LM3370_08 Datasheet, PDF (1/26 Pages) National Semiconductor (TI) – Dual Synchronous Step-Down DC-DC Converter with Dynamic Voltage Scaling Function

January 4, 2008
LM3370
Dual Synchronous Step-Down DC-DC Converter with
Dynamic Voltage Scaling Function
General Description
The LM3370 is a dual step-down DC-DC converter optimized
for powering ultra-low voltage circuits from a single Li-Ion bat-
tery and input rail ranging from 2.7V to 5.5V. It provides two
outputs with 600 mA load per channel. The output voltage
range varies from 1V to 3.3V and can be dynamically con-
trolled using the I²C compatible interface. This dynamic volt-
age scaling function allows processors to achieve maximum
performance at the lowest power level. The I²C compatible
interface can also be used to control auto PFM-PWM/PWM
mode selection and other performance enhancing features.
The LM3370 offers superior features and performance for
portable systems with complex power management require-
ments. Automatic intelligent switching between PWM low-
noise and PFM low-current mode offers improved system
efficiency. Internal synchronous rectification enhances the
converter efficiency without the use of further external de-
vices.
There is a power-on-reset function that monitors the level of
the output voltage to avoid unexpected power losses. The in-
dependent enable pin for each output allows for simple and
effective power sequencing.
LM3370 is available in a 4 mm by 5 mm 16-lead non-pullback
LLP and a 20-Bump micro SMD, 3.0 mm x 2.0 mm x 0.6 mm,
package. A high switching frequency—2 MHz (typ)—allows
use of tiny surface-mount components including a 2.2 µH in-
ductor.
Default fixed voltages for the 2 output voltages combination
can be customized to fit system requirements by contacting
National Semiconductor Corporation.
Features
■ ^{I2C compatible interface}
— V_OUT1 = 1V to 2V in 50 mV steps
— V_OUT2 = 1.8V to 3.3V in 100 mV steps
— Automatic PFM/PWM mode switching & Forced PWM
mode for low noise operation
— Spread Spectrum capability using I²C
■ ^{600 mA load per channel}
■ ^{2 MHz PWM fixed switching frequency (typ.)}
■ ^{Internal synchronous rectification for high efficiency}
■ ^{Internal soft start}
■ ^{Power-on-reset function for both outputs}
■ ^{2.7V ≤ V}_IN ^{≤ 5.5V}
■ ^{Operates from a single Li-Ion cell or 3 cell NiMH/NiCd}
batteries and 3.3V/5.5V fixed rails
■ ^{2.2 µH Inductor, 4.7 µF Input and 10 µF Output Capacitor}
per channel
■ ^{16-lead LLP Package (4 mm x 5 mm x 0.8 mm)}
■ ^{20-Bump micro SMD Package (3.0 mm x 2.0 mm x 0.6}
mm)
Applications
■ ^{Baseband Processors}
■ ^{Application Processors (Video, Audio)}
■ ^{I/O Power}
■ ^{FPGA Power and CPLD}
Typical Performance Curve
20167379
Dimensions: 3.0 mm x 2.0 mm x 0.60 mm
20167381
Efficiency vs. Output Current, V_OUT1= 1.2V
© 2008 National Semiconductor Corporation 201673
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