LM3670_14 Datasheet, PDF (1/24 Pages) Texas Instruments – Miniature Step-Down DC-DC Converter for Ultra Low Voltage Circuits

LM3670
www.ti.com
SNVS250D – NOVEMBER 2004 – REVISED JANUARY 2006
LM3670 Miniature Step-Down DC-DC Converter for Ultra Low Voltage Circuits
Check for Samples: LM3670
FEATURES
1
•2 V_OUT = Adj (0.7V min), 1.2, 1.5, 1.6, 1.8, 1.875,
2.5, 3.3V
• 2.5V ≤ V_IN ≤ 5.5V
• 15 µA typical quiescent current
• 350 mA 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 typical shutdown current
• Operates from a single Li-Ion cell or 3 cell
NiMH/NiCd batteries
• Only three tiny surface-mount external
components required (one inductor, two
ceramic capacitors)
• Current overload protection
APPLICATIONS
• Mobile phones
• HandHeld
• PDAs
• Palm-top PCs
• Portable Instruments
• Battery Powered Devices
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 NiMH/NiCd batteries. It provides up to 350 mA 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 (see ordering information).
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 full-power operation, a fixed-frequency 1 MHz (typ). PWM
mode drives loads from ∼70 mA to 350 mA 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 mA and
100 mA). 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 components. Only three external surface-mount components, an inductor and two ceramic
capacitors, are required.
1
Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of
Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.
All trademarks are the property of their respective owners.
2
PRODUCTION DATA information is current as of publication date.
Products conform to specifications per the terms of the Texas
Instruments standard warranty. Production processing does not
necessarily include testing of all parameters.
Copyright © 2004–2006, Texas Instruments Incorporated