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 I2C 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 I2C using the VTOP and VBOT bits or set the I2C 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 I2C bus by writing 8 bits words onto the System Registers (SR)
The ISL6423 is a highly integrated voltage regulator and I²C‑controlled interface IC designed for powering and controlling low‑noise blocks (LNBs) in advanced satellite set‑top box modules. It combines a current‑mode boost PWM converter, a low‑noise linear regulator, and circuitry for 22 kHz tone generation, modulation and DiSEqC 2.0 compatibility.
Key features include selectable 13.3 V/14.3 V or 18.3 V/19.3 V outputs, >92 % conversion efficiency, 750 mA continuous output current, programmable over‑current limits, internal temperature protection, and I²C register control. The device is offered in QFN and HTSSOP packages and meets RoHS requirements.
| Continuous Output Current | 750 mA |
|---|---|
| Efficiency | > 92 % |
| Operating Supply Voltage Range | 8 V – 14 V (typical 12 V) |
| Selectable Output Voltage | 13.3 V/14.3 V or 18.3 V/19.3 V |
The device can provide up to 750 mA of continuous output current.
All functions are controlled via the I²C bus by writing 8‑bit words to system registers.