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LM22670

www.ti.com

SNVS584O –SEPTEMBER 2008–REVISED MARCH 2013

LM22670/LM22670Q 42V, 3A SIMPLE SWITCHER

, Step-Down Voltage Regulator with

Features

Check for Samples: LM22670

FEATURES

DESCRIPTION

The LM22670 switching regulator provides all of the

• Wide Input Voltage Range: 4.5V to 42V

functions necessary to implement an efficient high

• Internally Compensated Voltage Mode Control

voltage step-down (buck) regulator using a minimum

• Stable with Low ESR Ceramic Capacitors

of external components. This easy to use regulator

incorporates a 42V N-channel MOSFET switch

• 120 mΩ N-channel MOSFET PFM Package

capable of providing up to 3A of load current.

• 100 mΩ N-channel MOSFET SO PowerPAD-8

Excellent line and load regulation along with high

Package

efficiency (>90%) are featured. Voltage mode control

• Output Voltage Options:

offers short minimum on-time, allowing the widest

ratio between input and output voltages. Internal loop

– -ADJ (outputs as low as 1.285V)

compensation means that the user is free from the

– -5.0 (output fixed to 5V)

tedious task of calculating the loop compensation

• ±1.5% Feedback Reference Accuracy

components. Fixed 5V output and adjustable output

voltage options are available. The default switching

• 500 kHz Default Switching Frequency

frequency is set at 500 kHz allowing for small

• Adjustable Switching Frequency and

external components and good transient response. In

Synchronization

addition, the frequency can be adjusted over a range

• -40°C to 125°C Operating Junction

of 200 kHz to 1MHz with a single external resistor.

Temperature Range

The internal oscillator can be synchronized to a

system clock or to the oscillator of another regulator.

• Precision Enable Pin

A precision enable input allows simplification of

• Integrated Boot-Strap Diode

regulator control and system power sequencing. In

• Integrated Soft-Start

shutdown mode the regulator draws only 25 µA (typ.).

Built in soft-start (500µs, typ) saves external

• Fully WEBENCH

enabled

components. The LM22670 also has built in thermal

• LM22670Q is an Automotive Grade Product

shutdown, and current limiting to protect against

that is AEC-Q100 Grade 1 Qualified (-40°C to

accidental overloads.

+125°C Operating Junction Temperature)

The LM22670 is a member of Texas Instruments'

• SO PowerPAD-8 (Exposed Pad) Package

SIMPLE SWITCHER

family. The SIMPLE

• PFM (Exposed Pad) Package

SWITCHER concept provides for an easy to use

complete design using a minimum number of external

APPLICATIONS

components and the TI WEBENCH design tool. TI's

WEBENCH tool includes features such as external

• Industrial Control

component calculation, electrical simulation, thermal

• Telecom and Datacom Systems

simulation, and Build-It boards for easy design-in.

• Embedded Systems

• Conversions from Standard 24V, 12V and 5V

Input Rails

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, WEBENCH are registered trademarks of Texas Instruments Incorporated.

3All other 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 (29 pages)

PAGE 1
LM22670 www.ti.com SNVS584O – SEPTEMBER 2008 – REVISED MARCH 2013 LM22670/LM22670Q 42V, 3A SIMPLE SWITCHER®, Step-Down Voltage Regulator with Features Check for Samples: LM22670 FEATURES DESCRIPTION • • • • • The LM22670 switching regulator provides all of the functions necessary to implement an efficient high voltage step-down (buck) regulator using a minimum of external components. This easy to use regulator incorporates a 42V N-channel MOSFET switch capable of providing up to 3A of load current.
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LM22670 SNVS584O – SEPTEMBER 2008 – REVISED MARCH 2013 www.ti.com Simplified Application Schematic VIN VIN FB LM22670-ADJ BOOT VOUT RT/SYNC EN GND SW Connection Diagram BOOT 1 8 SW NC 2 7 VIN RT/SYNC 3 6 GND FB 4 5 EN Exposed Pad Connect to GND Figure 1. 8-Lead SO PowerPAD-8 Package See Package Number DDA0008B 7 EN 6 FB 5 RT/SYNC 4 GND 3 BOOT 2 VIN 1 SW Exposed Pad Connect to GND Figure 2.
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LM22670 www.ti.com SNVS584O – SEPTEMBER 2008 – REVISED MARCH 2013 PIN DESCRIPTIONS (continued) Pin Numbers SO PowerPAD-8 Package Pin Numbers PFM Package Name 3 5 RT/SYNC 4 6 5 7 6 4 GND Ground input to regulator; system System ground pin. common 7 2 VIN Input voltage Supply input to the regulator. 8 1 SW Switch output Switching output of regulator. EP EP EP Exposed Pad Connect to ground. Provides thermal connection to PCB. See Application Information.
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LM22670 SNVS584O – SEPTEMBER 2008 – REVISED MARCH 2013 www.ti.com Electrical Characteristics Limits in standard type are for TJ = 25°C only; limits in boldface type apply over the junction temperature (TJ) range of -40°C to +125°C. Minimum and Maximum limits are ensured through test, design, or statistical correlation. Typical values represent the most likely parametric norm at TA = TJ = 25°C, and are provided for reference purposes only. Unless otherwise specified: VIN = 12V.
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LM22670 www.ti.com SNVS584O – SEPTEMBER 2008 – REVISED MARCH 2013 Typical Performance Characteristics Unless otherwise specified the following conditions apply: Vin = 12V, TJ = 25°C. Efficiency vs IOUT and VIN VOUT = 3.3V Normalized Switching Frequency vs Temperature Figure 3. Figure 4. Current Limit vs Temperature 1.5 Normalized RDS(ON) vs Temperature NORMALIZED RDS(ON) 1.4 PFM Package 1.3 1.2 1.1 1.0 SO Package 0.9 0.8 0.7 0.6 –50 –25 0 25 50 75 100 125 TEMPERATURE (°C) Figure 6.
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LM22670 SNVS584O – SEPTEMBER 2008 – REVISED MARCH 2013 www.ti.com Typical Performance Characteristics (continued) Unless otherwise specified the following conditions apply: Vin = 12V, TJ = 25°C. 6 Standby Quiescent Current vs Input Voltage Normalized Feedback Voltage vs Temperature Figure 9. Figure 10. Normalized Feedback Voltage vs Input Voltage Switching Frequency vs RT/SYNC Resistor Figure 11. Figure 12.
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LM22670 www.ti.com SNVS584O – SEPTEMBER 2008 – REVISED MARCH 2013 Simplified Block Diagram VIN VIN BOOT Vcc INT REG, EN,UVLO EN ILimit PWM Cmp. FB TYPE III COMP + + - LOGIC Error Amp. VOUT SW OSC 1.285V & Soft-Start RT/SYNC GND Figure 13. Simplified Block Diagram Detailed Operating Description The LM22670 incorporates a voltage mode constant frequency PWM architecture. In addition, input voltage feedforward is used to stabilize the loop gain against variations in input voltage.
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LM22670 SNVS584O – SEPTEMBER 2008 – REVISED MARCH 2013 www.ti.com Precision Enable and UVLO The precision enable input (EN) is used to control the regulator. The precision feature allows simple sequencing of multiple power supplies with a resistor divider from another supply. Connecting this pin to ground or to a voltage less than 1.6V (typ.) will turn off the regulator. The current drain from the input supply, in this state, is 25 µA (typ.) at an input voltage of 12V.
PAGE 9
LM22670 www.ti.com SNVS584O – SEPTEMBER 2008 – REVISED MARCH 2013 Where Fsw is the switching frequency and TON is the minimum on-time; both found in the Electrical Characteristics table. If the frequency adjust feature is used, that value should be used for Fsw. Nominal values should be used. The worst case is lowest output voltage, and highest switching frequency. If this input voltage is exceeded, the regulator will skip cycles, effectively lowering the switching frequency.
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LM22670 www.ti.com 45 45 40 40 35 35 INPUT VOLTAGE (v) INPUT VOLTAGE (v) SNVS584O – SEPTEMBER 2008 – REVISED MARCH 2013 30 25 SAFE OPERATING AREA 20 15 10 30 25 SAFE OPERATING AREA 20 15 10 5 5 0.0 0.2 0.4 0.6 0.8 1.0 SHORT CIRCUIT VOLTAGE (v) 1.2 0.0 Figure 15. SOA 300 kHz 0.2 0.4 0.6 0.8 1.0 SHORT CIRCUIT VOLTAGE (v) 1.2 Figure 16. SOA 500 kHz 45 INPUT VOLTAGE (v) 40 35 30 25 20 SAFE OPERATING AREA 15 10 5 0.0 0.2 0.4 0.6 0.8 1.0 SHORT CIRCUIT VOLTAGE (v) 1.2 Figure 17.
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LM22670 www.ti.com SNVS584O – SEPTEMBER 2008 – REVISED MARCH 2013 Frequency synchronization requires some care. First the external clock frequency must be greater than the internal clock frequency, and less than 1 MHz. The maximum internal switching frequency is ensured in the Electrical Characteristics table. Note that the frequency adjust feature and the synchronization feature can not be used simultaneously. The synchronizing frequency must always be greater than the internal clock frequency.
PAGE 12
LM22670 SNVS584O – SEPTEMBER 2008 – REVISED MARCH 2013 www.ti.com ENABLE EN EN LM22670 LM22670 RT/SYNC RT/SYNC 2N7002 1 k: 1 k: Vout Figure 19. Self Synchronization Set up Boot-Strap Supply The LM22670 incorporates a floating high-side gate driver to control the power MOSFET. The supply for this driver is the external boot-strap capacitor connected between the BOOT pin and SW. A good quality 10 nF ceramic capacitor must be connected to these pins with short, wide PCB traces.
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LM22670 www.ti.com SNVS584O – SEPTEMBER 2008 – REVISED MARCH 2013 COMPENSATOR GAIN (dB) 40 35 -ADJ -5.0 30 25 20 15 10 5 0 100 1k 10k 100k 1M FREQUENCY (Hz) 10M Figure 20. Compensator Gain In general, hand calculations or simulations can only aid in selecting good power stage components. Good design practice dictates that load and line transient testing should be done to verify the stability of the application. Also, Bode plot measurements should be made to determine stability margins.
PAGE 14
LM22670 SNVS584O – SEPTEMBER 2008 – REVISED MARCH 2013 www.ti.com APPLICATION INFORMATION TYPICAL BUCK REGULATOR APPLICATION Figure 21 shows an example of converting an input voltage range of 5.5V to 42V, to an output of 3.3v at 3A. See AN-1885 SNVA361for more information. RFBB 976: VIN 4.5V to 42V FB VIN EN C2 22 PF + C3 10 nF LM22670-ADJ EN BOOT SYNC C1 6.8 PF RT/SYNC R3 GND RFBT 1.54 k: L1 8.2 PH SW D1 60V, 5A VOUT 3.3V C4 120 PF + GND GND Figure 21.
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LM22670 www.ti.com SNVS584O – SEPTEMBER 2008 – REVISED MARCH 2013 INPUT CAPACITOR The input capacitor selection is based on both input voltage ripple and RMS current. Good quality input capacitors are necessary to limit the ripple voltage at the VIN pin while supplying most of the regulator current during switch on-time. Low ESR ceramic capacitors are preferred. Larger values of input capacitance are desirable to reduce voltage ripple and noise on the input supply.
PAGE 16
LM22670 SNVS584O – SEPTEMBER 2008 – REVISED MARCH 2013 www.ti.com OUTPUT VOLTAGE DIVIDER SELECTION For output voltages between about 1.285V and 5V, the -ADJ option should be used, with an appropriate voltage divider as shown in Figure 22. The following equation can be used to calculate the resistor values of this divider: (15) A good value for RFBB is 1k Ω. This will help to provide some of the minimum load current requirement and reduce susceptibility to noise pick-up.
PAGE 17
LM22670 www.ti.com SNVS584O – SEPTEMBER 2008 – REVISED MARCH 2013 Circuit Board Layout Board layout is critical for the proper operation of switching power supplies. First, the ground plane area must be sufficient for thermal dissipation purposes. Second, appropriate guidelines must be followed to reduce the effects of switching noise. Switch mode converters are very fast switching devices.
PAGE 18
LM22670 SNVS584O – SEPTEMBER 2008 – REVISED MARCH 2013 www.ti.com The regulator has an exposed thermal pad to aid power dissipation. Adding multiple vias under the device to the ground plane will greatly reduce the regulator junction temperature. Selecting a diode with an exposed pad will also aid the power dissipation of the diode. The most significant variables that affect the power dissipation of the regulator are output current, input voltage and operating frequency.
PAGE 19
LM22670 www.ti.com SNVS584O – SEPTEMBER 2008 – REVISED MARCH 2013 PCB Layout Example for SO PowerPAD-8 Package RFBB 2.55 k: VIN 5.5V to 35V VIN FB LM22670-ADJ EN BOOT C2 22 PF + C1 2.2 PF RT/SYNC C6 4.7 PF VOUT C3 10 nF L1 10 PH RFBT 7.32 k: SW GND D1 60V 5A C4 120 PF VOUT -5V Figure 24.
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LM22670 SNVS584O – SEPTEMBER 2008 – REVISED MARCH 2013 www.ti.com REVISION HISTORY Changes from Revision N (March 2013) to Revision O • 20 Page Changed layout of National Data Sheet to TI format ..........................................................................................................
PAGE 21
PACKAGE OPTION ADDENDUM www.ti.com 21-May-2013 PACKAGING INFORMATION Orderable Device Status (1) Package Type Package Pins Package Drawing Qty Eco Plan Lead/Ball Finish (2) MSL Peak Temp Op Temp (°C) Device Marking (3) (4/5) LM22670MR-5.0/NOPB ACTIVE SO PowerPAD DDA 8 95 Green (RoHS & no Sb/Br) CU SN Level-3-260C-168 HR -40 to 125 L22670 5.0 LM22670MR-ADJ/NOPB ACTIVE SO PowerPAD DDA 8 95 Green (RoHS & no Sb/Br) CU SN Level-3-260C-168 HR -40 to 125 L22670 ADJ LM22670MRE-5.
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PACKAGE OPTION ADDENDUM www.ti.com Orderable Device 21-May-2013 Status (1) Package Type Package Pins Package Drawing Qty Eco Plan Lead/Ball Finish (2) MSL Peak Temp Op Temp (°C) Device Marking (3) (4/5) LM22670TJ-ADJ/NOPB ACTIVE TO-263 NDR 7 1000 Green (RoHS & no Sb/Br) CU SN Level-1-260C-UNLIM -40 to 125 LM22670 TJ-ADJ LM22670TJE-5.0/NOPB ACTIVE TO-263 NDR 7 250 Green (RoHS & no Sb/Br) CU SN Level-1-260C-UNLIM -40 to 125 LM22670 TJ-5.
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PACKAGE OPTION ADDENDUM www.ti.
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PACKAGE MATERIALS INFORMATION www.ti.com 29-May-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 LM22670MRE-5.0/NOPB SO Power PAD DDA 8 250 178.0 12.4 6.5 5.4 2.0 8.0 12.0 Q1 LM22670MRE-ADJ/NOPB SO Power PAD DDA 8 250 178.0 12.4 6.5 5.4 2.0 8.0 12.0 Q1 LM22670MRX-5.0/NOPB SO Power PAD DDA 8 2500 330.0 12.4 6.5 5.4 2.
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PACKAGE MATERIALS INFORMATION www.ti.com 29-May-2013 Device Package Package Pins Type Drawing B Power PAD LM22670QTJ-5.0/NOPB SPQ Reel Reel A0 Diameter Width (mm) (mm) W1 (mm) B0 (mm) K0 (mm) P1 (mm) W Pin1 (mm) Quadrant TO-263 NDR 7 1000 330.0 24.4 10.6 15.4 2.45 12.0 24.0 Q2 LM22670QTJ-ADJ/NOPB TO-263 NDR 7 1000 330.0 24.4 10.6 15.4 2.45 12.0 24.0 Q2 LM22670QTJE-5.0/NOPB TO-263 NDR 7 250 178.0 24.4 10.6 15.4 2.45 12.0 24.
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PACKAGE MATERIALS INFORMATION www.ti.com 29-May-2013 Device Package Type Package Drawing Pins SPQ Length (mm) Width (mm) Height (mm) LM22670QMRX-5.0/NOPB SO PowerPAD DDA 8 2500 367.0 367.0 35.0 LM22670QMRX-ADJ/NOP B SO PowerPAD DDA 8 2500 367.0 367.0 35.0 LM22670QTJ-5.0/NOPB TO-263 NDR 7 1000 367.0 367.0 35.0 LM22670QTJ-ADJ/NOPB TO-263 NDR 7 1000 367.0 367.0 35.0 LM22670QTJE-5.0/NOPB TO-263 NDR 7 250 210.0 185.0 35.
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MECHANICAL DATA NDR0007A BOTTOM SIDE OF PACKAGE TOP SIDE OF PACKAGE TJ7A (Rev D) www.ti.
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MECHANICAL DATA DDA0008B MRA08B (Rev B) www.ti.
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