ISL6421A_06 datasheet(1/12 Pages) INTERSIL | Single Output LNB Supply and Control Voltage Regulator with I2C Interface for Advanced Satellite Set-top Box Designs

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FN9167.3

ISL6421A

Single Output LNB Supply and Control

Voltage Regulator with I2C Interface for

Advanced Satellite Set-top Box Designs

The ISL6421A is a highly integrated solution for providing

power and control signals from advanced satellite set-top

box (STB) modules to the low noise block (LNB). The

internal architecture of this device contains a current-mode

boost PWM and a low-noise linear regulator, along with the

circuitry required for I2C device interfacing and for providing

DiSEqC™ standard control signals to the LNB.

A regulated output voltage is available at the output terminal

(VOUT) to support the operation of the antenna port in

advanced satellite STB applications. The regulated output

may be set to either 13V or 18V by use of the voltage select

command bit (VSEL) through the I2C bus. Additionally, to

compensate for the voltage drop in the coaxial cable, the

voltage may be increased by 1V with the line length

compensation bit (LLC) feature. The device can be put into a

standby mode by means of the enable bit (EN), this disables

the PWM and Linear regulator combination and helps

conserve power.

The input to the linear regulator is derived from the current

mode boost converter, such that the required voltage is the

sum of the output voltage and the linear regulator drop (1.0V

typical). This ensures that the power dissipation is minimized

and maintains a constant voltage drop across the linear pass

element, while permitting an adequate voltage range for tone

injection.

The device is capable of providing 450mA (typical). The

overcurrent limit is either digitally or resistor programmable.

Pinout

ISL6421A (QFN) TOP VIEW

Features

• Switch-Mode Power Converter for Lowest Dissipation

- Boost PWM with >92% Efficiency

- Selectable 13V or 18V Outputs

- Digital Cable Length Compensation (1V)

- Vsw tracks Vout ensures low dissipation

•I2C Compatible Interface for Remote Device Control

- Registered Slave Address 0001 00XX

- Fully Functional 3.3V, 5V Operation up to 400kHz

• Built-In Tone Oscillator Factory Trimmed to 22kHz

- Facilitates DiSEqC™ (EUTELSAT) Encoding

- External Modulation input DSQIN

• Internal Over Temperature Protection and Diagnostics

• Internal Overload and Over Temperature Flags

(Visible on I2C)

• Output Back-Bias Protection to 24V

• 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

• External Pins to Select 13V/18V Options

• Pb-Free Available (RoHS Compliant)

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

PGND

SGND

SEL18V

BYPASS

PGND

GATE

CPSWOUT

AGND

VOUT

DSQIN

TCAP

1011

1415

Ordering Information

PART

NUMBER*

PART

MARKING

TEMP.

RANGE

(°C)

PACKAGE

PKG.

DWG. #

ISL6421AER

-20 to 85 32 Ld 5x5 QFN L32.5x5

ISL6421AERZ

(Note)

ISL6421AERZ -20 to 85 32 Ld 5x5 QFN

(Pb-free)

L32.5x5

*Add -T for tape and reel package.

NOTE: Intersil Pb-free products employ special Pb-free material sets;

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

termination finish, which are RoHS compliant and 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-020.

Data Sheet

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

1-888-INTERSIL or 1-888-468-3774

| Intersil (and design) is a registered trademark of Intersil Americas Inc.

All other trademarks mentioned are the property of their respective owners.

March 9, 2006

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