The LM3670 step-down DC-DC converter is optimized for powering ultralow voltage circuits
from a single Li-Ion cell or three-cell NiMH/NiCd batteries. It provides up to 350-mA load current,
over an input voltage range from 2.5 V to 5.5 V. 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 complex power management systems. Automatic intelligent switching
between pulse width modulation (PWM) low-noise and pulse frequency modulation (PFM) low-current
mode offers improved system control. During full-power operation, a fixed-frequency 1-MHz (typical)
PWM mode drives loads from approximately 70 mA to 350 mA maximum, with up to 95% efficiency.
Hysteretic PFM mode extends the battery life through reduction of the quiescent current to 15 µA
(typical) during light current loads and system standby. Internal synchronous rectification
provides high efficiency (90% to 95% typical at loads between 1 mA and 100 mA). In shutdown mode
(enable (EN) pin pulled low) the device turns off and reduces battery consumption to
0.1 µA (typical).
The LM3670 is available in a 5-pin SOT-23 package. A high switching frequency (1 MHz
typical) allows use of tiny surface-mount components. Only three external surface-mount components,
an inductor and two ceramic capacitors, are required.
For all available packages, see the orderable addendum at the
end of the data sheet.
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