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LM3103

www.ti.com

SNVS523F –SEPTEMBER 2007–REVISED APRIL 2013

LM3103 SIMPLE SWITCHER® Synchronous 1MHz 0.75A

Step-Down Voltage Regulator

Check for Samples: LM3103

FEATURES

KEY SPECIFICATIONS

• Low Component Count and Small Solution

• Input Voltage Range 4.5 V to 42 V

Size

• 0.75 A Output Current

• Stable with Ceramic and Other Low ESR

• 0.6V, ±2% Reference

Capacitors

• Integrated Dual N-Channel Main and

• No Loop Compensation Required

Synchronous MOSFETs

• High Efficiency at a Light Load by DCM

• Thermally Enhanced HTSSOP-16 Package

Operation

• Pre-bias Startup DESCRIPTION

The LM3103 Synchronously Rectified Buck Converter

• Ultra-Fast Transient Response

features all required functions to implement a highly

• Programmable Soft-Start

efficient and cost effective buck regulator. It is

• Programmable Switching Frequency up to 1

capable of supplying 0.75A to loads with an output

MHz

voltage as low as 0.6V. Dual N-Channel synchronous

MOSFET switches allow a low component count, thus

• Valley Current Limit

reducing complexity and minimizing board size.

• Thermal Shutdown

Different from most other COT regulators, the

• Output Over-Voltage Protection

LM3103 does not rely on output capacitor ESR for

• Precision Internal Reference for an Adjustable

stability, and is designed to work exceptionally well

Output Voltage Down to 0.6V

with ceramic and other very low ESR output

capacitors. It requires no loop compensation, results

TYPICAL APPLICATIONS

in a fast load transient response and simple circuit

implementation. The operating frequency remains

• 5VDC, 12VDC, 24VDC, 12VAC, and 24VAC

nearly constant with line variations due to the inverse

Systems

relationship between the input voltage and the on-

• Embedded Systems

time. The operating frequency can be externally

• Industrial Control

programmed up to 1 MHz. Protection features include

under-voltage lock-out, output over-voltage

• Automotive Telematics and Body Electronics

protection, thermal shutdown, and gate drive under-

• Point of Load Regulators

voltage lock-out. The LM3103 is available in the

• Storage Systems

thermally enhanced HTSSOP-16 package.

• Broadband Infrastructure

• Direct Conversion from 2/3/4 Cell Lithium

Batteries Systems

Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of

Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.

2All trademarks are the property of their respective owners.

PRODUCTION DATA information is current as of publication date.

Products conform to specifications per the terms of the Texas

Instruments standard warranty. Production processing does not

necessarily include testing of all parameters.

Summary of content (20 pages)

PAGE 1
LM3103 www.ti.com SNVS523F – SEPTEMBER 2007 – REVISED APRIL 2013 LM3103 SIMPLE SWITCHER® Synchronous 1MHz 0.
PAGE 2
LM3103 SNVS523F – SEPTEMBER 2007 – REVISED APRIL 2013 www.ti.com Typical Application Connection Diagram Figure 1. 16-Lead Plastic HTSSOP Package Number PWP0016A PIN DESCRIPTIONS Pin Name Description 1, 2 VIN Input supply voltage 3, 4 SW Switch Node 5 BST Connection for bootstrap capacitor 6 AGND Analog Ground 7 SS Soft-start Application Information Supply pin to the device. Nominal input range is 4.5V to 42V.
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LM3103 www.ti.com SNVS523F – SEPTEMBER 2007 – REVISED APRIL 2013 Absolute Maximum Ratings (1) (2) VIN, RON to AGND -0.3V to 43.5V SW to AGND -0.3V to 43.5V SW to AGND (Transient) -2V (< 100ns) VIN to SW -0.3V to 43.5V BST to SW -0.3V to 7V VCC to AGND -0.3V to 7V FB to AGND -0.3V to 5V All Other Inputs to AGND ESD Rating (3) -0.
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LM3103 SNVS523F – SEPTEMBER 2007 – REVISED APRIL 2013 www.ti.com Electrical Characteristics Specifications with standard type are for TJ = 25°C only; limits in boldface type apply over the full Operating Junction Temperature (TJ) range. Minimum and Maximum limits are specified through test, design, or statistical correlation. Typical values represent the most likely parametric norm at TJ = 25°C, and are provided for reference purposes only.
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LM3103 www.ti.com SNVS523F – SEPTEMBER 2007 – REVISED APRIL 2013 Typical Performance Characteristics All curves are taken at VIN = 18V with the configuration in the typical application circuit for VOUT = 3.3V shown in this datasheet. TA = 25°C, unless otherwise specified. Quiescent Current, IIN vs VIN VCC vs ICC Figure 2. Figure 3. VCC vs VIN ton vs VIN Figure 4. Figure 5. Switching Frequency, fSW vs VIN VFB vs Temperature Figure 6. Figure 7.
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LM3103 SNVS523F – SEPTEMBER 2007 – REVISED APRIL 2013 www.ti.com Typical Performance Characteristics (continued) All curves are taken at VIN = 18V with the configuration in the typical application circuit for VOUT = 3.3V shown in this datasheet. TA = 25°C, unless otherwise specified. 6 RDS(on) vs Temperature Efficiency vs Load Current (VOUT = 3.3V) Figure 8. Figure 9. VOUT Regulation vs Load Current (VOUT = 3.3V) Efficiency vs Load Current (VOUT = 0.6V) Figure 10. Figure 11.
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LM3103 www.ti.com SNVS523F – SEPTEMBER 2007 – REVISED APRIL 2013 Typical Performance Characteristics (continued) All curves are taken at VIN = 18V with the configuration in the typical application circuit for VOUT = 3.3V shown in this datasheet. TA = 25°C, unless otherwise specified. Enable Transient (VOUT = 3.3V, 0.75A Loaded) Shutdown Transient (VOUT = 3.3V, 0.75A Loaded) Figure 14. Figure 15. Continuous Mode Operation (VOUT = 3.3V, 2.5A Loaded) Discontinuous Mode Operation (VOUT = 3.3V, 0.
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LM3103 SNVS523F – SEPTEMBER 2007 – REVISED APRIL 2013 www.ti.com SIMPLIFIED FUNCTIONAL BLOCK DIAGRAM Functional Description The LM3103 Step Down Switching Regulator features all required functions to implement a cost effective, efficient buck power converter which is capable of supplying 0.75A to loads. It contains dual N-Channel main and synchronous MOSFETs.
PAGE 9
LM3103 www.ti.com SNVS523F – SEPTEMBER 2007 – REVISED APRIL 2013 The regulator will operate in the discontinuous conduction mode (DCM) at a light load, and the continuous conduction mode (CCM) with a heavy load. In the DCM, the current through the inductor starts at zero and ramps up to a peak during the on-time, and then ramps back to zero before the end of the off-time. It remains zero and the load current is supplied entirely by the output capacitor.
PAGE 10
LM3103 SNVS523F – SEPTEMBER 2007 – REVISED APRIL 2013 www.ti.com The inverse relationship of ton and VIN gives a nearly constant frequency as VIN is varied. RON should be selected such that the on-time at maximum VIN is greater than 100 ns. The on-timer has a limiter to ensure a minimum of 100 ns for ton.
PAGE 11
LM3103 www.ti.com SNVS523F – SEPTEMBER 2007 – REVISED APRIL 2013 N-Channel MOSFET and Driver The LM3103 integrates an N-Channel main MOSFET and an associated floating high voltage main MOSFET gate driver. The gate drive circuit works in conjunction with an external bootstrap capacitor CBST and an internal high voltage diode. CBST connected between the BST and SW pins powers the main MOSFET gate driver during the main MOSFET on-time.
PAGE 12
LM3103 SNVS523F – SEPTEMBER 2007 – REVISED APRIL 2013 www.ti.com If RON calculated from Equation 2 is smaller than the minimum value determined in Equation 8, a lower frequency should be selected to re-calculate RON by Equation 2. Alternatively, VIN(MAX) can also be limited in order to keep the frequency unchanged. The relationship of VIN(MAX) and RON is shown in Figure 23. On the other hand, the minimum off-time of 240 ns can limit the maximum duty ratio. This may be significant at low VIN.
PAGE 13
LM3103 www.ti.com SNVS523F – SEPTEMBER 2007 – REVISED APRIL 2013 Figure 25. Inductor selection for VOUT = 0.6V Figure 24 and Figure 25 show curves on inductor selection for various VOUT and RON. According to Equation 8, VIN is limited for small RON. Some curves are therefore limited as shown in the figures. CVCC: The capacitor on the VCC output provides not only noise filtering and stability, but also prevents false triggering of the VCC UVLO at the main MOSFET on/off transitions.
PAGE 14
LM3103 SNVS523F – SEPTEMBER 2007 – REVISED APRIL 2013 www.ti.com PC BOARD LAYOUT The LM3103 regulation, over-voltage, and current limit comparators are very fast so they will respond to short duration noise pulses. Layout is therefore critical for optimum performance. It must be as neat and compact as possible, and all external components must be as close to their associated pins of the LM3103 as possible. Refer to the Simplified Functional Block Diagram.
PAGE 15
LM3103 www.ti.com SNVS523F – SEPTEMBER 2007 – REVISED APRIL 2013 REVISION HISTORY Changes from Revision E (April 2013) to Revision F • Page Changed layout of National Data Sheet to TI format ..........................................................................................................
PAGE 16
PACKAGE OPTION ADDENDUM www.ti.
PAGE 17
PACKAGE MATERIALS INFORMATION www.ti.com 11-Feb-2014 TAPE AND REEL INFORMATION *All dimensions are nominal Device LM3103MHX/NOPB Package Package Pins Type Drawing SPQ HTSSOP 2500 PWP 16 Reel Reel A0 Diameter Width (mm) (mm) W1 (mm) 330.0 12.4 Pack Materials-Page 1 6.95 B0 (mm) K0 (mm) P1 (mm) 8.3 1.6 8.0 W Pin1 (mm) Quadrant 12.
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PACKAGE MATERIALS INFORMATION www.ti.com 11-Feb-2014 *All dimensions are nominal Device Package Type Package Drawing Pins SPQ Length (mm) Width (mm) Height (mm) LM3103MHX/NOPB HTSSOP PWP 16 2500 367.0 367.0 35.
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MECHANICAL DATA PWP0016A MXA16A (Rev A) www.ti.
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