DC/DC Converter. LM3668 Datasheet

LM3668 Converter. Datasheet pdf. Equivalent

Part LM3668
Description High Efficiency Dual Mode Single Inductor Buck-Boost DC/DC Converter
Feature www.DataSheet4U.com June 2007 LM3668 1A, High Efficiency Dual Mode Single Inductor Buck-Boost DC/DC.
Manufacture National Semiconductor
Download LM3668 Datasheet

June 2007
1A, High Efficiency Dual Mode Single Inductor Buck-Boost
DC/DC Converter
General Description
The LM3668 is a synchornous buck or boost DC-DC convert-
er optimized for powering low voltage circuits from a Li-Ion
battery and input voltage rails between 2.5V and 5.5V. It has
the capability to support up to 1A output current over a output
voltage range of 2.8V/3.3V. The LM3668 regulates the output
voltage over the complete input voltage range by automati-
cally switching between buck or boost modes depending on
the input voltage.
The LM3668 has 2 N-channel MOSFETS and 2 P-channel
MOSFETS arranged in a topology that provides continuous
operation through the buck and boost operating modes.
There is a MODE pin that allows the user to choose between
an intelligent automatic PFM-PWM mode operation and
forced PWM operation. During PWM mode, a fixed-frequency
2.2MHz (typ.) is used. PWM mode drives load up to 1A. Hys-
teretic PFM mode extends the battery life through reduction
of the quiescent current to 45µA (typ.) at light loads during
system standby. Internal synchronous retification provides
high efficiency. In shutdown mode (Enable pin pulled low) the
device turns off and reduces battery consumption to 0.01µA
The LM3668 is available in a 12-pin LLP package. A high
switching frequency of 2.2MHz (typ.) allows the use of tiny
surface-mount components including a 2.2µH inductor, a
10µF input capacitor, and a 22µF output capacitor.
45µA typical quiescent current
1A maximum load current for VIN = 2.8V to 5.5V
800mA maximum load current for VIN = 2.7V
600mA maximum load current for VIN = 2.5V
2.2 MHz PWM fixed switching frequency (typ.)
Automatic PFM-PWM Mode or Forced PWM Mode
Wide Input Voltage Range: 2.5V to 5.5V
Output Voltage Range: 2.8V/3.3V
Internal synchronous rectification for high efficiency
Internal soft start: 600µs Maximum start-up time
0.01µA typical shutdown current
Current overload and Thermal shutdown protection
Frequency Sync Pin: 1.6Mhz to 2.7MHz
Handset Peripherals
MP3 players
Pre-Regulation for linear regulators
Portable Hard Disk Drives
WiMax Modems
Typical Applications
Typical Application Circuit
Efficiency at 3.3V Output
© 2007 National Semiconductor Corporation 201914

Functional Block Diagram
FIGURE 1. Functional Block Diagram

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