LINEAR TECHNOLOGY LTC3778 User's Manual
Summary
The LTC3778 is a highly efficient synchronous step-down regulator controller engineered for sophisticated DC/DC power supply design. Featuring a wide operating range (4V to 36V) and true Kelvin sensing, it maintains high performance without requiring an external sense resistor. This resource provides detailed specifications on its advanced features, including synchronized drive, adjustable frequency, programmable soft-start, and multiple protection circuits. It is ideal for engineers designing reliable power solutions for demanding applications such as notebook computers, automotive systems, and high-density memory modules.
Page 1 Text Content
LTC3778
Wide Operating Range, TM Step-Down Controller
No RSENSE
FEATURES DESCRIPTIO
Wide VIN Range: 4V to 36V The LTC®3778 is a synchronous step-down switching Sense Resistor Optional regulator controller for computer memory, automobile True Current Mode Control and other DC/DC power supplies. The controller uses a 2% to 90% Duty Cycle at 200k Hz valley current control architecture to deliver very low duty t ON(MIN) ≤ 100ns cycles without requiring a sense resistor. Operating fre- Stable with Ceramic COUT quency is selected by an external resistor and is compen- Dual N-Channel MOSFET Synchronous Drive sated for variations in VIN and VOUT.
Power Good Output Voltage Monitor
Discontinuous mode operation provides high efficiency
±1% 0.6V Reference
operation at light loads. A forced continuous control pin
Adjustable Current Limit
reduces noise and RF interference, and can assist second-
Adjustable Switching Frequency
ary winding regulation when the main output is lightly
Programmable Soft-Start
loaded. SENSE+ and SENSE– pins provide true Kelvin
Output Overvoltage Protection
sensing across the optional sense resistor or the
Optional Short-Circuit Shutdown Timer
sychronous MOSFET.
Micropower Shutdown: IQ ≤ 30µA
Available in a 1mm 20-Lead TSSOP Package Fault protection is provided by internal foldback current limiting, an output overvoltage comparator, optional short-
EF FI CI EN CY
APPLICATIO S circuit shutdown timer and input undervoltage lockout. Soft-start capability for supply sequencing is accom-
Notebook and Palmtop Computers, PDAs
plished using an external timing capacitor. The regulator
Battery Chargers
current limit level is user programmable. Wide supply
Distributed Power Systems
range allows operation from 4V to 36V at the input and
DDR Memory Power Supply
from 0.6V up to (0.9)VIN at the output.
Automobile DC Power Supply
, LTC and LT are registered trademarks of Linear Technology Corporation. No RSENSE is a trademark of Linear Technology Corporation.
TYPICAL APPLICATIO
RON 1.4M
ION Efficiency vs Load Current
0.1µF VIN
CIN 5V TO 28V
RUN/SS TG 10µF VIN = 5V
Si4884 L1
CC 1.8µH
SW ×3 VOUT
CB 0.22µF 2.5V ITH BOOST COUT 10A+
DB VIN = 25V
RC 180µF
LTC3778
20k CMDSH-3 4V
SGND INTVCC ×2M2
DRVCC D1
Si4874
BG B340A
SENSE+
CVCC R2 4.7µF 40.2k
SENSE– PGOOD PGND
R1 LOAD CURRENT (A) 12.7k
Figure 1. High Efficiency Step-Down Converter
Page Summary Contents For LINEAR TECHNOLOGY LTC3778 User's Manual
Manual Details
| Brand | Linear |
|---|---|
| Pages | 24 |
| File Size | 297.82 KB |
| Published | June 22, 2026 |
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Frequently Asked Questions
What is the input supply voltage range for the LTC3778?
The device operates with a wide input range from 4V to 36V.
How does the controller handle light loads?
It provides high efficiency in discontinuous mode operation and features a 0.6V reference operation at light loads.
Can I sense voltage without an external resistor?
Yes, it uses true Kelvin sensing on the SENSE and SENSE pins for accurate measurement.
Does the LTC3778 offer protection features?
It includes internal foldback current limiting, output overvoltage protection, optional short-circuit shutdown timer, and input undervoltage lockout.