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LM25575, LM25575-Q1

www.ti.com

SNVS479G –JANUARY 2007–REVISED APRIL 2013

LM25575/LM25575-Q1 SIMPLE SWITCHER® 42V, 1.5A Step-Down Switching Regulator

Check for Samples: LM25575, LM25575-Q1

FEATURES

DESCRIPTION

The LM25575 is an easy to use SIMPLE

• LM25575-Q1 is an Automotive Grade Product

SWITCHER® buck regulator which allows design

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

engineers to design and optimize a robust power

125°C Operating Junction Temperature)

supply using a minimum set of components.

• Integrated 42V, 330mΩ N-channel MOSFET

Operating with an input voltage range of 6 - 42V, the

LM25575 delivers 1.5A of continuous output current

• Ultra-Wide Input Voltage Range from 6V to 42V

with an integrated 330mΩ N-Channel MOSFET. The

• Adjustable Output Voltage as Low as 1.225V

regulator utilizes an Emulated Current Mode

• 1.5% Feedback Reference Accuracy

architecture which provides inherent line regulation,

• Operating Frequency Adjustable Between

tight load transient response, and ease of loop

compensation without the usual limitation of low-duty

50kHz and 1MHz with Single Resistor

cycles associated with current mode regulators. The

• Master or Slave Frequency Synchronization

operating frequency is adjustable from 50kHz to

• Adjustable Soft-Start

1MHz to allow optimization of size and efficiency. To

• Emulated Current Mode Control Architecture reduce EMI, a frequency synchronization pin allows

multiple IC’s from the LM(2)557x family to self-

• Wide Bandwidth Error Amplifier

synchronize or to synchronize to an external clock.

• Built-in Protection

The LM25575 ensures robustness with cycle-by-cycle

• Automotive Grade Product Datasheet that is

current limit, short-circuit protection, thermal shut-

down, and remote shut-down. The device is available

AEC-Q100 Grade 0 Qualified is Available Upon

in a power enhanced HTSSOP-16 package featuring

Request

an exposed die attach pad for thermal dissipation.

– (−40°C to + 150°C Operating Junction

The LM25575 is supported by the full suite of

Temperature)

WEBENCH

On-Line design tools.

APPLICATIONS

PACKAGE

• Automotive

• HTSSOP-16EP (Exposed Pad)

• Industrial

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.

2WEBENCH is a registered trademark of Texas Instruments.

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 (30 pages)

PAGE 1
LM25575, LM25575-Q1 www.ti.com SNVS479G – JANUARY 2007 – REVISED APRIL 2013 LM25575/LM25575-Q1 SIMPLE SWITCHER® 42V, 1.5A Step-Down Switching Regulator Check for Samples: LM25575, LM25575-Q1 FEATURES DESCRIPTION • The LM25575 is an easy to use SIMPLE SWITCHER® buck regulator which allows design engineers to design and optimize a robust power supply using a minimum set of components. Operating with an input voltage range of 6 - 42V, the LM25575 delivers 1.
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LM25575, LM25575-Q1 SNVS479G – JANUARY 2007 – REVISED APRIL 2013 www.ti.com Simplified Application Schematic VIN VIN BST SYNC SW VOUT LM25575 SD IS OUT RT FB VCC SS COMP RAMP GND Connection Diagram 1 VCC BST SD PRE VIN SW 2 3 4 5 6 7 8 SYNC IS COMP PGND FB OUT RT SS RAMP AGND 16 15 14 13 12 11 10 9 Figure 1. Top View 16-Lead HTSSOP PIN DESCRIPTIONS 2 Pin(s) Name 1 VCC 2 Description Application Information Output of the bias regulator Vcc tracks Vin up to 9V.
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LM25575, LM25575-Q1 www.ti.com SNVS479G – JANUARY 2007 – REVISED APRIL 2013 PIN DESCRIPTIONS (continued) Pin(s) Name 8 RAMP Ramp control signal Description An external capacitor connected between this pin and the AGND pin sets the ramp slope used for current mode control. Recommended capacitor range 50pF to 2000pF.
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LM25575, LM25575-Q1 SNVS479G – JANUARY 2007 – REVISED APRIL 2013 www.ti.com Operating Ratings (1) VIN 6V to 42V −40°C to + 125°C Operation Junction Temperature (1) 4 Absolute Maximum Ratings are limits beyond which damage to the device may occur. Operating Ratings are conditions under which operation of the device is intended to be functional. For ensured specifications and test conditions, see the Electrical Characteristics.
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LM25575, LM25575-Q1 www.ti.com SNVS479G – JANUARY 2007 – REVISED APRIL 2013 Electrical Characteristics Specifications with standard typeface are for TJ = 25°C, and those with boldface type apply over full Operating Junction Temperature range. VIN = 24V, RT = 32.4kΩ unless otherwise stated. (1) Symbol Parameter Conditions Min Typ Max Units 6.85 7.15 7.
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LM25575, LM25575-Q1 SNVS479G – JANUARY 2007 – REVISED APRIL 2013 www.ti.com Electrical Characteristics (continued) Specifications with standard typeface are for TJ = 25°C, and those with boldface type apply over full Operating Junction Temperature range. VIN = 24V, RT = 32.4kΩ unless otherwise stated.(1) Symbol Parameter Conditions Min Typ Max 1.207 1.225 1.
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LM25575, LM25575-Q1 www.ti.com SNVS479G – JANUARY 2007 – REVISED APRIL 2013 Typical Performance Characteristics Oscillator Frequency vs Temperature FOSC = 200kHz Oscillator Frequency vs RT NORMALIZED OSCILLATOR FREQUENCY OSCILLATOR FREQUENCY (kHz) 1000 100 10 1 10 100 1000 1.010 1.005 1.000 0.995 0.990 -50 -25 0 25 50 75 100 125 RT (k:) o TEMPERATURE ( C) VCC vs ICC VIN = 12V Soft Start Current vs Temperature 8 6 1.05 VCC (V) NORMALIZED SOFTSTART CURRENT 1.10 1.00 4 2 0.
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LM25575, LM25575-Q1 SNVS479G – JANUARY 2007 – REVISED APRIL 2013 www.ti.com Typical Performance Characteristics (continued) Demoboard Efficiency vs IOUT and VIN 100 VIN = 7V 90 EFFICIENCY (%) 80 VIN = 24V 70 60 50 40 30 20 10 0 0.25 0.5 0.75 1 1.25 1.
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LM25575, LM25575-Q1 www.ti.com SNVS479G – JANUARY 2007 – REVISED APRIL 2013 TYPICAL APPLICATION CIRCUIT AND BLOCK DIAGRAM VIN 7V - 42V C1 1.0 VIN 3 C2 1.0 7V REGULATOR 5 PA R1 OPEN LM25575 1.225V 2 SD STANDBY VCC SHUTDOWN 0.7V SD C12 OPEN R2 OPEN 10 SS BST UVLO C7 0.022 DRIVER S Q 1.225V 16 VIN DIS CLK 10 PA C4 0.01 C8 0.47 THERMAL SHUTDOWN UVLO 1 R Q LEVEL SHIFT PWM 0.7V PRE 15 C_LIMIT 6 FB C6 open C5 0.01 R4 49.
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LM25575, LM25575-Q1 SNVS479G – JANUARY 2007 – REVISED APRIL 2013 www.ti.com An auxiliary supply voltage can be applied to the Vcc pin to reduce the IC power dissipation. If the auxiliary voltage is greater than 7.3V, the internal regulator will essentially shut off, reducing the IC power dissipation. The Vcc regulator series pass transistor includes a diode between Vcc and Vin that should not be forward biased in normal operation. Therefore the auxiliary Vcc voltage should never exceed the Vin voltage.
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LM25575, LM25575-Q1 www.ti.com SNVS479G – JANUARY 2007 – REVISED APRIL 2013 LM25575 SYNC SW SYNC AGND CLK SW 500 ns Figure 3. Sync from External Clock LM25575 SYNC LM25575 SYNC UP TO 5 TOTAL DEVICES Figure 4. Sync from Multiple Devices Multiple LM25575 devices can be synchronized together simply by connecting the SYNC pins together. In this configuration all of the devices will be synchronized to the highest frequency device.
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LM25575, LM25575-Q1 SNVS479G – JANUARY 2007 – REVISED APRIL 2013 www.ti.com Error Amplifier and PWM Comparator The internal high gain error amplifier generates an error signal proportional to the difference between the regulated output voltage and an internal precision reference (1.225V). The output of the error amplifier is connected to the COMP pin allowing the user to provide loop compensation components, generally a type II network, as illustrated in Typical Application Circuit and Block Diagram.
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LM25575, LM25575-Q1 www.ti.com SNVS479G – JANUARY 2007 – REVISED APRIL 2013 For duty cycles greater than 50%, peak current mode control circuits are subject to sub-harmonic oscillation. Sub-harmonic oscillation is normally characterized by observing alternating wide and narrow pulses at the switch node. Adding a fixed slope voltage ramp (slope compensation) to the current sense signal prevents this oscillation.
PAGE 14
LM25575, LM25575-Q1 SNVS479G – JANUARY 2007 – REVISED APRIL 2013 www.ti.com Soft-Start The soft-start feature allows the regulator to gradually reach the initial steady state operating point, thus reducing start-up stresses and surges. The internal soft-start current source, set to 10µA, gradually increases the voltage of an external soft-start capacitor connected to the SS pin. The soft-start capacitor voltage is connected to the reference input of the error amplifier.
PAGE 15
LM25575, LM25575-Q1 www.ti.com SNVS479G – JANUARY 2007 – REVISED APRIL 2013 L1 The inductor value is determined based on the operating frequency, load current, ripple current, and the minimum and maximum input voltage (VIN(min), VIN(max)). L1 Current IPK+ IRIPPLE IO IPK- 1/Fs 0 mA Figure 8. Inductor Current Waveform To keep the circuit in continuous conduction mode (CCM), the maximum ripple current IRIPPLE should be less than twice the minimum load current, or 0.4Ap-p.
PAGE 16
LM25575, LM25575-Q1 SNVS479G – JANUARY 2007 – REVISED APRIL 2013 www.ti.com The forward voltage drop has a significant impact on the conversion efficiency, especially for applications with a low output voltage. “Rated” current for diodes vary widely from various manufacturers. The worst case is to assume a short circuit load condition. In this case the diode will carry the output current almost continuously. For the LM25575 this current can be as high as 2.1A.
PAGE 17
LM25575, LM25575-Q1 www.ti.com SNVS479G – JANUARY 2007 – REVISED APRIL 2013 Capacitor C12 provides filtering for the divider. The voltage at the SD pin should never exceed 8V, when using an external set-point divider it may be necessary to clamp the SD pin at high input voltage conditions. The reference design utilizes the full range of the LM25575 (6V to 42V); therefore these components can be omitted. With the SD pin open circuit the LM25575 responds once the Vcc UVLO threshold is satisfied.
PAGE 18
LM25575, LM25575-Q1 SNVS479G – JANUARY 2007 – REVISED APRIL 2013 www.ti.com For the design example, a target loop bandwidth (crossover frequency) of 15kHz was selected. The compensation network zero (fZ) should be selected at least an order of magnitude less than the target crossover frequency. This constrains the product of R4 and C5 for a desired compensation network zero 1 / (2π R4 C5) to be less than 2kHz. Increasing R4, while proportionally decreasing C5, increases the error amp gain.
PAGE 19
LM25575, LM25575-Q1 www.ti.com SNVS479G – JANUARY 2007 – REVISED APRIL 2013 BIAS POWER DISSIPATION REDUCTION Buck regulators operating with high input voltage can dissipate an appreciable amount of power for the bias of the IC. The VCC regulator must step-down the input voltage VIN to a nominal VCC level of 7V. The large voltage drop across the VCC regulator translates into a large power dissipation within the Vcc regulator.
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LM25575, LM25575-Q1 SNVS479G – JANUARY 2007 – REVISED APRIL 2013 www.ti.com PCB LAYOUT AND THERMAL CONSIDERATIONS The circuit in Typical Application Circuit and Block Diagram serves as both a block diagram of the LM25575 and a typical application board schematic for the LM25575. In a buck regulator there are two loops where currents are switched very fast. The first loop starts from the input capacitors, to the regulator VIN pin, to the regulator SW pin, to the inductor then out to the load.
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LM25575, LM25575-Q1 www.ti.com SNVS479G – JANUARY 2007 – REVISED APRIL 2013 Table 1. 5V, 1.5A Demo Board Bill of Materials ITEM PART NUMBER DESCRIPTION VALUE C 1 C3225X7R2A105M CAPACITOR, CER, TDK C 2 C3225X7R2A105M CAPACITOR, CER, TDK C 3 C0805A471K1GAC CAPACITOR, CER, KEMET 470p, 100V C 4 C2012X7R2A103K CAPACITOR, CER, TDK 0.01µ, 100V C 5 C2012X7R2A103K CAPACITOR, CER, TDK 0.01µ, 100V C 6 OPEN NOT USED C 7 C2012X7R2A223K CAPACITOR, CER, TDK 0.
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LM25575, LM25575-Q1 SNVS479G – JANUARY 2007 – REVISED APRIL 2013 www.ti.com PCB Layout Figure 14. Component Side Figure 15. Solder Side Figure 16.
PAGE 23
LM25575, LM25575-Q1 www.ti.com SNVS479G – JANUARY 2007 – REVISED APRIL 2013 Typical Schematic for High Frequency (1MHz) Application BST 9V - 32V 0.022P VIN 10P 3.3V, 1.5A SD 1P SW 5.11k SYNC CMSH3-40 COMP LM25575 130P IS 49.9k 3.01k GND 0.01P OUT FB RAMP RT SS VCC 3.57k 0.1P 100p 0.
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LM25575, LM25575-Q1 SNVS479G – JANUARY 2007 – REVISED APRIL 2013 www.ti.com REVISION HISTORY Changes from Revision F (April 2013) to Revision G • 24 Page Changed layout of National Data Sheet to TI format ..........................................................................................................
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PACKAGE OPTION ADDENDUM www.ti.
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PACKAGE OPTION ADDENDUM www.ti.com 1-Nov-2013 (5) Multiple Device Markings will be inside parentheses. Only one Device Marking contained in parentheses and separated by a "~" will appear on a device. If a line is indented then it is a continuation of the previous line and the two combined represent the entire Device Marking for that device. (6) Lead/Ball Finish - Orderable Devices may have multiple material finish options. Finish options are separated by a vertical ruled line.
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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 HTSSOP PWP 16 2500 330.0 12.4 LM25575Q0MHX/NOPB HTSSOP PWP 16 2500 330.0 LM25575QMHX/NOPB PWP 16 2500 330.0 LM25575MHX/NOPB HTSSOP Reel Reel A0 Diameter Width (mm) (mm) W1 (mm) B0 (mm) K0 (mm) P1 (mm) 6.95 8.3 1.6 8.0 12.0 Q1 12.4 6.95 8.3 1.6 8.0 12.0 Q1 12.4 6.95 8.3 1.6 8.0 12.
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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) LM25575MHX/NOPB HTSSOP PWP 16 2500 367.0 367.0 35.0 LM25575Q0MHX/NOPB HTSSOP PWP 16 2500 367.0 367.0 35.0 LM25575QMHX/NOPB HTSSOP PWP 16 2500 367.0 367.0 35.
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MECHANICAL DATA PWP0016A MXA16A (Rev A) www.ti.
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