LM2679S-5.0/NOPB National Semiconductor, LM2679S-5.0/NOPB Datasheet

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LM2679S-5.0/NOPB

Manufacturer Part Number
LM2679S-5.0/NOPB
Description
IC REG SIMPLE SWITCHER TO-263-7
Manufacturer
National Semiconductor
Series
SIMPLE SWITCHER®r
Type
Step-Down (Buck)r
Datasheets

Specifications of LM2679S-5.0/NOPB

Internal Switch(s)
Yes
Synchronous Rectifier
No
Number Of Outputs
1
Voltage - Output
5V
Current - Output
5A
Frequency - Switching
260kHz
Voltage - Input
8 ~ 40 V
Operating Temperature
-40°C ~ 125°C
Mounting Type
Surface Mount
Package / Case
D²Pak, TO-263 (7 leads + tab)
Current, Input Bias
85 nA
Current, Output
5 A
Current, Supply
6 mA
Frequency, Oscillator
260 kHz
Package Type
TO-263
Regulator Type
Buck (Step-Down)
Resistance, Thermal, Junction To Case
2 °C/W
Temperature, Operating, Range
-40 to +125 °C
Voltage, Input
8 to 40 V
Voltage, Output
5 V
Primary Input Voltage
12V
No. Of Outputs
1
Output Voltage
5V
Output Current
5A
No. Of Pins
7
Operating Temperature Range
-40°C To +125°C
Msl
MSL 3 - 168 Hours
Filter Terminals
SMD
Rohs Compliant
Yes
For Use With
LM2679-5.0EVAL - EVALUATION BOARD FOR LM2679-5.0
Lead Free Status / RoHS Status
Lead free / RoHS Compliant
Power - Output
-
Lead Free Status / Rohs Status
RoHS Compliant part Electrostatic Device
Other names
*LM2679S-5.0
*LM2679S-5.0/NOPB
LM2679S-5.0
© 2008 National Semiconductor Corporation
LM2679
SIMPLE SWITCHER
Adjustable Current Limit
General Description
The LM2679 series of regulators are monolithic integrated
circuits which provide all of the active functions for a step-
down (buck) switching regulator capable of driving up to 5A
loads with excellent line and load regulation characteristics.
High efficiency (>90%) is obtained through the use of a low
ON-resistance DMOS power switch. The series consists of
fixed output voltages of 3.3V, 5V and 12V and an adjustable
output version.
The SIMPLE SWITCHER concept provides for a complete
design using a minimum number of external components. A
high fixed frequency oscillator (260KHz) allows the use of
physically smaller sized components. A family of standard in-
ductors for use with the LM2679 are available from several
manufacturers to greatly simplify the design process.
Other features include the ability to reduce the input surge
current at power-ON by adding a softstart timing capacitor to
gradually turn on the regulator. The LM2679 series also has
built in thermal shutdown and resistor programmable current
limit of the power MOSFET switch to protect the device and
load circuitry under fault conditions. The output voltage is
guaranteed to a ±2% tolerance. The clock frequency is con-
trolled to within a ±11% tolerance.
Typical Application
SIMPLE SWITCHER
®
is a registered trademark of National Semiconductor Corporation
100847
®
5A Step-Down Voltage Regulator with
Features
Applications
Efficiency up to 92%
Simple and easy to design with (using off-the-shelf
external components)
Resistor programmable peak current limit over a range of
3A to 7A.
120 mΩ DMOS output switch
3.3V, 5V and 12V fixed output and adjustable (1.2V to
37V ) versions
±2%maximum output tolerance over full line and load
conditions
Wide input voltage range: 8V to 40V
260 KHz fixed frequency internal oscillator
Softstart capability
−40 to +125°C operating junction temperature range
Simple to design, high efficiency (>90%) step-down
switching regulators
Efficient system pre-regulator for linear voltage regulators
Battery chargers
February 21, 2008
www.national.com
10084703

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LM2679S-5.0/NOPB Summary of contents

Page 1

... The output voltage is guaranteed to a ±2% tolerance. The clock frequency is con- trolled to within a ±11% tolerance. Typical Application SIMPLE SWITCHER ® registered trademark of National Semiconductor Corporation © 2008 National Semiconductor Corporation ® 5A Step-Down Voltage Regulator with Features ■ ...

Page 2

... Connection Diagrams and Ordering Information TO-263 Package Top View Order Number LM2679S-3.3, LM2679S-5.0, LM2679S-12 or LM2679S-ADJ See NSC Package Number TS7B Ordering Information for LLP Package Output Voltage Order Information 12 LM2679SD-12 12 LM2679SDX-12 3.3 LM2679SD-3.3 3.3 LM2679SDX-3.3 5.0 LM2679SD-5.0 5.0 LM2679SDX-5.0 ADJ LM2679SD-ADJ ...

Page 3

... Absolute Maximum Ratings If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications. Input Supply Voltage Softstart Pin Voltage Switch Voltage to Ground (Note 13) Boost Pin Voltage Feedback Pin Voltage Power Dissipation Electrical Characteristics of operation, −40°C to 125°C. Specifications appearing in normal type apply for T LM2679-3 ...

Page 4

All Output Voltage Versions Electrical Characteristics Limits appearing in bold type face apply over the entire junction temperature range of operation, −40°C to 125°C. Specifications appearing in normal type apply for T justable versions and V =24V for the 12V ...

Page 5

Note 1: Absolute Maximum Ratings are limits beyond which damage to the device may occur. Operating Ratings indicate conditions under which of the device is guaranteed. Operating Ratings do not imply guaranteed performance limits. For guaranteed performance limits and associated ...

Page 6

Typical Performance Characteristics Normalized Output Voltage Efficiency vs Input Voltage Switch Current Limit www.national.com 10084704 10084706 Operating Quiescent Current 10084708 6 Line Regulation 10084705 Efficiency vs I LOAD 10084707 10084709 ...

Page 7

Switching Frequency Continuous Mode Switching Waveforms V = 20V 5V OUT LOAD μ 400 μF, C OUT OUT A: V Pin Voltage, 10 V/div Inductor Current, 2 A/div C: ...

Page 8

Load Transient Response for Continuous Mode V = 20V OUT μ 400 μF, C OUT A: Output Voltage, 100 mV//div, AC-Coupled. B: Load Current: 500 Load Pulse Horizontal Time Base: ...

Page 9

... LM267X Made Simple (version 2.0) a complete switching power supply can be de- signed quickly. The software is provided free of charge and can be downloaded from National Semiconductor's Internet site located at http://www.national.com. SWITCH OUTPUT This is the output of a power MOSFET switch connected di- rectly to the input voltage ...

Page 10

DESIGN CONSIDERATIONS FIGURE 1. Basic circuit for fixed output voltage applications. FIGURE 2. Basic circuit for adjustable output voltage applications Power supply design using the LM2679 is greatly simplified by using recommended external components. A wide range of inductors, capacitors ...

Page 11

Both surface mount and through-hole devices are available. The inductors from each of the three manufacturers have unique character- istics. Renco: ferrite stick core inductors; benefits are typically low- est cost and ...

Page 12

The peak switch current is equal to a factor of 37,125 divided resistance of 5.6KΩ sets the current limit to typi- ADJ cally 6.3A and 8.25KΩ reduces the maximum ADJ current to approximately ...

Page 13

... Vout = 14.8V in Vin max = 28V Iload max = 3.5A Step 2: Select an LM2679S-ADJ. To set the output voltage to 14.9V two resistors need to be chosen (R1 and R2 in Figure 2). For the adjustable device the output voltage is set by the following relationship: Where V is the feedback voltage of typically 1.21V. ...

Page 14

Using Figure 6, the intersection of 27V•μS horizontally and the 3.5A vertical line (I max) indicates that L48 , a 47μH load inductor, or L49, a 33μH inductor could be used. Either in- ductor will be suitable, but for this ...

Page 15

Inductor Selection Guides For Continuous Mode Operation FIGURE 3. LM2679-3.3 FIGURE 4. LM2679-5.0 10084719 10084720 15 10084721 FIGURE 5. LM2679-12 10084722 FIGURE 6. LM2679-ADJ www.national.com ...

Page 16

Inductor Inductance Current Reference (µH) Number L23 33 1.35 L24 22 1.65 L25 15 2.00 L29 100 1.41 L30 68 1.71 L31 47 2.06 L32 33 2.46 L33 22 3.02 L34 3.65 15 L38 68 2.97 L39 47 3.57 L40 ...

Page 17

Capacitor Selection Guides Capacitor AVX TPS Series Reference C (µF) WV (V) Code C1 330 C2 100 C3 220 100 C10 22 C11 C12 C13 Table 2. Input and ...

Page 18

Capacitor Sanyo OS-CON SA Series Reference C (µF) WV (V) Code C1 47 6.3 C2 150 6.3 C3 330 6.3 C4 100 10 C5 220 100 16 C8 150 16 C9 100 20 C10 47 ...

Page 19

Table 3. Output Capacitors for Fixed Output Voltage Application Output Inductance Voltage (V) (µ 3 100 Output Inductance Sanyo OS-CON SA Voltage (V) ...

Page 20

Table 4. Input Capacitors for Fixed Output Voltage Application (Assumes worst case maximum input voltage and load current for a given inductance value) Output Inductance Voltage (V) (µ 3 ...

Page 21

Table 5. Schottky Diode Selection Table Reverse Surface Mount Voltage More (V) 20V SK32 30V SK33 MBRD835L 30WQ03F 40V SK34 MBRD1545CT 30BQ040 6TQ045S 30WQ04F MBRS340 MBRD340 SK35 50V or More 30WQ05F Diode Manufacturer Contact Numbers Phone International ...

Page 22

Table 6. Output Capacitors for Adjustable Output Voltage Applications Output Voltage Inductance (V) 1.21 to 2.50 2.5 to 3.75 3. 6.25 6.25 to 7.5 7 12.5 12 ...

Page 23

Output Capacitors for Adjustable Output Voltage Applications (continued) Output Voltage Inductance Sanyo OS-CON SA (V) (µH) No. 33* 2 1.21 to 2.50 47* 2 33* 1 2.5 to 3. ...

Page 24

... Physical Dimensions www.national.com inches (millimeters) unless otherwise noted TO-263 Surface Mount Power Package Order Number LM2679S-3.3, LM2679S-5.0, LM2679S-12 or LM2679S-ADJ NS Package Number TS7B 24 ...

Page 25

TO-220 Power Package Order Number LM2679T-3.3, LM2679T-5.0, LM2679T-12 or LM2679T-ADJ NS Package Number TA07B 14-Lead LLP Package NS Package Number SRC14A 25 www.national.com ...

Page 26

... For more National Semiconductor product information and proven design tools, visit the following Web sites at: Products Amplifiers www.national.com/amplifiers Audio www.national.com/audio Clock Conditioners www.national.com/timing Data Converters www.national.com/adc Displays www.national.com/displays Ethernet www.national.com/ethernet Interface www.national.com/interface LVDS www.national.com/lvds Power Management www.national.com/power Switching Regulators www.national.com/switchers LDOs www ...

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