LM3670 Datasheet | National Semiconductor

LM3670 Miniature Step-Down DC-DC Converter for Ultra Low Voltage Circuits December 2004 LM3670 Miniature Step-Down DC-DC Converter for Ultra Low Voltage Circuits General Description The LM3670 step-down DC-DC converter is optimized for powering ultra-low voltage circuits from a single Li-Ion cell or 3 cell Ni MH/Ni Cd batteries. It provides up to 350 m A load current, over an input voltage range from 2.5V to 5.5V. There are several different fixed voltage output options available as well as an adjustable output voltage version. 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 full-power operation, a fixed-frequency 1 MHz (typ). PWM mode drives loads from ∼70 m A to 350 m A max, with up to 95% efficiency. Hysteretic PFM mode extends the battery life through reduction of the quiescent current to 15 µA (typ) during light current loads and system standby. Internal synchronous rectification provides high efficiency (90 to 95% typ. at loads between 1 m A and 100 m A). In shutdown mode (Enable pin pulled low) the device turns off and reduces battery consumption to 0.1 µA (typ.). The LM3670 is available in a SOT23-5 package. A high switching frequency - 1 MHz (typ) - allows use of tiny surface-mount ponents. Only three external surfacemount ponents, an inductor and two ceramic capacitors, are required. Features n n n n n n n n n n n n n n n VOUT = adj (.7V min), 1.2, 1.5, 1.6, 1.8, 1.875, 2.5, 3.3V 2.5V ≤ VIN ≤ 5.5V 15 µA typical quiescent current 350 m A maximum load capability 1 MHz PWM fixed switching frequency (typ.) Automatic PFM/PWM mode switching Available in fixed output voltages as well as an adjustable version SOT23-5 package Low drop out operation - 100% duty cycle mode Internal synchronous rectification for high efficiency Internal soft start 0.1 µA...