LINEAR TECHNOLOGY LT1533 User Guide
Summary
Achieve exceptional electrical performance with this ultralow noise switching regulator designed for demanding environments. This precision component significantly minimizes conducted and radiated EMI, making it ideal for sensitive systems. The comprehensive manual covers rigorous electrical characteristics, operational parameters, and diverse circuit schematics. It is essential reading for engineers developing critical applications such as medical devices, industrial automation gear, wireless communication equipment, and single-board data acquisition systems requiring stable power and ultra-low noise.
Page 1 Text Content
LT1533
Ultralow Noise
1A Switching Regulator FEATURES DESCRIPTION
Greatly Reduced Conducted and Radiated EMI The LT®1533 is a new class of switching regulator designed (<100µVP-P in Typical Application) to reduce conducted and radiated electromagnetic interfer- Low Switching Harmonic Content ence (EMI). Ultralow noise and EMI are achieved by providing Independent Control of Switch Voltage and user control of the output switch slew rates. Voltage and Current Slew Rates current slew rates can be independently programmed to Two 1A Current Limited Power Switches optimize switcher harmonic content versus efficiency. The Regulates Positive and Negative Voltages LT1533 can reduce high frequency harmonic power by as 20k Hz to 250k Hz Oscillator Frequency much as 40d B with only minor losses in efficiency. Easily Synchronized to External Clock
The LT1533 utilizes a dual output switch current mode
Wide Input Voltage Range: 2.7V to 23V
architecture optimized for low noise topologies. The IC
Low Shutdown Current: 12µA Typical
includes two 1A power switches along with all necessary
Easier Layout than with Conventional Switchers
oscillator, control and protection circuitry. Unique error amp
Outputs Can Be Forced to 50% Duty Cycle for
circuitry can regulate both positive and negative voltages.
Unregulated Applications
The internal oscillator may be synchronized to an external clock for more accurate placement of switching harmonics.
APPLICATIONS
Protection features include cycle by cycle current limit pro- tection, undervoltage lockout and thermal shutdown.
Precision Instrumentation Systems
Isolated Supplies for Industrial Automation Low minimum supply voltage and low supply current during
Medical Instruments shutdown make the LT1533 well suited for portable applica- Wireless Communications tions. The part may also be forced into a 50% duty cycle mode Single Board Data Acquisition Systems for unregulated applications. The LT1533 is available in the
16-pin narrow SO package.
, LTC and LT are registered trademarks of Linear Technology Corporation.
TYPICAL APPLICATION Low Noise 5V to 12V Forward Push-Pull DC/DC Converter
1N4148 300µH 33µH 12V Output Noise (BW = 100MHz) T1
33µF VIN 150m A
SHDN COL A
COL B 16V 20V
820p F SYNC Note 1
<100µVP-P
PGND 100µV/DIV
CT LT1533 15k
16.9k RVSL
RCSL 2m V/DIV
1533 TA01
VC FB
GND NFB
C1: SANYO OS-CON
0.015µF 1000p F C2: AVX TPS TANTALUM
L1: COILTRONICS CTX300-2 2µs/DIV
L2: COILCRAFT DT1608C-333 1533 TA02
T1: COILTRONICS CTX02-13834 NOTE 1: 25n H TRACE INDUCTANCE OR COILCRAFT B07T
Page Summary Contents For LINEAR TECHNOLOGY LT1533 User Guide
Manual Details
| Brand | Linear |
|---|---|
| Pages | 20 |
| File Size | 318.10 KB |
| Published | June 03, 2026 |
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Frequently Asked Questions
What is the minimum input voltage range for the LT1533?
The required operating range is from 2.7V to 23V.
How can I reduce electromagnetic interference (EMI)?
It features independent control of switch and current slew rates to achieve ultralow noise and reduced EMI.
Can the regulator handle both positive and negative voltages?
Yes, it is designed to regulate both positive and negative voltages and can be forced into a 50% duty cycle mode.
What protection features are included with this Regulator?
It includes cycle by cycle current limit protection, undervoltage lockout, and thermal shutdown protections.