Manufacturer Part NumberLM22677TJE-5.0/NOPB
DescriptionIC REG SWITCH BUCK 5A 5V TO263-7
ManufacturerNational Semiconductor
TypeStep-Down (Buck)
LM22677TJE-5.0/NOPB datasheet

Specifications of LM22677TJE-5.0/NOPB

Internal Switch(s)YesSynchronous RectifierNo
Number Of Outputs1Voltage - Output5V
Current - Output5AFrequency - Switching200kHz ~ 1MHz
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-263LM22677EVAL - BOARD EVALUATION FOR LM22677
Lead Free Status / RoHS StatusLead free / RoHS CompliantPower - Output-
Other namesLM22677TJE-5.0TR  
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5A SIMPLE SWITCHER®, Step-Down Voltage Regulator
with Synchronization or Adjustable Switching Frequency
General Description
The LM22677 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 switching frequency
can also be adjusted with an external resistor or synchronized
to an external clock up to 1MHz. It is also possible to self-
synchronize multiple regulators to share the same switching
frequency. The LM22677 series also has built in thermal shut-
down, 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
© 2011 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, adjustable between 200
kHz and 1 MHz
-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
LM22677Q 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
January 24, 2011

LM22677TJE-5.0/NOPB Summary of contents

  • Page 1

    ... The LM22677 series also has built in thermal shut- down, 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 © 2011 National Semiconductor Corporation LM22677/LM22677Q Features ■ Wide input voltage range: 4.5V to 42V ■ ...

  • Page 2

    ... Connection Diagram Ordering Information Output Order Number Voltage ADJ LM22677TJE-ADJ ADJ LM22677TJ-ADJ 5.0 LM22677TJE-5.0 5.0 LM22677TJ-5.0 ADJ LM22677QTJE-ADJ ADJ LM22677QTJ-ADJ 5.0 LM22677QTJE-5.0 5.0 LM22677QTJ-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 RT/SYNC Pin Voltage SW to GND (Note 2) BOOT Pin Voltage FB Pin Voltage Power Dissipation Electrical Characteristics junction temperature (T ) range of -40° ...

  • 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 30074105 Normalized Feedback Voltage vs Temperature 30074106 Switching Frequency vs RT/SYNC Resistor 30074109 5 30074110 30074107 30074113 ...

  • Page 6

    Typical Application Circuit and Block Diagram www.national.com FIGURE 1. 3. 600 kHz OUT 6 30074114 ...

  • Page 7

    Detailed Operating Description The LM22677 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

    Self Synchronize It is also possible to self-synchronize multiple LM22677 reg- ulators to share the same switching frequency. This can be done by attaching the RT/SYNC pins together and putting a 1 kΩ resistor to ground. The diagram in Figure ...

  • Page 10

    F is the switching frequency which is 500 kHz without an external frequency set resistor or external sync signal ap- plied to the RT/SYNC pin. If the switching frequency is set higher than 500kHz, the inductance value may not ...

  • Page 11

    FIGURE 5. Resistive Feedback Divider A maximum value of 10 kΩ is recommended for the sum of R1 and R2 to keep high output voltage accuracy for the –ADJ option. A maximum of 2 kΩ is recommended for the ...

  • Page 12

    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 13

    PCB Layout Example 13 30074125 www.national.com ...

  • Page 14

    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. www.national.com 30074126 14 ...

  • Page 15

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