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LM25011, LM25011-Q1

www.ti.com

SNVS617G –APRIL 2009–REVISED FEBRUARY 2013

LM25011, LM25011Q, LM25011A, LM25011AQ

42V 2A Constant On-Time Switching Regulator With Adjustable Current Limit

Check for Samples: LM25011, LM25011-Q1

FEATURES

• Thermal Shutdown

• Precision 2% Feedback Reference

• LM25011Q is an Automotive Grade Product

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

• Package: 10-Pin, VSSOP

+125°C Operating Junction Temperature)

DESCRIPTION

• LM25011A Allows Low Dropout Operation at

The LM25011 Constant On-time Step-Down

High Switching Frequency

Switching Regulator features all the functions needed

• Input Operating Voltage Range: 6V to 42V

to implement a low cost, efficient, buck bias regulator

• Absolute Maximum Input Rating: 45V

capable of supplying up to 2A of load current. This

• Integrated 2A N-Channel Buck Switch

high voltage regulator contains an N-Channel Buck

switch, a startup regulator, current limit detection, and

• Adjustable Current Limit Allows for Smaller

internal ripple control. The constant on-time

Inductor

regulation principle requires no loop compensation,

• Adjustable Output Voltage from 2.51V

results in fast load transient response, and simplifies

• Minimum Ripple Voltage at V

OUT

circuit implementation. The operating frequency

remains constant with line and load. The adjustable

• Power Good Output

valley current limit detection results in a smooth

• Switching Frequency Adjustable to 2 MHz

transition from constant voltage to constant current

• COT Topology Features:

mode when current limit is reached, without the use

of current limit foldback. The PGD output indicates

– Switching Frequency Remains Nearly

the output voltage has increased to within 5% of the

Constant with Load Current and Input

expected regulation value. Additional features

Voltage Variations

include: Low output ripple, VIN under-voltage lock-

– Ultra-Fast Transient Response

out, adjustable soft-start timing, thermal shutdown,

gate drive pre-charge, gate drive under-voltage lock-

– No Loop Compensation Required

out, and maximum duty cycle limit.

– Stable Operation with Ceramic Output

Capacitors

The LM25011A has a shorter minimum off-time than

the LM25011, which allows for higher frequency

– Allows for Smaller Output Capacitor and

operation at low input voltages.

Current Sense Resistor

• Adjustable Soft-Start Timing

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 (27 pages)

PAGE 1
LM25011, LM25011-Q1 www.ti.
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LM25011, LM25011-Q1 SNVS617G – APRIL 2009 – REVISED FEBRUARY 2013 www.ti.com TYPICAL APPLICATION 6V to 42V Input VIN BST CBST LM25011 CIN RT L1 SW D1 RT VOUT CS RPGD VPGD Power Good RS PGD COUT RFB2 CSG SS CSS SGND FB RFB1 CONNECTION DIAGRAM Exposed Pad on Bottom Connect to Ground VIN 1 10 BST RT 2 9 SW PGD 3 8 CS SS 4 7 CSG SGND 5 6 FB Figure 1.
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LM25011, LM25011-Q1 www.ti.com SNVS617G – APRIL 2009 – REVISED FEBRUARY 2013 PIN DESCRIPTIONS Pin No. Name Description Application Information 1 VIN Input supply voltage 2 RT On-time Control An external resistor from VIN to this pin sets the buck switch on-time, and the switching frequency. 3 PGD Power Good Logic output indicates when the voltage at the FB pin has increased to above 95% of the internal reference voltage. Hysteresis is provided.
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LM25011, LM25011-Q1 SNVS617G – APRIL 2009 – REVISED FEBRUARY 2013 www.ti.com ELECTRICAL CHARACTERISTICS Specifications with standard type are for TJ = 25°C only; limits in boldface type apply over the full Operating Junction Temperature (TJ) range. Minimum and Maximum limits are guaranteed through test, design, or statistical correlation. Typical values represent the most likely parametric norm at TJ = 25°C, and are provided for reference purposes only.
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LM25011, LM25011-Q1 www.ti.com SNVS617G – APRIL 2009 – REVISED FEBRUARY 2013 ELECTRICAL CHARACTERISTICS (continued) Specifications with standard type are for TJ = 25°C only; limits in boldface type apply over the full Operating Junction Temperature (TJ) range. Minimum and Maximum limits are guaranteed through test, design, or statistical correlation. Typical values represent the most likely parametric norm at TJ = 25°C, and are provided for reference purposes only.
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LM25011, LM25011-Q1 SNVS617G – APRIL 2009 – REVISED FEBRUARY 2013 www.ti.com TYPICAL PERFORMANCE CHARACTERISTICS 6 Efficiency (Circuit of Figure 21) Efficiency at 2 MHz Figure 2. Figure 3. On-Time vs VIN and RT Voltage at the RT Pin Figure 4. Figure 5. Shutdown Current into VIN Operating Current into VIN Figure 6. Figure 7.
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LM25011, LM25011-Q1 www.ti.com SNVS617G – APRIL 2009 – REVISED FEBRUARY 2013 TYPICAL PERFORMANCE CHARACTERISTICS (continued) PGD Low Voltage vs. Sink Current Reference Voltage vs. Temperature Figure 8. Figure 9. Current Limit Threshold vs. Temperature Operating Current vs. Temperature Figure 10. Figure 11. VIN UVLO vs. Temperature SS Pin ShutdownThreshold vs. Temperature Figure 12. Figure 13.
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LM25011, LM25011-Q1 SNVS617G – APRIL 2009 – REVISED FEBRUARY 2013 www.ti.com TYPICAL PERFORMANCE CHARACTERISTICS (continued) On-Time vs. Temperature Minimum Off-Time vs. Temperature 190 MINIMUM OFF-TIME (ns) 170 LM25011 150 130 110 90 LM25011A 70 50 -40 -20 0 20 40 60 80 100 120 JUNCTION TEMPERATURE (°C) Figure 14. Figure 15. BLOCK DIAGRAM 6V to 42V LM25011(A) VIN 5V REGULATOR Input CIN CBYP UVLO CL RT THERMAL SHUTDOWN OFF TIMER ON TIMER RT FINISH START START FINISH BST 2.
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LM25011, LM25011-Q1 www.ti.com SNVS617G – APRIL 2009 – REVISED FEBRUARY 2013 UVLO VIN SW Pin Inductor Current SS Pin VOUT PGD t1 Figure 17.
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LM25011, LM25011-Q1 SNVS617G – APRIL 2009 – REVISED FEBRUARY 2013 www.ti.com FUNCTIONAL DESCRIPTION The LM25011 Constant On-time Step-down Switching Regulator features all the functions needed to implement a low cost, efficient buck bias power converter capable of supplying up to 2.0A to the load. This high voltage regulator contains an N-Channel buck switch, is easy to implement, and is available in a 10-pin VSSOP, PowerPAD power enhanced package.
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LM25011, LM25011-Q1 www.ti.com SNVS617G – APRIL 2009 – REVISED FEBRUARY 2013 Ripple voltage, which is required at the input of the regulation comparator for proper output regulation, is generated internally in the LM25011, and externally when the LM25011A is used. In the LM25011 the ERM (Emulated Ripple Mode) control circuit generates the required internal ripple voltage from the ripple waveform at the CS pin.
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LM25011, LM25011-Q1 SNVS617G – APRIL 2009 – REVISED FEBRUARY 2013 www.ti.com IPK IOCL Current Limit Threshold IO2 'I Inductor Current IO1 0V Voltage at the CS Pin Voltage at the FB Pin 2.51V Load Current Increases Normal Operation Current Limited Load Current Decreases Normal Operation Figure 18. Normal and Current Limit Operation RIPPLE REQUIREMENTS The LM25011 requires about 25mVp-p of ripple voltage at the CS pin. Higher switching frequency may require more ripple.
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LM25011, LM25011-Q1 www.ti.com SNVS617G – APRIL 2009 – REVISED FEBRUARY 2013 N-CHANNEL BUCK SWITCH AND DRIVER The LM25011 integrates an N-Channel buck switch and associated floating high voltage gate driver. The gate driver circuit works in conjunction with an external bootstrap capacitor (CBST) and an internal high voltage diode. A 0.1 µF capacitor connected between BST and SW provides the supply voltage for the driver during the ontime.
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LM25011, LM25011-Q1 SNVS617G – APRIL 2009 – REVISED FEBRUARY 2013 www.ti.com THERMAL SHUTDOWN The LM25011 should be operated so the junction temperature does not exceed 125°C. If the junction temperature increases above that, an internal Thermal Shutdown circuit activates (typically) at 155°C, taking the controller to a low power reset state by disabling the buck switch and taking the SS pin to ground. This feature helps prevent catastrophic failures from accidental device overheating.
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LM25011, LM25011-Q1 www.ti.com SNVS617G – APRIL 2009 – REVISED FEBRUARY 2013 APPLICATIONS INFORMATION EXTERNAL COMPONENTS The procedure for calculating the external components is illustrated with a design example using the LM25011. Referring to the Block Diagram, the circuit is to be configured for the following specifications: • VOUT = 5V • VIN = 8V to 36V • Minimum load current for continuous conduction mode (IOUT(min) = 300 mA • Maximum load current (IOUT(max) = 1.5 A • Switching frequency (FS) = 1.
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LM25011, LM25011-Q1 SNVS617G – APRIL 2009 – REVISED FEBRUARY 2013 www.ti.com RS: The minimum current limit threshold is calculated at maximum load current, using the minimum ripple current calculated above. The current limit threshold is the lower peak of the inductor current waveform when in current limit (see Figure 18). ILIM = 1.5A – (0.2 A/2) = 1.4A (14) Current limit detection occurs when the voltage across the sense resistor (RS) reaches the current limit threshold.
PAGE 17
LM25011, LM25011-Q1 www.ti.com SNVS617G – APRIL 2009 – REVISED FEBRUARY 2013 CSS: The capacitor at the SS pin determines the soft-start time, i.e. the time for the output voltage to reach its final value (t1 in Figure 17). For a soft-start time of 5 ms, the capacitor value is determined from the following: 5 ms x 10 PA = 0.02 PF CSS = 2.51V (21) D1: A Schottky diode is recommended.
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LM25011, LM25011-Q1 SNVS617G – APRIL 2009 – REVISED FEBRUARY 2013 www.ti.com OUTPUT RIPPLE CONTROL (LM25011A) The LM25011A most likely will require more ripple voltage than is generated across the RS resistor. Additional ripple can be supplied to the FB pin, in phase with the switching waveform at the SW pin, for proper operation. The required ripple can be supplied from ripple generated at VOUT, through the feedback resistors, as described in Option A below.
PAGE 19
LM25011, LM25011-Q1 www.ti.com R1 = SNVS617G – APRIL 2009 – REVISED FEBRUARY 2013 VRIPPLE 'I (24) where ΔI is the minimum ripple current amplitude, which occurs at minimum Vin. The minimum value for Cff is calculated from: 3 x tON(max) Cff > RFB1//RFB2 (25) where tON(max) is the maximum on-time (at minimum VIN), and RFB1//RFB2 is the parallel equivalent of the feedback resistors.
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LM25011, LM25011-Q1 SNVS617G – APRIL 2009 – REVISED FEBRUARY 2013 www.ti.com where RL is the inductor’s DC resistance, and the 1.1 factor is an approximation for the AC losses. If it is expected that the internal dissipation of the LM25011 will produce excessive junction temperatures during normal operation, good use of the PC board’s ground plane can help to dissipate heat. Additionally the use of wide PC board traces, where possible, can help conduct heat away from the IC pins.
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LM25011, LM25011-Q1 www.ti.com SNVS617G – APRIL 2009 – REVISED FEBRUARY 2013 REVISION HISTORY Changes from Revision F (February 2013) to Revision G • 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 20-May-2014 (3) MSL, Peak Temp. - The Moisture Sensitivity Level rating according to the JEDEC industry standard classifications, and peak solder temperature. (4) There may be additional marking, which relates to the logo, the lot trace code information, or the environmental category on the device. (5) Multiple Device Markings will be inside parentheses. Only one Device Marking contained in parentheses and separated by a "~" will appear on a device.
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PACKAGE MATERIALS INFORMATION www.ti.com 20-May-2014 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 LM25011AMY MSOPPower PAD DGQ 10 1000 178.0 12.4 5.3 3.4 1.4 8.0 12.0 Q1 LM25011AMYE MSOPPower PAD DGQ 10 250 178.0 12.4 5.3 3.4 1.4 8.0 12.0 Q1 LM25011AMYX MSOPPower PAD DGQ 10 3500 330.0 12.4 5.3 3.4 1.4 8.0 12.
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PACKAGE MATERIALS INFORMATION www.ti.com 20-May-2014 Device Package Package Pins Type Drawing SPQ Reel Reel A0 Diameter Width (mm) (mm) W1 (mm) B0 (mm) K0 (mm) P1 (mm) 3.4 1.4 8.0 W Pin1 (mm) Quadrant Power PAD LM25011Q1MYX/NOPB MSOPPower PAD DGQ 10 3500 330.0 12.4 5.3 12.0 Q1 *All dimensions are nominal Device Package Type Package Drawing Pins SPQ Length (mm) Width (mm) Height (mm) LM25011AMY MSOP-PowerPAD DGQ 10 1000 213.0 191.0 55.
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MECHANICAL DATA DGQ0010A MUC10A (Rev A) BOTTOM VIEW www.ti.
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