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Dual Output LNB Supply and Control

Advanced Satellite Set-Top Box Designs

The ISL6405 is a highly integrated voltage regulator and

interface IC, specifically designed for supplying power and

control signals from advanced satellite set-top box (STB)

modules to the low noise blocks (LNBs) of two antenna

ports. The device is comprised of two independent current-

mode boost PWMs and two low-noise linear regulators along

with the circuitry required for 22kHz tone generation,

total LNB supply design simple, efficient and compact with

low external component count.

Two independent current-mode boost converters provide the

linear regulators with input voltages that are set to the final

output voltages, plus typically 1.2V to insure minimum power

dissipation across each linear regulator. This maintains

constant voltage drops across each linear pass element

while permitting adequate voltage range for tone injection.

The final regulated output voltages are available at two

output terminals to support simultaneous operation of two

antenna ports for dual tuners. The outputs for each PWM are

set to 13V or 18V by independent voltage select commands

compensate for the voltage drop in the coaxial cable, the

selected voltage may be increased by 1V with the line length

compensation (LLC) feature. All the functions on this IC are

Register (SR, 8 bits). The same register can be read back,

and two bits will report the diagnostic status. Separate enable

mode control for each PWM and linear combination, disabling

the output into shutdown mode.

Each output channel is capable of providing 750mA of

continuous current. The overcurrent limit can be digitally

programmed. The SEL18V pin with QFN package allows the

input.

Features

• Single Chip Power solution

- True Dual Operation for 2-Tuner/2-Dish Applications

- Both Outputs May be Enabled Simultaneously at

Maximum Power

• Switch-Mode Power Converter for Lowest Dissipation

- Boost PWMs with > 92% Efficiency

- Selectable 13V or 18V Outputs

- Digital Cable Length Compensation (1V)

- Registered Slave Address 0001 00XX

- Full 3.3V/5V Operation up to 400kHz

• External Pins to Select 13V/18V Options

- Available with QFN Package Only

• Built-In Tone Oscillator Factory Trimmed to 22kHz

• Internal Over-Temperature Protection and Diagnostics

• LNB Short-Circuit Protection and Diagnostics

• QFN Package

- Compliant to JEDEC PUB95 MO-220 QFN - Quad Flat

No Leads - Product Outline

- Near Chip-Scale Package Footprint

• Pb-free Packaging Available

- Designated with “Z” Suffix (Refer to Note Below)

Applications

• LNB Power Supply and Control for Satellite Set-Top Box

References

• Tech Brief 389 (TB389) - “PCB Land Pattern Design and

Surface Mount Guidelines for QFN Packages”; Available

on the Intersil website, www.intersil.com

Ordering Information

PART #

PACKAGE

PKG. DWG. #

ISL6405EEB

-20 to 85

28 Ld EPSOIC M28.3B

ISL6405EEBZ

(Note 1)

-20 to 85

28 Ld EPSOIC

(Pb-free)

M28.3B

ISL6405ER

-20 to 85

32 Ld 5x5 QFN L32.5x5

ISL6405ERZ

(Note 1)

-20 to 85

32 Ld 5x5 QFN

(Pb-free)

L32.5x5

NOTES:

1. Intersil Pb-free products employ special Pb-free material sets; molding

compounds/die attach materials and 100% matte tin plate termination

finish, which is compatible with both SnPb and Pb-free soldering

operations. Intersil Pb-free products are MSL classified at Pb-free peak

reflow temperatures that meet or exceed the Pb-free requirements of

IPC/JEDEC J Std-020B.

2. Tape and Reel available. Add “-T” suffix for Tape and Reel Packing Option.

FN9026.2

ISL6405

Data Sheet

July 2004

CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.

1-888-INTERSIL or 321-724-7143

Copyright © Intersil Americas Inc. 2004. All Rights Reserved