Analog Devices / Linear Technology

The LT® 3012B is a high voltage, micropower low dropout linear regulator. The device is capable of supplying 250mA of output current with a dropout voltage of 400mV. Designed for use in battery-powered or high voltage systems, the low quiescent current (40µA operating) makes the LT3012B an ideal choice. Quiescent current is also well controlled in dropout.

Other features of the LT3012B include the ability to operate with very small output capacitors. The regulators are stable with only 3.3µF on the output while most older devices require between 10µF and 100µF for stability. Small ceramic capacitors can be used without any need for series resistance (ESR) as is common with other regulators. Internal protection circuitry includes reverse-battery protection, current limiting, thermal limiting and reverse current protection.

The device is available with an adjustable output with a 1.24V reference voltage. The LT3012B regulator is available in the 16-lead TSSOP and 12 pin low profile (0.75mm) (4mm × 3mm) DFN packages with an exposed pad for enhanced thermal handling capability.

• Wide Input Voltage Range: 4V to 80V
• Low Quiescent Current: 40µA
• Low Dropout Voltage: 400mV
• Output Current: 250mA
• No Protection Diodes Needed
• Adjustable Output from 1.24V to 60V
• Stable with 3.3µF Output Capacitor
• Stable with Aluminum, Tantalum or Ceramic Capacitors
• Reverse-Battery Protection
• No Reverse Current Flow from Output to Input
• Thermal Limiting
• Thermally Enhanced 16-Lead TSSOP and 12-Pin(4mm × 3mm) DFN Packages

The LT®3741 and LT3741-1 are fixed frequency synchronous step-down DC/DC controllers designed to accurately regulate the output current at up to 20A. The average currentmode controller will maintain inductor current regulation over a wide output voltage range of 0V to (VIN – 2V). The regulated current is set by an analog voltage on the CTRL pins and an external sense resistor. Due to its unique topology, the LT3741 is capable of sourcing and sinking current. If sinking current is not required, or for parallel applications, use the LT3741-1.

The regulated voltage and overvoltage protection are set with a voltage divider from the output to the FB pin. Soft-Start is provided to allow a gradual increase in the regulated current during startup. The switching frequency is programmable from 200kHz to 1MHz through an external resistor on the RT pin or through the use of the SYNC pin and an external clock signal.

The LTC®4151 is a high side power monitor that operates over a wide voltage range of 7V to 80V. In default operation mode, the onboard 12-bit ADC continuously measures high side current, input voltage and an external voltage. Data is reported through the I2C interface when polled by a host. The LTC4151 can also perform on-demand measurement in a snapshot mode.

The LTC4151 features a dedicated shutdown pin to reduce power consumption. The LTC4151-1/LTC4151-2 feature split I2C data pins to drive opto-isolators. The data out on the LTC4151-1 is inverted while that on the LTC4151-2 is not.

The LTC®4355 is a positive voltage ideal diode-OR controller that drives two external N-channel MOSFETs. Forming the diode-OR with N-channel MOSFETs instead of Schottky diodes reduces power consumption, heat dissipation and
PC board area. With the LTC4355, power sources can easily be ORed together to increase total system reliability. The LTC4355 can diode-OR two positive supplies or the return paths of two negative supplies, such as in a –48V system.

In the forward direction the LTC4355 controls the voltage drop across the MOSFET to ensure smooth current transfer from one path to the other without oscillation. If a power source fails or is shorted, fast turnoff minimizes
reverse current transients. Power fault detection indicates if the input supplies are not in regulation, the inline fuses are blown, or the voltages across the MOSFETs are greater than the fault threshold.