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An IMPORTANT NOTICE at the end of this data sheet addresses availability, warranty, changes, use in safety-critical applications,

intellectual property matters and other important disclaimers. PRODUCTION DATA.

LM2591HV

SNVS074E –MAY 2001–REVISED MAY 2016

LM2591HV SIMPLE SWITCHER

Power Converter 150-kHz, 1-A Step-Down Voltage

Regulator

1 Features

1• 3.3-V, 5-V, and Adjustable Output Versions

• Adjustable Version Output Voltage Range: 1.2 V

to 57 V ±4% Maximum Over Line and Load

Conditions

• Specified 1-A Output Load Current

• Available in 5-Pin Package

• Input Voltage Range Up to 60 V

• 150-kHz Fixed Frequency Internal Oscillator

• ON and OFF Control

• Low Power Standby Mode, IQTypically 90 μA

• High Efficiency

• Thermal Shutdown and Current-Limit Protection

2 Applications

• Simple High-Efficiency Step-Down (Buck)

Regulators

• Efficient Preregulator for Linear Regulators

• On-Card Switching Regulators

• Positive-to-Negative Converters

3 Description

The LM2591HV series of regulators are monolithic

integrated circuits that provide all the active functions

for a step-down (buck) switching regulator, capable of

driving a 1-A load with excellent line and load

regulation. These devices are available in fixed output

voltages of 3.3 V, 5 V, and an adjustable output

version.

This series of switching regulators is similar to the

LM2590HV, but without some of the supervisory and

control features of the latter.

Requiring a minimum number of external

components, these regulators are simple to use and

include internal frequency compensation, improved

line and load specifications, and a fixed-frequency

oscillator.

The LM2591HV operates at a switching frequency of

150 kHz, thus allowing smaller sized filter

components than what would be needed with lower

frequency switching regulators. Available in a

standard 5-pin package with several different lead

bend options, and a 5-pin surface mount package.

Device Information(1)

PART

NUMBER PACKAGE BODY SIZE (NOM)

LM2591HV DDPAK/TO-263 (5) 10.18 mm × 8.41 mm

TO-220 (5) 14.986 mm × 10.16 mm

(1) For all available packages, see the orderable addendum at

the end of the data sheet.

Typical Application

(Fixed Output Voltage Versions)

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Table of Contents

1 Features.................................................................. 1

2 Applications ........................................................... 1

3 Description............................................................. 1

4 Revision History..................................................... 2

5 Description (continued)......................................... 3

6 Pin Configuration and Functions......................... 3

7 Specifications......................................................... 4

7.1 Absolute Maximum Ratings ...................................... 4

7.2 ESD Ratings.............................................................. 4

7.3 Recommended Operating Conditions....................... 4

7.4 Thermal Information.................................................. 4

7.5 Electrical Characteristics LM2591HV-3.3 ................. 5

7.6 Electrical Characteristics LM2591HV-5.0 ................. 5

7.7 Electrical Characteristics LM2591HV-ADJ................ 5

7.8 Electrical Characteristics All Output Voltage

Versions..................................................................... 6

7.9 Typical Characteristics.............................................. 7

8 Parameter Measurement Information ................ 10

8.1 Test Circuits............................................................ 10

9 Detailed Description............................................ 11

9.1 Overview................................................................. 11

9.2 Functional Block Diagram....................................... 11

9.3 Feature Description................................................. 11

9.4 Device Functional Modes........................................ 13

10 Application and Implementation........................ 14

10.1 Application Information.......................................... 14

10.2 Typical Application ............................................... 18

11 Power Supply Recommendations ..................... 21

12 Layout................................................................... 21

12.1 Layout Guidelines ................................................. 21

12.2 Layout Examples................................................... 22

13 Device and Documentation Support................. 24

13.1 Community Resources.......................................... 24

13.2 Trademarks........................................................... 24

13.3 Electrostatic Discharge Caution............................ 24

13.4 Glossary................................................................ 24

14 Mechanical, Packaging, and Orderable

Information........................................................... 24

4 Revision History

NOTE: Page numbers for previous revisions may differ from page numbers in the current version.

Changes from Revision D (April 2013) to Revision E Page

• Added ESD Ratings table, Feature Description section, Device Functional Modes,Application and Implementation

section, Power Supply Recommendations section, Layout section, Device and Documentation Support section, and

Mechanical, Packaging, and Orderable Information section.................................................................................................. 1

Changes from Revision C (April 2013) to Revision D Page

• Changed layout of National Data Sheet to TI format ........................................................................................................... 21

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5 Description (continued)

Other features include a specified ±4% tolerance on output voltage under all conditions of input voltage and

output load conditions, and ±15% on the oscillator frequency. External shutdown is included, featuring typically

90-μA standby current. Self-protection features include a two stage current limit for the output switch and an over

temperature shutdown for complete protection under fault conditions.

6 Pin Configuration and Functions

KTT Package

5-Pin DDPAK/TO-26

Top View NDH Package

5-Pin TO-220

Top View

Pin Functions

PIN I/O DESCRIPTION

NO. NAME

1 +VIN IThis is the positive input supply for the IC switching regulator. A suitable input bypass

capacitor must be present at this pin to minimize voltage transients and to supply the

switching currents needed by the regulator.

2 Output O Internal switch. The voltage at this pin switches between approximately (+VIN −VSAT) and

approximately −0.5 V, with a duty cycle of VOUT/VIN.

3 Ground — Circuit ground.

4 Feedback I

Senses the regulated output voltage to complete the feedback loop. This pin is directly

connected to the Output for the fixed voltage versions, but is set to 1.23 V by means of a

resistive divider from the output for the Adjustable version. If a feedforward capacitor is used

(Adjustable version), then a negative voltage spike is generated on this pin whenever the

output is shorted. This happens because the feedforward capacitor cannot discharge fast

enough, and because one end of it is dragged to Ground, the other end goes momentarily

negative. To prevent the energy rating of this pin from being exceeded, a small-signal

Schottky diode to Ground is recommended for DC input voltages above 40 V whenever a

feedforward capacitor is present (See Test Circuits). Feedforward capacitor values larger

than 0.1 μF are not recommended for the same reason, whatever be the DC input voltage.

5 ON/OFF I The regulator is in shutdown mode, drawing about 90 μA, when this pin is driven to a high

level (≥2 V), and is in normal operation when this Pin is left floating or driven to a low level

(≤0.6 V). The typical value of the threshold is 1.3 V and the voltage on this pin must not

exceed 25 V.

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(1) Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. These are stress ratings

only, which do not imply functional operation of the device at these or any other conditions beyond those indicated under Recommended

Operating Conditions. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.

(2) If Military/Aerospace specified devices are required, please contact the TI Sales Office/ Distributors for availability and specifications.

7 Specifications

7.1 Absolute Maximum Ratings(1)(2)

MIN MAX UNIT

Maximum supply voltage (VIN) 63 V

ON/OFF pin voltage −0.3 25 V

Feedback pin voltage −0.3 25 V

Output voltage to ground (Steady-state) −1 V

Power dissipation Internally limited

Lead temperature KTT package Vapor phase (60 sec.) 215 °CInfrared (10 sec.) 245

NDH package (Soldering, 10 sec.) 260

Maximum junction temperature 150 °C

Storage temperature, Tstg −65 150 °C

(1) JEDEC document JEP155 states that 500-V HBM allows safe manufacturing with a standard ESD control process.

(2) The human body model is a 100-pF capacitor discharged through a 1.5-kΩresistor into each pin.

7.2 ESD Ratings VALUE UNIT

V(ESD) Electrostatic discharge Human-body model (HBM), per ANSI/ESDA/JEDEC JS-001(1)(2) ±2000 V

7.3 Recommended Operating Conditions MIN MAX UNIT

Temperature −40 125 °C

Supply voltage 4.5 60 V

(1) For more information about traditional and new thermal metrics, see the Semiconductor and IC Package Thermal Metrics application

report, SPRA953.

(2) The package thermal impedance is calculated in accordance to JESD 51-7

(3) Thermal Resistances were simulated on a 4-layer, JEDEC board

7.4 Thermal Information

THERMAL METRIC(1) LM2591HV

UNITKTT (DDPAK/TO-263) NDH (TO-220)

5 PINS 5 PINS

RθJA Junction-to-ambient thermal resistance See (2)(3) 50 50 °C/W

RθJC(top) Junction-to-case (top) thermal resistance 2 2 °C/W

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(1) All limits ensured at room temperature (TJ= 25°C) unless otherwise noted. All room temperature limits are 100% production tested. All

limits at temperature extremes are ensured through correlation using standard Statistical Quality Control (SQC) methods. All limits are

used to calculate Average Outgoing Quality Level (AOQL).

(2) Typical numbers are at 25°C and represent the most likely norm.

(3) External components such as the catch diode, inductor, input and output capacitors can affect switching regulator system performance.

When the LM2591HV is used as shown in Test Circuits test circuit, system performance will be as shown in Electrical Characteristics.

7.5 Electrical Characteristics LM2591HV-3.3

Specifications are for TJ= 25°C unless otherwise noted.

PARAMETER TEST CONDITIONS MIN(1) TYP(2) MAX(1) UNIT

SYSTEM PARAMETERS – See Test Circuits(3)

VOUT Output Voltage 4.75 V ≤VIN ≤60 V,

0.2 A ≤ILOAD ≤1 A 3.168 3.3 3.432 V

TA= –40°C to 125°C 3.135 3.465

ηEfficiency VIN = 12 V, ILOAD = 1 A 77%

(1) All limits ensured at room temperature (TJ= 25°C) unless otherwise noted. All room temperature limits are 100% production tested. All

limits at temperature extremes are ensured through correlation using standard Statistical Quality Control (SQC) methods. All limits are

used to calculate Average Outgoing Quality Level (AOQL).

(2) Typical numbers are at 25°C and represent the most likely norm.

(3) External components such as the catch diode, inductor, input and output capacitors can affect switching regulator system performance.

When the LM2591HV is used as shown in Test Circuits test circuit, system performance will be as shown in Electrical Characteristics.

7.6 Electrical Characteristics LM2591HV-5.0

Specifications are for TJ= 25°C unless otherwise noted.

PARAMETER TEST CONDITIONS MIN(1) TYP(2) MAX(1) UNIT

SYSTEM PARAMETERS – See Test Circuits(3)

VOUT Output Voltage 7 V ≤VIN ≤60 V, 0.2 A ≤ILOAD ≤1 A 4.8 5 5.2 V

TA= –40°C to 125°C 4.75 5.25

ηEfficiency VIN = 12 V, ILOAD = 1 A 82%

(1) All limits ensured at room temperature (TJ= 25°C) unless otherwise noted. All room temperature limits are 100% production tested. All

limits at temperature extremes are ensured through correlation using standard Statistical Quality Control (SQC) methods. All limits are

used to calculate Average Outgoing Quality Level (AOQL).

(2) Typical numbers are at 25°C and represent the most likely norm.

(3) External components such as the catch diode, inductor, input and output capacitors can affect switching regulator system performance.

When the LM2591HV is used as shown in Test Circuits test circuit, system performance will be as shown in Electrical Characteristics.

7.7 Electrical Characteristics LM2591HV-ADJ

Specifications are for TJ= 25°C unless otherwise noted

PARAMETER TEST CONDITIONS MIN(1) TYP(2) MAX(1) UNIT

SYSTEM PARAMETERS – See Test Circuits(3)

VFB Feedback Voltage 4.5 V ≤VIN ≤60 V, 0.2 A ≤ILOAD ≤1 A

VOUT programmed for 3 V. Circuit of

Test Circuits.

1.193 1.23 1.267 V

TA= –40°C to 125°C 1.18 1.28

ηEfficiency VIN = 12 V, VOUT = 3 V, ILOAD = 1 A 76%

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(1) All limits ensured at room temperature (TJ= 25°C) unless otherwise noted. All room temperature limits are 100% production tested. All

limits at temperature extremes are ensured through correlation using standard Statistical Quality Control (SQC) methods. All limits are

used to calculate Average Outgoing Quality Level (AOQL).

(2) Typical numbers are at 25°C and represent the most likely norm.

(3) The switching frequency is reduced when the second stage current limit is activated. The amount of reduction is determined by the

severity of current overload.

(4) No diode, inductor or capacitor connected to output pin.

(5) Feedback pin removed from output and connected to 0 V to force the output transistor switch ON.

(6) Feedback pin removed from output and connected to 12 V for the 3.3-V, 5-V, and the ADJ. version to force the output transistor switch

OFF.

(7) VIN = 60 V.

7.8 Electrical Characteristics All Output Voltage Versions

Specifications are for TJ= 25°C, ILOAD = 500 mA, and VIN = 12V for the 3.3-V, 5-V, and adjustable versions, unless otherwise

noted. PARAMETER TEST CONDITIONS MIN(1) TYP(2) MAX(1) UNIT

DEVICE PARAMETERS

IbFeedback Bias Current Adjustable Version Only, VFB = 1.3 V 10 50 nA

TA= –40°C to 125°C 100

fOOscillator Frequency See (3) 127 150 173 kHz

TA= –40°C to 125°C 110 173

VSAT Saturation Voltage IOUT = 1 A (4)(5) 0.95 1.2 V

TA= –40°C to 125°C 1.3

DC Max Duty Cycle (ON) See (5)(6) 100%

Min Duty Cycle (OFF) 0%

ICLIM Switch current Limit Peak Current(4)(5) 1.3 1.9 2.8 A

TA= –40°C to 125°C 1.2 3.0

ILOutput Leakage Current Output = 0 V 5 50 μA

Output = −1 V (4)(6)(7) 5 30 mA

IQOperating Quiescent

Current SD/SS Pin Open (6) 510 mA

ISTBY Standby Quiescent

Current SD/SS pin = 0 V (7) 90 200 μA

TA= –40°C to 125°C 250

ON/OFF CONTROL – See Test Circuits

VIH

VIL

ON/OFF Pin Logic Input

Threshold Voltage Low (Regulator ON)

High (Regulator OFF) 1.3 V

TA= –40°C to 125°C 2.0 0.6

IHON/OFF Pin Input

Current VLOGIC = 2.5 V (Regulator OFF) 5 15 μA

ILVLOGIC = 0.5 V (Regulator ON) 0.02 5 μA

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7.9 Typical Characteristics

(Circuit of Test Circuits)

Figure 1. Normalized Output Voltage Figure 2. Line Regulation

Figure 3. Efficiency Figure 4. Switch Saturation Voltage

Figure 5. Switch Current Limit Figure 6. Dropout Voltage

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Typical Characteristics (continued)

(Circuit of Test Circuits)

Figure 7. Operating Quiescent Current Figure 8. Shutdown Quiescent Current

Figure 9. Minimum Operating Supply Voltage Figure 10. Feedback Pin Bias Current

Figure 11. Switching Frequency Figure 12. ON/OFF Threshold Voltage

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Typical Characteristics (continued)

(Circuit of Test Circuits)

Figure 13. ON/OFF Pin Current (Sinking) Figure 14. Internal Gain-Phase Characteristics

Continuous Mode Switching Waveforms VIN = 20V, VOUT = 5V,

ILOAD = 1A L = 52 μH, COUT = 100 μF, COUT ESR = 100 mΩ

Output Pin Voltage, 10V/div.

Inductor Current 0.5A/div.

Output Ripple Voltage, 50 mV/div.

Figure 15. Horizontal Time Base: 2 μs/div

Discontinuous Mode Switching Waveforms VIN = 20V, VOUT = 5V,

ILOAD = 250 mA L = 15 μH, COUT = 150 μF, COUT ESR = 90 mΩ

Output Pin Voltage, 10V/div.

Inductor Current 0.25A/div.

Output Ripple Voltage, 100 mV/div.

Figure 16. Horizontal Time Base: 2 μs/div

Load Transient Response for Continuous Mode VIN = 20V, VOUT =

5V, ILOAD = 250 mA to 1A L = 52 μH, COUT = 100 μF, COUT ESR =

100 mΩ

Output Voltage, 100 mV/div. (AC)

250 mA to 1A Load Pulse

Figure 17. Horizontal Time Base: 50 μs/div

Load Transient Response for Discontinuous Mode VIN = 20V,

VOUT = 5V, ILOAD = 250 mA to 1A L = 15 μH, COUT = 150 μF, COUT

ESR = 90 mΩ

Output Voltage, 100 mV/div. (AC)

250 mA to 1A Load Pulse

Figure 18. Horizontal Time Base: 200 μs/div

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8 Parameter Measurement Information

8.1 Test Circuits

Component Values shown are for VIN = 15V,

VOUT = 5V, ILOAD = 1A.

CIN — 470 μF, 50V, Aluminum Electrolytic Nichicon “PM Series”

COUT — 220 μF, 25V Aluminum Electrolytic, Nichicon “PM Series”

D1 — 2A, 60V Schottky Rectifier, 21DQ06 (International Rectifier)

L1 — 68 H, See Inductor Selection Procedure

Figure 19. Fixed Output Voltage Versions

Select R1to be approximately 1 kΩ, use a 1% resistor for best stability.

Component Values shown are for VIN = 20V,

VOUT = 10V, ILOAD = 1A.

CIN: — 470 μF, 35V, Aluminum Electrolytic Nichicon “PM Series”

COUT: — 220 μF, 35V Aluminum Electrolytic, Nichicon “PM Series”

D1 — 2A, 60V Schottky Rectifier, 21DQ06 (International Rectifier)

See Inductor Selection Procedure L1 — 100 μH,

R1— 1 kΩ, 1%

R2— 7.15k, 1%

CFF — 3.3 nF

Typical Values

CSS—0.1 μF

CDELAY—0.1 μF

RPULL UP — 4.7k (use 22k if VOUT is ≥45V)

† Small signal Schottky diode to prevent damage to feedback pin by negative spike when output is shorted. Required

if VIN > 40V

Figure 20. Adjustable Output Voltage Versions

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9 Detailed Description

9.1 Overview

The LM2591HV SIMPLE SWITCHER®regulator is an easy-to-use, nonsynchronous, step-down DC-DC

converter with a wide input voltage range up to 60 V. The regulator is capable of delivering up to 1-A DC load

current with excellent line and load regulation. These devices are available in fixed output voltages of 3.3 V, 5 V,

and an adjustable output version. The family requires few external components, and the pin arrangement was

designed for simple, optimum PCB layout.

9.2 Functional Block Diagram

9.3 Feature Description

9.3.1 Delayed Start-Up

The circuit in Figure 21 uses the ON/OFF pin to provide a time delay between the time the input voltage is

applied and the time the output voltage comes up (only the circuitry pertaining to the delayed start-up is shown).

As the input voltage rises, the charging of capacitor C1 pulls the ON/OFF pin high, keeping the regulator off.

When the input voltage reaches its final value and the capacitor stops charging, the resistor R2pulls the ON/OFF

pin low, thus allowing the circuit to start switching. Resistor R1is included to limit the maximum voltage applied to

the ON/OFF pin (maximum of 25 V), reduces power supply noise sensitivity, and also limits the capacitor, C1,

discharge current. When high input ripple voltage exists, avoid long delay time, because this ripple can be

coupled into the ON/OFF pin and cause problems.

This delayed start-up feature is useful in situations where the input power source is limited in the amount of

current it can deliver. It allows the input voltage to rise to a higher voltage before the regulator starts operating.

Buck regulators require less input current at higher input voltages.

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Feature Description (continued)

Figure 21. Delayed Start-Up

9.3.2 Undervoltage Lockout

Some applications require the regulator to remain off until the input voltage reaches a predetermined voltage. An

undervoltage lockout feature applied to a buck regulator is shown in Figure 22, while Figure 23 and Figure 24

applies the same feature to an inverting circuit. The circuit in Figure 23 features a constant threshold voltage for

turnon and turnoff (Zener voltage plus approximately one volt). If hysteresis is needed, the circuit in Figure 24

has a turnon voltage which is different than the turnoff voltage. The amount of hysteresis is approximately equal

to the value of the output voltage. If Zener voltages greater than 25 V are used, an additional 47-kΩresistor is

needed from the ON/OFF pin to the ground pin to stay within the 25-V maximum limit of the ON/OFF pin.

Figure 22. Undervoltage Lockout for Buck Regulator

This circuit has an ON/OFF threshold of approximately 13 V.

Figure 23. Undervoltage Lockout for Inverting Regulator

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9.4 Device Functional Modes

9.4.1 Shutdown Mode

The ON/OFF pin provides electrical ON and OFF control for the LM2591HV. When the voltage of this pin is

higher than 2 V, the device is shutdown mode. The typical standby current in this mode is 90 μA.

9.4.2 Active Mode

When the ON/OFF pin is left floating or pull below 0.6 V, the device starts switching and the output voltage rises

until it reaches a normal regulation voltage.

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10 Application and Implementation

NOTE

Information in the following applications sections is not part of the TI component

specification, and TI does not warrant its accuracy or completeness. TI’s customers are

responsible for determining suitability of components for their purposes. Customers should

validate and test their design implementation to confirm system functionality.

10.1 Application Information

10.1.1 Feedforward Capacitor

CFF – A feedforward capacitor, shown across R2 in Test Circuits, is used when the output voltage is greater than

10 V or when COUT has a very low ESR. This capacitor adds lead compensation to the feedback loop and

increases the phase margin for better loop stability.

If the output voltage ripple is large (>5% of the nominal output voltage), this ripple can be coupled to the

feedback pin through the feedforward capacitor and cause the error comparator to trigger the error flag. In this

situation, adding a resistor, RFF, in series with the feedforward capacitor, approximately 3 times R1, will attenuate

the ripple voltage at the feedback pin.

10.1.2 Input Capacitor

CIN – A low ESR aluminum or tantalum bypass capacitor is needed between the input pin and ground pin. It must

be placed near the regulator using short leads. This capacitor prevents large voltage transients from appearing at

the input, and provides the instantaneous current needed each time the switch turns on.

The important parameters for the Input capacitor are the voltage rating and the RMS current rating. Because of

the relatively high RMS currents flowing in a buck regulator's input capacitor, this capacitor should be chosen for

its RMS current rating rather than its capacitance or voltage ratings, although the capacitance value and voltage

rating are directly related to the RMS current rating. The voltage rating of the capacitor and its RMS ripple current

capability must never be exceeded.

10.1.3 Output Capacitor

COUT – An output capacitor is required to filter the output and provide regulator loop stability. Low impedance or

low ESR Electrolytic or solid tantalum capacitors designed for switching regulator applications must be used.

When selecting an output capacitor, the important capacitor parameters are the 100-kHz Equivalent Series

Resistance (ESR), the RMS ripple current rating, voltage rating, and capacitance value. For the output capacitor,

the ESR value is the most important parameter. The ESR must generally not be less than 100 mΩor there will

be loop instability. If the ESR is too large, efficiency and output voltage ripple are effected, so ESR must be

chosen carefully.

10.1.4 Catch Diode

Buck regulators require a diode to provide a return path for the inductor current when the switch turns off. This

must be a fast diode and must be placed close to the LM2591HV using short leads and short printed-circuit

traces.

Because of their very fast switching speed and low forward voltage drop, Schottky diodes provide the best

performance, especially in low output voltage applications (5 V and lower). Ultra-fast recovery, or high-efficiency

rectifiers are also a good choice, but some types with an abrupt turnoff characteristic may cause instability or

EMI problems. Ultra-fast recovery diodes typically have reverse recovery times of 50 ns or less. The diode must

be chosen for its average/RMS current rating and maximum voltage rating. The voltage rating of the diode must

be greater than the DC input voltage (not the output voltage).

10.1.5 Inverting Regulator

The circuit in Figure 25 converts a positive input voltage to a negative output voltage with a common ground. The

circuit operates by bootstrapping the regulator's ground pin to the negative output voltage, then grounding the

feedback pin. The regulator senses and regulates the inverted output voltage.

( )

IN OUT IN OUT

PEAK LOAD

IN IN OUT

V V V V 10

I I

V2 L f V V

æ ö

+ ´ ´

= ´ +

ç ÷ ´ ´ ´ +

è ø

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Application Information (continued)

This example uses the LM2591HV-5.0 to generate a −5-V output, but other output voltages are possible by

selecting other output voltage versions, including the adjustable version. Because this regulator topology can

produce an output voltage that is either greater than or less than the input voltage, the maximum output current

greatly depends on both the input and output voltage.

To determine how much load current is possible before the internal device current limit is reached (and power

limiting occurs), the system must be evaluated as a buck-boost configuration rather than as a buck. The peak

switch current in amperes, for such a configuration is given as Equation 1:

where

• L is in μH

• and f is in Hz

• The maximum possible load current ILOAD is limited by the requirement that IPEAK ≤ICLIM (1)

While checking for this, take ICLIM to be the lowest possible current limit value (minimum across tolerance and

temperature is 1.2 A for the LM2591HV). Also to account for inductor tolerances, take the minimum value of

inductance for L in Equation 1 (typically 20% less than the nominal value). Further, Equation 1 disregards the

drop across the switch and the diode. This is equivalent to assuming 100% efficiency, which is never so.

Therefore expect IPEAK to be an additional 10% to 20% higher than calculated from Equation 1.

See Application Note AN-1157 (SNVA022) for examples based on positive to negative configuration.

The maximum voltage appearing across the regulator is the absolute sum of the input and output voltage, and

this must be limited to a maximum of 60 V. For example, when converting +20 V to −12 V, the regulator would

see 32 V between the input pin and ground pin. The LM2591HV has a maximum input voltage spec of 60 V.

Additional diodes are required in this regulator configuration. Diode D1 is used to isolate input voltage ripple or

noise from coupling through the CIN capacitor to the output, under light or no load conditions. Also, this diode

isolation changes the topology to closely resemble a buck configuration thus providing good closed loop stability.

A Schottky diode is recommended for low input voltages, (because of its lower voltage drop) but for higher input

voltages, a fast recovery diode could be used.

Without diode D3, when the input voltage is first applied, the charging current of CIN can pull the output positive

by several volts for a short period of time. Adding D3 prevents the output from going positive by more than a

diode voltage.

This circuit has hysteresis

Regulator starts switching at VIN= 13 V

Regulator stops switching at VIN= 8 V

Figure 24. Undervoltage Lockout With Hysteresis for Inverting Regulator

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Application Information (continued)

CIN —68-μF, 25-V Tant. Sprague 595D

470 μF/50V Elec. Panasonic HFQ

COUT—47-μF, 20-V Tant. Sprague 595D

220-μF, 25-V Elec. Panasonic HFQ

Figure 25. Inverting −5-V Regulator With Delayed Start-Up

Because of differences in the operation of the inverting regulator, the standard design procedure is not used to

select the inductor value. In the majority of designs, a 33-μH, 3-A inductor is the best choice. Capacitor selection

can also be narrowed down to just a few values.

This type of inverting regulator can require relatively large amounts of input current when starting up, even with

light loads. Input currents as high as the LM2591HV current limit (approx 4 A) are needed for at least 2 ms or

more, until the output reaches its nominal output voltage. The actual time depends on the output voltage and the

size of the output capacitor. Input power sources that are current-limited or sources that can not deliver these

currents without getting loaded down, may not work correctly. Because of the relatively high start-up currents

required by the inverting topology, the delayed start-up feature (C1, R1, and R2) shown in Figure 25 is

recommended. By delaying the regulator start-up, the input capacitor is allowed to charge up to a higher voltage

before the switcher begins operating. A portion of the high input current needed for start-up is now supplied by

the input capacitor (CIN). For severe start-up conditions, the input capacitor can be made much larger than

normal.

LM2591HV

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Application Information (continued)

10.1.6 Inverting Regulator Shutdown Methods

Using the ON/OFF pin in a standard buck configuration is simple. To turn the regulator ON, pull the ON/OFF pin

below 1.3 V (at 25°C, referenced to ground). To turn regulator OFF, pull the ON/OFF pin above 1.3 V. With the

inverting configuration, some level shifting is required, because the ground pin of the regulator is no longer at

ground, but is now setting at the negative output voltage level. Two different shutdown methods for inverting

regulators are shown in Figure 26 and Figure 27.

Figure 26. Inverting Regulator Ground Referenced Shutdown

Figure 27. Inverting Regulator Ground Referenced Shutdown Using Opto Device

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10.2 Typical Application

Figure 28. Typical Application

10.2.1 Design Requirements

Table 1 lists the parameters for this design example.

Table 1. Example Parameters

PARAMETER EXAMPLE VALUE

Regulated output voltage, VOUT 20 V

Maximum input voltage, VIN(max) 24 V

Maximum load current, ILOAD(max) 1 A

Switching frequency, F Fixed at a nominal 150 kHz

10.2.2 Detailed Design Procedure

10.2.2.1 Inductor Selection Procedure

See Application Note AN-1197 (SNVA038) for detailed information on selecting inductors for buck converters.

For a quick-start, the designer may refer to the nomographs provided in Figure 29 to Figure 31. To give

designers more options of available inductors, the nomographs provide the required inductance and also the

energy in the core expressed in microjoules (µJ), as an alternative to just prescribing custom parts. The following

points must be highlighted:

1. The energy values shown on the nomographs apply to steady operation at the corresponding x-coordinate

(rated maximum load current). However, under start-up, without soft start, or a short circuit on the output, the

current in the inductor will momentarily or repetitively hit the current limit ICLIM of the device, and this current

could be much higher than the rated load, ILOAD. This represents an overload situation, and can cause the

inductor to saturate (if it has been designed only to handle the energy of steady operation). However, most

types of core structures used for such applications have a large inherent air gap (for example, powdered iron

types or ferrite rod inductors), so the inductance does not fall off too sharply under an overload. The device

is usually able to protect itself by preventing the current from exceeding ICLIM. However, if the DC input

voltage to the regulator is over 40 V, the current can slew up so fast under core saturation that the device

may not be able to act fast enough to restrict the current. The current can then rise without limit until the

device is destroyed.

NOTE

To ensure reliability, TI recommends that, if the DC Input Voltage exceeds 40 V, the

inductor must be sized to handle an instantaneous current equal to ICLIM without

saturating, irrespective of the type of core structure or material

D = VOUT + VD

VIN - VSAT + VD

eCLIM = 1

2x 100 x 32 = 450 PJ

eCLIM = 1

2x L x ICLIM2 PJ

e = 1

2x L x IPEAK2 PJ

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2. The energy under steady operation is given in Equation 2:

where

• L is in µH

• IPEAK is the peak of the inductor current waveform with the regulator delivering ILOAD. (2)

These are the energy values shown in the nomographs. See Example 1.

3. The energy under overload is given in Equation 3:

(3)

If VIN > 40 V, the inductor must be sized to handle eCLIM instead of the steady energy values. The worst case

ICLIM for the LM2591HV is 3 A. The energy rating depends on the inductance. See Example 2.

4. The nomographs were generated by allowing a greater amount of percentage current ripple in the inductor

as the maximum rated load decreases (see Figure 32). This was done to allow smaller inductors to be used

at light loads. However, Figure 32 shows only the median value of the current ripple. In reality there may be

a great spread around this because the nomographs approximate the exact calculated inductance to

standard available values. It is a good idea to refer to AN-1197 (SNVA038) for detailed calculations if a

certain maximum inductor current ripple is required for various possible reasons. Also consider the rather

wide tolerance on the nominal inductance of commercial inductors.

5. Figure 31 shows the inductor selection curves for the Adjustable version. The y-axis is 'Et', in Vμsecs. It is

the applied volts across the inductor during the ON time of the switch (VIN – VSAT – VOUT) multiplied by the

time for which the switch is on in μs. See Example 3.

Example 1: (VIN ≤40 V) LM2591HV-5.0, VIN = 24 V, Output 5 V at 0.8 A

1. A first pass inductor selection is based upon inductance and rated max load current. Choose an inductor with

the inductance value indicated by the nomograph (see Figure 30) and a current rating equal to the maximum

load current. Therefore, quick-select a 100-μH, 0.8-A inductor (designed for 150-kHz operation) for this

application.

2. Confirm that it is rated to handle 50 μJ (see Figure 30) by either estimating the peak current or by a detailed

calculation as shown in AN-1197 (SNVA038). Also, confirm that the losses are acceptable.

Example 2: (VIN > 40 V) LM2591HV-5.0, VIN = 48 V, Output 5 V at 1 A

1. A first pass inductor selection is based upon inductance and the switch currrent limit. We choose an inductor

with the inductance value indicated by the nomograph (Figure 30) and a current rating equal to ICLIM.

Therefore, quick-select a 100-μH, 3-A inductor (designed for 150-kHz operation) for this application.

2. Confirm that it is rated to handle eCLIM by the procedure shown in AN-1197 (SNVA038) and that the losses

are acceptable. Here eCLIM is calculated using Equation 4:

(4)

Example 3: (VIN ≤40 V) LM2591HV-ADJ, VIN = 20 V, Output 10 V at 1 A

1. Because input voltage is less than 40 V, a first pass inductor selection is based upon inductance and rated

maximum load current. We choose an inductor with the inductance value indicated by the nomograph

Figure 31 and a current rating equal to the maximum load. First, calculate Et for the given application. The

duty cycle is calculated with Equation 5:

where

• VDis the drop across the catch diode (≊0.5 V for a Schottky)

• VSAT the drop across the switch (≊1.5 V) (5)

= (20 - 1.5 - 10) x 0.55

Et = (VIN - VSAT - VOUT) x tON

150000 x 106 VPsecs

= 31.3 VPsecs

tON = D

fx 106 Ps

D = 10 + 0.5

20 - 1.5 + 0.5 = 0.55

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Substituting in the values gives Equation 6:

(6)

And the switch ON time is calculated with Equation 7:

where

• f is the switching frequency in Hz (7)

(8)

Therefore, looking at Figure 29, quick-select a 100-μH, 1-A inductor (designed for 150-kHz operation) for this

application.

2. Confirm that the inductor is rated to handle 100 μJ (see Figure 31) by the procedure shown in AN-1197

(SNVA038) and that the losses are acceptable. (If the DC input voltage is greater than 40 V, consider eCLIM

as shown in Example 2).

NOTE

Take VSAT as 1.5 V which includes an estimated resistive drop across the inductor.

This completes the simplified inductor selection procedure. See AN-1197 (SNVA038), for more general

applications and better optimization.

10.2.3 Application Curves

(For Continuous Mode Operation)

Figure 29. LM2591HV-3.3 Figure 30. LM2591HV-5.0

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(For Continuous Mode Operation)

Figure 31. LM2591HV-ADJ Figure 32. Current Ripple Ratio

11 Power Supply Recommendations

The LM2591HV is designed to operate from an input voltage supply up to 60 V. This input supply must be well

regulated, able to withstand maximum input current, and maintain a stable voltage.

12 Layout

12.1 Layout Guidelines

As in any switching regulator, layout is very important. Rapid switching currents associated with wiring

inductance can generate voltage transients, which can cause problems. For minimal inductance and ground

loops (see Test Circuits), the wires indicated by heavy lines must be wide printed-circuit traces and must be kept

as short as possible. For best results, external components must be placed as close to the switcher lC as

possible using ground plane construction or single-point grounding.

If open core inductors are used, take special care as to the location and positioning of this type of inductor.

Allowing the inductor flux to intersect sensitive feedback, lC groundpath, and COUT wiring can cause problems.

When using the adjustable version, take special care as to the location of the feedback resistors and the

associated wiring. Physically place both resistors near the IC, and route the wiring away from the inductor,

especially an open core type of inductor.

LM2591HV

SNVS074E –MAY 2001–REVISED MAY 2016

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Product Folder Links: LM2591HV

12.2 Layout Examples

CIN = 470-μF, 50-V, aluminum electrolytic Panasonic HFQ Series

COUT = 330-μF, 35-V, aluminum electrolytic Panasonic HFQ Series

D1 = 5-A, 40-V Schottky rectifier, 1N5825

L1 = 47-μH, L39, Renco through hole

RPULL UP = 10k

CDELAY = 0.1 μF

CSD/SS = 0.1 μF

Thermalloy heat sink #7020

Figure 33. Typical Through-Hole PCB Layout, Fixed Output (1x Size), Double-Sided

LM2591HV

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Layout Examples (continued)

CIN = 470-μF, 50-V, aluminum electrolytic Panasonic, HFQ Series

COUT = 220-μF, 35-V, aluminum electrolytic Panasonic, HFQ Series

D1 = 5-A, 40-V Schottky Rectifier, 1N5825

L1 = 47-μH, L39, Renco, through-hole

R1= 1 kΩ, 1%

R2= Use formula in Detailed Design Procedure

RFF = See Feedforward Capacitor

RPULL UP = 10k

CDELAY = 0.1 μF

CSD/SS= 0.1 μF

Thermalloy heat sink #7020

Figure 34. Typical Through-Hole PCB Layout, Adjustable Output (1x Size), Double-Sided

LM2591HV

SNVS074E –MAY 2001–REVISED MAY 2016

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Product Folder Links: LM2591HV

13 Device and Documentation Support

13.1 Community Resources

The following links connect to TI community resources. Linked contents are provided "AS IS" by the respective

contributors. They do not constitute TI specifications and do not necessarily reflect TI's views; see TI's Terms of

Use.

TI E2E™ Online Community TI's Engineer-to-Engineer (E2E) Community. Created to foster collaboration

among engineers. At e2e.ti.com, you can ask questions, share knowledge, explore ideas and help

solve problems with fellow engineers.

Design Support TI's Design Support Quickly find helpful E2E forums along with design support tools and

contact information for technical support.

13.2 Trademarks

E2E is a trademark of Texas Instruments.

SIMPLE SWITCHER is a registered trademark of Texas Instruments.

All other trademarks are the property of their respective owners.

13.3 Electrostatic Discharge Caution

These devices have limited built-in ESD protection. The leads should be shorted together or the device placed in conductive foam

during storage or handling to prevent electrostatic damage to the MOS gates.

13.4 Glossary

SLYZ022 —TI Glossary.

This glossary lists and explains terms, acronyms, and definitions.

14 Mechanical, Packaging, and Orderable Information

The following pages include mechanical, packaging, and orderable information. This information is the most

current data available for the designated devices. This data is subject to change without notice and revision of

this document. For browser-based versions of this data sheet, refer to the left-hand navigation.

PACKAGE OPTION ADDENDUM

www.ti.com 11-Jan-2021

Addendum-Page 1

PACKAGING INFORMATION

Orderable Device Status

(1)

Package Type Package

Drawing Pins Package

Qty Eco Plan

(2)

Lead finish/

Ball material

(6)

MSL Peak Temp

(3)

Op Temp (°C) Device Marking

(4/5)

Samples

LM2591HVS-3.3/NOPB ACTIVE DDPAK/

TO-263 KTT 5 45 RoHS-Exempt

& Green SN Level-3-245C-168 HR -40 to 125 LM2591HVS

-3.3 P+

LM2591HVS-5.0/NOPB ACTIVE DDPAK/

TO-263 KTT 5 45 RoHS-Exempt

& Green SN Level-3-245C-168 HR -40 to 125 LM2591HVS

-5.0 P+

LM2591HVS-ADJ NRND DDPAK/

TO-263 KTT 5 45 Non-RoHS

& Green Call TI Call TI -40 to 125 LM2591HVS

-ADJ P+

LM2591HVS-ADJ/NOPB ACTIVE DDPAK/

TO-263 KTT 5 45 RoHS-Exempt

& Green SN Level-3-245C-168 HR -40 to 125 LM2591HVS

-ADJ P+

LM2591HVSX-3.3/NOPB ACTIVE DDPAK/

TO-263 KTT 5 500 RoHS-Exempt

& Green SN Level-3-245C-168 HR -40 to 125 LM2591HVS

-3.3 P+

LM2591HVSX-5.0/NOPB ACTIVE DDPAK/

TO-263 KTT 5 500 RoHS-Exempt

& Green SN Level-3-245C-168 HR -40 to 125 LM2591HVS

-5.0 P+

LM2591HVSX-ADJ/NOPB ACTIVE DDPAK/

TO-263 KTT 5 500 RoHS-Exempt

& Green SN Level-3-245C-168 HR -40 to 125 LM2591HVS

-ADJ P+

LM2591HVT-3.3/NOPB ACTIVE TO-220 NDH 5 45 RoHS & Green SN Level-1-NA-UNLIM -40 to 125 LM2591HVT

-3.3 P+

LM2591HVT-5.0/NOPB ACTIVE TO-220 NDH 5 45 RoHS & Green SN Level-1-NA-UNLIM -40 to 125 LM2591HVT

-5.0 P+

LM2591HVT-ADJ/NOPB ACTIVE TO-220 NDH 5 45 RoHS & Green SN Level-1-NA-UNLIM -40 to 125 LM2591HVT

-ADJ P+

(1) The marketing status values are defined as follows:

ACTIVE: Product device recommended for new designs.

LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect.

NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in a new design.

PREVIEW: Device has been announced but is not in production. Samples may or may not be available.

OBSOLETE: TI has discontinued the production of the device.

(2) RoHS: TI defines "RoHS" to mean semiconductor products that are compliant with the current EU RoHS requirements for all 10 RoHS substances, including the requirement that RoHS substance

do not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, "RoHS" products are suitable for use in specified lead-free processes. TI may

reference these types of products as "Pb-Free".

RoHS Exempt: TI defines "RoHS Exempt" to mean products that contain lead but are compliant with EU RoHS pursuant to a specific EU RoHS exemption.

Green: TI defines "Green" to mean the content of Chlorine (Cl) and Bromine (Br) based flame retardants meet JS709B low halogen requirements of <=1000ppm threshold. Antimony trioxide based

flame retardants must also meet the <=1000ppm threshold requirement.

PACKAGE OPTION ADDENDUM

www.ti.com 11-Jan-2021

Addendum-Page 2

(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. 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 finish/Ball material - Orderable Devices may have multiple material finish options. Finish options are separated by a vertical ruled line. Lead finish/Ball material values may wrap to two

lines if the finish value exceeds the maximum column width.

Important Information and Disclaimer:The information provided on this page represents TI's knowledge and belief as of the date that it is provided. TI bases its knowledge and belief on information

provided by third parties, and makes no representation or warranty as to the accuracy of such information. Efforts are underway to better integrate information from third parties. TI has taken and

continues to take reasonable steps to provide representative and accurate information but may not have conducted destructive testing or chemical analysis on incoming materials and chemicals.

TI and TI suppliers consider certain information to be proprietary, and thus CAS numbers and other limited information may not be available for release.

In no event shall TI's liability arising out of such information exceed the total purchase price of the TI part(s) at issue in this document sold by TI to Customer on an annual basis.

TAPE AND REEL INFORMATION

*All dimensions are nominal

Device Package

Type Package

Drawing Pins SPQ Reel

Diameter

(mm)

Reel

Width

W1 (mm)

(mm) B0

(mm) K0

(mm) P1

(mm) W

(mm) Pin1

Quadrant

LM2591HVSX-3.3/NOPB DDPAK/

TO-263 KTT 5 500 330.0 24.4 10.75 14.85 5.0 16.0 24.0 Q2

LM2591HVSX-5.0/NOPB DDPAK/

TO-263 KTT 5 500 330.0 24.4 10.75 14.85 5.0 16.0 24.0 Q2

LM2591HVSX-ADJ/NOPB DDPAK/

TO-263 KTT 5 500 330.0 24.4 10.75 14.85 5.0 16.0 24.0 Q2

PACKAGE MATERIALS INFORMATION

www.ti.com 27-Jan-2016

Pack Materials-Page 1

*All dimensions are nominal

Device Package Type Package Drawing Pins SPQ Length (mm) Width (mm) Height (mm)

LM2591HVSX-3.3/NOPB DDPAK/TO-263 KTT 5 500 367.0 367.0 45.0

LM2591HVSX-5.0/NOPB DDPAK/TO-263 KTT 5 500 367.0 367.0 45.0

LM2591HVSX-ADJ/NOPB DDPAK/TO-263 KTT 5 500 367.0 367.0 45.0

PACKAGE MATERIALS INFORMATION

www.ti.com 27-Jan-2016

Pack Materials-Page 2

MECHANICAL DATA

NDH0005D

www.ti.com

MECHANICAL DATA

KTT0005B

www.ti.com

BOTTOM SIDE OF PACKAGE

TS5B (Rev D)

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