LM3677 Datasheet | National Semiconductor

Description The LM3677 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 2.7V to 5.5V. It provides up to 600m A load current, over the entire input voltage range. The LM3677 is configured to four output voltages of 1.3V, 1.5V, 1.8V and 2.5V. The device offers superior features and performance for mobile phones and similar portable applications with plex 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 ~ 80m A to 600m A 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 down), the device turns off and reduces battery consumption to 0.01 µA (typ). The LM3677 is available in a lead-free (NO PB) 5-bump micro SMD package. A switching frequency of 3 MHz (typ) allows use of tiny surface-mount ponents. Only three external surface-mount ponents, an inductor and two ceramic capacitors, are required. Features - - - - - - - - - - 16 µA typical quiescent current 600 m A maximum load capability 3 MHz PWM fixed switching frequency (typ) Automatic PFM/PWM mode switching Available in 5-bump micro SMD package Internal synchronous rectification for high efficiency Internal soft start 0.01 µA typical shutdown current Operates from a single Li-Ion cell battery Only three tiny surface-mount external ponents required (solution size less than 20 mm2) - Current overload and Thermal shutdown protection Applications - - - - - - - Mobile phones PDAs MP3 players W-LAN Portable Instruments Digital still cameras Portable Hard disk drives Typical Application Circuit Efficiency vs. Output Current (VOUT = 1.8V) FIGURE 1....