Manufacturer Part NumberLM22678TJE-5.0/NOPB
DescriptionIC REG SWITCH BUCK 5A 5V TO263-7
ManufacturerNational Semiconductor
TypeStep-Down (Buck)
LM22678TJE-5.0/NOPB datasheet

Specifications of LM22678TJE-5.0/NOPB

Internal Switch(s)YesSynchronous RectifierNo
Number Of Outputs1Voltage - Output5V
Current - Output5AFrequency - Switching500kHz
Voltage - Input4.5 ~ 42 VOperating Temperature-40°C ~ 125°C
Mounting TypeSurface MountPackage / CaseTO-263-7 Thin
Primary Input Voltage12VNo. Of Outputs1
Output Voltage5VOutput Current5A
No. Of Pins7Operating Temperature Range-40°C To +125°C
MslMSL 1 - UnlimitedFilter TerminalsSMD
Rohs CompliantYesFor Use With551600233-001 - WEBENCH BUILD IT LM2267X TO-263
Lead Free Status / RoHS StatusLead free / RoHS CompliantPower - Output-
Other namesLM22678TJE-5.0TR  
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5A SIMPLE SWITCHER®, Step-Down Voltage Regulator
with Precision Enable
General Description
The LM22678 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 N-channel MOSFET. The series consists of a
fixed 5V output and an adjustable version.
concept provides for an easy to
use complete design using a minimum number of external
components and National’s WEBENCH
National’s WEBENCH
tool includes features such as exter-
nal component calculation, electrical simulation, thermal sim-
ulation, and Build-It boards for easy design-in. The switching
clock frequency is provided by an internal fixed frequency os-
cillator which operates at 500 kHz. The LM22678 series also
has built in thermal shutdown, current limiting and an enable
control input that can power down the regulator to a low 25
µA quiescent current standby condition.
Simplified Application Schematic
© 2010 National Semiconductor Corporation
Wide input voltage range: 4.5V to 42V
Internally compensated voltage mode control
Stable with low ESR ceramic capacitors
100 mΩ N-channel MOSFET
Output voltage options:
-ADJ (outputs as low as 1.285V)
-5.0 (output fixed to 5V)
±1.5% feedback reference accuracy
design tool.
Switching frequency of 500 kHz
-40°C to 125°C operating junction temperature range
Precision enable pin
Integrated boot diode
Integrated soft-start
Step-down and inverting buck-boost applications
LM22678Q is an Automotive Grade product that is AEC-
Q100 grade 1 qualified (-40°C to +125°C operating
junction temperature)
TO-263 THIN (Exposed Pad)
Industrial Control
Telecom and Datacom Systems
Embedded Systems
Automotive Telematics and Body Electronics
Conversions from Standard 24V, 12V and 5V Input Rails
December 10, 2010

LM22678TJE-5.0/NOPB Summary of contents

  • Page 1

    ... The LM22678 series also has built in thermal shutdown, current limiting and an enable control input that can power down the regulator to a low 25 µA quiescent current standby condition. Simplified Application Schematic © 2010 National Semiconductor Corporation LM22678/LM22678Q Features ■ Wide input voltage range: 4.5V to 42V ■ ...

  • Page 2

    ... Connection Diagram Ordering Information Output Order Number Voltage ADJ LM22678TJE-ADJ ADJ LM22678TJ-ADJ 5.0 LM22678TJE-5.0 5.0 LM22678TJ-5.0 ADJ LM22678QTJE-ADJ ADJ LM22678QTJ-ADJ 5.0 LM22678QTJE-5.0 5.0 LM22678QTJ-5.0 *Automotive Grade (Q) product incorporates enhanced manufacturing and support processes for the automotive market, including defect detection methodologies. ...

  • Page 3

    ... Absolute Maximum Ratings If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications. VIN to GND EN Pin Voltage SW to GND (Note 2) BOOT Pin Voltage FB Pin Voltage Power Dissipation Electrical Characteristics junction temperature (T ) range of -40°C to +125°C. Minimum and Maximum limits are guaranteed through test, design, or statistical J correlation ...

  • Page 4

    Note 1: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur, including inoperability and degradation of device reliability and/or performance. Functional operation of the device and/or non-degradation at the Absolute Maximum Ratings or other conditions beyond ...

  • Page 5

    Feedback Bias Current vs Temperature Standby Quiescent Current vs Input Voltage Normalized Feedback Voltage vs Input Voltage Normalized Enable Threshold Voltage vs Temperature 30076105 Normalized Feedback Voltage vs Temperature 30076106 30076109 5 30076110 30076107 www.national.com ...

  • Page 6

    Typical Application Circuit and Block Diagram www.national.com FIGURE 1. 3. OUT 6 30076114 ...

  • Page 7

    Detailed Operating Description The LM22678 switching regulator features all of the functions necessary to implement an efficient high voltage buck regu- lator using a minimum of external components. This easy to use regulator integrates a 42V N-Channel switch with an ...

  • Page 8

    FIGURE 2. Output Current in Foldback vs. Nominal Duty Cycle The percentage of output current limit fold back is affected by duty cycle, inductance, and See Figure 2 for details. The current limit will only protect the inductor from a ...

  • Page 9

    Application Information EXTERNAL COMPONENTS The following design procedures can be used to design a non- synchronous buck converter with the LM22678. Inductor The inductor value ...

  • Page 10

    Where V = 1.285V typical for the -ADJ option and 5V for the FB -5.0 option FIGURE 3. Resistive Feedback Divider A maximum value of 10 kΩ is recommended for the sum of R1 and R2 to keep ...

  • Page 11

    Circuit Board Layout Board layout is critical for switching power supplies. First, the ground plane area must be sufficient for thermal dissipation purposes. Second, appropriate guidelines must be followed to reduce the effects of switching noise. Switch mode con- verters ...

  • Page 12

    PCB Layout Example www.national.com 30076125 12 ...

  • Page 13

    Schematic for Buck/Boost (Inverting) Application See AN-1888 for more information on the inverting (buck- boost) application generating a negative output voltage from a positive input voltage. 13 30076126 www.national.com ...

  • Page 14

    Physical Dimensions www.national.com inches (millimeters) unless otherwise noted 7-Lead Plastic TO-263 THIN Package NS Package Number TJ7A 14 ...

  • Page 15

    Notes 15 www.national.com ...

  • Page 16

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