Datasheet

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LM2991

www.ti.com

SNVS099H –MAY 1999–REVISED JUNE 2013

LM2991 Negative Low Dropout Adjustable Regulator

Check for Samples: LM2991

FEATURES

DESCRIPTION

The LM2991 is a low dropout adjustable negative

• Output Voltage Adjustable from −3V to −24V,

regulator with a output voltage range between −3V to

Typically −2V to −25V

−24V. The LM2991 provides up to 1A of load current

• Output Current in Excess of 1A

and features a On /Off pin for remote shutdown

• Dropout Voltage Typically 0.6V at 1A Load

capability.

• Low Quiescent Current

The LM2991 uses new circuit design techniques to

provide a low dropout voltage, low quiescent current

• Internal Short Circuit Current Limit

and low temperature coefficient precision reference.

• Internal Thermal Shutdown with Hysteresis

The dropout voltage at 1A load current is typically

• TTL, CMOS Compatible ON/OFF Switch

0.6V and an ensured worst-case maximum of 1V

• Functional Complement to the LM2941 Series

over the entire operating temperature range. The

quiescent current is typically 1 mA with a 1A load

current and an input-output voltage differential greater

APPLICATIONS

than 3V. A unique circuit design of the internal bias

• Post Switcher Regulator

supply limits the quiescent current to only 9 mA

• Local, On-Card, Regulation

(typical) when the regulator is in the dropout mode

OUT

− V

≤ 3V).

• Battery Operated Equipment

The LM2991 is short-circuit proof, and thermal

shutdown includes hysteresis to enhance the

reliability of the device when inadvertently overloaded

for extended periods. The LM2991 is available in 5-

lead TO-220 and DDPAK/TO-263 packages and is

rated for operation over the automotive temperature

range of −40°C to +125°C. Mil-Aero versions are also

available.

Typical Application

OUT

= V

REF

(1 + R2/R1)

*Required if the regulator is located further than 6 inches from the power supply filter capacitors. A 1 μF solid

tantalum or a 10 μF aluminum electrolytic capacitor is recommended.

**Required for stability. Must be at least a 10 μF aluminum electrolytic or a 1 μF solid tantalum to maintain stability.

May be increased without bound to maintain regulation during transients. Locate the capacitor as close as possible to

the regulator. The equivalent series resistance (ESR) is critical, and should be less than 10Ω over the same operating

temperature range as the regulator.

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 (19 pages)

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LM2991 www.ti.com SNVS099H – MAY 1999 – REVISED JUNE 2013 LM2991 Negative Low Dropout Adjustable Regulator Check for Samples: LM2991 FEATURES 1 • 2 • • • • • • • Output Voltage Adjustable from −3V to −24V, Typically −2V to −25V Output Current in Excess of 1A Dropout Voltage Typically 0.
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LM2991 SNVS099H – MAY 1999 – REVISED JUNE 2013 www.ti.com Connection Diagrams Front View Top View Figure 1. TO-220 Package, 5-Lead See Package Number KC and NDH Figure 2. DDPAK, TO-263 Package, 5-Lead, Surface-Mount See Package Number KTT 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. ABSOLUTE MAXIMUM RATINGS (1) (2) −26V to +0.
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LM2991 www.ti.com SNVS099H – MAY 1999 – REVISED JUNE 2013 ELECTRICAL CHARACTERISTICS VIN = −10V, VO = −3V, IO = 1A, CO = 47 μF, R1 = 2.7 kΩ, TJ = 25°C, unless otherwise specified. Boldface limits apply over the entire operating junction temperature range. Parameter Reference Voltage Output Voltage Range Conditions Typical (1) Min Max −1.210 −1.234 −1.186 −1.27 −1.
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LM2991 SNVS099H – MAY 1999 – REVISED JUNE 2013 www.ti.com TYPICAL PERFORMANCE CHARACTERISTICS 4 Dropout Voltage Normalized Output Voltage Figure 3. Figure 4. Output Voltage Output Noise Voltage Figure 5. Figure 6. Quiescent Current Maximum Output Current Figure 7. Figure 8.
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LM2991 www.ti.com SNVS099H – MAY 1999 – REVISED JUNE 2013 TYPICAL PERFORMANCE CHARACTERISTICS (continued) Line Transient Response Load Transient Response Figure 9. Figure 10. Maximum Output Current Ripple Rejection Figure 11. Figure 12. Output Impedance ON /OFF Control Voltage Figure 13. Figure 14.
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LM2991 SNVS099H – MAY 1999 – REVISED JUNE 2013 www.ti.com TYPICAL PERFORMANCE CHARACTERISTICS (continued) (1) 6 Adjust Pin Current Low Voltage Behavior Figure 15. Figure 16. Maximum Power Dissipation (TO-220) Maximum Power Dissipation (DDPAK/TO-263) (1) Figure 17. Figure 18. The maximum allowable power dissipation is a function of the maximum operating junction temperature (TJ(MAX)), the thermal resistance of the package (θJA), and the ambient temperature (TA).
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LM2991 www.ti.com SNVS099H – MAY 1999 – REVISED JUNE 2013 APPLICATION HINTS External Capacitors Like any low-dropout regulator, external capacitors are required to stabilize the control loop. These capacitors must be correctly selected for proper performance. Input Capacitor An input capacitor is required if the regulator is located more than 6 inches from the input power supply filter capacitor (or if no other input capacitor is present).
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LM2991 SNVS099H – MAY 1999 – REVISED JUNE 2013 www.ti.com Minimum Load A minimum load current of 500 μA is required for proper operation. The external resistor divider can provide the minimum load, with the resistor from the adjust pin to ground set to 2.4 kΩ. Setting the Output Voltage The output voltage of the LM2991 is set externally by a resistor divider using the following equation: VOUT = VREF x (1 + R2/R1) − (IADJ x R2) where • VREF = −1.
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LM2991 www.ti.com SNVS099H – MAY 1999 – REVISED JUNE 2013 Typical Applications Figure 20. Fully Isolated Post-Switcher Regulator Figure 21.
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LM2991 SNVS099H – MAY 1999 – REVISED JUNE 2013 www.ti.
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LM2991 www.ti.com SNVS099H – MAY 1999 – REVISED JUNE 2013 REVISION HISTORY Changes from Revision G (April 2013) to Revision H • 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 (4) 1-Nov-2013 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.
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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) LM2991SX DDPAK/ TO-263 KTT 5 500 330.0 24.4 LM2991SX/NOPB DDPAK/ TO-263 KTT 5 500 330.0 24.4 Pack Materials-Page 1 B0 (mm) K0 (mm) P1 (mm) W Pin1 (mm) Quadrant 10.75 14.85 5.0 16.0 24.0 Q2 10.75 14.85 5.0 16.0 24.
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PACKAGE MATERIALS INFORMATION www.ti.com 8-Apr-2013 *All dimensions are nominal Device Package Type Package Drawing Pins SPQ Length (mm) Width (mm) Height (mm) LM2991SX DDPAK/TO-263 KTT 5 500 367.0 367.0 45.0 LM2991SX/NOPB DDPAK/TO-263 KTT 5 500 367.0 367.0 45.
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MECHANICAL DATA NDH0005D www.ti.
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MECHANICAL DATA KTT0005B TS5B (Rev D) BOTTOM SIDE OF PACKAGE www.ti.
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