NSC LM2853MHX-3.3, LM2853 Datasheet

LM2853 3A 550 kHz Synchronous SIMPLE SWITCHER Regulator

Buck

LM2853 3A 550 kHz Synchronous SIMPLE SWITCHER

October 2006

General Description

The LM2853 synchronous SIMPLE SWITCHER®buck regulator is a 550 kHz step-down switching voltage regulator capable of driving up to a 3A load with excellent line and load regulation. The LM2853 accepts an input voltage between

3.0V and 5.5V and delivers a customizable output voltage that is factory programmable from 0.8V to 3.3V in 100mV increments. Internal type-three compensation enables a low component count solution and greatly simplifies external component selection. The exposed-pad TSSOP-14 package enhances the thermal performance of the LM2853.

Typical Application Circuit

Features

n Input voltage range of 3.0V to 5.5V n Factory EEPROM set output voltages from 0.8V to 3.3V

in 100 mV increments

n Maximum load current of 3A n Voltage Mode Control n Internal type-three compensation n Switching frequency of 550 kHz n Low standby current of 12 µA n Internal 40 mΩ MOSFET switches n Standard voltage options

0.8/1.0/1.2/1.5/1.8/2.5/3.0/3.3 volts

n Exposed pad TSSOP-14 package

Applications

n Low voltage point of load regulation n Local solution for FPGA/DSP/ASIC core power n Broadband networking and communications

infrastructure

Buck Regulator

20201502

Efficiency vs Load Current (V

SIMPLE SWITCHER®is a Registered Trademark of National Semiconductor Corporation.

OUT

20201501

= 3.3V)

Connection Diagram

LM2853

Ordering Information

20201503

Voltage

Order Number

LM2853MH-0.8

LM2853MHX-0.8 2500 Units, Tape and Reel

LM2853MH-1.0

LM2853MHX-1.0 2500 Units, Tape and Reel

LM2853MH-1.2

LM2853MHX-1.2 2500 Units, Tape and Reel

LM2853MH-1.5

LM2853MHX-1.5 2500 Units, Tape and Reel

LM2853MH-1.8

LM2853MHX-1.8 2500 Units, Tape and Reel

LM2853MH-2.5

LM2853MHX-2.5 2500 Units, Tape and Reel

LM2853MH-3.0

LM2853MHX-3.0 2500 Units, Tape and Reel

LM2853MH-3.3

LM2853MHX-3.3 2500 Units, Tape and Reel

Note: Contact factory for other voltage options.

Option

0.8 LM2853-0.8

1.0 LM2853-1.0

1.2 LM2853-1.2

1.5 LM2853-1.5

1.8 LM2853-1.8

2.5 LM2853-2.5

3.0 LM2853-3.0

3.3 LM2853-3.3

Package

Marking Package Type

TSSOP-14 exposed

pad

Package Drawing Supplied As

94 Units, Rail

MXA14A

94 Units, Rail

Pin Descriptions

Pin # Name Function

1 AVIN Input Voltage for Control Circuitry.

2 EN Enable.

3 SGND Low noise ground.

4 SS Soft-Start Pin.

5 NC No Connect. This pin must be tied to ground.

6,7 PVIN Input Voltage for Power Circuitry.

8,9 SW Switch Pin.

10,11 PGND Power Ground.

12,13 NC No-Connect. These pins must be tied to ground.

14 SNS Output Voltage Sense Pin.

Exposed Pad EP The exposed pad is internally connected to GND, but it cannot be

used as the primary GND connection. The exposed pad should be soldered to an external GND plane.

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LM2853

Absolute Maximum Ratings (Note 1)

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

14-Pin Exposed Pad TSSOP Package

Infrared (15 sec) 220˚C

Vapor Phase (60 sec) 215˚C

Soldering (10 sec) 260˚C

AVIN, PVIN, EN, SNS, SW, SS −0.3V to 6.0V

ESD Susceptibility (Note 2) 2kV

Operating Ratings (Note 1)

Power Dissipation Internally Limited

Storage Temperature Range −65˚C to +150˚C

Maximum Junction Temp. 150˚C

PVIN to GND 1.5V to 5.5V

AVIN to GND 3.0V to 5.5V

Junction Temperature −40˚C to +125˚C

Electrical Characteristics Specifications with standard typeface are for T

= 25˚C, and those in bold face

type apply over the full Junction Temperature Range (−40˚C to 125˚C). Minimum and Maximum limits are guaranteed through test, design or statistical correlation. Typical values represent the most likely parametric norm at T

= 25˚C and are provided

for reference purposes only. Unless otherwise specified AVIN = PVIN = 5V.

Symbol Parameter Conditions Min Typ Max Units

SYSTEM PARAMETERS

OUT

∆V

/∆AVIN Line Regulation (Note 3) V

OUT

Voltage Tolerance (Note 3) V

= 0.8V option 0.782 0.8 0.818

OUT

= 1.0V option 0.9775 1.0 1.0225

OUT

= 1.2V option 1.1730 1.2 1.227

OUT

= 1.5V option 1.4663 1.5 1.5337

OUT

= 1.8V option 1.7595 1.8 1.8405

OUT

= 2.5V option 2.4437 2.5 2.5563

OUT

= 3.0V option 2.9325 3.0 3.0675

OUT

= 3.3V option 3.2257 3.3 3.3743

OUT

= 0.8V, 1.0V, 1.2V, 1.5V,

OUT

0.2 1.1 %

1.8V or 2.5V

3.0V ≤ AVIN ≤ 5.5V

= 3.0V or 3.3V

OUT

0.2 1.1 %

3.5V ≤ AVIN ≤ 5.5V

∆V

OUT

/∆I

Load Regulation Normal operation 2 mV/A

UVLO Threshold (AVIN) Rising 2.47 3.0 V

Falling Hysteresis 50 155 260 mV

DS(ON)-P

DS(ON)-N

SNS

PFET On Resistance Isw = 3A 40 120 mΩ

NFET On Resistance Isw = 3A 32 100 mΩ

Soft-Start Resistance 450 kΩ

Peak Current Limit Threshold 3.6 5A

Operating Current Non-switching 0.85 2 mA

Shutdown Quiescent Current EN = 0V 12 50 µA

Sense Pin Resistance 432 kΩ

PWM

osc

range

Switching Frequency . 325 550 725 kHz

Duty Cycle Range 0 100 %

ENABLE CONTROL (Note 4)

EN Pin Minimum High Input 75 %of

EN Pin Maximum Low Input 25 %of

EN Pin Pullup Current EN = 0V 1.5 µA

AVIN

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Electrical Characteristics Specifications with standard typeface are for T

apply over the full Junction Temperature Range (−40˚C to 125˚C). Minimum and Maximum limits are guaranteed through test,

LM2853

design or statistical correlation. Typical values represent the most likely parametric norm at T

= 25˚C, and those in bold face type

= 25˚C and are provided for

reference purposes only. Unless otherwise specified AVIN = PVIN = 5V. (Continued)

Symbol Parameter Conditions Min Typ Max Units

THERMAL CONTROLS

SD-HYS

Thermal Shutdown Threshold 165 ˚C

Hysteresis for Thermal

10 ˚C

Shutdown

THERMAL RESISTANCE

Note 1: Absolute maximum ratings indicate limits beyond which damage to the device may occur. Operating Range indicates conditions for which the device is intended to be functional, but does not guarantee specific performance limits. For guaranteed specifications and test conditions, see the Electrical Characteristics.

Note 2: The human body model is a 100 pF capacitor discharged through a 1.5 kΩ resistor into each pin. Test Method is per JESD22-AI14.

Note 3: V

Note 4: The enable pin is internally pulled up, so the LM2853 is automatically enabled unless an external enable voltage is applied.

Junction to Ambient MXA14A 38 ˚C/W

measured in a non-switching, closed-loop configuration at the SNS pin.

OUT

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