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LM20125 -
5A, 500kHz PowerWise Synchronous Buck Regulator
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Features
| • | Input voltage range 2.95V to 5.5V |
| • | Accurate current limit minimizes inductor size |
| • | 97% efficiency with 500 kHz switching frequency |
| • | 32 mΩ integrated FET switches |
| • | Starts up into pre-biased loads |
| • | Output voltage tracking |
| • | Peak current mode control |
| • | Adjustable output voltage down to 0.8V |
| • | Adjustable Soft-Start with external capacitor |
| • | Precision enable pin with hysteresis |
| • | Integrated OVP, UVLO, power good and thermal shutdown |
| • | eTSSOP-16 exposed pad package |
General Description
The LM20125 is a full featured 500 kHz synchronous buck regulator capable of delivering up to 5A of continuous output current.
The current mode control loop can be compensated to be stable with virtually any type of output capacitor. More...
Applications
| • | Simple to design, high efficiency point of load regulation from a 5V or 3.3V bus |
| • | High Performance DSPs, FPGAs, ASICs and microprocessors |
| • | Broadband, Networking and Optical Communications Infrastructure |
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Typical Application
click for larger image
| Parameters | Values |
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| Output Current |
5000 mA |
| Input Min Voltage |
2.95 Volt |
| Input Max Voltage |
5.5 Volt |
| Output Min |
0.8 Volt |
| Output Max |
5 Volt |
| Frequency Min |
Undefined kHz |
| Frequency Max |
Undefined kHz |
| Efficiency (peak) |
96 % |
| On/Off Pin |
Yes |
| Error Flag |
Yes |
| SoftStart |
Yes |
| Sync Pin |
No |
| Inverting |
Undefined |
| Flyback |
Undefined |
| RegType |
Switching Regulator |
| Temperature Min |
-40 deg C |
| Temperature Max |
125 deg C |
| Adjustable Output |
Yes |
| Adj Switch Frequency |
No |
| PWM Mode |
Current Mode Control |
| Topology |
Synchronous Buck |
| Special Features |
Undefined |
| Step-Down |
Yes |
| Multiple Output Capability |
No |
| Output Power |
Undefined Watt |
| Output Voltage |
Undefined Volt |
| Output Range |
0.8V to 5.0V |
| Switching Frequency |
500 kHz |
| Feedback Voltage |
0.8 Volt |
| Regulator Family |
LM20k |
| PowerWise |
Yes |
| Synchronous Rectification |
Yes |
Typical Performance
click for larger image
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WEBENCH Live Simulation!
Also Recommended
| LM20123▲ | 3A, 1.5 MHz Switching Frequency |
| LM20124▲ | 4A, 1 MHz Switching Frequency |
| LM20133▲ | 3A, Input Synchronization (500 KHz - 1.5 MHz) |
| LM20134▲ | 4A, Input Synchronization (500 KHz - 1.5 MHz) |
| LM20143▲ | 3A, Adjustable Frequency (500 KHz - 1.5 MHz) |
| LM20144▲ | 4A, Adjustable Frequency (500 KHz - 1.5 MHz) |
| LM20145▲ | 5A, Adjustable Frequency (250 KHz - 750 KHz) |
| LM20154▲ | 4A, SYNCOUT |
| LM20242▲ | 36V, 2A Adjustable Frequency (250 KHz - 750 KHz) |
Additional Resources
Design Tools
Application Notes
Block Diagram
click for larger image
Block Diagram
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Datasheet
RoHS Compliance Information
| Size in Kbytes | Date |
 |
| LM20125 5A, 500kHz PowerWise ® Synchronous Buck Regulator |
583
Kbytes |
16-Jan-08 |
Download |
LM20125 5A, 500kHz PowerWise ® Synchronous Buck Regulator (Japanese)
 |
838 Kbytes |
|
 |
Package Availability, Models, Samples & Pricing
General Description
The LM20125 is a full featured 500 kHz synchronous buck regulator capable of delivering up to 5A of continuous output current.
The current mode control loop can be compensated to be stable with virtually any type of output capacitor. For most cases,
compensating the device only requires two external components, providing maximum flexibility and ease of use. The device is
optimized to work over the input voltage range of 2.95V to 5.5V making it suited for a wide variety of low voltage systems.
The device features internal over voltage protection (OVP) and over current protection (OCP) circuits for increased system
reliability. A precision enable pin and integrated UVLO allows the turn-on of the device to be tightly controlled and sequenced.
Start-up inrush currents are limited by both an internally fixed and externally adjustable Soft-Start circuit. Fault detection
and supply sequencing is possible with the integrated power good circuit.
The LM20125 is designed to work well in multi-rail power supply architectures. The output voltage of the device can be configured
to track a higher voltage rail using the SS/TRK pin. If the output of the LM20125 is pre-biased at startup it will not sink
current to pull the output low until the internal soft-start ramp exceeds the voltage at the feedback pin.
The LM20125 is offered in a 16-pin eTSSOP package with an exposed pad that can be soldered to the PCB, eliminating the need
for bulky heatsinks.
Reliability Metrics
| Part Number |
Process |
EFR Reject |
EFR Sample Size |
PPM |
LTA Rejects |
LTA Device Hours |
FITS |
MTTF (Hours) |
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LM20125MH | CMOS7 | 0 | 18406 | 0 | 0 | 1089000 | 4 | 309006723
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LM20125MHE | CMOS7 | 0 | 18406 | 0 | 0 | 1089000 | 4 | 309006723
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LM20125MHX | CMOS7 | 0 | 18406 | 0 | 0 | 1089000 | 4 | 309006723
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Note: The Early Failure Rates (EFR) were calculated as point estimate PPM based on rejects and sample size for EFR.
The Long Term Failure Rates were calculated
at 60% confidence using the Arrhenius equation at 0.7eV activation energy and derating the assumed stress
temperature of 150°C to an application temperature of 55°C.
For more information on Reliability Metrics, please click here.
Design Tools
| Title | Size in Kbytes |
Date |
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| Current Mode Modeling - Reference Guide |
1372 Kbytes |
1-Aug-2007 |
View Online |
Download |
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| Understanding and Applying Current-Mode Control Theory |
427 Kbytes |
8-Jan-2008 |
View Online |
Download |
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| Download LM20125 Design Spreadsheet |
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View |
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| Article - Reducing Buck Converter Input Capacitance through Multi-Phasing and Clock Synchronization |
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View |
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Application Notes
| Title | Size in Kbytes |
Date |
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| AN-1687: Application Note 1687 LM20125 Evaluation Board |
816
Kbytes |
30-Oct-07 |
Download |
AN-1687 (Japanese): Application Note 1687 LM20125 Evaluation Board
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991 Kbytes |
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| AN-1752: Application Note 1752 5A LM20k Reference Designs |
174
Kbytes |
13-Nov-07 |
Download |
More Application Notes
| Title | Size in Kbytes |
Date |
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| AN-1747: Application Note 1747 3A LM20k Reference Designs |
227
Kbytes |
9-Nov-07 |
Download |
| AN-1751: Application Note 1751 4A LM20k Reference Designs |
206
Kbytes |
9-Nov-07 |
Download |
| AN-1654: Application Note 1654 LM20124 Evaluation Board |
804
Kbytes |
30-Oct-07 |
Download |
AN-1654 (Japanese): Application Note 1654 LM20124 Evaluation Board
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509 Kbytes |
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| AN-1686: Application Note 1686 LM20123 Evaluation Board |
405
Kbytes |
30-Oct-07 |
Download |
AN-1686 (Japanese): Application Note 1686 LM20123 Evaluation Board
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827 Kbytes |
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[Information as of 7-Nov-2009]
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