1
®
FN9191.2
ISL6423
Single Output LNB Supply and Control
Voltage Regulator with I
2
C Interface for
Advanced Satellite Set-Top Box Designs
DiSEqC 2.0 Compatible
The ISL6423 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 single antenna
ports. The device consists of a current-mode boost PWM
and a low-noise linear regulator 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.
The current mode boost converter provides the linear
regulator with input voltage that is set to the final output
voltages, plus typically 0.8V to insure minimum power
dissipation across the linear regulator. This maintains
constant voltage drop across the linear pass element while
permitting adequate voltage range for tone injection.
The final regulated output voltage is available at output
terminals to support the operation of an antenna port for
single tuners. The outputs for each PWM can be controlled
in two ways, full control from I
2
C using the VTOP and VBOT
bits or set the I
2
C to the lower range (i.e., 13.3V/14.3V) and
switch to higher range (i.e., 18.3V/19.3V) with the SELVTOP
pin. All the functions on this IC are controlled via the I
2
C bus
by writing 8 bits words onto the System Registers (SR). The
same register can be read back, and five I
2
C bits will report
the diagnostic status. Separate enable command sent on the
I
2
C bus provides for standby mode control for the PWM and
linear combination, disabling the output and forcing a shutdown
mode. The output channel is capable of providing 750mA of
continuous current. The overcurrent limit can be digitally
programmed to four levels.
The External modulation input EXTM can accept a
modulated DiSEqC command and transfer it symmetrically
to the output. Alternatively the EXTM pin can be used to
modulate the continuous internal tone.
The FLT
pin serves as an interrupt for the processor when
an over temperature fault condition is detected by the LNB
controller. The nature of the fault can be read of the I
2
C
registers.
Features
• Single Chip Power solution
- Operation for 1-Tuner/1-Dish Applications
- Integrated DC/DC Converter and I
2
C Interface
• Switch-Mode Power Converter for Lowest Dissipation
- Boost PWM with > 92% Efficiency
- Selectable 13.3V or 18.3V Outputs
- Digital Cable Length Compensation (1V)
-I
2
C and Pin Controllable Output
• Output Back Bias Capability of 28V
•I
2
C Compatible Interface for Remote Device Control
• Registered Slave Address 0001 00XX
• 2.5V/3.3V/5V Logic Compatible
• External Pin to Toggle between V & H Polarization
• Built-In Tone Oscillator Factory Trimmed to 22kHz
- Facilitates DiSEqC (EUTELSAT) Encoding
- External Modulation Input
• Internal Over-Temperature Protection and Diagnostics
• Internal OV, UV, Overload and Overtemp Flags
(Visible on I
2
C)
•FLT
signal
• LNB Short-Circuit Protection and Diagnostics
• QFN, HTSSOP Packages
• Pb-Free Plus Anneal Available (RoHS Compliant)
Applications
• LNB Power Supply and Control for Satellite Set-Top Box
Ordering Information
PART NUMBER
(Note)
PART
MARKING
TEMP.
RANGE
(°C)
PACKAGE
(Pb-Free)
PKG.
DWG. #
ISL6423ERZ 6423ERZ -20 to +85 24 Ld 4x4 QFN L24.4x4D
ISL6423ERZ-T 6423ERZ -20 to +85 24 Ld 4x4 QFN
(Tape & Reel)
L24.4x4D
ISL6423EVEZ ISL6423EVEZ -20 to +85 28 Ld HTSSOP M28.173B
ISL6423EVEZ-T ISL6423EVEZ -20 to +85 28 Ld HTSSOP
(Tape & Reel)
M28.173B
NOTE: Intersil Pb-free plus anneal 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.
Copyright Intersil Americas Inc. 2006, 2007, 2008. All Rights Reserved
All other trademarks mentioned are the property of their respective owners.
December 5, 2008
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