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LM2670

www.ti.com

SNVS036J –APRIL 2000–REVISED APRIL 2013

LM2670 SIMPLE SWITCHER

High Efficiency 3A Step-Down Voltage Regulator with Sync

Check for Samples: LM2670

FEATURES

DESCRIPTION

The LM2670 series of regulators are monolithic

• Efficiency Up to 94%

integrated circuits which provide all of the active

• Simple and Easy to Design with (Using Off-

functions for a step-down (buck) switching regulator

The-Shelf External Components)

capable of driving up to 3A loads with excellent line

• 150 mΩ DMOS Output Switch

and load regulation characteristics. High efficiency

(>90%) is obtained through the use of a low ON-

• 3.3V, 5V and 12V Fixed Output and Adjustable

resistance DMOS power switch. The series consists

(1.2V to 37V) Versions

of fixed output voltages of 3.3V, 5V and 12V output

• 50μA Standby Current When Switched OFF

version.

• ±2% Maximum Output Tolerance Over Full

The SIMPLE SWITCHER concept provides for a

Line and Load Conditions

complete design using a minimum number of external

• Wide Input Voltage Range: 8V to 40V

components. The switching clock frequency can be

provided by an internal fixed frequency oscillator

• External Sync Clock Capability (280kHz to

(260KHz) or from an externally provided clock in the

400kHz)

range of 280 kHz to 400 kHz which allows the use of

• 260 kHz Fixed Frequency Internal Oscillator

physically smaller sized components. A family of

• −40 to +125°C Operating Junction Temperature

standard inductors for use with the LM2670 are

Range

available from several manufacturers to greatly

simplify the design process. The external Sync clock

provides direct and precise control of the output ripple

APPLICATIONS

frequency for consistent filtering or frequency

• Simple to Design, High Efficiency (>90%) Step-

spectrum positioning.

Down Switching Regulators

The LM2670 series also has built in thermal

• Efficient System Pre-Regulator for Linear

shutdown, current limiting and an ON/OFF control

Voltage Regulators

input that can power down the regulator to a low

• Battery Chargers

50μA quiescent current standby condition. The output

voltage is ensured to a ±2% tolerance.

• Communications and Radio Equipment

Regulator with Synchronized Clock Frequency

Typical Application

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.

2SIMPLE SWITCHER, Switchers Made Simple are registered trademarks of Texas Instruments.

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 (36 pages)

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LM2670 www.ti.com SNVS036J – APRIL 2000 – REVISED APRIL 2013 LM2670 SIMPLE SWITCHER® High Efficiency 3A Step-Down Voltage Regulator with Sync Check for Samples: LM2670 FEATURES DESCRIPTION • • The LM2670 series of regulators are monolithic integrated circuits which provide all of the active functions for a step-down (buck) switching regulator capable of driving up to 3A loads with excellent line and load regulation characteristics.
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LM2670 SNVS036J – APRIL 2000 – REVISED APRIL 2013 www.ti.com Connection Diagram Figure 1. DDPAK Package (Top View) See Package Number KTW Figure 2. TO-220 Package (Top View) See Package Number NDZ * 1 14 VSW VIN 2 13 VSW VIN 3 12 VSW CB 4 11 * * 5 10 * SYNC 6 9 GND FB 7 8 ON/OFF DAP** * No Connections ** Connect to Pin 9 on PCB Figure 3. VSON-14 Package (Top View) See Package Number NHM These devices have limited built-in ESD protection.
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LM2670 www.ti.com SNVS036J – APRIL 2000 – REVISED APRIL 2013 Operating Ratings Supply Voltage 8V to 40V −40°C to 125°C Junction Temperature Range (TJ) Electrical Characteristics LM2670-3.3 Limits appearing in bold type face apply over the entire junction temperature range of operation, −40°C to 125°C. Specifications appearing in normal type apply for TA = TJ = 25°C. Sync pin open circuited. Symbol Parameter Conditions Typ (1) Min (2) Max (2) Units 3.234/3.201 3.366/3.
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LM2670 SNVS036J – APRIL 2000 – REVISED APRIL 2013 www.ti.com All Output Voltage Versions Electrical Characteristics Limits appearing in bold type face apply over the entire junction temperature range of operation, −40°C to 125°C. Specifications appearing in normal type apply for TA = TJ = 25°C. Unless otherwise specified VIN=12V for the 3.3V, 5V and Adjustable versions and VIN=24V for the 12V version, Sync pin open circuited.. Symbol Parameter Conditions Typ Min Max Units 4.
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LM2670 www.ti.com SNVS036J – APRIL 2000 – REVISED APRIL 2013 Typical Performance Characteristics Normalized Output Voltage Line Regulation Figure 4. Figure 5. Efficiency vs Input Voltage Efficiency vs ILOAD Figure 6. Figure 7. Switch Current Limit Operating Quiescent Current Figure 8. Figure 9.
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LM2670 SNVS036J – APRIL 2000 – REVISED APRIL 2013 www.ti.com Typical Performance Characteristics (continued) Standby Quiescent Current ON/OFF Threshold Voltage Figure 10. Figure 11. ON/OFF Pin Current (Sourcing) Switching Frequency Figure 12. Figure 13. Feedback Pin Bias Current Continuous Mode Switching Waveforms VIN = 20V, VOUT = 5V, ILOAD = 3A L = 33 μH, COUT = 200 μF, COUTESR = 26 mΩ Figure 14.
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LM2670 www.ti.com SNVS036J – APRIL 2000 – REVISED APRIL 2013 Typical Performance Characteristics (continued) Discontinuous Mode Switching Waveforms VIN = 20V, VOUT = 5V, ILOAD = 500 mA L = 10 μH, COUT = 400 μF, COUTESR = 13 mΩ A: VSW Pin Voltage, 10 V/div B: Inductor Current, 1 A/div C: Output Ripple Voltage, 20 mV/div AC-Coupled Figure 16.
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LM2670 SNVS036J – APRIL 2000 – REVISED APRIL 2013 www.ti.
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LM2670 www.ti.com SNVS036J – APRIL 2000 – REVISED APRIL 2013 APPLICATION HINTS The LM2670 provides all of the active functions required for a step-down (buck) switching regulator. The internal power switch is a DMOS power MOSFET to provide power supply designs with high current capability, up to 3A, and highly efficient operation. The LM2670 is part of the SIMPLE SWITCHER family of power converters.
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LM2670 SNVS036J – APRIL 2000 – REVISED APRIL 2013 www.ti.com FEEDBACK This is the input to a two-stage high gain amplifier, which drives the PWM controller. It is necessary to connect pin 6 to the actual output of the power supply to set the dc output voltage. For the fixed output devices (3.3V, 5V and 12V outputs), a direct wire connection to the output is all that is required as internal gain setting resistors are provided inside the LM2670.
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LM2670 www.ti.com SNVS036J – APRIL 2000 – REVISED APRIL 2013 DESIGN CONSIDERATIONS Figure 19. Basic Circuit for Fixed Output Voltage Applications Figure 20. Basic Circuit for Adjustable Output Voltage Applications Power supply design using the LM2670 is greatly simplified by using recommended external components.
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LM2670 SNVS036J – APRIL 2000 – REVISED APRIL 2013 www.ti.com INDUCTOR The inductor is the key component in a switching regulator. For efficiency the inductor stores energy during the switch ON time and then transfers energy to the load while the switch is OFF. Nomographs are used to select the inductance value required for a given set of operating conditions. The nomographs assume that the circuit is operating in continuous mode (the current flowing through the inductor never falls to zero).
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LM2670 www.ti.com SNVS036J – APRIL 2000 – REVISED APRIL 2013 INPUT CAPACITOR Fast changing currents in high current switching regulators place a significant dynamic load on the unregulated power source. An input capacitor helps to provide additional current to the power supply as well as smooth out input voltage variations. Like the output capacitor, the key specifications for the input capacitor are RMS current rating and working voltage.
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LM2670 SNVS036J – APRIL 2000 – REVISED APRIL 2013 www.ti.com If the output capacitance is sufficiently ‘large’, it may be possible that as the output tries to recover, the output capacitor charging current is large enough to repeatedly re-trigger the current limit circuit before the output has fully settled.
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LM2670 www.ti.com SNVS036J – APRIL 2000 – REVISED APRIL 2013 Step 2: Select an LM2670T-3.3. The output voltage will have a tolerance of ±2% at room temperature and ±3% over the full operating temperature range. Step 3: Use the nomograph for the 3.3V device, Figure 21. The intersection of the 16V horizontal line (Vin max) and the 2.5A vertical line (Iload max) indicates that L33, a 22μH inductor, is required.
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LM2670 SNVS036J – APRIL 2000 – REVISED APRIL 2013 www.ti.com Step 2: Select an LM2670S-ADJ. To set the output voltage to 14.9V two resistors need to be chosen (R1 and R2 in Figure 20). For the adjustable device the output voltage is set by the following relationship: where • VFB is the feedback voltage of typically 1.21V (1) A recommended value to use for R1 is 1K. In this example then R2 is determined to be: (2) R2 = 11.23KΩ The closest standard 1% tolerance value to use is 11.
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LM2670 www.ti.com SNVS036J – APRIL 2000 – REVISED APRIL 2013 Step 6: From Table 10 a 3A Schottky diode must be selected. For surface mount diodes with a margin of safety on the voltage rating one of five diodes can be used: SK34 30BQ040 30WQ04F MBRS340 MBRD340 Step 7: A 0.01μF capacitor will be used for Cboost. VSON PACKAGE DEVICES The LM2670 is offered in the 14 lead VSON surface mount package to allow for a significantly decreased footprint with equivalent power dissipation compared to the DDPAK.
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LM2670 SNVS036J – APRIL 2000 – REVISED APRIL 2013 www.ti.com Figure 23. LM2670-12 Figure 24.
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LM2670 www.ti.com SNVS036J – APRIL 2000 – REVISED APRIL 2013 Table 1. Inductor Manufacturer Part Numbers Inductor Reference Number Inductance (µH) Current (A) L23 33 L24 22 L25 Renco Pulse Engineering Through Hole Surface Mount Coilcraft Through Hole Surface Mount 1.35 RL-5471-7 RL1500-33 PE-53823 PE-53823S DO3316-333 1.65 RL-1283-22-43 RL1500-22 PE-53824 PE-53824S DO3316-223 15 2.00 RL-1283-15-43 RL1500-15 PE-53825 PE-53825S DO3316-153 L29 100 1.
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LM2670 SNVS036J – APRIL 2000 – REVISED APRIL 2013 www.ti.com Capacitor Selection Guides Table 3. Input and Output Capacitor Codes—Surface Mount Capacitor Reference Code 20 Surface Mount AVX TPS Series Sprague 594D Series Kemet T495 Series C (µF) WV (V) Irms (A) C (µF) WV (V) Irms (A) C (µF) WV (V) Irms (A) C1 330 6.3 1.15 120 6.3 1.1 100 6.3 0.82 C2 100 10 1.1 220 6.3 1.4 220 6.3 1.1 C3 220 10 1.15 68 10 1.05 330 6.3 1.1 C4 47 16 0.89 150 10 1.
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LM2670 www.ti.com SNVS036J – APRIL 2000 – REVISED APRIL 2013 Table 4. Input and Output Capacitor Codes—Through Hole Through Hole Capacitor Reference Code Sanyo OS-CON SA Series C (µF) WV (V) C1 47 C2 150 C3 C4 C5 Sanyo MV-GX Series Nichicon PL Series Irms (A) C (µF) WV (V) Irms (A) C (µF) WV (V) 6.3 1 1000 6.3 0.8 680 10 6.3 1.95 270 16 0.6 820 10 330 6.3 2.45 470 16 0.75 1000 10 100 10 1.87 560 16 0.95 1200 10 220 10 2.36 820 16 1.
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LM2670 SNVS036J – APRIL 2000 – REVISED APRIL 2013 www.ti.com Table 6. Output Capacitors for Fixed Output Voltage Application—Surface Mount (1) (2) Surface Mount Output Voltage (V) Inductance (µH) 3.3 5 12 (1) (2) AVX TPS Series Sprague 594D Series Kemet T495 Series No. C Code No. C Code No.
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LM2670 www.ti.com SNVS036J – APRIL 2000 – REVISED APRIL 2013 Table 8. Input Capacitors for Fixed Output Voltage Application—Surface Mount (1) (2) (3) Surface Mount Output Voltage (V) Inductance (µH) 3.3 5 12 (1) (2) (3) (4) AVX TPS Series Sprague 594D Series Kemet T495 Series No. C Code No. C Code No.
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LM2670 SNVS036J – APRIL 2000 – REVISED APRIL 2013 www.ti.com Table 10. Schottky Diode Selection Table Reverse Voltage (V) Surface Mount 3A 20V SK32 30V SK33 Through Hole 5A or More 3A 5A or More 1N5820 SR302 MBRD835L 30WQ03F 40V 1N5821 31DQ03 SK34 MBRB1545CT 1N5822 30BQ040 6TQ045S MBR340 MBR745 30WQ04F 31DQ04 80SQ045 MBRS340 SR403 6TQ045 MBRD340 50V or More SK35 MBR350 30WQ05F 31DQ05 SR305 Table 11.
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LM2670 www.ti.com SNVS036J – APRIL 2000 – REVISED APRIL 2013 Table 12. Output Capacitors for Adjustable Output Voltage Applications—Surface Mount (1) (2) Surface Mount Output Voltage (V) 1.21 to 2.50 2.5 to 3.75 3.75 to 5 5 to 6.25 6.25 to 7.5 7.5 to 10 10 to 12.5 12.5 to 15 15 to 20 20 to 30 30 to 37 (1) (2) (3) Inductance (µH) AVX TPS Series Sprague 594D Series Kemet T495 Series No. C Code No. C Code No.
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LM2670 SNVS036J – APRIL 2000 – REVISED APRIL 2013 www.ti.com Table 13. Output Capacitors for Adjustable Output Voltage Applications—Through Hole (1) (2) Through Hole Output Voltage (V) 1.21 to 2.50 2.5 to 3.75 3.75 to 5 5 to 6.25 6.25 to 7.5 7.5 to 10 10 to 12.5 12.5 to 15 15 to 20 Inductance (µH) Sanyo OS-CON SA Series 30 to 37 (1) (2) (3) 26 Nichicon PL Series Panasonic HFQ Series No. C Code No. C Code No. C Code No.
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LM2670 www.ti.com SNVS036J – APRIL 2000 – REVISED APRIL 2013 REVISION HISTORY Changes from Revision I (April 2013) to Revision J • Page Changed layout of National Data Sheet to TI format ..........................................................................................................
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PACKAGE OPTION ADDENDUM www.ti.com 1-Nov-2013 PACKAGING INFORMATION Orderable Device Status (1) Package Type Package Pins Package Drawing Qty Eco Plan Lead/Ball Finish MSL Peak Temp (2) (6) (3) Op Temp (°C) Device Marking (4/5) LM2670S-12/NOPB ACTIVE DDPAK/ TO-263 KTW 7 45 Pb-Free (RoHS Exempt) CU SN Level-3-245C-168 HR -40 to 125 LM2670 S-12 LM2670S-3.3/NOPB ACTIVE DDPAK/ TO-263 KTW 7 45 Pb-Free (RoHS Exempt) CU SN Level-3-245C-168 HR -40 to 125 LM2670 S-3.3 LM2670S-5.
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PACKAGE OPTION ADDENDUM www.ti.com Orderable Device 1-Nov-2013 Status (1) Package Type Package Pins Package Drawing Qty Eco Plan Lead/Ball Finish MSL Peak Temp (2) (6) (3) Op Temp (°C) Device Marking (4/5) LM2670SX-ADJ/NOPB ACTIVE DDPAK/ TO-263 KTW 7 500 Pb-Free (RoHS Exempt) CU SN Level-3-245C-168 HR -40 to 125 LM2670 S-ADJ LM2670T-12/NOPB ACTIVE TO-220 NDZ 7 45 Green (RoHS & no Sb/Br) CU SN Level-1-NA-UNLIM -40 to 125 LM2670 T-12 LM2670T-3.
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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.
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PACKAGE MATERIALS INFORMATION www.ti.com 11-Oct-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) B0 (mm) K0 (mm) P1 (mm) W Pin1 (mm) Quadrant LM2670SD-12/NOPB VSON NHM 14 250 178.0 16.4 5.3 6.3 1.5 12.0 16.0 Q1 LM2670SD-3.3/NOPB VSON NHM 14 250 178.0 16.4 5.3 6.3 1.5 12.0 16.0 Q1 LM2670SD-5.0/NOPB VSON NHM 14 250 178.0 16.4 5.3 6.3 1.5 12.0 16.
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PACKAGE MATERIALS INFORMATION www.ti.com 11-Oct-2013 *All dimensions are nominal Device Package Type Package Drawing Pins SPQ Length (mm) Width (mm) Height (mm) LM2670SD-12/NOPB VSON NHM 14 250 210.0 185.0 35.0 LM2670SD-3.3/NOPB VSON NHM 14 250 210.0 185.0 35.0 LM2670SD-5.0/NOPB VSON NHM 14 250 210.0 185.0 35.0 LM2670SD-ADJ/NOPB VSON NHM 14 250 210.0 185.0 35.0 LM2670SDX-3.3/NOPB VSON NHM 14 2500 367.0 367.0 35.0 LM2670SDX-5.
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MECHANICAL DATA NDZ0007B TA07B (Rev E) www.ti.
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MECHANICAL DATA NHM0014A SRC14A (Rev A) www.ti.
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MECHANICAL DATA KTW0007B TS7B (Rev E) BOTTOM SIDE OF PACKAGE www.ti.
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