LINEAR TECHNOLOGY LT3684 User's Guide
Summary
The LT3684 is a high-efficiency step-down switching regulator designed for reliable power conversion in demanding applications. This manual details its operation, featuring comprehensive specifications including an adjustable output frequency up to 2.8MHz and handling inputs from 3.6V to 34V while providing up to 2A of output current. Ideal for engineers designing portable electronics, industrial equipment, or automotive battery systems; the regulator includes advanced protective features like soft-start and a power good flag to ensure system stability.
Page 1 Text Content
LT3684
36V, 2A, 2.8MHz Step-Down Switching Regulator
FEATURES DESCRIPTION ■ Wide Input Range: 3.6V to 34V Operating, The LT®3684 is an adjustable frequency (300k Hz to 2.8MHz) 36V Maximum monolithic buck switching regulator that accepts input ■ 2A Maximum Output Current voltages up to 34V (36V maximum). A high effi ciency ■ Adjustable Switching Frequency: 300k Hz to 2.8MHz 0.18Ω switch is included on the die along with a boost ■ Low Shutdown Current: IQ < 1µA Schottky diode and the necessary oscillator, control and ■ Integrated Boost Diode logic circuitry. Current mode topology is used for fast ■ Power Good Flag transient response and good loop stability. The LT3684’s ■ Saturating Switch Design: 0.18Ω On-Resistance high operating frequency allows the use of small, low cost ■ 1.265V Feedback Reference Voltage inductors and ceramic capacitors resulting in low output ■ Output Voltage: 1.265V to 20V ripple while keeping total solution size to a minimum. ■ Soft-Start Capability The low current shutdown mode reduces input supply ■ Small 10-Pin Thermally Enhanced MSOP and current to less than 1µA while a resistor and capacitor on (3mm × 3mm) DFN Packages the RUN/SS pin provide a controlled output voltage ramp
(soft-start). A power good fl ag signals when VOUT reaches
APPLICATIONS 90% of the programmed output voltage. The LT3684 is
available in 10-Pin MSOP and 3mm × 3mm DFN packages
■ Automotive Battery Regulation
with Exposed Pads for low thermal resistance.
■ Power for Portable Products
, LT, LTC and LTM are registered trademarks of Linear Technology Corporation.
■ Distributed Supply Regulation
EF FI CI EN CY All other trademarks are the property of their respective owners.
■ Industrial Supplies
■ Wall Transformer Regulation
TYPICAL APPLICATION
3.3V Step-Down Converter Effi ciency
4.5V TO VOUT 3.3V
VIN BD OFF ON RUN/SS BOOST
VC SW
LT3684 RT
PG BIAS
60.4k FB
GND VIN = 12V VOUT = 3.3V
L = 4.7µH f = 800k Hz
3684 TA01
0.5 1.5 LOAD CURRENT (A)
3684 TA01b
Page Summary Contents For LINEAR TECHNOLOGY LT3684 User's Guide
Manual Details
| Brand | Linear |
|---|---|
| Pages | 24 |
| File Size | 326.18 KB |
| Published | June 22, 2026 |
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Frequently Asked Questions
What is the wide input voltage range supported by the LT3684?
The regulator supports a wide input range from 3.6V to 34V (up to 36V maximum).
How can I start up my circuit safely?
Using the RUN/SS pin provides controlled output voltage ramping, offering soft-start capability.
Are there different package options for this regulator?
The LT3684 is available in 10-Pin MSOP and 3mm × 3mm DFN packages.
What happens if I need to regulate power for industrial or automotive uses?
The datasheet notes the LT3684's suitability for Automotive Battery Regulation, Industrial Supplies, and Wall Transformer Regulation.