Datasheet

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

LM22671

www.ti.com

SNVS589M –SEPTEMBER 2008–REVISED APRIL 2013

LM22671/LM22671-Q1 42V, 500mA SIMPLE SWITCHER® Step-Down Voltage Regulator

with Features

Check for Samples: LM22671

FEATURES

DESCRIPTION

The LM22671 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 500mA 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 Operating Junction

external components and good transient response. In

Temperature Range

addition, the frequency can be adjusted over a range

• Precision Enable Pin

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

The internal oscillator can be synchronized to a

• Integrated Boot-Strap Diode

system clock or to the oscillator of another regulator.

• Adjustable Soft-Start

A precision enable input allows simplification of

• Fully WEBENCH

Enabled

regulator control and system power sequencing. In

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

• LM22671-Q1 is an Automotive Grade Product

An adjustable soft-start feature is provided through

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

the selection of a single external capacitor. The

+125°C Operating Junction Temperature)

LM22671 also has built in thermal shutdown, and

current limiting to protect against accidental

PACKAGE

overloads.

• SO PowerPAD (Exposed Pad)

The LM22671 is a member of Texas Instruments'

SIMPLE SWITCHER™ family. The SIMPLE

APPLICATIONS

SWITCHER™ concept provides for an easy to use

complete design using a minimum number of external

• Industrial Control

components and the TI WEBENCH

design tool. TI's

• Telecom and Datacom Systems

WEBENCH

tool includes features such as external

• Embedded Systems

component calculation, electrical simulation, thermal

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

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

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.

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
LM22671 www.ti.com SNVS589M – SEPTEMBER 2008 – REVISED APRIL 2013 LM22671/LM22671-Q1 42V, 500mA SIMPLE SWITCHER® Step-Down Voltage Regulator with Features Check for Samples: LM22671 FEATURES DESCRIPTION • • • • • The LM22671 switching regulator provides all of the functions necessary to implement an efficient high voltage step-down (buck) regulator using a minimum of external components.
PAGE 2
LM22671 SNVS589M – SEPTEMBER 2008 – REVISED APRIL 2013 www.ti.com Simplified Application Schematic VIN FB VIN LM22671-ADJ BOOT VOUT SW RT/SYNC SS EN BOOT 1 8 SW SS 2 7 VIN RT/SYNC 3 6 GND FB 4 5 EN GND Connection Diagram 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.
PAGE 3
LM22671 www.ti.com SNVS589M – 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
LM22671 SNVS589M – 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
LM22671 www.ti.com SNVS589M – 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
LM22671 SNVS589M – 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
LM22671 www.ti.com SNVS589M – 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 LM22671 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
LM22671 SNVS589M – 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
LM22671 www.ti.com SNVS589M – 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. 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
LM22671 www.ti.com 45 45 40 40 35 35 INPUT VOLTAGE (v) INPUT VOLTAGE (v) SNVS589M – SEPTEMBER 2008 – REVISED APRIL 2013 30 25 SAFE OPERATING AREA 20 15 30 25 SAFE OPERATING AREA 20 15 10 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 at 300 kHz 0.2 0.4 0.6 0.8 1.0 SHORT CIRCUIT VOLTAGE (v) 1.2 Figure 16. SOA at 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.
PAGE 11
LM22671 www.ti.com SNVS589M – SEPTEMBER 2008 – REVISED APRIL 2013 The choice of switching frequency is governed by several considerations. As an example, lower frequencies may be desirable to reduce switching losses or improve duty cycle limits. Higher frequencies, or a specific frequency, may be desirable to avoid problems with EMI or reduce the physical size of external components.
PAGE 12
LM22671 SNVS589M – SEPTEMBER 2008 – REVISED APRIL 2013 www.ti.com ENABLE EN EN LM22671 LM22671 RT/SYNC RT/SYNC 2N7002 1k 1k Vout Figure 19. Self Synchronizing Setup Boot-Strap Supply The LM22671 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.
PAGE 13
LM22671 www.ti.com SNVS589M – SEPTEMBER 2008 – REVISED APRIL 2013 COMPENSATOR GAIN (dB) 40 -ADJ -5.0 35 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
LM22671 SNVS589M – SEPTEMBER 2008 – REVISED APRIL 2013 www.ti.com (11) where Fsw is the switching frequency and Vin should be taken at its maximum value, for the given application. The above formula provides a guide to select the value of the inductor L; the nearest standard value will then be used in the circuit.
PAGE 15
LM22671 www.ti.com SNVS589M – SEPTEMBER 2008 – REVISED APRIL 2013 OUTPUT CAPACITOR The output capacitor is responsible for filtering the output voltage and supplying load current during transients. Capacitor selection depends on application conditions as well as ripple and transient requirements. Best performance is achieved with a parallel combination of ceramic capacitors and a low ESR SP™ or POSCAP™ type.
PAGE 16
LM22671 SNVS589M – SEPTEMBER 2008 – REVISED APRIL 2013 www.ti.com Vout RFBT FB RFBB Figure 22. Resistive Feedback Divider A maximum value of 10 kΩ is recommended for the sum of RFBB and RFBT to maintain good output voltage accuracy for the -ADJ option. A maximum of 2 kΩ is recommended for the -5.0 option. For the -5.0 option, the total internal divider resistance is typically 9.93 kΩ.
PAGE 17
LM22671 www.ti.com SNVS589M – SEPTEMBER 2008 – REVISED APRIL 2013 Figure 23. Current Flow in a Buck Application Thermal Considerations The components with the highest power dissipation are the power diode and the power MOSFET internal to the LM22671 regulator. The easiest method to determine the power dissipation within the LM22671 is to measure the total conversion losses then subtract the power losses in the diode and inductor.
PAGE 18
LM22671 SNVS589M – SEPTEMBER 2008 – REVISED APRIL 2013 www.ti.com PCB Layout Example RFBB 2.55 k: VIN 5.5V to 35V EN C2 22 PF + C1 2.2 PF C3 10 nF BOOT L1 10 PH RFBT 7.32 k: SW RT/SYNC C6 4.7 PF VOUT FB VIN SS LM22671-ADJ GND D1 60V 3A C4 120 PF VOUT -5V Figure 24.
PAGE 19
LM22671 www.ti.com SNVS589M – SEPTEMBER 2008 – REVISED APRIL 2013 REVISION HISTORY Changes from Revision L (April 2013) to Revision M • Page Changed layout of National Data Sheet to TI format ..........................................................................................................
PAGE 20
PACKAGE OPTION ADDENDUM www.ti.com 23-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) LM22671MR-5.0/NOPB ACTIVE SO PowerPAD DDA 8 95 Green (RoHS & no Sb/Br) SN | CU SN Level-3-260C-168 HR -40 to 125 L22671 5.
PAGE 21
PACKAGE OPTION ADDENDUM www.ti.com 23-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 LM22671MRE-5.0/NOPB SO Power PAD DDA 8 250 178.0 12.4 6.5 5.4 2.0 8.0 12.0 Q1 LM22671MRE-ADJ/NOPB SO Power PAD DDA 8 250 178.0 12.4 6.5 5.4 2.0 8.0 12.0 Q1 LM22671MRX-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) LM22671MRE-5.0/NOPB SO PowerPAD DDA 8 250 213.0 191.0 55.0 LM22671MRE-ADJ/NOPB SO PowerPAD DDA 8 250 213.0 191.0 55.0 LM22671MRX-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.