NSC LM2698MM-ADJ, LM2698EVAL, LM2698MMX-ADJ Datasheet

LM2698
SIMPLE SWITCHER

®

1.35A Boost Regulator

General Description

The LM2698 is a general purpose PWM boost converter.
The 1.9A, 18V, 0.2ohm internal switch enables the LM2698
to provide efficient power conversion to outputs ranging from

2.2V to 17V.Itcanoperate with input voltages as low as 2.2V
and as high as 12V. Current-mode architecture provides
superior line and load regulation and simple frequency com­pensation over the device’s 2.2V to 12V input voltagerange.
The LM2698 sets the standard in power density and is
capable of supplying 12V at 400mA from a 5V input. The
LM2698 can also be used in flyback or SEPIC topologies.

The LM2698 SIMPLE SWITCHER

®

features a pin selectable
switching frequency of either 600kHz or 1.25MHz. This pro­motes flexibility in component selection and filtering tech­niques. A shutdown pin is available to suspend the device
and decrease the quiescent current to 5µA. An external
compensation pin gives the user flexibility in setting fre­quency compensation, which makes possible the use of
small, low ESR ceramic capacitors at the output. Switchers
Made Simple

®

software is available to insure a quick, easy
and guaranteed design. The LM2698 is available in a low
profile 8-lead MSOP package.

Features

n 1.9A, 0.2Ω, internal switch (typical)
n Operating voltage as low as 2.2V
n 600kHz/1.25MHz adjustable frequency operation
n Switchers Made Simple

®

software

n 8-Lead MSOP package

Applications

n 3.3V to 5V, 5V to 12V conversion
n Distributed Power
n Set-Top Boxes
n DSL Modems
n Diagnostic Medical Instrumentation
n Boost Converters
n Flyback Converters
n SEPIC Converters

Typical Application Circuit

20012658

SIMPLE SWITCHER®is a registered trademark of National Semiconductor Corporation.

October 2001

LM2698 SIMPLE SWITCHER

®

1.35A Boost Regulator

© 2001 National Semiconductor Corporation DS200126 www.national.com

Connection Diagram

Top View

20012604

8-Lead Plastic MSOP

NS Package Number MUA08A

Ordering Information

Order Number Package Type NSC Package

Drawing

Supplied As Package ID

LM2698MM-ADJ MSOP-8 MUA08A 1000 Units, Tape and Reel S22B

LM2698MMX-ADJ MSOP-8 MUA08A 3500 Units, Tape and Reel S22B

Pin Description

Pin Name Function

1V

C

Compensation network connection. Connected to the output of the voltage error amplifier.
2 FB Output voltage feedback input.
3 SHDN

Shutdown control input, active low.
4 GND Analog and power ground.
5V

SW

Power switch input. Switch connected between SW pin and GND pin.
6V

IN

Analog power input.
7 FSLCT Switching frequency select input. V

IN

= 1.25MHz. Ground = 600kHz.

8 NC Connect to ground.

LM2698

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Block Diagram

20012603

LM2698

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Absolute Maximum Ratings (Note 1)

If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales Office/
Distributors for availability and specifications.

V

IN

−0.3V ≤ VIN≤ 12V

SW Voltage −0.3V ≤ V

SW

≤ 18V

FB Voltage −0.3V ≤ V

FB

≤ 7V

V

C

Voltage 0.965<V

C

<

1.565

SHDN Voltage
(Note 2) −0.3V ≤ V

SHDN

≤ 7V

FSLCT
(Note 2) −0.3V ≤ V

FSLCT

≤ 12V

Maximum Junction
Temperature

150˚C

Power Dissipation (Note 3) Internally Limited
Lead Temperature 300˚C

Vapor Phase (60 sec.) 215˚C
Infrared (15 sec.) 220˚C

ESD Susceptibility
(Note 4)

Human Body Model

(Note 5) 2kV

Machine Model 200V

Operating Conditions

Operating Junction
Temperature Range
(Note 6) −40˚C to +125˚C

Storage Temperature −65˚C to +150˚C
Supply Voltage 2.2V to 12V
SW Voltage 0 ≤ V

SW

≤ 17.5V

Electrical Characteristics

Specifications in standard type face are for TJ= 25˚C and those with boldface type apply over the full Operating Tempera­ture Range (T

J

= −40˚C to +125˚C)Unless otherwise specified. VIN=2.2V and IL= 0A, unless otherwise specified.

Symbol Parameter Conditions

Min

(Note 6)

Typ

(Note 7)

Max

(Note 6)

Units

I

Q

Quiescent Current FB = 0V (Not Switching) 1.3 2.0 mA

V

SHDN

=0V 5 10 µA

V

FB

Feedback Voltage 1.2285 1.26 1.2915 V

I

CL

Switch Current Limit VIN= 2.7V (Note 8) 1.35 1.9 2.4 A

%V

FB

/∆VINFeedback Voltage Line

Regulation

2.2V ≤ VIN≤ 12.0V 0.013 0.1 %/V

I

B

FB Pin Bias Current
(Note 9)

0.5 20 nA

V

IN

Input Voltage Range 2.2 12 V

g

m

Error Amp Transconductance ∆I = 5µA 40 135 290 µmho

A

V

Error Amp Voltage Gain 120 V/V

D

MAX

Maximum Duty Cycle FSLCT = Ground 78 85 %

D

MIN

Minimum Duty Cycle FSLCT = Ground 15 %

FSLCT = V

IN

30

f

S

Switching Frequency FSLCT = Ground 480 600 720 kHz

FSLCT = V

IN

1 1.25 1.5 MHz

I

SHDN

Shutdown Pin Current V

SHDN

=V

IN

0.01 0.1 µA

V

SHDN

=0V −0.5 -1

I

L

Switch Leakage Current VSW= 18V 0.01 3 µA

R

DS(ON)

Switch R

DS(ON)

VIN= 2.7V, ISW= 1A 0.2 0.4 Ω

TH

SHDN

SHDN Threshold Voltage Output High 0.6 0.9 V

Output Low 0.3 0.6 V

UVP On Threshold 1.95 2.05 2.2 V

Off Threshold 1.85 1.95 2.1 V

LM2698

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Electrical Characteristics (Continued)

Specifications in standard type face are for TJ= 25˚C and those with boldface type apply over the full Operating Tempera­ture Range (T

J

= −40˚C to +125˚C)Unless otherwise specified. VIN=2.2V and IL= 0A, unless otherwise specified.

Symbol Parameter Conditions

Min

(Note 6)

Typ

(Note 7)

Max

(Note 6)

Units

θ

JA

Thermal Resistance Junction to Ambient

(Note 10)

235 ˚C/W

Junction to Ambient
(Note 11)

225

Junction to Ambient
(Note 12)

220

Junction to Ambient
(Note 13)

200

Junction to Ambient
(Note 14)

195

Note 1: Absolute maximum ratings are limits beyond which damage to the device may occur. Operating Ratings are conditions for which the device is intended to
be functional, but device parameter specifications may not be guaranteed. For guaranteed specifications and test conditions, see the Electrical Characteristics.

Note 2: Shutdown and voltage frequency select should not exceed V

IN

.

Note 3: The maximum allowable power dissipation is a function of the maximum junction temperature, T

J

(MAX), the junction-to-ambient thermal resistance, θJA,

and the ambient temperature, T

A

. See the Electrical Characteristics table for the thermal resistance of various layouts. The maximum allowable power dissipation

at any ambient temperature is calculated using: P

D

(MAX) = (T

J(MAX)−TA

)/θJA. Exceeding the maximum allowable power dissipation will cause excessive die

temperature, and the regulator will go into thermal shutdown.
Note 4: The human body model is a 100 pF capacitor discharged through a 1.5kΩ resistor into each pin. The machine model is a 200pF capacitor discharged

directly into each pin.
Note 5: ESD susceptibility using the human body model is 500V for V

C

.

Note 6: All limits guaranteed at room temperature (standard typeface) and at temperature extremes (bold typeface). All room temperature limits are 100% tested
or guaranteed through statistical analysis.All limits at temperature extremes are guaranteed via correlation using standard Statistical Quality Control (SQC) methods.
All limits are used to calculate Average Outgoing Quality Level (AOQL).

Note 7: Typical numbers are at 25˚C and represent the most likely norm.
Note 8: This is the switch current limit at 0% duty cycle. The switch current limit will change as a function of duty cycle. See Typical performance Characteristics

section for I

CL

vs. V

IN

Note 9: Bias current flows into FB pin.
Note 10: Junction to ambient thermal resistance (no external heat sink) for the MSO8 package with minimal trace widths (0.010 inches) from the pins to the circuit.

See ’Scenario ’A’’ in the Power Dissipation section.
Note 11: Junction to ambient thermal resistance for the MSO8 package with minimal trace widths (0.010 inches) from the pins to the circuit and approximately

0.0191 sq. in. of copper heat sinking. See ’Scenario ’B’’ in the Power Dissipation section.
Note 12: Junction to ambient thermal resistance for the MSO8 package with minimal trace widths (0.010 inches) from the pins to the circuit and approximately

0.0465 sq. in. of copper heat sinking. See ’Scenario ’C’’ in the Power Dissipation section.
Note 13: Junction to ambient thermal resistance for the MSO8 package with minimal trace widths (0.010 inches) from the pins to the circuit and approximately

0.2523 sq. in. of copper heat sinking. See ’Scenario ’D’’ in the Power Dissipation section.
Note 14: Junction to ambient thermal resistance for the MSO8 package with minimal trace widths (0.010 inches) from the pins to the circuit and approximately

0.0098 sq. in. of copper heat sinking on the top layer and 0.0760 sq. in. of copper heat sinking on the bottom layer, with three 0.020 in. vias connecting the planes.
See ’Scenario ’E’’ in the Power Dissipation section.

LM2698

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Typical Performance Characteristics

Efficiency vs Load Current

(V

OUT

= 8V, fS= 600kHz)

Efficiency vs Load Current

(V

OUT

= 8V, fS= 1.25MHz)

20012667 20012666

Iqvs VIN(600 kHz, non-switching) Iqvs VIN(600 kHz, switching)

20012618

20012619

Iqvs. VIN(1.25MHz, non-switching) Iqvs VIN(1.25MHz, switching)

20012622

20012617

LM2698

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