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LM2825

www.ti.com

SNVS127C –MAY 1997–REVISED APRIL 2013

LM2825 Integrated Power Supply 1A DC-DC Converter

Check for Samples: LM2825

FEATURES

DESCRIPTION

The LM2825 is a complete 1A DC-DC Buck converter

• Minimum Design Time Required

packaged in a 24-lead molded Dual-In-Line integrated

• 3.3V, 5V and 12V Fixed Output Versions

circuit package.

• Two Adjustable Versions Allow 1.23V to 15V

Contained within the package are all the active and

Outputs

passive components for a high efficiency step-down

• Wide Input Voltage Range, up to 40V

(buck) switching regulator. Available in fixed output

voltages of 3.3V, 5V and 12V, as well as two

• Low-Power Standby Mode, I

Typically 65 μA

adjustable versions, these devices can provide up to

• High Efficiency, Typically 80%

1A of load current with fully ensured electrical

• ±4% Output Voltage Tolerance

specifications.

• Excellent Line and Load Regulation

Self-contained, this converter is also fully protected

• TTL Shutdown Capability/Programmable Soft-

from output fault conditions, such as excessive load

Start

current, short circuits, or excessive temperatures.

• Thermal Shutdown and Current Limit

Protection

• −40°C to +85°C Ambient Temperature Range

APPLICATIONS

• Simple High-Efficiency Step-Down (Buck)

Regulator

• On-Card Switching Regulators

• Efficient Pre-Regulator for Linear Regulators

Standard Application

• Distributed Power Systems

(Fixed output voltage versions)

• DC/DC Module Replacement

HIGHLIGHTS

• No External Components Required (Fixed

Output Voltage Versions)

• Integrated Circuit Reliability

• MTBF Over 20 Million Hours

• Radiated EMI Meets Class B Stipulated by

Radiated EMI

CISPR 22

Radiated emission of electromagnetic fields is

• High Power Density, 35 W/in

measured at 10m distance. The emission levels are

within the Class B limits stipulated by CISPR 22.

• 24-pin PDIP Package Profile (1.25 x 0.54 x 0.26

Inches)

30. . . .230 MHz 30 dB μV/m

230. . . .1000 MHz 37 dB μV/m

1. . . .10 GHz 46 dB μV/m

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.

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 (21 pages)

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LM2825 www.ti.com SNVS127C – MAY 1997 – REVISED APRIL 2013 LM2825 Integrated Power Supply 1A DC-DC Converter Check for Samples: LM2825 FEATURES DESCRIPTION • • • The LM2825 is a complete 1A DC-DC Buck converter packaged in a 24-lead molded Dual-In-Line integrated circuit package. 1 • • • • • • • • Minimum Design Time Required 3.3V, 5V and 12V Fixed Output Versions Two Adjustable Versions Allow 1.
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LM2825 SNVS127C – MAY 1997 – REVISED APRIL 2013 www.ti.com Connection Diagram “NC (Do not use)” pins: See Figure 25 Figure 1. PDIP Package Top View See Package Number NFL 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) Maximum Input Supply (VIN) +45V SD/SS Pin Input Voltage (3) Output Pin Voltage 6V (3.3V, 5.
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LM2825 www.ti.com SNVS127C – MAY 1997 – REVISED APRIL 2013 LM2825-3.3 Electrical Characteristics (1) Specifications with standard type face are for TA = 25°C, and those with boldface type apply over full Operating Temperature Range. Test Circuit, see Figure 17. Symbol Parameter Conditions LM2825-3.3 Typical (2) VOUT Output Voltage Line Regulation 4.75V ≤ VIN ≤ 40V, 0.1A ≤ ILOAD ≤ 1A 4.75V ≤ VIN ≤ 40V Limit (3) Units (Limits) 3.3 V 3.168/3.135 V(min) 3.432/3.465 V(max) 1.
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LM2825 SNVS127C – MAY 1997 – REVISED APRIL 2013 www.ti.com LM2825-12 Electrical Characteristics (1) Specifications with standard type face are for TA = 25°C, and those with boldface type apply over full Operating Temperature Range. Test Circuit, see Figure 17. Symbol Parameter Conditions LM2825-12 Typical (2) VOUT Output Voltage Line Regulation 15V ≤ VIN ≤ 40V, 0.1A ≤ ILOAD ≤ 0.75A Limit (3) 12.0 15V ≤ VIN ≤ 40V Units (Limits) V 11.52/11.40 V(min) 12.48/12.60 V(max) 8.
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LM2825 www.ti.com SNVS127C – MAY 1997 – REVISED APRIL 2013 All Output Voltage Versions Electrical Characteristics Specifications with standard type face are for TA = 25°C, and those with boldface type apply over full Operating Range. Unless otherwise specified, VIN = 12V for 3.3V, 5.0V and ADJ versions, VIN = 24V for 12V and H-ADJ versions, ILOAD = 100 mA. Symbol Parameter Conditions LM2825-XX Typical (1) ICL DC Output Current Limit RL = 0Ω Limit (2) Units (Limits) 1.4 A 1.2 A(min) 2.
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LM2825 SNVS127C – MAY 1997 – REVISED APRIL 2013 www.ti.com Typical Performance Characteristics (Circuits of Figure 17 and Figure 18) Unless otherwise specified, VIN = 12V for 3.3V, 5.0V and ADJ versions, VIN = 24V for 12V and H-ADJ versions, ILOAD = 100 mA, TA = 25°C 6 Normalized Output Voltage Efficiency Figure 2. Figure 3. Dropout Voltage Line Regulation Figure 4. Figure 5. Load Regulation Output Ripple Voltage Figure 6. Figure 7.
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LM2825 www.ti.com SNVS127C – MAY 1997 – REVISED APRIL 2013 Typical Performance Characteristics (continued) (Circuits of Figure 17 and Figure 18) Unless otherwise specified, VIN = 12V for 3.3V, 5.0V and ADJ versions, VIN = 24V for 12V and H-ADJ versions, ILOAD = 100 mA, TA = 25°C Operating Quiescent Current Shutdown Quiescent Current Figure 8. Figure 9. Switching Frequency Soft-start Figure 10. Figure 11. Shutdown/Soft-start Current Soft-start Response Figure 12. Figure 13.
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LM2825 SNVS127C – MAY 1997 – REVISED APRIL 2013 www.ti.com Typical Performance Characteristics (continued) (Circuits of Figure 17 and Figure 18) Unless otherwise specified, VIN = 12V for 3.3V, 5.0V and ADJ versions, VIN = 24V for 12V and H-ADJ versions, ILOAD = 100 mA, TA = 25°C Switch Current Limit Adjust Pin Bias Current Figure 14. Figure 15.
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LM2825 www.ti.com SNVS127C – MAY 1997 – REVISED APRIL 2013 Test Circuit *Optional—Required if package is more than 6″ away from main filter or bypass capacitor. **Optional Soft-start Capacitor VIN = 40V (max) VOUT = 3.3V or 5V @ 1A or 12V @ 0.75A Figure 17. Standard Test Circuit (Fixed Output Voltage Versions) *Optional—Required if package is more than 6″ away from main filter or bypass capacitor. **Optional Soft-start Capacitor ***Optional—See Application Information. VIN = 40V (max) VOUT = 1.
PAGE 10
LM2825 SNVS127C – MAY 1997 – REVISED APRIL 2013 www.ti.com APPLICATION INFORMATION PROGRAMMING OUTPUT VOLTAGE (Selecting R1 and R2 as shown in Figure 18) The LM2825 is available in two adjustable output versions. The LM2825-ADJ has been optimized for output voltages between 1.23V and 8V, while the LM2825H-ADJ covers the output voltage range of 7V to 15V. Both adjustable versions are set in the following way. (1) Select a value for R1 between 240Ω and 1.5 kΩ.
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LM2825 www.ti.com SNVS127C – MAY 1997 – REVISED APRIL 2013 LOWERING OUTPUT RIPPLE When using the adjustable parts, one can achieve lower output ripple voltage by shorting a resistor internal to the LM2825. However, if this resistor is shorted, a feed forward capacitor must be used to keep the regulator stable. For this reason, this resistor must be left open on all of the fixed output voltage versions or instability will result. See the FEED FORWARD CAPACITOR SELECTION (CFF) selection below.
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LM2825 SNVS127C – MAY 1997 – REVISED APRIL 2013 www.ti.com Figure 19. Usage of the Soft-start Capacitor OUTPUT CURRENT DERATING FOR TJ = −40°C to −25°C AND TJ = −25°C to 0°C At the lower temperature extremes, the switch current limit drops off sharply. As a result, a lower output current is available in this temperature range. See Figure 20 and Figure 21 for the typical available output current at these temperature ranges. Figure 20.
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LM2825 www.ti.com SNVS127C – MAY 1997 – REVISED APRIL 2013 Figure 21.
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LM2825 SNVS127C – MAY 1997 – REVISED APRIL 2013 www.ti.com OUTPUT CURRENT DERATING FOR TA = 0°C to 70°C Due to the limited switch current, the LM2825 cannot supply the full one ampere output current over the entire input and output voltage range. Figure 22 shows the typical available output current for any input and output voltage combination. This applies for all output voltage versions. Figure 22.
PAGE 15
LM2825 www.ti.com SNVS127C – MAY 1997 – REVISED APRIL 2013 OUTPUT CURRENT DERATING FOR TA = 70°C to 85°C At high these high ambient temperatures, the LM2825 cannot supply the full one ampere over the entire input and output voltage range. This is due to thermal reasons and Figure 23 shows the typical available output current for any input and output voltage combination. This applies for all output voltage versions. Figure 23. LM2825 Output Current Derating for TA = 70°C to 85°C Figure 24.
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LM2825 SNVS127C – MAY 1997 – REVISED APRIL 2013 www.ti.com TYPICAL THROUGH HOLE PC BOARD LAYOUT (2X SIZE), SINGLE SIDED, THROUGH HOLE PLATED Note: Holes are not shown. “No Connect Pins” are connected to copper pads for thermal reasons only and must remain electrically isolated. Figure 25.
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LM2825 www.ti.com SNVS127C – MAY 1997 – REVISED APRIL 2013 REVISION HISTORY Changes from Revision B (April 2013) to Revision C • 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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MECHANICAL DATA NFL0024F N0024F NA24F (Rev D) www.ti.
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