Single Output LNB Supply and Control Voltage Regulator
2
with I C Interface for Satellite Set-Top Box Designs
ISL9492
The ISL9492 is a highly integrated voltage regulator and
Features
• Single-Chip Power Solution
interface IC specifically designed for supplying power and control
signals from advanced satellite set-top box (STB) modules to the
low noise blocks (LNB) of a single antenna port. It also supports
DiSEqC tone generation and modulation with diagnostic status
read-back. Controlling the ISL9492 is simple via the I C bus by
writing 8 bit words onto the System Registers (SR).
- Operation for 1-Tuner/1-Dish Applications
- Integrated DC/DC Converter and I C Interface
2
• Integrated Boost MOSFET
2
• Switch-Mode Power Converter for Lowest Dissipation
- 490kHz Boost Switching Frequency
- Boost PWMs with > 92% Efficiency
The device design makes the total LNB supply design simple,
efficient and compact with low external component count by
integrating Boost power MOSFET, current-mode boost PWM and
a low-noise linear regulator. The current-mode boost converters
provide the linear regulator with input voltage that is set to the
final output voltages, plus typically 0.9V to insure minimum
power dissipation across each linear regulator.
- Selectable 13.5V or 18.5V Outputs
2
- I C and Pin Controllable Output
• 31V Output Back-Bias Capability
• Built-in Tone Oscillator Factory
- Facilitates DiSEqC (EUTELSAT) Encoding
- Trimmed to 22kHz
The LNB output voltage can be controlled in two ways; by full control
- External Modulation Input
2
2
from I C using the VTOP and VBOT bits or by setting the I C to the
lower range and switching to higher range with the select VTOP pin.
• DiSEqC 2.0 Support and Diagnostics
The External modulation input EXTM accepts a modulated DISEqC
command and transfers it symmetrically to the output. The EXTM
pin can be used to modulate the continuous internal tone. The fault
signal serves as an interrupt for the processor when any condition
turns OFF the LNB controller (over-temperature, overcurrent,
disable). The states of these flags to the faults can be thoroughly
• Internal Overvoltage, Undervoltage, Overcurrent Protection,
Over-Temperature Flags Accessible through the I C Interface
and Fault Signal Status Pin
2
• Short-Circuit Protection
Applications
• LNB Power Supply and Control for Satellite Set-Top Box
2
examined through the I C registers.
TXT
TDOUT
EXTM
FLT#
R1
27
21
17
16
FLT#
3.3V
CPVOUT
CPSWOUT
CPSWIN
C5
100k
C1
0.047µF
28
1
SCL
SDA
SCL
2.2nF
SDA
6
20
25
5
VCC
C2
1µF
ISL9492
C6
10
22
4
LDO_SGND
LDO_SGND
ABYP
DBYP
TCAP
NC
0.1µF
C4
1µF
C8
0.22µF
RL
100
C3
1µF
9
23
PGND
DGATE
FERRITE
BEAD
Q1
NDS356AP
C9
LNB
POWER
0.22µF
L3
Cp
See pg 14
C10
0.1µF
Rp
L1
L2
220µH
R2
VIN
D1
CMS06
100
10µH
1µH
15
C7
C10
100µF
C11
10µF
100µF
D4
CMS06
FIGURE 1. TYPICAL APPLICATION
March 17, 2011
FN6547.1
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
1-888-INTERSIL or 1-888-468-3774 |Copyright Intersil Americas Inc. 2011. All Rights Reserved
Intersil (and design) is a trademark owned by Intersil Corporation or one of its subsidiaries.
All other trademarks mentioned are the property of their respective owners.
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