The ISL9492 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 (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 I2C bus by

writing 8 bit words onto the System Registers (SR).

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.

The LNB output voltage can be controlled in two ways; by full control

from I2C using the VTOP and VBOT bits or by setting the I2C to the

lower range and switching to higher range with the select VTOP pin.

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

examined through the I2C registers.

Features

• Single-Chip Power Solution

- Operation for 1-Tuner/1-Dish Applications

- Integrated DC/DC Converter and I2C Interface

• Integrated Boost MOSFET

• Switch-Mode Power Converter for Lowest Dissipation

- 490kHz Boost Switching Frequency

- Boost PWMs with > 92 Efficiency

- Selectable 13.5V or 18.5V Outputs

- I2C and Pin Controllable Output

• 31V Output Back-Bias Capability

• Built-in Tone Oscillator Factory

- Facilitates DiSEqC (EUTELSAT) Encoding

- Trimmed to 22kHz

- External Modulation Input

• DiSEqC 2.0 Support and Diagnostics

• Internal Overvoltage, Undervoltage, Overcurrent Protection,

Over-Temperature Flags Accessible through the I2C Interface

and Fault Signal Status Pin

• Short-Circuit Protection

Applications

• LNB Power Supply and Control for Satellite Set-Top Box