1 Features

1• MIPI® RFFE Digital Control Interface

• High-Efficiency PFM and PWM Modes with

Internal Seamless Transition

• Operates from a Single Li-Ion Cell: 2.7 V to 5.5 V

• Adjustable Output Voltage:

– RFFE Digital Control: 0.4 V to 4.2 V

– Analog Control: 0.5 V to 4.2 V

• 1-A Maximum Load Capability for VBATT ≥ 3.2 V,

VOUT = 3.6 V

• 2.4-MHz (typ.) Switching Frequency

• Seamless Buck-Boost Mode Transition

• Fast Output Voltage Transition: 0.8 V to 4 V in 20

μs

• High-Efficiency: 95% typ. at VBATT = 3.7 V,

VOUT = 3.3 V, at 300 mA

• Input Overcurrent Limit

• Output Overvoltage Clamp

• Internal Compensation

2 Applications

• 3G/4G Smartphones

• RF PC Cards

• Tablets, eBooks Readers

• Battery-Powered RF Devices

3 Description

The LM3279 is a buck-boost DC/DC converter

designed to generate output voltages above or below

a given input voltage and is particularly suitable for

Power Amplifiers operating from single-cell Li-Ion

batteries in portable applications.

The LM3279 has four modes of operation: Pulse

Width Modulation (PWM), Pulse Frequency

Modulation (PFM), standby, and shutdown. During

normal conditions, the LM3279 operates in full

synchronous PWM mode at 2.4-MHz typical switching

frequency, providing seamless transitions between

buck and boost operating regimes. Energy-saving

PFM mode increases efficiencies and current savings

during low-power RF transmission modes. For hightransmit

power, the device operates in PWM buck or

boost mode, whereas the device can transition

between PWM and PFM modes during low-power

transmit. The LM3279 can be controlled either via an

included MIPI RFFE Digital Control Interface or by

using an analog control from an external MCU,

offering design flexibility.

The power converter topology enables minimum total

solution size by using one small footprint and case

size inductor and two surface mount capacitors.

The LM3279 is internally compensated for buck and

boost modes of operation thus providing an optimal

transient response.