National Semiconductor LM20333 36V Owner's Manual and User Guide
Summary
This high-performance synchronous buck regulator delivers dependable, efficient power for demanding circuits operating from 4.5V to 36V input. With advanced features like frequency synchronization (250kHz–1.5MHz), integrated overvoltage/overcurrent protection, and programmable soft-start, it excels in multi-rail power designs. The technical manual provides detailed specifications, pinouts, and guidance necessary for engineers developing complex embedded systems, including those used in communications, industrial control, or automotive applications.
Page 1 Text Content
, 3 r W is ro la to r w ith re ro iza tio
June 2, 2008
LM20333 36V, 3A Power Wise® Synchronous Buck Regulator with Frequency Synchronization General Description Features The LM20333 is a full featured synchronous buck regulator 4.5V to 36V input voltage range capable of delivering up to 3A of load current. The current
3A output current, 5.2A peak current
mode control loop is externally compensated with only two
130 mΩ/110 mΩ integrated power MOSFETs
components, offering both high performance and ease of use.
94% peak efficiency with synchronous rectification
The device is optimized to work over the input voltage range
of 4.5V to 36V making it well suited for high voltage systems. 1.5% feedback voltage accuracy The device features internal Over Voltage Protection (OVP) Current mode control, selectable compensation
and Over Current Protection (OCP) circuits for increased sys- Oscillator synchronization from 250k Hz to 1.5MHz tem reliability. A precision Enable pin and integrated UVLO
Adjustable output voltage down to 0.8V
allows the turn on of the device to be tightly controlled and
Compatible with pre-biased loads
sequenced. Startup inrush currents are limited by both an in-
ternally fixed and externally adjustable soft-start circuit. Fault Programmable soft-start with external capacitor
detection and supply sequencing are possible with the inte- Precision enable pin with hysteresis grated power good (PGOOD) circuit.
OVP, UVLO inputs and PGOOD output
The LM20333 is designed to work well in multi-rail power
Internally protected with peak current limit, thermal
supply architectures. The output voltage of the device can be
shutdown and restart
configured to track a higher voltage rail using the SS/TRK pin.
Accurate current limit minimizes inductor size
If the output of the LM20333 is pre-biased at startup it will not
Non-linear current mode slope compensation
sink current to pull the output low until the internal soft-start
ramp exceeds the voltage at the feedback pin. e TSSOP-20 exposed pad package
The switching frequency of the LM20333 can be synchro-
nized to an external clock by use of the SYNC pin. The SYNC Applications
pin is capable of synchronizing to input signals ranging from
Simple to design, high efficiency point of load regulation
250 k Hz to 1.5 MHz.
from a 4.5V to 36V bus
The LM20333 is offered in an exposed pad 20-pin e TSSOP
High Performance DSPs, FPGAs, ASICs and
package that can be soldered to the PCB, eliminating the
Microprocessors
need for bulky heatsinks.
Communications Infrastructure, Automotive
Simplified Application Circuit
Power Wise® is a registered trademark of National Semiconductor Corporation.
© 2008 National Semiconductor Corporation www.national.com
Page Summary Contents For National Semiconductor LM20333 36V Owner's Manual and User Guide
Manual Details
| Brand | National |
|---|---|
| Pages | 20 |
| File Size | 524.04 KB |
| Published | June 18, 2026 |
Enter the captcha to get the download link:
Frequently Asked Questions
What is the nominal operating voltage range for this regulator?
The input supply voltage handles a nominal range of 4.5V to 36V, capable of delivering up to 3A.
How can I synchronize the switching frequency with an external clock?
Use the dedicated SYNC pin; it supports synchronization to external inputs ranging from 250 kHz to 1.5 MHz.
What key protection features does the LM20333 include?
It integrates Over Voltage Protection (OVP) and Over Current Protection (OCP) circuits for enhanced system reliability.
How can I control the power-up sequencing of the device?
You can use the internal soft-start circuit, which allows precise control over startup inrush currents and sequenced operation.