermediate bus voltages and battery chemistries.

The separate TRACK/SS pin for each controller is responsible for ramping the output voltage during startup. The current foldback feature limits MOSFET heat dissipation in the event of a short circuit. The PLLIN/MODE pin is used to select burst mode operation, pulse skip mode, or continuous conduction mode under light load conditions. For a leaded version (28-pin narrow SSOP package), please consult the LTC3890-1 product manual.

Characteristics

Wide VIN range: 4V to 60V (absolute maximum is 65V)
Low working IQ: 50μA (one channel is on)
Wide output voltage range: 0.8V ≤ VOUT ≤ 24V
RSENSE or DCR current sense out-of-phase controller reduces the noise input phase frequency (75kHz to 850kHz) caused by the required input capacitance and power supply
Programmable fixed frequency (50kHz to 900kHz)
Continuous, pulse skip or low ripple burst mode (Burst Mode?) operation under light load conditions Optional current limit Very low dropout operation: 99% duty cycle adjustable output voltage Soft start or tracking function Good power Output voltage monitor output overvoltage protection low shutdown current IQ: <14μA
Internal LDO supplies power to the gate driver from VIN or EXTVCC. No current foldback during startup. Small flat (0.75mm) 5mm x 5mm QFN package

application

System-powered digital device distributed DC power system for "always on" in the car

LTC3890 application circuit

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