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.