TI LM3279TLX/NOPB

The LM3279 is a buck-boost DC/DC converter designed to generate output voltages either above or below a given input voltage, particularly suited for power amplifiers powered by a single-cell Li-ion battery in portable applications.

The LM3279 features four operating modes: PWM, PFM, standby, and shutdown. Under normal conditions, the LM3279 operates in fully synchronous PWM mode at a typical switching frequency of 2.4MHz, enabling seamless transitions between buck and boost operation. The power-saving PFM mode improves efficiency and reduces current consumption during low-power RF transmission modes. For high transmit power, the device operates in PWM buck or boost mode, while it can transition between PWM and PFM modes during low-power transmission. The LM3279 can be controlled via a built-in MIPI PFFE digital control interface or an analog control interface from an external MCU, offering design flexibility.

The power converter topology achieves the smallest possible overall solution size by using a single compact, case-size inductor and two SMT capacitors.

The LM3279 is internally compensated for both buck and boost mode operation, providing optimal transient response.

• MIPI RFFE digital control interface
• High-efficiency PFM and PWM modes with internal seamless transition
• Single Li-Ion cell operation: 2.7V to 5.5V
• Adjustable output voltage: RFFE digital control: 0.4V to 4.2V; analog control: 0.5V to 4.2V
• Maximum load capability of 1A at VBATT ≥ 3.2V, VOUT = 3.6V
• 2.4MHz (typical) switching frequency
• Seamless buck-boost mode transition
• Fast output voltage transition: 0.8V to 4V in 20μs
• High efficiency: 95% (typical) (VBATT = 3.7V, VOUT = 3.3V, 300mA)
• Input overcurrent limiting
• Output overvoltage clamping
• Internal compensation

• 3G/4G smartphones
• RF PC cards
• Tablets, e-readers
• Battery-powered RF devices