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LM22680-ADJ

VIN

BOOT

GND

VIN

VOUT

RT/SYNC

LM22680

www.ti.com

SNVS595K –SEPTEMBER 2008–REVISED APRIL 2013

LM22680/LM22680-Q1 42V, 2A SIMPLE SWITCHER® Step-Down Voltage Regulator with

Features

Check for Samples: LM22680

FEATURES

DESCRIPTION

The LM22680 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

• 200 mΩ N-Channel MOSFET

capable of providing up to 2A of load current.

• Output Voltage Option:

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

• ±1.5% Feedback Reference Accuracy

ratio between input and output voltages. Internal loop

• 500 kHz Default Switching Frequency

compensation means that the user is free from the

• Adjustable Switching Frequency and

tedious task of calculating the loop compensation

Synchronization

components. Fixed 5V output and adjustable output

voltage options are available. The default switching

• –40°C to 125°C Operating Junction

frequency is set at 500 kHz allowing for small

Temperature Range

external components and good transient response. In

• Precision Enable Pin

addition, the frequency can be adjusted over a range

• Integrated Boot-Strap Diode

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

The internal oscillator can be synchronized to a

• Adjustable Soft-Start

system clock or to the oscillator of another regulator.

• Fully WEBENCH

Enabled

A precision enable input allows simplification of

• LM22680-Q1 is an Automotive Grade Product

regulator control and system power sequencing. In

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

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

+125°C Operating Junction Temperature)

An adjustable soft-start feature is provided through

the selection of a single external capacitor. The

LM22680 also has built in thermal shutdown, and

PACKAGE

current limiting to protect against accidental

• SO PowerPAD (Exposed Pad)

overloads.

The LM22680 is a member of Texas Instruments'

APPLICATIONS

SIMPLE SWITCHER™ family. The SIMPLE

• Industrial Control

SWITCHER™ concept provides for an easy to use

complete design using a minimum number of external

• Telecom and Datacom Systems

components and the TI WEBENCH

design tool. TI's

• Embedded Systems

WEBENCH

tool includes features such as external

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

component calculation, electrical simulation, thermal

Input Rails

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

Simplified Application Schematic

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
LM22680 www.ti.com SNVS595K – SEPTEMBER 2008 – REVISED APRIL 2013 LM22680/LM22680-Q1 42V, 2A SIMPLE SWITCHER® Step-Down Voltage Regulator with Features Check for Samples: LM22680 FEATURES DESCRIPTION • • • • • The LM22680 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 2A of load current.
PAGE 2
LM22680 SNVS595K – SEPTEMBER 2008 – REVISED APRIL 2013 www.ti.com Connection Diagram BOOT 1 8 SW SS 2 7 VIN RT/SYNC 3 6 GND FB 4 5 EN Exposed Pad Connect to GND Figure 1. Connection Diagram Package Number MRA08B PIN DESCRIPTIONS Pin Name Description Application Information 1 BOOT Bootstrap input Provides the gate voltage for the high side NFET. 2 SS Soft-start pin Used to increase soft-start time. See Soft-Start section of data sheet.
PAGE 3
LM22680 www.ti.com SNVS595K – 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
LM22680 SNVS595K – 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, fO= 500 kHz 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
LM22680 www.ti.com SNVS595K – 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. Soft-start Current vs Temperature Figure 12.
PAGE 6
LM22680 SNVS595K – SEPTEMBER 2008 – REVISED APRIL 2013 www.ti.com SIMPLIFIED BLOCK DIAGRAM VIN VIN BOOT Vcc INT REG, EN,UVLO EN ILimit PWM Cmp. FB TYPE III COMP + + - LOGIC Error Amp. VOUT SW OSC SS 1.285V/SS 50 µA RT/SYNC GND Figure 13. Simplified Block Diagram Detailed Operating Description The LM22680 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
LM22680 www.ti.com SNVS595K – SEPTEMBER 2008 – REVISED APRIL 2013 Precision Enable and UVLO The precision enable input (EN) is used to control the regulator. The precision feature allows simple sequencing of multiple power supplies with a resistor divider from another supply. Connecting this pin to ground or to a voltage less than 1.6V (typ.) will turn off the regulator. The current drain from the input supply, in this state, is 25 µA (typ.) at an input voltage of 12V.
PAGE 8
LM22680 SNVS595K – SEPTEMBER 2008 – REVISED APRIL 2013 www.ti.com where • Fsw is the switching frequency and TON is the minimum on-time; both found in the Electrical Characteristics table. (3) If the frequency adjust feature is used, that value should be used for Fsw. Nominal values should be used. The worst case is lowest output voltage, and highest switching frequency. If this input voltage is exceeded, the regulator will skip cycles, effectively lowering the switching frequency.
PAGE 9
LM22680 www.ti.com SNVS595K – SEPTEMBER 2008 – REVISED APRIL 2013 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
LM22680 SNVS595K – SEPTEMBER 2008 – REVISED APRIL 2013 www.ti.com Switching Frequency Adjustment and Synchronization The LM22680 will operate in three different modes, depending on the condition of the RT/SYNC pin. With the RT/SYNC pin floating, the regulator will switch at the internally set frequency of 500 kHz (typ.). With a resistor in the range of 25 kΩ to 200 kΩ, connected from RT/SYNC to ground, the internal switching frequency can be adjusted from 1MHz to 200 kHz.
PAGE 11
LM22680 www.ti.com SNVS595K – SEPTEMBER 2008 – REVISED APRIL 2013 Self Synchronization It is possible to synchronize multiple LM22680 regulators together to share the same switching frequency. This can be done by tieing the RT/SYNC pins together through a MOSFET and connecting a 1 KΩ resistor to ground at each pin. Figure 19 shows this connection. The gate of the MOSFET should be connected to the regulator with the highest output voltage.
PAGE 12
LM22680 SNVS595K – SEPTEMBER 2008 – REVISED APRIL 2013 www.ti.com (9) Alternatively, this pole should be placed between 1.5kHz and 15kHz and is given by the equation shown below: (10) 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.
PAGE 13
LM22680 www.ti.com SNVS595K – SEPTEMBER 2008 – REVISED APRIL 2013 INDUCTOR The inductor value is determined based on the load current, ripple current, and the minimum and maximum input voltages. To keep the application in continuous conduction mode (CCM), the maximum ripple current, IRIPPLE , should be less than twice the minimum load current.
PAGE 14
LM22680 SNVS595K – SEPTEMBER 2008 – REVISED APRIL 2013 www.ti.com It is good practice to include a high frequency bypass capacitor as close as possible to the LM22680. This small case size, low ESR, ceramic capacitor should be connected directly to the VIN and GND pins with the shortest possible PCB traces. Values in the range of 0.47 µF to 1 µF are appropriate. This capacitor helps to provide a low impedance supply to sensitive internal circuitry.
PAGE 15
LM22680 www.ti.com SNVS595K – SEPTEMBER 2008 – REVISED APRIL 2013 The output voltage divider should be placed as close as possible to the FB pin of the LM22680; since this is a high impedance input and is susceptible to noise pick-up. POWER DIODE A Schottky type power diode is required for all LM22680 applications. Ultra-fast diodes are not recommended and may result in damage to the IC due to reverse recovery current transients.
PAGE 16
LM22680 SNVS595K – SEPTEMBER 2008 – REVISED APRIL 2013 www.ti.com Thermal Considerations The components with the highest power dissipation are the power diode and the power MOSFET internal to the LM22680 regulator. The easiest method to determine the power dissipation within the LM22680 is to measure the total conversion losses then subtract the power losses in the diode and inductor. The total conversion loss is the difference between the input power and the output power.
PAGE 17
LM22680 www.ti.com SNVS595K – SEPTEMBER 2008 – REVISED APRIL 2013 PCB Layout Example RFBB 2.55 k: VIN 5.5V to 35V EN C2 22 PF + C1 6.8 PF C3 10 nF BOOT L1 12 PH RFBT 7.32 k: SW RT/SYNC C6 4.7 PF VOUT FB VIN SS LM22680-ADJ GND D1 60V 5A C4 120 PF VOUT -5V Figure 24.
PAGE 18
LM22680 SNVS595K – SEPTEMBER 2008 – REVISED APRIL 2013 www.ti.com REVISION HISTORY Changes from Revision J (April 2013) to Revision K • 18 Page Changed layout of National Data Sheet to TI format ..........................................................................................................
PAGE 19
PACKAGE OPTION ADDENDUM www.ti.
PAGE 20
PACKAGE OPTION ADDENDUM www.ti.com 5-Feb-2014 (6) Lead/Ball Finish - Orderable Devices may have multiple material finish options. Finish options are separated by a vertical ruled line. Lead/Ball Finish values may wrap to two lines if the finish value exceeds the maximum column width. Important Information and Disclaimer:The information provided on this page represents TI's knowledge and belief as of the date that it is provided.
PAGE 21
PACKAGE MATERIALS INFORMATION www.ti.com 8-Apr-2013 TAPE AND REEL INFORMATION *All dimensions are nominal Device 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 LM22680MRE-ADJ/NOPB SO Power PAD DDA 8 250 178.0 12.4 6.5 5.4 2.0 8.0 12.0 Q1 LM22680MRX-ADJ/NOPB SO Power PAD DDA 8 2500 330.0 12.4 6.5 5.4 2.0 8.0 12.0 Q1 LM22680QMRE-ADJ/NOP B SO Power PAD DDA 8 250 178.0 12.4 6.5 5.4 2.
PAGE 22
PACKAGE MATERIALS INFORMATION www.ti.com 8-Apr-2013 *All dimensions are nominal Device Package Type Package Drawing Pins SPQ Length (mm) Width (mm) Height (mm) LM22680MRE-ADJ/NOPB SO PowerPAD DDA LM22680MRX-ADJ/NOPB SO PowerPAD DDA 8 250 213.0 191.0 55.0 8 2500 367.0 367.0 35.0 LM22680QMRE-ADJ/NOP B SO PowerPAD DDA 8 250 213.0 191.0 55.0 LM22680QMRX-ADJ/NOP B SO PowerPAD DDA 8 2500 367.0 367.0 35.
PAGE 23
MECHANICAL DATA DDA0008B MRA08B (Rev B) www.ti.
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