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Dell LM20323 36V, 3A PowerWise 500 kHz Synchronous Buck Regulator Owner's Manual

Summary

This datasheet describes the Texas Instruments LM20323 PowerWise 36V synchronous buck regulator capable of delivering up to 3A continuous load current with 5.2A peak capability. Operating at a fixed 500kHz switching frequency, the device accepts 4.5V to 36V input and provides an adjustable output voltage down to 0.8V with ±1.5% feedback accuracy. Integrated 130mΩ high-side and 110mΩ low-side N-channel MOSFETs achieve up to 93% peak efficiency with synchronous rectification. Protection features i

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, 3 r W is z S ro la to

June 2, 2008

LM20323 36V, 3A Power Wise® 500 k Hz Synchronous Buck Regulator General Description Features The LM20323 is a full featured 500k Hz synchronous buck 4.5V to 36V input voltage range regulator capable of delivering up to 3A of load current. The

3A output current, 5.2A peak current

current mode control loop is externally compensated with only

130 mΩ/110 mΩ integrated power MOSFETs

two components, offering both high performance and ease of

93% peak efficiency with synchronous rectification

use. The device is optimized to work over the input voltage

range of 4.5V to 36V making it well suited for high voltage 1.5% feedback voltage accuracy

systems. Current mode control, selectable compensation The device features internal Over Voltage Protection (OVP) Fixed 500 k Hz switching frequency and Over Current Protection (OCP) circuits for increased sys-

Adjustable output voltage down to 0.8V

tem reliability. A precision Enable pin and integrated UVLO

Compatible with pre-biased loads

allows the turn-on of the device to be tightly controlled and

sequenced. Startup inrush currents are limited by both an in- Programmable soft-start with external capacitor

ternally fixed and externally adjustable soft-start circuit. Fault Precision enable pin with hysteresis detection and supply sequencing are possible with the inte-

Integrated OVP, UVLO, PGOOD

grated power good (PGOOD) circuit.

Internally protected with peak current limit, thermal

The LM20323 is designed to work well in multi-rail power

shutdown and restart

supply architectures. The output voltage of the device can be

Accurate current limit minimizes inductor size

configured to track a higher voltage rail using the SS/TRK pin.

Non-linear current mode slope compensation

If the output of the LM20323 is pre-biased at startup it will not

sink current to pull the output low until the internal soft-start e TSSOP-20 exposed pad package

ramp exceeds the voltage at the feedback pin.

The LM20323 is offered in an exposed pad 20-pin e TSSOP Applications

package that can be soldered to the PCB, eliminating the

Simple to design, high efficiency point of load regulation

need for bulky heatsinks.

from a 4.5V to 36V bus High Performance DSPs, FPGAs, ASICs and Microprocessors 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 Dell LM20323 36V, 3A PowerWise 500 kHz Synchronous Buck Regulator Owner's Manual

Page 1 , 3 r W is z S ro la to June 2, 2008 LM20323 36V, 3A Power Wise® 500 k Hz Synchronous Buck Regulator General Description Features The LM20323 is a full featured 500k Hz synchronous buck 4.5V to 36V in...
Page 2 Connection Diagram Top View e TSSOP-20 Package Ordering Information Order Number Package Type NSC Package Drawing Package Marking Supplied As LM20323MH e TSSOP-20 MXA20A 20323MH 73 Units per Rail LM20...
Page 3 VCC to GND -0.3V to +8V Absolute Maximum Ratings (Note 1) Storage Temperature -65°C to 150°C If Military/Aerospace specified devices are required, ESD Rating please contact the National Semiconductor ...
Page 4 Symbol Parameter Conditions Min Typ Max Units Current Limit ILIM Cycle By Cycle Positive Current Limit 4.3 5.2 6.0 ILIMNEG Cycle By Cycle Negative Current Limit 2.8 TILIM Cycle By Cycle Current Limit ...
Page 5 Error Amplifier Phase Line Regulation Load Regulation VCC vs. VIN Non-Switching IQ vs. VIN Shutdown IQ vs. VIN www.national.com
Page 6 PGOOD Output Low Level Voltage vs. IPGOOD Enable Threshold and Hysteresis vs. Temperature UVLO Threshold and Hysteresis vs. Temperature Enable Current vs. Temperature Oscillator Frequency vs. VIN High...
Page 7 Load Transient Response Low-Side FET Resistance vs. Temperature Peak Current Limit vs. Temperature Startup with Prebiased Output Startup with CSS = 0 Startup with CSS = 100 n F www.national.com
Page 8 Startup with Applied Track Signal www.national.com
Page 9 Block Diagram www.national.com
Page 10 decremented and PWM pulses are skipped resulting in a cur- Operation Description rent limit that does not aggressively fold back for brief over- current events, while at the same time providing freque...
Page 11 the junction cools to approximately 150°C, the part starts up using the normal start up routine. This feature is provided to prevent catastrophic failures from accidental device over- heating. Design ...
Page 12 where, COUT (F) is the minimum required output capacitance, capacitor, inductor, load and the device itself. Table 2 below L (H) is the value of the inductor, VDROOP (V) is the output gives values for...
Page 13 The power stage transfer function is dictated by the modula- mended for most applications. The VCC regulator should not tor, output LC filter, and load; while the feedback transfer be used for other f...
Page 14 The value for resistor RB can be selected by the user to control the current through the divider. Typically this resistor will be selected to be between 1 kΩ and 49.9 kΩ. Once the value for RB is chos...
Page 15 the synchronous MOSFET body diode and eliminating re- verse recovery losses. The external Schottky conducts currents for a very small por- tion of the switching cycle, therefore the average current is...
Page 16 input and output capacitor should consist of a small localized top side plane that connects to GND and the exposed pad (EP). The inductor should be placed as close as possible to the SW pin and output...
Page 17 FIGURE 12. Typical Application Schematic Bill of Materials (VIN = 12V, VOUT = 3.3V, IOUT = 3A) ID Qty Part Number Size Description Vendor U1 LM20323MH e TSSOP-20 IC, Switching Regulator NSC C1 C3225X5...
Page 18 Physical Dimensions inches (millimeters) unless otherwise noted 20-Lead e TSSOP Package NS Package Number MXA20A www.national.com
Page 19 Notes www.national.com
Page 20 r W is ro la to Notes For more National Semiconductor product information and proven design tools, visit the following Web sites at: Products Design Support Amplifiers www.national.com/amplifiers WEBE...

Manual Details

Brand Dell
Pages 20
File Size 491.00 KB
Published July 06, 2026
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Frequently Asked Questions

What is the operational voltage range for this regulator?

It operates on an input voltage range of 4.5V to 36V.

Does it have built-in protection features?

Yes, it includes internal Over Voltage Protection (OVP), Over Current Protection (OCP), and UVLO circuits.

How can I control the power startup sequence?

The device supports controlled turn-on via a precision Enable pin and programmable soft-start with an external capacitor.

What package is used for this regulator?

It comes in an exposed pad 20-pin eTSSOP package that eliminates the need for bulky heatsinks.