LX7167CLD-TR [MICROSEMI]

Switching Regulator, Voltage-mode, 2.4A, 3400kHz Switching Freq-Max, PDSO8;


型号：	LX7167CLD-TR
厂家：	Microsemi
描述：	Switching Regulator, Voltage-mode, 2.4A, 3400kHz Switching Freq-Max, PDSO8 开关光电二极管
文件：	总12页 (文件大小：569K)
中文：	中文翻译
下载：	下载PDF数据表文档文件

LX7167

3MHz, 2.4A

Step Down Converter

Features

. 2.4A Step-down Regulator

Description

. Operational Input Supply Voltage Range:

LX7167 is a step-down PWM Switching Regulator

IC with integrated high side P-CH and low side N-

CH MOSFETs. The IC operates using a hysteretic

control topology with a full load operating switching

frequency of 3MHz allowing small output filter

components while maintaining excellent dynamic

load response.

3V-5.5V

. Integrated PMOS and NMOS

. Load Current from Zero to 2.4A

. 3MHz Switching Frequency

. SKIP Pulse to Improve Light Load

Efficiency

. Input UVLO and OV Protection

. Enable Pin

The operational input voltage range of LX7167 is

from 3V to 5.5V. The part has a Power Save Mode

(PSM) that automatically transitions between PWM

and PSM mode depending on the load current. This

allows the converter’s efficiency to remain high

when load current drops. There is a Power Good

function to indicate the status of the IC.

. Power Good

. Internal Soft-start

. Cycle-by-Cycle Over Current Protection

. Hiccup Mode Operation Under FB UVLO

. RoHS Compliant for Pb Free

In the shutdown mode, the IC’s current consumption

is reduced to less than 1µA and the output capacitor

is discharged.

Applications

. HDD

Other features of the part are: a) Cycle-by-cycle

current limit followed by HICCUP mode which

reduces the overall power dissipation of the internal

MOSFETs, b) thermal protection and internal digital

soft start.

. Set-Top Box

. LCD TV’s

. Notebook/Netbook

. Routers

The LX7167 is available in a 2mm x 2mm 8 pin

exposed pad DFN package.

. Video Cards

. PC Peripherals

. PoE Powered Devices Smart Phone

100k

PGOOD

VIN

PVIN

VOUT

C_OUT

0.68µF

C_IN

VCC

LX7167

PGND

GND

Figure 1 · Typical Application of LX7167

Aug 2013 Rev. 1.1

www.microsemi.com

3MHz 2.4A Synchronous Buck Converter

Pin Configuration and Pinout

PVIN

PGND

⁷VCC

GND

FB⁴

Figure 2 · Pinout DFN 2mmx2mm 8L Top View

Marking: First Line 7167

Second Line YWWA (Year/Work Week/Lot Code)

Ordering Information

Ambient Temperature

Type

Package

DFN 2mmx2mm 8L

Part Number

LX7167CLD

Packaging Type

Bulk / Tube

RoHS Compliant,

Pb-free

-10°C to 85°C

LX7167CLD-TR

Tape and Reel

Pin Description

Description

Number Designator

PGND

Ground pin for the power stage.

Switch-node pin. Connect the output inductor between this pin and output capacitor.

When the chip is DISABLED, the internal discharge resistor will be enabled to discharge

the output capacitance. The current will flow into this pin.

GND

Ground pin.

Voltage feedback pin. Connect to the output terminal through a resistor divider network

to set the output voltage of the regulator to the desired value.

Pull this pin higher than 1V will enable the controller. When pulled low, the IC will turn

off and the Internal discharge FET will turn on to discharge the output capacitor through

the SW pin.

Power-good pin. This is an open-drain output and should be connected to a voltage

rail with an external pull-up resistor. During the power on, this pin switches from

LOW to HI state when FB voltage reaches above the power good threshold and the

internal soft start has finished its operation. It will be pulled low when the FB falls

below the power-good threshold minus the hysteresis. It will turn back on when the

pull FB rises above the threshold.

Analog input voltage terminal. Connect this pin to VIN with a 10ohm resistor and

connect a 1µF ceramic capacitor from VCC to GND.

VCC

PVIN

Input voltage terminal of the regulator. A minimum of 10µF, X5R type ceramic

capacitor must be connected as close as possible from this pin to PGND plane to

insure proper operation.

For good thermal connection, this PAD must be connected using thermal VIAs to the

GND plane and to the LAND pattern of the IC.

Power PAD

Block Diagram

V_IN

V_OUT

V_FB

Hysteresis = XmV

Delay = Xns

ramp

Freq Correction

Hysteretic

Engine

Vref

Freq

Ref

Figure 3 · Simplified Block Diagram of LX7167

3MHz 2.4A Synchronous Buck Converter

Absolute Maximum Ratings

Min

-0.3

-2

Max

Units

Parameter

PVIN, EN, FB, PG to GND

SW to GND

SW to GND ( Shorter than 50ns)

Junction Temperature

150

°C

Storage Temperature

-65

150

Peak Package Solder Reflow Temperature (40s, reflow)

260 (+0,-5)

Note: Performance is not necessarily guaranteed over this entire range. These are maximum stress ratings only.

Exceeding these ratings, even momentarily, can cause immediate damage, or negatively impact long-term

operating reliability

Operating Ratings

Min

Max

5.5

Units

Parameter

VCC, PVIN

V_OUT

0.6

-10

VIN – 0.5

Ambient Temperature

Output Current

°C

2.4

Thermal Properties

Thermal Resistance

Typ

Units

°C/W

θ_JA

Note: The _JAnumber assumes no forced airflow. Junction Temperature is calculated using T_J= T_A+ (PD x _JA). In

particular, θ_JAis a function of the PCB construction. The stated number above is for a four-layer board in

accordance with JESD-51 (JEDEC).

Electrical Characteristics

Note: Unless otherwise specified, the following specifications apply over the operating ambient temperature of

-10°C ≤ T_A≤ 85°C except where otherwise noted with the following test conditions: VCC = PVIN = 5V.

Typical parameter refers to T_J= 25°C

Symbol

Parameter

Test Condition

Min

Typ

Max

Units

Operating Current

I_Q

Input Current

I_LOAD= 0

350

0.1

µA

I_SHDN

Input Current at Shut Down V_EN= GND

PVIN Input UVLO

PVIN Under Voltage Lockout

UVLO Hysteresis

PVIN rising

2.4

2.8

260

Electrical Characteristics

Symbol

Parameter

Test Condition

Min

Typ

Max

Units

FEEDBACK

T_A= 25°C

0.594

0.591

0.600

0.606

0.609

V_REF

I_FB

Feedback Voltage

-10°C to 85°C

FB Pin Input Current

Line Regulation

PVIN from 3V to 5.5V

I_LOAD= 0 to 2A. Note 1

0.70

1.0

Load Regulation

%/A

FB UVLO

V_FBUVLO

FB UVLO Threshold

%V_REF

OUTPUT DEVICE

R_{DSON_H}

R_{DSON_L}

I_L

R_DSONof High Side

150

100

4.5

mΩ

R_DSONof Low Side

Peak Current Limit

2.6

3.5

Thermal Shutdown

Threshold

T_SH

T_H

150

°C

Thermal Shutdown

Hysteresis

PVIN OVP

OVP_R

Rising Threshold

Falling Threshold

6.1

OVP_F

5.5

2.6

OSCILLATOR FREQUENCY

Switching Frequency

SOFT START

3.4

MHz

From EN High to V_OUTreach

regulation

T_SS

Soft Start Time

500

1.2

µs

T_HICCUP

EN INPUT

EN_VIN

EN_VIL

Hiccup Time

V_FB= 0.2V

Input High

Input Low

Hysteresis

Input Bias

0.4

EN_H

0.1

EN_II

0.01

µA

PG ( Power Good)

Power Good Transition

High Threshold

V_PG

Ω

V_PGHY

PG_RDSON

Hysteresis

Either V_FBrising or falling

VCC = 5V

Power Good Internal FET

R_DSON

100

300

PG FET Leakage Current

PG internal Glitch Filter

0.01

µA

µs

Note 1

OUTPUT DISCHARGE

Internal Discharge Resistor

Note 1: Guaranteed by design, not tested during production.

200

1400

Ω

3MHz 2.4A Synchronous Buck Converter

Typical Performance Curves -- (Efficiency)

100

VOUT = 0.9V

VOUT = 1.2V

VOUT = 1.8V

100

1000

Load Current (mA)

Figure 4 · Efficiency vs. Output Current with 3.3V Input

100

VOUT = 0.9V

VOUT = 1.8V

VOUT = 3.3V

VOUT = 1.2V

VOUT = 2.5V

100

1000

Load Current (mA)

Figure 5 · Efficiency vs. Output Current with 5V Input

Typical Performance Curves -- (Step Load Response.)

Figure 6 · Step Response (V_IN= 5V, V_OUT= 3.3V, L = 0.47µH, C_OUT= 22µF)

3MHz 2.4A Synchronous Buck Converter

Theory of Operation / Application Information

Basic Operation

The operation of the controller consists of comparing the V_FBvoltage to an internal reference. When

the VFB voltage is lower than the V_REF, the upper switch turns on. When the VFB voltage is higher

than V_REF, the upper switch turns off and the lower switch turns on. An internal ramp is used to

stabilize the switching frequency and keep the V_FBimmune to the output capacitor, C_O, value or

parasitic components (i.e. esr, esl). In addition, a frequency control loop ensures the switching

frequency is constant under continuous conduction mode of operation.

At light load, the converter automatically reduces the switching frequency to optimize efficiency while

ensuring the ripple voltage is low.

Setting of the Output Voltage

The LX7167A develops a 0.6V reference voltage between the feedback pin, FB, and the signal

ground. The output voltage is set by a resistive divider according to the following formula:

ꢌꢊ

ꢀꢁꢂ

ꢃꢄꢅ_ꢆꢇꢈꢄꢉ (ꢊ ꢋꢄ

)

ꢌꢍ

The output component values are recommended below.

VOUT

COUT

5V input

3.3V input

22μF

2x22μF

4x22μF

22μF

2x22μF

4x22μF

22μF

2x22μF

4x22μF

22μF

2x22μF

4x22μF

22μF

2x22μF

4x22μF

22μF

2x22μF

4x22μF

22μF

2x22μF

4x22μF

22μF

2x22μF

4x22μF

10pF

15pF

22pF

0.47μH &

0.68μH

66.5kΩ

100kΩ

15pF

22pF

27pF

12pF

22pF

27pF

1.0μH

10pF

15pF

22pF

15pF

22pF

27pF

15pF

22pF

33pF

0.47μH &

0.68μH

1.8V

2.5V

3.3V

100kΩ

158kΩ

49.9kΩ

34.8kΩ

1.0μH

0.47μH &

0.68μH

10pF

15pF

22pF

33pF

47pF

22pF

33pF

47pF

22pF

27pF

33pF

1.0μH

0.47μH

& 0.68μH

1.0μH

Theory of Operation / Application Information

Start Up

The reference (V_REF) is ramped up from zero voltage to 0.6V in 500µs. During this time, the PG is

pulled low. When the reference reaches 0.6V, signaling the end of the soft start cycle, the PG pin will

go high within 5µs.

Over Current Protection

The IC has the ability to protect against all types of short circuit protection. It has cycle by cycle short

protection that turns off the upper MOSFET and ends the cycle when the current exceeds the OCP

threshold, when this occurs, the off-time is at least 200ns before the upper FET is turned on again.

After startup, if the FB pin drops below the Feedback UVLO threshold, the chip will go into a hiccup

mode of operation. This helps to protect against a crowbar short circuit. The FB UVLO Alarm is not

active during startup.

Hiccup Mode of Operation

Hiccup mode of operation will protect the IC during a short of the output. After startup, it will be

triggered when the FB UVLO is exceeded.

Input Over Voltage Protection

The IC is protected against damage when the input voltage rapidly rises to the absolute maximum

level. When the input voltage rises over the PVIN OVP rising threshold, the IC will turn off switching.

It will resume switching when the input voltage drops below the PVIN OVP falling threshold with

hysteresis.

Typical Application Diagram

100k

PGOOD

VIN

PVIN

VOUT

0.47µF

0.01µF

22µF

X5R

100k

2*10µF

X5R

VCC

LX7167

49.9k

PGND

GND

Figure 7 · LX7167 Typical Application Diagram

3MHz 2.4A Synchronous Buck Converter

PACKAGE OUTLINE DIMENSIONS

MILLIMETERS

INCHES

Dim

MIN MAX

MIN

MAX

0.70 0.80 0.0276 0.0315

0.05 0.0020

0.20 ref 0.0079 ref

0.18 0.30 0.0071 0.0118

2.00 BSC 0.0787 BSC

D2 1.55 1.80 0.0610 0.0709

top

bottom

0.50 BSC

2.00 BSC

0.0197 BSC

0.0787 BSC

side

0.75 1.00 0.0295 0.0394

0.20 0.40 0.0079 0.0157

Figure 8 · 8 Pin Plastic DFN 2x2mm Dual Exposed Pad Package Dimensions

Note: 1. Dimensions do not include mold flash or protrusions; these shall not exceed

0.155mm(.006”) on any side. Lead dimension shall not include solder coverage.

Note: 2. Dimensions are in mm, inches are for reference only.

LAND PATTERN RECOMMENDATION

Center Thermal Pad

0.8

R 2x0.3

6x0.5

63% Printed

solder coverage

on thermal pad

1.7

Defined Pad

PCB Land Pattern

0.28

Figure 9 · 8 Pin Plastic DFN 2x2mm Dual Exposed Pad Package Footprint

Disclaimer:

This PCB land pattern recommendation is based on information available to Microsemi by its suppliers. The actual land pattern to be used could be different depending on the

materials and processes used in the PCB assembly, end user must account for this in their final layout. Microsemi makes no warranty or representation of performance based

on this recommended land pattern.

PRODUCTION DATA – Information contained in this document is proprietary to Microsemi and is current

as of publication date. This document may not be modified in any way without the express written

consent of Microsemi. Product processing does not necessarily include testing of all parameters.

Microsemi reserves the right to change the configuration and performance of the product and to

discontinue product at any time.

Microsemi Corporation (NASDAQ: MSCC) offers a comprehensive portfolio of semiconductor

solutions for: aerospace, defense and security; enterprise and communications; and industrial

and alternative energy markets. Products include high-performance, high-reliability analog and

RF devices, mixed signal and RF integrated circuits, customizable SoCs, FPGAs, and

complete subsystems. Microsemi is headquartered in Aliso Viejo, Calif. Learn more at

www.microsemi.com.

Microsemi Corporate Headquarters

One Enterprise, Aliso Viejo CA 92656 USA

Within the USA: +1(949) 380-6100

Sales: +1 (949) 380-6136

Microsemi Corporation. All other trademarks and service marks are the property of their respective owners.

Fax: +1 (949) 215-4996

LX7167-3/1.1

LX7167CLD-TR [MICROSEMI]

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