1
®
Dual Output LNB Supply and Control
Voltage Regulator with I
2
C Interface for
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,
modulation and I
2
C device interface. The device makes the
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
(VSEL1, VSEL2) through the I
2
C bus. Additionally, to
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
controlled via the I
2
C bus by writing 8 bits on System
Register (SR, 8 bits). The same register can be read back,
and two bits will report the diagnostic status. Separate enable
commands sent on the I
2
C bus provide independent standby
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
13V to 18V transition with an external pin, over-riding the I
2
C
input.
Features
• Single Chip Power solution
- True Dual Operation for 2-Tuner/2-Dish Applications
- Both Outputs May be Enabled Simultaneously at
Maximum Power
- Integrated DC-DC Converter and I
2
C Interface
• Switch-Mode Power Converter for Lowest Dissipation
- Boost PWMs with > 92% Efficiency
- Selectable 13V or 18V Outputs
- Digital Cable Length Compensation (1V)
•I
2
C Compatible Interface for Remote Device Control
- 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
- Facilitates DiSEqC
TM
(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 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 # TEMP. RANGE (
o
C) 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
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Copyright © Intersil Americas Inc. 2004. All Rights Reserved
