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LM22677-ADJ

VIN

BOOT

GND

VIN

VOUT

RT/SYNC

LM22677

www.ti.com

SNVS582M –SEPTEMBER 2008–REVISED APRIL 2013

LM22677/LM22677-Q1 42V, 5A SIMPLE SWITCHER®, Step-Down Voltage Regulator with

Features

Check for Samples: LM22677

FEATURES

DESCRIPTION

The LM22677 switching regulator provides all of the

• Wide Input Voltage Range: 4.5V to 42V

functions necessary to implement an efficient high

• Internally Compensated Voltage Mode Control

voltage step-down (buck) regulator using a minimum

• Stable with low ESR Ceramic Capacitors

of external components. This easy to use regulator

incorporates a 42V N-channel MOSFET switch

• 100 mΩ N-Channel MOSFET

capable of providing up to 5A of load current.

• Output Voltage Options:

Excellent line and load regulation along with high

– ADJ (Outputs as Low as 1.285V)

efficiency (>90%) are featured. Voltage mode control

offers short minimum on-time, allowing the widest

– 5.0 (Output Fixed to 5V)

ratio between input and output voltages. Internal loop

• ±1.5% Feedback Reference Accuracy

compensation means that the user is free from the

• 500 kHz Default Switching Frequency

tedious task of calculating the loop compensation

components. Fixed 5V output and adjustable output

• Adjustable Switching Frequency and

voltage options are available. The default switching

Synchronization

frequency is set at 500 kHz allowing for small

• -40°C to 125°C Operating Junction

external components and good transient response. In

Temperature Range

addition, the frequency can be adjusted over a range

• Precision Enable Pin

of 200 kHz to 1MHz with a single external resistor.

The internal oscillator can be synchronized to a

• Integrated Boot-Strap Diode

system clock or to the oscillator of another regulator.

• Integrated Soft-Start

A precision enable input allows simplification of

• Fully WEBENCH

enabled

regulator control and system power sequencing. In

shutdown mode the regulator draws only 25 µA (typ.).

• LM22677-Q1 is an Automotive Grade Product

The LM22677 also has built in thermal shutdown, and

that is AEC-Q100 Grade 1 Qualified (-40°C to

current limiting to protect against accidental

+125°C Operating Junction Temperature)

overloads.

PACKAGE

The LM22677 is a member of Texas Instruments'

SIMPLE SWITCHER™ family. The SIMPLE

• PFM (Exposed Pad)

SWITCHER™ concept provides for an easy to use

complete design using a minimum number of external

APPLICATIONS

components and the TI WEBENCH

design tool. TI's

WEBENCH

tool includes features such as external

• Industrial Control

component calculation, electrical simulation, thermal

• Telecom and Datacom Systems

simulation, and Build-It boards for easy design-in.

• Embedded Systems

• Conversions from Standard 24V, 12V and 5V

Simplified Application Schematic

Input Rails

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 (24 pages)

PAGE 1
LM22677 www.ti.com SNVS582M – SEPTEMBER 2008 – REVISED APRIL 2013 LM22677/LM22677-Q1 42V, 5A SIMPLE SWITCHER®, Step-Down Voltage Regulator with Features Check for Samples: LM22677 FEATURES DESCRIPTION • • • • • The LM22677 switching regulator provides all of the functions necessary to implement an efficient high voltage step-down (buck) regulator using a minimum of external components. This easy to use regulator incorporates a 42V N-channel MOSFET switch capable of providing up to 5A of load current.
PAGE 2
LM22677 SNVS582M – SEPTEMBER 2008 – REVISED APRIL 2013 www.ti.com Connection Diagram 7 EN 6 FB 5 RT/SYNC 4 GND 3 BOOT 2 VIN 1 SW Exposed Pad Connect to GND Figure 1. 7-Lead Plastic PFM Package Package Number NDR0007A PIN DESCRIPTIONS Pin Name Description Application Information 1 SW Switch output Switching output of regulator. 2 VIN Input voltage Supply input to the regulator.
PAGE 3
LM22677 www.ti.com SNVS582M – SEPTEMBER 2008 – REVISED APRIL 2013 Operating Ratings (1) Supply Voltage (VIN) 4.5V to 42V Junction Temperature Range (1) -40°C to +125°C Absolute Maximum Ratings indicate limits beyond which damage to the device may occur, including inoperability and degradation of device reliability and/or performance.
PAGE 4
LM22677 SNVS582M – SEPTEMBER 2008 – REVISED APRIL 2013 www.ti.com Typical Performance Characteristics Unless otherwise specified the following conditions apply: Vin = 12V, TJ = 25°C. 4 Efficiency vs IOUT and VIN VOUT = 3.3V Normalized Switching Frequency vs Temperature Figure 2. Figure 3. Current Limit vs Temperature Normalized RDS(ON) vs Temperature Figure 4. Figure 5. Feedback Bias Current vs Temperature Normalized Enable Threshold Voltage vs Temperature Figure 6. Figure 7.
PAGE 5
LM22677 www.ti.com SNVS582M – SEPTEMBER 2008 – REVISED APRIL 2013 Typical Performance Characteristics (continued) Unless otherwise specified the following conditions apply: Vin = 12V, TJ = 25°C. Standby Quiescent Current vs Input Voltage Normalized Feedback Voltage vs Temperature Figure 8. Figure 9. Normalized Feedback Voltage vs Input Voltage Switching Frequency vs RT/SYNC Resistor Figure 10. Figure 11.
PAGE 6
LM22677 SNVS582M – SEPTEMBER 2008 – REVISED APRIL 2013 www.ti.com SIMPLIFIED BLOCK DIAGRAM VIN VIN Vcc BOOT INT REG, EN,UVLO EN ILimit PWM Cmp. FB + TYPE III COMP + - LOGIC Error Amp. VOUT SW OSC 1.285V & Soft-Start RT/SYNC GND Figure 12. Simplified Block Diagram Detailed Operating Description The LM22677 incorporates a voltage mode constant frequency PWM architecture. In addition, input voltage feedforward is used to stabilize the loop gain against variations in input voltage.
PAGE 7
LM22677 www.ti.com SNVS582M – SEPTEMBER 2008 – REVISED APRIL 2013 Although an internal pull-up is provided on the EN pin, it is good practice to pull the input high, when this feature is not used, especially in noisy environments. This can most easily be done by connecting a resistor between VIN and the EN pin. The resistor is required, since the internal zener diode, at the EN pin, will conduct for voltages above about 6V. The current in this zener must be limited to less than 100 µA.
PAGE 8
LM22677 SNVS582M – SEPTEMBER 2008 – REVISED APRIL 2013 www.ti.com Duty-Cycle Limits Ideally the regulator would control the duty cycle over the full range of zero to one. However due to inherent delays in the circuitry, there are limits on both the maximum and minimum duty cycles that can be reliably controlled. This in turn places limits on the maximum and minimum input and output voltages that can be converted by the LM22677.
PAGE 9
LM22677 www.ti.com SNVS582M – SEPTEMBER 2008 – REVISED APRIL 2013 Where Vsc is the value of output voltage during the overload and Fsw is the normal switching frequency. If the input voltage should exceed this value, while in foldback mode, the regulator and/or the diode may be damaged. It is important to note that the voltages in these equations are measured at the inductor. Normal trace and wiring resistance will cause the voltage at the inductor to be higher than that at a remote load.
PAGE 10
LM22677 SNVS582M – SEPTEMBER 2008 – REVISED APRIL 2013 www.ti.com worse than that of the internal oscillator; about +/- 25% is to be expected. Finally, an external clock can be applied to the RT/SYNC pin to allow the regulator to synchronize to a system clock or another LM22677. The mode is set during start-up of the regulator.
PAGE 11
LM22677 www.ti.com SNVS582M – SEPTEMBER 2008 – REVISED APRIL 2013 regulators will be clocked at the same frequency but slightly phase shifted according to the minimum off-time of the regulator with the fastest internal oscillator. The slight phase shift helps to reduce stress on the input capacitors of the regulator. It is important to choose a MOSFET with a low gate threshold voltage so that the MOSFET will be fully enhanced. Also, a MOSFET with low inter-electrode capacitance is required.
PAGE 12
LM22677 SNVS582M – SEPTEMBER 2008 – REVISED APRIL 2013 www.ti.com The Q factor depends on the parasitic resistance of the power stage components and is not typically in the control of the designer. Of course, loop compensation is only one consideration when selecting power stage components; see the Application Information section for more details. COMPENSATOR GAIN (dB) 40 35 -ADJ -5.0 30 25 20 15 10 5 0 100 1k 10k 100k 1M FREQUENCY (Hz) 10M Figure 19.
PAGE 13
LM22677 www.ti.com SNVS582M – SEPTEMBER 2008 – REVISED APRIL 2013 (10) where Fsw is the switching frequency and Vin should be taken at its maximum value, for the given application. The above formula provides a guide to select the value of the inductor L; the nearest standard value will then be used in the circuit.
PAGE 14
LM22677 SNVS582M – SEPTEMBER 2008 – REVISED APRIL 2013 www.ti.com OUTPUT CAPACITOR The output capacitor is responsible for filtering the output voltage and supplying load current during transients. Capacitor selection depends on application conditions as well as ripple and transient requirements. Best performance is achieved with a parallel combination of ceramic capacitors and a low ESR SP™ or POSCAP™ type.
PAGE 15
LM22677 www.ti.com SNVS582M – SEPTEMBER 2008 – REVISED APRIL 2013 Vout RFBT FB RFBB Figure 21. Resistive Feedback Divider A maximum value of 10 kΩ is recommended for the sum of RFBB and RFBT to maintain good output voltage accuracy for the -ADJ option. A maximum of 2 kΩ is recommended for the -5.0 option. For the -5.0 option, the total internal divider resistance is typically 9.93 kΩ.
PAGE 16
LM22677 SNVS582M – SEPTEMBER 2008 – REVISED APRIL 2013 www.ti.com Figure 22. Current Flow in a Buck Application Thermal Considerations The components with the highest power dissipation are the power diode and the power MOSFET internal to the LM22677 regulator. The easiest method to determine the power dissipation within the LM22677 is to measure the total conversion losses then subtract the power losses in the diode and inductor.
PAGE 17
LM22677 www.ti.com SNVS582M – SEPTEMBER 2008 – REVISED APRIL 2013 PCB Layout Example RFBB 2.55 k: VIN 5.5V to 35V VIN FB LM22677-ADJ EN BOOT C2 22 PF + C1 2.2 PF RT/SYNC C6 4.7 PF VOUT C3 10 nF L1 10 PH RFBT 7.32 k: SW GND D1 60V 5A C4 120 PF VOUT -5V Figure 23.
PAGE 18
LM22677 SNVS582M – SEPTEMBER 2008 – REVISED APRIL 2013 www.ti.com REVISION HISTORY Changes from Revision L (April 2013) to Revision M • 18 Page Changed layout of National Data Sheet to TI format ..........................................................................................................
PAGE 19
PACKAGE OPTION ADDENDUM www.ti.com 21-May-2013 PACKAGING INFORMATION Orderable Device Status (1) Package Type Package Pins Package Drawing Qty Eco Plan Lead/Ball Finish (2) MSL Peak Temp Op Temp (°C) Device Marking (3) (4/5) LM22677QTJ-5.0/NOPB ACTIVE TO-263 NDR 7 1000 Green (RoHS & no Sb/Br) CU SN Level-1-260C-UNLIM -40 to 125 LM22677 QTJ-5.
PAGE 20
PACKAGE OPTION ADDENDUM www.ti.com (4) 21-May-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.
PAGE 21
PACKAGE MATERIALS INFORMATION www.ti.com 29-May-2013 TAPE AND REEL INFORMATION *All dimensions are nominal Device LM22677QTJ-5.0/NOPB Package Package Pins Type Drawing SPQ Reel Reel A0 Diameter Width (mm) (mm) W1 (mm) B0 (mm) K0 (mm) P1 (mm) W Pin1 (mm) Quadrant TO-263 NDR 7 1000 330.0 24.4 10.6 15.4 2.45 12.0 24.0 Q2 LM22677QTJ-ADJ/NOPB TO-263 NDR 7 1000 330.0 24.4 10.6 15.4 2.45 12.0 24.0 Q2 LM22677QTJE-5.0/NOPB TO-263 NDR 7 250 178.0 24.4 10.6 15.4 2.45 12.
PAGE 22
PACKAGE MATERIALS INFORMATION www.ti.com 29-May-2013 *All dimensions are nominal Device Package Type Package Drawing Pins SPQ Length (mm) Width (mm) Height (mm) LM22677QTJ-5.0/NOPB TO-263 NDR 7 1000 367.0 367.0 35.0 LM22677QTJ-ADJ/NOPB TO-263 NDR 7 1000 367.0 367.0 35.0 LM22677QTJE-5.0/NOPB TO-263 NDR 7 250 210.0 185.0 35.0 LM22677QTJE-ADJ/NOPB TO-263 NDR 7 250 210.0 185.0 35.0 LM22677TJ-5.0/NOPB TO-263 NDR 7 1000 367.0 367.0 35.
PAGE 23
MECHANICAL DATA NDR0007A BOTTOM SIDE OF PACKAGE TOP SIDE OF PACKAGE TJ7A (Rev D) www.ti.
PAGE 24
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