描述 Description

The LM3679 step-down DC-DC converter is optimized for powering ultra-low voltage circuits from a single Li-Ion cell battery and input voltage rails from 2.5V to 5.5V. It provides up to 350mA load current, over the entire input voltage range. The LM3679 output voltage can be configured to 1.2V, 1.5V, or 1.8V.

The device offers superior features and performance for mobile phones and similar portable applications with complex power management systems. Automatic intelligent switching between PWM low-noise and PFM low-current mode offers improved system control. During PWM mode operation, the device operates at a fixed-frequency of 3 MHz (typ). PWM mode drives loads from ~ 80mA to 350mA max. Hysteretic PFM mode extends the battery life by reducing the quiescent current to 16 μA (typ) during light load and standby operation. Internal synchronous rectification provides high efficiency. In shutdown mode (Enable pin pulled low), the device turns off and reduces battery consumption to 0.01 μA (typ).

The LM3679 is available in a lead-free (No PB) 5-bump micro SMD package, 0.6mm height, and in an ultra thin 0.3mm height UR package. Using the UR package along with specific external components, allows for a low profile solution size with a max height of 0.55mm. A switching frequency of 3 MHz (typ) allows use of tiny surface-mount components. Only three external surface-mount components, an inductor and two ceramic capacitors, are required. .

特性 Features

? 16 μA typical quiescent current
? 350 mA maximum load capability
? 3 MHz PWM fixed switching frequency (typ)
? Automatic PFM/PWM mode switching
? Available in 5-bump micro SMD package and UR package
? Internal synchronous rectification for high efficiency
? Internal soft start
? 0.01 μA typical shutdown current
? Operates from a single Li-Ion cell battery
? Current overload and Thermal shutdown protection
? Three external components required for typical applications
? Low profile solution (0.55mm max height, includes four external components)