1
®
FN9190.2
ISL6422
Dual Output LNB Supply and Control
Voltage Regulator with I
2
C Interface for
Advanced Satellite Set-Top Box Designs
The ISL6422 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 consists 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 0.8V 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
can be controlled in two ways:
• Full control from I
2
C using the VTOP1, VTOP2, VBOT1,
and VBOT12 bits, or
• Set the I
2
C to the lower range (13V/14V) and switch to the
higher range (18V/19V) with the SELVTOP1 or
SELVTOP2 pin.
All the functions on this IC are controlled via the I
2
C bus by
writing 8-bit words onto the System Registers (SR). The
same register can be read back, and 4-bits per output 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 External modulation input EXTM1, EXTM2 can accept a
modulated Diseqc command and transfer it symmetrically to
the output. Alternatively, the EXTM1 or EXTM2 pin can be
used to modulate the continuous internal tone.
The FLT
pin serves as an interrupt for the processor when
an over temperature, overcurrent or backwards overcurrent
fault conditions is detected by the LNB controller or when
both channels are disabled by the I
2
C EN bits set low. The
nature of the fault can be read of the I
2
C registers.
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 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
• Four level Slave Address 0001 00XX
• 2.5V, 3.3V, 5V Logic Compatible
• External Pins to Toggle Between V and H Polarization.
• Supports DiSEqC 2.0 Protocol
• 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 Over-Temperature Flags
(Visible on I
2
C)
•FLT
Signal
• LNB Short-Circuit Protection and Diagnostics
• QFN, EPTSSOP 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. #
ISL6422ERZ* ISL6422 ERZ -20 to +85 40 Ld 6x6 QFN L40.6x6
ISL6422EVEZ* ISL6422 EVEZ -20 to+ 85 38 Ld EPTSSOP M38.173B
*Add “-T” suffix for tape and reel.
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. All Rights Reserved
All other trademarks mentioned are the property of their respective owners.
August 10, 2007
