1
®
FN9176.1
ISL6425
Single Output LNB Supply and Control
Voltage Regulator with I
2
C Interface for
Advanced Satellite Set-top Box Designs
The ISL6425 is a highly integrated solution for supplying
power and control signals from advanced satellite set-top
box (STB) modules to the low noise block (LNB). This device
is comprised of a current-mode boost PWM and a low-noise
linear regulator, along with the circuitry required for I
2
C
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 (VSEL) through the I
2
C bus. Additionally, to
compensate for the voltage drop in the coaxial cable, the
voltage may be increased by 1V with the line length
compensation (LLC) feature. An enable command sent on
the I
2
C bus provides standby mode control for the PWM and
linear combination, disabling the output to conserve power.
A current-mode boost converter provides the linear regulator
with an input voltage that is set to the required output
voltage, plus 1.2V (typ.) to insure minimum power
dissipation. This 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 750mA (typ.).
Features
• Switch-Mode Power Converter for Lowest Dissipation
- Boost PWM with >92% Efficiency
- Selectable 13V or 18V Outputs
- Digital Cable Length Compensation (1V)
• External Pin to Select 13V/18V Options
• DSQIN and SEL18V pins are 2.5V logic compatible
•I
2
C 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
• Internal Over-Temperature Protection and Diagnostics
• Internal Overload and Overtemp Flags (Visible on I
2
C)
• 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 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
Ordering Information
PART NUMBER
TEMP.
RANGE (°C) PACKAGE
PKG.
DWG. #
ISL6425ER -20 to 85 32 Ld 5x5 QFN L32.5x5
ISL6425ER-T 32 Ld 5x5 QFN Tape and Reel L32.5x5
ISL6425ERZ
(Note)
-20 to 85 32 Ld 5x5 QFN
(Pb-free)
L32.5x5
ISL6425ERZ-T
(Note)
32 Ld 5x5 QFN Tape and Reel
(Pb-free)
L32.5x5
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 321-724-7143
| Intersil (and design) is a trademark of Intersil Americas Inc.
Copyright © Intersil Americas Inc. 2004-2005. All Rights Reserved
All other trademarks mentioned are the property of their respective owners.
February 8, 2005
