Datasheet

ManualsBrandsTEXAS INSTRUMENTS ManualsPMICsPMIC - DC/DC voltage regulator Holder SO 8

LM22672-ADJ

VIN

BOOT

GND

VIN

VOUT

RT/SYNC

LM22672

www.ti.com

SNVS588L –SEPTEMBER 2008–REVISED APRIL 2013

LM22672/LM22672-Q1 42V, 1A SIMPLE SWITCHER® Step-Down Voltage Regulator with

Features

Check for Samples: LM22672

FEATURES

DESCRIPTION

The LM22672 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

• 200 mΩ N-Channel MOSFET

capable of providing up to 1A of load current.

• Output Voltage Options:

Excellent line and load regulation along with high

– ADJ (Outputs as Low as 1.285V)

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

offers short minimum on-time, allowing the widest

– 5.0 (Output Fixed to 5V)

ratio between input and output voltages. Internal loop

• ±1.5% Feedback Reference Accuracy

compensation means that the user is free from the

• 500 kHz Default Switching Frequency

tedious task of calculating the loop compensation

components. Fixed 5V output and adjustable output

• Adjustable Switching Frequency and

voltage options are available. The default switching

Synchronization

frequency is set at 500 kHz allowing for small

• -40°C to 125°C Junction Temperature Range

external components and good transient response. In

• Precision Enable Input

addition, the frequency can be adjusted over a range

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

• Integrated Boot-Strap Diode

The internal oscillator can be synchronized to a

• Adjustable Soft-Start

system clock or to the oscillator of another regulator.

• Fully WEBENCH

Enabled

A precision enable input allows simplification of

• LM22672-Q1 is an Automotive Grade Product

regulator control and system power sequencing. In

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

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

An adjustable soft-start feature is provided through

+125°C Junction Temperature)

the selection of a single external capacitor. The

LM22672 also has built in thermal shutdown, and

PACKAGE

current limiting to protect against accidental

• SO PowerPAD (Exposed Pad)

overloads.

The LM22672 is a member of Texas Instruments'

APPLICATIONS

SIMPLE SWITCHER™ family. The SIMPLE

• Industrial Control

SWITCHER™ concept provides for an easy to use

complete design using a minimum number of external

• Telecom and Datacom Systems

components and the TI WEBENCH

design tool. TI's

• Embedded Systems

WEBENCH

tool includes features such as external

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

component calculation, electrical simulation, thermal

Input Rails

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

Simplified Application Schematic

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 (25 pages)

PAGE 1
LM22672 www.ti.com SNVS588L – SEPTEMBER 2008 – REVISED APRIL 2013 LM22672/LM22672-Q1 42V, 1A SIMPLE SWITCHER® Step-Down Voltage Regulator with Features Check for Samples: LM22672 FEATURES DESCRIPTION • • • • • The LM22672 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 1A of load current.
PAGE 2
LM22672 SNVS588L – SEPTEMBER 2008 – REVISED APRIL 2013 www.ti.com Connection Diagram BOOT 1 8 SW SS 2 7 VIN RT/SYNC 3 6 GND FB 4 5 EN Exposed Pad Connect to GND Figure 1. 8-Lead Plastic SO PowerPAD Package Package Number DDA0008B PIN DESCRIPTIONS Pin Name Description Application Information 1 BOOT Bootstrap input Provides the gate voltage for the high side NFET. 2 SS Soft-start input Used to increase soft-start time. See Soft-Start section of data sheet.
PAGE 3
LM22672 www.ti.com SNVS588L – SEPTEMBER 2008 – REVISED APRIL 2013 Absolute Maximum Ratings (1) (2) VIN to GND 43V EN Pin Voltage -0.5V to 6V SS, RT/SYNC Pin Voltage -0.5V to 7V SW to GND (3) -5V to VIN BOOT Pin Voltage VSW + 7V FB Pin Voltage -0.5V to 7V Power Dissipation Internally Limited Junction Temperature 150°C For soldering specifications, refer to the following document: www.ti.
PAGE 4
LM22672 SNVS588L – SEPTEMBER 2008 – REVISED APRIL 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.
PAGE 5
LM22672 www.ti.com SNVS588L – SEPTEMBER 2008 – REVISED APRIL 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 2. Figure 3. Current Limit vs Temperature Normalized RDS(ON) vs Temperature Figure 4. Figure 5. Feedback Bias Current vs Temperature Normalized Enable Threshold Voltage vs Temperature Figure 6. Figure 7.
PAGE 6
LM22672 SNVS588L – SEPTEMBER 2008 – REVISED APRIL 2013 www.ti.com Typical Performance Characteristics (continued) Unless otherwise specified the following conditions apply: Vin = 12V, TJ = 25°C. Standby Quiescent Current vs Input Voltage Normalized Feedback Voltage vs Temperature Figure 8. Figure 9. Normalized Feedback Voltage vs Input Voltage Switching Frequency vs RT/SYNC Resistor Figure 10. Figure 11. Soft-start Current vs Temperature Figure 12.
PAGE 7
LM22672 www.ti.com SNVS588L – SEPTEMBER 2008 – REVISED APRIL 2013 SIMPLIFIED BLOCK DIAGRAM VIN VIN Vcc BOOT INT REG, EN,UVLO EN ILimit PWM Cmp. FB TYPE III COMP + + - LOGIC Error Amp. VOUT SW OSC SS 1.285V/SS 50 µA RT/SYNC GND Figure 13. Simplified Block Diagram Detailed Operating Description The LM22672 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.
PAGE 8
LM22672 SNVS588L – SEPTEMBER 2008 – REVISED APRIL 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
LM22672 www.ti.com SNVS588L – SEPTEMBER 2008 – REVISED APRIL 2013 where • Fsw is the switching frequency and TON is the minimum on-time; both found in the Electrical Characteristics table. (3) 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.
PAGE 10
LM22672 SNVS588L – SEPTEMBER 2008 – REVISED APRIL 2013 www.ti.com If the input voltage should exceed this value, while in foldback mode, the regulator and/or the diode may be damaged. It is important to note that the voltages in these equations are measured at the inductor. Normal trace and wiring resistance will cause the voltage at the inductor to be higher than that at a remote load.
PAGE 11
LM22672 www.ti.com SNVS588L – SEPTEMBER 2008 – REVISED APRIL 2013 Switching Frequency Adjustment and Synchronization The LM22672 will operate in three different modes, depending on the condition of the RT/SYNC pin. With the RT/SYNC pin floating, the regulator will switch at the internally set frequency of 500 kHz (typ.). With a resistor in the range of 25 kΩ to 200 kΩ, connected from RT/SYNC to ground, the internal switching frequency can be adjusted from 1MHz to 200 kHz.
PAGE 12
LM22672 SNVS588L – SEPTEMBER 2008 – REVISED APRIL 2013 www.ti.com Self Synchronization It is possible to synchronize multiple LM22672 regulators together to share the same switching frequency. This can be done by tieing the RT/SYNC pins together through a MOSFET and connecting a 1 KΩ resistor to ground at each pin. Figure 19 shows this connection. The gate of the MOSFET should be connected to the regulator with the highest output voltage.
PAGE 13
LM22672 www.ti.com SNVS588L – SEPTEMBER 2008 – REVISED APRIL 2013 The complete transfer function for the regulator loop is found by combining the compensation and power stage transfer functions. The LM22672 has internal type III loop compensation, as detailed in Figure 20. This is the approximate "straight line" function from the FB pin to the input of the PWM modulator. The power stage transfer function consists of a D.C. gain and a second order pole created by the inductor and output capacitor(s).
PAGE 14
LM22672 SNVS588L – SEPTEMBER 2008 – REVISED APRIL 2013 www.ti.com RFBB 976: VIN 4.5V to 35V FB VIN EN C2 22 PF + C3 10 nF LM22672-ADJ EN BOOT SYNC C1 2.2 PF R3 RFBT 1.54 k: L1 22 PH RT/SYNC SW GND SS C6 1 PF D1 60V, 1A VOUT 3.3V C4 120 PF + GND GND Figure 21. Typical Buck Regulator Application EXTERNAL COMPONENTS The following guidelines should be used when designing a step-down (buck) converter with the LM22672.
PAGE 15
LM22672 www.ti.com SNVS588L – SEPTEMBER 2008 – REVISED APRIL 2013 where • Vri is the peak-to-peak ripple voltage at the switching frequency. (13) Another concern is the RMS current passing through this capacitor. The following equation gives an approximation to this current: (14) The capacitor must be rated for at least this level of RMS current at the switching frequency. All ceramic capacitors have large voltage coefficients, in addition to normal tolerances and temperature coefficients.
PAGE 16
LM22672 SNVS588L – SEPTEMBER 2008 – REVISED APRIL 2013 www.ti.com (16) 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. The top of RFBT should be connected directly to the output capacitor or to the load for remote sensing. If the divider is connected to the load, a local high-frequency bypass should be provided at that location. For output voltages of 5V, the -5.0 option should be used.
PAGE 17
LM22672 www.ti.com SNVS588L – SEPTEMBER 2008 – REVISED APRIL 2013 The most important layout rule is to keep the AC current loops as small as possible. Figure 23 shows the current flow in a buck converter. The top schematic shows a dotted line which represents the current flow during the FET switch on-state. The middle schematic shows the current flow during the FET switch off-state. The bottom schematic shows the currents referred to as AC currents.
PAGE 18
LM22672 SNVS588L – SEPTEMBER 2008 – REVISED APRIL 2013 www.ti.com large continuous ground plane on the top or bottom PCB layer will provide the most effective heat dissipation. The integrity of the solder connection from the IC exposed pad to the PC board is critical. Excessive voids will greatly diminish the thermal dissipation capacity. The junction-to-ambient thermal resistance of the LM22672 SO PowerPAD package is specified in the Electrical Characteristics table.
PAGE 19
LM22672 www.ti.com SNVS588L – SEPTEMBER 2008 – REVISED APRIL 2013 REVISION HISTORY Changes from Revision K (April 2013) to Revision L • Page Changed layout of National Data Sheet to TI format ..........................................................................................................
PAGE 20
PACKAGE OPTION ADDENDUM www.ti.com 5-Feb-2014 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) LM22672MR-5.0/NOPB ACTIVE SO PowerPAD DDA 8 95 Green (RoHS & no Sb/Br) CU SN Level-3-260C-168 HR -40 to 125 L22672 5.
PAGE 21
PACKAGE OPTION ADDENDUM www.ti.com 5-Feb-2014 Pb-Free (RoHS): TI's terms "Lead-Free" or "Pb-Free" mean semiconductor products that are compatible with the current RoHS requirements for all 6 substances, including the requirement that lead not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, TI Pb-Free products are suitable for use in specified lead-free processes.
PAGE 22
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) B0 (mm) K0 (mm) P1 (mm) W Pin1 (mm) Quadrant LM22672MRE-5.0/NOPB SO Power PAD DDA 8 250 178.0 12.4 6.5 5.4 2.0 8.0 12.0 Q1 LM22672MRE-ADJ/NOPB SO Power PAD DDA 8 250 178.0 12.4 6.5 5.4 2.0 8.0 12.0 Q1 LM22672MRX-5.0/NOPB SO Power PAD DDA 8 2500 330.0 12.4 6.5 5.4 2.
PAGE 23
PACKAGE MATERIALS INFORMATION www.ti.com 8-Apr-2013 Device B 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 Power PAD *All dimensions are nominal Device Package Type Package Drawing Pins SPQ Length (mm) Width (mm) Height (mm) LM22672MRE-5.0/NOPB SO PowerPAD DDA 8 250 213.0 191.0 55.0 LM22672MRE-ADJ/NOPB SO PowerPAD DDA 8 250 213.0 191.0 55.0 LM22672MRX-5.
PAGE 24
MECHANICAL DATA DDA0008B MRA08B (Rev B) www.ti.
PAGE 25
IMPORTANT NOTICE Texas Instruments Incorporated and its subsidiaries (TI) reserve the right to make corrections, enhancements, improvements and other changes to its semiconductor products and services per JESD46, latest issue, and to discontinue any product or service per JESD48, latest issue. Buyers should obtain the latest relevant information before placing orders and should verify that such information is current and complete.