LX1675ILQ MICROSEMI [Microsemi Corporation], LX1675ILQ Datasheet

LX1675ILQ

Manufacturer Part Number

LX1675ILQ

Description

Manufacturer

MICROSEMI [Microsemi Corporation]

Datasheet

1.LX1675ILQ.pdf (19 pages)

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Rev. 1.2a, 2006-02-16

power supply controller IC featuring

three voltage mode PWM switching

regulator stages with an additional

onboard linear regulator driver.

phases can be easily configured for a

single Bi-Phase high current output or

operated as two independently regulated

outputs. All outputs (PWM phases and

LDO) have separate, programmable soft-

start sequencing. This versatility yields

either

regulated

sequencing capability giving system

designers the ultimate flexibility in power

supply design.

is provided by monitoring the voltage

drop across the lower MOSFET power

stage during conduction, utilizing the

Rds(on) impedance. This eliminates the

need

resistors. Once current limit has been

reached and persist for 4 clock cycles, the

output is shut off and Soft Start is

initialized to force a hiccup mode for

protection.

IMPORTANT: For the most current data, consult MICROSEMI’s website:

LoadSHARE is a Trademark of Microsemi Corporation

Protected by U.S. Patents 6,285,571 and 6,292,378

VIN 4.5V to 24V

VOUT4

The LX1675 is a highly integrated

Two of the constant frequency PWM

Current limit for each PWM regulator

for

three

outputs

expensive

four

11861 Western Avenue, Garden Grove, CA. 92841, 714-898-8121, Fax: 714-893-2570

with

P R O D U C T H I G H L I G H T

current

VIN

VSLR

LDGD

LDFB

SSX

AGND

EOX

independently

full

D E S C R I P T I O N

LX1675

VCCL

power

sense

HOX

driven to provide an LDO output of 5A

and 15A for each PWM controller. This

is useful for I/O, memory, termination,

and other supplies surrounding today’s

micro-processor based designs.

supply voltage ranging from 4.5V to 24V.

Each PWM regulator output voltage is

programmed via a simple voltage-divider

network.

engineers

respect to the MOSFET supply.

phase can utilize different supply voltages

for efficient use of available supply rails.

configured

LoadSHARE

programmed via inductor ESR selection.

The split phase operation reduces power

loss, noise due to the ESR of the input

capacitors and allows for reduction in

capacitance values while maximizing

regulator response time.

reference voltage is buffered and brought

out on a separate pin to be used as an

external reference voltage.

VCX

HRX

CSX

LOX

PGX

FBX

Additionally, when two phases are

High current MOSFETs can be directly

The LX1675 accepts a wide range of

ONE OF 3 PWM SECTIONS

Integrated Products Division

Microsemi

maximum

The LX1675 design gives

™

http://www.microsemi.com

Bi-Phase

topology

5µh

flexibility

Multiple Output LoadSHARE™ PWM

The internal

output,

VOUT1, 2, 3

can

Each

with

the

RODUCTION

Note: Available in Tape & Reel. Append the

-40 to 85

P A C K A G E O R D E R I N F O

0 to 85

Four Independently Regulated

Outputs

Single Input Supply with Wide

Voltage Range: 4.5-24V

Outputs As Low As 0.8V

Generated From a Precision

Internal Reference

Selectable PWM Frequency of

300KHz or 600KHz

Buffered Reference Voltage

Output

Multiphase Output Reduces

Need for Large Input

Capacitance at High Currents

Integrated High Current

MOSFET Drivers

Independent Soft-Start and

Power Sequencing

Adjustable Linear Regulator

Driver Output

No Current-Sense Resistors

DDR Termination Compliant

RoHS Compliant for Pb Free

Multi-Output Power Supplies

Video Card Power Supplies

PC Peripherals

Portable PC Processor and I/O

Supply

(°C)

letters “TR” to the part number. (i.e.

LX1675CLQ-TR)

ATA

K E Y F E A T U R E S

A P P L I C A T I O N S

RoHS Compliant / Pb-free

HEET

LX1675CLQ

LX1675ILQ

38-Pin

Plastic MLPQ

LX1675

Page 1

Related parts for LX1675ILQ

LX1675ILQ Summary of contents

Page 1

... Video Card Power Supplies PC Peripherals Portable PC Processor and I/O Supply Plastic MLPQ LQ T (°C) 38-Pin A RoHS Compliant / Pb-free LX1675CLQ - LX1675ILQ Note: Available in Tape & Reel. Append the letters “TR” to the part number. (i.e. LX1675CLQ-TR) Page 1 ...

Page 2

Supply Voltage (VIN VSLR, HRX) ............................................................... -0.3V to 24V , Supply Voltage (VCCL) ................................................................................ -0.3V to 6.0V ...

Page 3

TM Name Bi-Phase Operation: Phase 1 and 2 Voltage Feedback FB1 Single Phase Operation: Phase 1 Voltage Feedback, connect to the output through a resistor network to set desired output voltage of Phase 1. Bi-Phase Operation: Load Sharing Voltage Sense ...

Page 4

... TM For the LX1675ILQ the following specifications apply over the ambient temperature -40°C < TA < 85°C and for the LX1675CLQ 0°C ≤ T 85°C except where otherwise noted and the following test conditions Load 300KHz). Parameter SWITCHING REGULATORS Input Voltage ...

Page 5

... For the LX1675ILQ the following specifications apply over the ambient temperature -40°C < TA < 85°C and for the LX1675CLQ 0°C < T < 85°C except where otherwise noted and the following test conditions Load 300KHz) ...

Page 6

Page 7

TM CS2 LPF2 I SET 50uA CS Comp - + CLK EO2 Error Comp + - - FB2 + Amplifier/ Compensation 100mv RF2 LPF1 20K V REF SS2 Phase 1 500k CSS Figure 3 – Block Diagram of Phase 2 ...

Page 8

TM TP1 +VIN C7 TP2 + 470uF 16V TP4 TP3 L2 6.8uh Q3A TP20 FDS6898A +3.3V C12 + TP5 OUT 470uF TP21 16V Q3B FDS6898A TP7 R8 R19 20 2.00K C17 TP10 R6 C22 R12 TP11 100K 1.2nF 24.3K TP8 ...

Page 9

ENERAL ESCRIPTION The LX1675 is a voltage-mode pulse-width modulation controller integrated circuit. The internal ramp generator frequency is set to 300kHz or 600kHz by the FS logic input. The device has external compensation, for more flexibility of ...

Page 10

SHARE (ESR M I HASE OAD ETHOD The first method is to change the ratio of the inductors ...

Page 11

L1, Switch Side 100 62k LPF1 Not Resistor Used Divider L2, Resistor Switch Divider Side LPF2 62k 62k 100 TBD 4700pF Where ...

Page 12

SHARE (P I HASE OAD ROPORTIONAL The best topology for generating a current ratio at full load and ...

Page 13

The circuit in Figure 9 sums a current through a 1MΩ ...

Page 14

UTPUT NDUCTOR The output inductor should be selected to meet the requirements of the output voltage ripple in steady-state operation and the inductor current slew-rate during transient. The peak-to- peak output voltage ripple is: = × V ...

Page 15

NPUT APACITOR The input capacitor and the input inductor, if used, are to filter the pulsating current generated by the buck converter to reduce interference to other circuits connected to the same 5V rail. In addition, the ...

Page 16

UTPUT NABLE The LX1675 MOSFET driver outputs are shut off by pulling the soft-start pin below 0.1V. The LDO voltage regulator has its own soft-start pin: SSL, that is the same as any of the other switching ...

Page 17

The power N-MOSFET transistor’s total gate charge spec, (Qg) ...

Page 18

TM LQ 38-Pin Plastic MLPQ (5x7mm EP Note: Dimensions do not include mold flash or protrusions; these shall not exceed 0.155mm(0.006”) on any side. Lead dimension shall not include solder coverage. 5.50mm 4.10mm Copyright © 2004 Rev. 1.2a, ...

Page 19

TM 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 ...

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