LM27313XMFX/NOPB

The Texas Instruments LM27313XMFX/NOPB is a high-efficiency boost switching regulator featuring a 28V, 1A internal NPN power switch. The 1.6MHz switching frequency allows the use of tiny surface-mount inductors and capacitors, minimizing solution footprint. The device operates from 2.7V to 14V input and provides an adjustable output voltage set by two external resistors. Current-mode control with internal compensation simplifies design and provides excellent line and load regulation. The low 0.19Ohm switch on-resistance and 10nA shutdown current optimize efficiency across the operating range. With only five external components required, the LM27313 is one of the simplest boost converter solutions available in the tiny SOT-23 package.

The LM27313XMFX/NOPB operates as a fixed-frequency current-mode boost converter: 1) Power Stage: The internal 28V, 1A NPN transistor acts as the switching element. During on-time, current ramps up in the external inductor, storing energy. During off-time, the inductor releases energy through the external Schottky diode to the output capacitor and load. 2) Current-Mode Control: The oscillator sets the 1.6MHz switching frequency. The error amplifier compares the FB pin voltage with the internal 1.23V reference and adjusts the peak switch current threshold. When the current-sense signal reaches this threshold, the switch turns off for the remainder of the cycle. This provides inherent input voltage feedforward and single-pole loop response. 3) Soft-Start: The internal soft-start circuit gradually increases the current limit on start-up, preventing excessive inrush current. 4) Protection: Cycle-by-cycle current limiting protects the switch during overload. Thermal shutdown at 165C junction temperature disables the device during thermal stress.

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