1 Features

• V_{OUT_RANGE}
• V_{OUT_ET} = 0.6 V to 4.5 V
• V_{OUT_APT} = 0.4 V to 3.81 V (or V_IN – 200 mV)
• DC Boost For ET Operation:
• Boost Input Voltage Range: 2.5 V to 5 V
• High-Efficiency (90% typical) with Internal Synchronous Rectification
• Boost Bypass Function with Low Resistance (150 mΩ typ.)
• 2.7-MHz PWM Switching Frequency
• Buck DC-DC for APT and ET Operation:
• High Operating Frequency for Small External Inductor and Capacitors
• V_{OUT_RANGE} = 0.4 V to 3.81 V
  (or V_IN – 200 mV)
• High-Efficiency (95% typical) with Internal Synchronous Rectification
• Low-Power PFM Mode
• LM3291 Control:
• Automatic Control of LM3291 in ET Mode
• RFFE Control Interface:
• 1.8-V MIPI® RFFE 1.1-Compatible Digital Control Interface
• 26-MHz Write Capability
• 13-MHz Read Capability
• 

2 Description

The LM3290, with its companion IC LM3291, is an RF envelope supply modulator (EM) with integrated DC-DC boost converter optimized for Envelope Tracking (ET) RF power amplifiers (PAs). The device enables maximum transmit output power independent of the input battery voltage (battery as low as 2.5 V) and is controlled by the MIPI® RFFE 1.1.

The LM3290 operates in two active modes:

Active Mode 1: For low TX output power, LM3290 may operate in Average Power Tracking (APT) mode, providing a static, but programmable, output voltage to supply the PA. At light load and in APT mode, the LM3290 enters into Pulse Frequency Mode (PFM) operation automatically and operates with reduced switching frequency. In PFM mode, the quiescent current is reduced, which extends the battery life.

Active Mode 2: In ET mode, the LM3290 with LM3291 efficiently provides a dynamic, high-bandwidth supply voltage for the PA to maximize total EM + PA efficiency. The envelope modulator follows the envelope reference input signal delivered by the RFIC to the LM3291 via a differential analog input. The output is a single-ended power supply signal to the PA.

The LM3290 and LM3291 support 3G, as well as LTE operation up to 20-MHz signal bandwidth.

The LM3290 controls the LM3291 companion-IC through direct control signals, and no additional controls are needed from the system. Shutdown, standby, and idle modes turn the EM off and reduce battery current consumption.

For the full datasheet, samples, or the EVM hardware and software please contact a TI representative at ET@list.ti.com.

1. For all available packages, see the orderable addendum at the end of the datasheet.