LM2676 SIMPLE SWITCHER® High Efficiency 3A Step-Down Voltage
Regulator
FEATURES
• Efficiency Up to 94%
• Simple and Easy to Design with (Using Off- The-Shelf External
Components)
• 150 mΩ DMOS Output Switch
• 3.3V, 5V and 12V Fixed Output and Adjustable(1.2V to 37V)
Versions
• 50μA Standby Current When Switched OFF
• ±2% Maximum Output Tolerance Over Full Line and Load Conditions
• Wide Input Voltage Range: 8V to 40V
• 260 KHz Fixed Frequency Internal Oscillator
• −40 to +125°C Operating Junction Temperature range
APPLICATIONS
• Simple to Design, High Efficiency (>90%) Step-Down Switching
Regulators
• Efficient System Pre-Regulator for Linear Voltage Regulators
• Battery Chargers
DESCRIPTION
The LM2676 series of regulators are monolithic integrated circuits
which provide all of the active functions for a step-down (buck)
switching regulator capable of driving up to 3A loads with
excellent line and load regulation characteristics. High efficiency
(>90%) is obtained through the use of a low ON-resistance DMOS
power switch. The series consists of fixed output voltages of 3.3V,
5V and 12V and an adjustable output version.
The SIMPLE SWITCHER concept provides for a complete design using a
minimum number of external components. A high fixed frequency
oscillator (260KHz) allows the use of physically smaller sized
components. A family of standard inductors for use with the LM2676
are available from several manufacturers to greatly simplify the
design process.
The LM2676 series also has built in thermal shutdown, current
limiting and an ON/OFF control input that can power down the
regulator to a low 50μA quiescent current standby condition. The
output voltage is ensured to a ±2% tolerance. The clock frequency
is controlled to within a ±11% tolerance.
Typical Application
Connection Diagrams
Absolute Maximum Ratings(1)(2)
| Input Supply Voltage | 45V |
| ON/OFF Pin Voltage | −0.1V to 6V |
| Switch Voltage to Ground(3) | −1V to VIN |
| Boost Pin Voltage | VSW + 8V |
| Feedback Pin Voltage | −0.3V to 14V |
| Power Dissipation | Internally Limited |
| ESD(4) | 2 kV |
| Storage Temperature Range | −65°C to 150°C |
| Soldering Temperature | Wave | 4 sec, 260°C |
| Infrared | 10 sec, 240°C |
| Vapor Phase | 75 sec, 219°C |
(1) Absolute Maximum Ratings are limits beyond which damage to the
device may occur. Operating Ratings indicate conditions under which
of the device is ensured. Operating Ratings do not imply ensured
performance limits. For ensured performance limits and associated
test condition, see the Electrical Characteristics tables.
(2) If Military/Aerospace specified devices are required, please
contact the Texas Instruments Sales Office/Distributors for
availability and specifications.
(3) The absolute maximum specification of the 'Switch Voltage to
Ground' applies to DC voltage. An extended negative voltage limit
of -8V applies to a pulse of up to 20 ns, -6V of 60 ns and -3V of
up to 100 ns.
(4) ESD was applied using the human-body model, a 100pF capacitor
discharged through a 1.5 kΩ resistor into each pin.
