Datasheet

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OUT

BST

FB1

FB2

VCC

N/C

VIN

BST

GND

N/C

PGND

VCC

RON

N/C

TST

LM3100

OUT

N/C

LM3100

www.ti.com

SNVS421G –JANUARY 2006–REVISED APRIL 2013

LM3100 SIMPLE SWITCHER® Synchronous 1MHz 1.5A Step-Down Voltage Regulator

Check for Samples: LM3100

FEATURES

DESCRIPTION

The LM3100 Synchronously Rectified Buck Converter

• Input Voltage Range 4.5V - 36V

features all functions needed to implement a highly

• 1.5A Output Current

efficient, cost effective buck regulator capable of

• 0.8V, ±1.5% Reference

supplying 1.5A to loads with voltages as low as 0.8V.

Dual 40V N-Channel synchronous MOSFET switches

• Integrated 40V, Dual N-Channel Buck

allow for low external component thus reducing

Synchronous Switches

complexity and minimizing board space. The LM3100

• Low Component Count and Small Solution

is designed to work exceptionally well with ceramic

Size

and other very low ESR output capacitors. The

• No Loop Compensation Required

Constant ON-Time (COT) regulation scheme requires

no loop compensation, results in fast load transient

• Ultra-Fast Transient Response

response, and simplifies circuit implementation.

• Stable with Ceramic and Other Low ESR

Through the use of a unique design the regulator

Capacitors

does not rely on output capacitor ESR for stability, as

• Programmable Switching Frequency up to do most other COT regulators. The operating

frequency remains nearly constant with line and load

1MHz

variations due to the inverse relationship between the

• Max. Duty Cycle Limited During Start-Up

input voltage and the on-time. The oprating frequency

• Valley Current Limit

can be externally programmed up to 1MHz.

Protection features include V

under-voltage

• Precision Internal Reference for Adjustable

lockout, thermal shutdown and gate drive under-

Output Voltage Down to 0.8V

voltage lockout. The part is available in a thermally

• Thermal Shutdown

enhanced HTSSOP-20 package

• Thermally Enhanced HTSSOP-20 Package

Typical Application

TYPICAL APPLICATIONS

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

Systems

• Embedded Systems

• Industrial Controls

• Automotive Telematics and Body Electronics

• Point of Load Regulators

• Storage Systems

• 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 (21 pages)

PAGE 1
LM3100 www.ti.com SNVS421G – JANUARY 2006 – REVISED APRIL 2013 LM3100 SIMPLE SWITCHER® Synchronous 1MHz 1.5A Step-Down Voltage Regulator Check for Samples: LM3100 FEATURES DESCRIPTION • • • • The LM3100 Synchronously Rectified Buck Converter features all functions needed to implement a highly efficient, cost effective buck regulator capable of supplying 1.5A to loads with voltages as low as 0.8V.
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LM3100 SNVS421G – JANUARY 2006 – REVISED APRIL 2013 www.ti.com Connection Diagram 1 N/C 2 SW 3 SW 4 VIN 5 VIN 6 BST 7 GND 8 SS 9 N/C 10 N/C LM3100 EP 20 19 18 17 16 15 14 13 12 11 N/C N/C PGND PGND VCC RON EN FB N/C TST Figure 1. 20-lead Plastic HTSSOP (PWP0020A) PIN DESCRIPTIONS Pin Name Description 1,9,10,12,19,20 N/C No Connection Application Information These pins must be left unconnected. 2, 3 SW Switching Node Internally connected to the buck switch source. Connect to output inductor.
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LM3100 www.ti.com SNVS421G – JANUARY 2006 – REVISED APRIL 2013 Absolute Maximum Ratings (1) (2) VIN, RON to GND -0.3V to 40V SW to GND -0.3V to 40V SW to GND (Transient) -2V (< 100ns) VIN to SW -0.3V to 40V BST to SW -0.3V to 7V All Other Inputs to GND ESD Rating (3) -0.3V to 7V Human Body Model Storage Temperature Range ±2kV -65°C to +150°C Junction Temperature (TJ) (1) (2) (3) 150°C Absolute Maximum Ratings are limits beyond which damage to the device may occur.
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LM3100 SNVS421G – JANUARY 2006 – 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 ensured 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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LM3100 www.ti.com SNVS421G – JANUARY 2006 – REVISED APRIL 2013 Typical Performance Characteristics All curves taken at VIN = 18V with configuration in typical application circuit for VOUT = 3.3V shown in this datasheet. TA = 25°C, unless otherwise specified.
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LM3100 SNVS421G – JANUARY 2006 – REVISED APRIL 2013 www.ti.com Typical Performance Characteristics (continued) All curves taken at VIN = 18V with configuration in typical application circuit for VOUT = 3.3V shown in this datasheet. TA = 25°C, unless otherwise specified. Efficiency vs Load Current (VOUT = 3.3V) RDS(ON) vs Temperature 100 0.4 VIN = 8V 90 EFFICIENCY (%) RDS(ON) (:) 0.3 Main MOSFET 0.2 0.1 Syn. MOSFET 0 -50 80 VIN = 18V VIN = 36V 70 60 50 40 -20 10 40 70 100 0 130 0.3 0.
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LM3100 www.ti.com SNVS421G – JANUARY 2006 – REVISED APRIL 2013 Typical Performance Characteristics (continued) All curves taken at VIN = 18V with configuration in typical application circuit for VOUT = 3.3V shown in this datasheet. TA = 25°C, unless otherwise specified. Enable Transient (VOUT = 3.3V, 1.5A Loaded) Shutdown Transient (VOUT = 3.3V, 1.5A Loaded) Figure 14. Figure 15. Continuous Mode Operation (VOUT = 3.3V, 1.5A Loaded) Discontinuous Mode Operation (VOUT = 3.3V, 0.15A Loaded) Figure 16.
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LM3100 SNVS421G – JANUARY 2006 – REVISED APRIL 2013 www.ti.com SIMPLIFIED FUNCTIONAL BLOCK DIAGRAM LM 3100 EN 11 EN VIN AVDD 6V LDO 4,5 VIN 1.26V 0.92V 0.8V VREF VDD VCC 16 VCC CIN THERMAL SHUTDOWN UVLO C VCC 1.26V GND R ON ON TIMER 15 RON Ron START COMPLETE BST 6 260 ns OFF TIMER START VIN Gate Drive SD UVLO COMPLETE CBST VDD 8 PA DrvH 8 SS LOGIC DrvL CSS REGULATION COMPARATOR 0.
PAGE 9
LM3100 www.ti.com SNVS421G – JANUARY 2006 – REVISED APRIL 2013 In continuous conduction mode (CCM), current always flows through the inductor and never reaches zero during the off-time. In this mode, the operating frequency remains relatively constant with load and line variations. The CCM operating frequency can be calculated approximately as follows: FSW = VOUT 1.3 x 10-10 x RON (2) The output voltage is set by two external resistors (RFB1, RFB2).
PAGE 10
LM3100 SNVS421G – JANUARY 2006 – REVISED APRIL 2013 www.ti.com VIN VIN LM3100 EN STOP RUN Figure 20. Shutdown Implementation Current Limit Current limit detection occurs during the off-time by monitoring the re-circulating current through the low-side synchronous switch. Referring to Functional Block Diagram, when the buck switch is turned off, inductor current flows through the load, into PGND, and through the internal low-side synchronous switch. If that current exceeds 1.
PAGE 11
LM3100 www.ti.com SNVS421G – JANUARY 2006 – REVISED APRIL 2013 Soft-Start The soft-start feature allows the converter to gradually reach a steady state operating point, thereby reducing start-up stresses and current surges. Upon turn-on, after VCC reaches the under-voltage threshold, an internal 8µA current source charges up the external capacitor at the SS pin. The ramping voltage at SS (and the noninverting input of the regulation comparator) ramps up the output voltage in a controlled manner.
PAGE 12
LM3100 SNVS421G – JANUARY 2006 – REVISED APRIL 2013 www.ti.com IOR(MAX1) = 2 x IO(min) (9) or IOR(MAX2) = 2 x (1.9A - IO(max)) (10) The lesser of the two ripple amplitudes calculated above is then used in the following equation: L= VOUT x (VIN - VOUT) IOR x FS x VIN (11) where VIN is the maximum input voltage and Fs is determined from Equation 1. This provides a value for L. The next larger standard value should be used. L should be rated for the IPK current level shown in Figure 21. Figure 23.
PAGE 13
LM3100 www.ti.com SNVS421G – JANUARY 2006 – REVISED APRIL 2013 At maximum load current, when the buck switch turns on, the current into VIN suddenly increases to the lower peak of the inductor’s ripple current, ramps up to the peak value, then drop to zero at turn-off. The average current during the on-time is the load current. For a worst case calculation, CIN must supply this average load current during the maximum on-time.
PAGE 14
LM3100 SNVS421G – JANUARY 2006 – REVISED APRIL 2013 www.ti.com CFB CO3 10 nF 47 nF L 15 mH CBST 33 nF VIN = 8V – 36V CIN1, CIN2 2 x 10 mF CIN3 0.1 mF CSS 10 nF N/C SW SW VIN VIN BST GND SS N/C N/C LM3100 RON 100k REN 200k VOUT = 3.3V IOUT = 1.5A RFB1 6.8k RFB2 2.2k N/C N/C PGND PGND VCC RON EN FB N/C TST CO1, CO2 2 x 22 mF CVCC 680 nF Figure 25. Typical Application Schematic for VOUT = 3.3V CBST 33 nF VIN = 4.5V – 24V CIN1, CIN2 2 x 10 mF CIN3 0.
PAGE 15
LM3100 www.ti.com SNVS421G – JANUARY 2006 – REVISED APRIL 2013 REVISION HISTORY Changes from Revision F (April 2013) to Revision G • Page Changed layout of National Data Sheet to TI format ..........................................................................................................
PAGE 16
PACKAGE OPTION ADDENDUM www.ti.
PAGE 17
PACKAGE OPTION ADDENDUM www.ti.com 1-Nov-2013 Important Information and Disclaimer:The information provided on this page represents TI's knowledge and belief as of the date that it is provided. TI bases its knowledge and belief on information provided by third parties, and makes no representation or warranty as to the accuracy of such information. Efforts are underway to better integrate information from third parties.
PAGE 18
PACKAGE MATERIALS INFORMATION www.ti.com 8-Apr-2013 TAPE AND REEL INFORMATION *All dimensions are nominal Device Package Package Pins Type Drawing SPQ Reel Reel A0 Diameter Width (mm) (mm) W1 (mm) LM3100MHX HTSSOP PWP 20 2500 330.0 16.4 LM3100MHX/NOPB HTSSOP PWP 20 2500 330.0 16.4 Pack Materials-Page 1 B0 (mm) K0 (mm) P1 (mm) W Pin1 (mm) Quadrant 6.95 7.1 1.6 8.0 16.0 Q1 6.95 7.1 1.6 8.0 16.
PAGE 19
PACKAGE MATERIALS INFORMATION www.ti.com 8-Apr-2013 *All dimensions are nominal Device Package Type Package Drawing Pins SPQ Length (mm) Width (mm) Height (mm) LM3100MHX HTSSOP PWP 20 2500 367.0 367.0 35.0 LM3100MHX/NOPB HTSSOP PWP 20 2500 367.0 367.0 35.
PAGE 20
MECHANICAL DATA PWP0020A MXA20A (Rev C) www.ti.
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