ISL6424

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 I²C Interface
• Switch-Mode Power Converter for Lowest Dissipation
- Boost PWMs with > 92% Efficiency
- Selectable 13V or 18V Outputs
- Digital Cable Length Compensation (1V)
•I²C Compatible Interface for Remote Device Control
- Registered Slave Address 0001 00XX
- Full 3.3V/5V Operation up to 400kHz
• External Pins to Select 13V/18V Option
• DSQIN1&2 and SEL18V1&2 pins 2.5V Logic Compatible
• Built-In Tone Oscillator Factory Trimmed to 22kHz
- Facilitates DiSEqC (EUTELSAT) Encoding
• Internal Over-Temperature Protection and Diagnostics
• Internal Overload and Overtemp Flags (Visible on I²C)
• LNB Short-Circuit Protection and Diagnostics
• QFN Package
- Compliant to JEDEC PUB95 MO-220 QFN - Quad Flat No Leads - Product Outline
- Near Chip-Scale Package Footprint
• Pb-Free Plus Anneal Available (RoHS Compliant)




Application

LNB Power Supply and Control for Satellite Set-Top Box




Pinout






Specifications

Supply Voltage, V_CC . . . . . . . . . . . . . . . . . . . . . . . 8.0V to 18.0V
Logic Input Voltage Range
(SDA, SCL, ENT, DSQIN 1&2, SEL18V 1&2) . . . . . -0.5V to 7V




Description

The ISL6424 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 ISL6424 is comprised of two independent currentmode boost PWMs and two low-noise linear regulators along with the circuitry required for 22kHz tone generation, modulation and I2C device interface. The ISL6424 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 1.2V 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 are set to 13V or 18V by independent voltage select commands (VSEL1, VSEL2) through the I2C bus. Additionally, to compensate for the voltage drop in the coaxial cable, the selected voltage may be increased by 1V with the line length compensation (LLC) feature. All the functions on this IC are controlled via the I2C bus by writing 8 bits on System Register (SR, 8 bits). The same register can be read back, and two bits will report the diagnostic status. Separate enable commands sent on the I2C 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 SEL18V pin allows the 13V to 18V transition with an external pin, overriding the I2C input. The ISL6424 is offered in a 32 Ld 5x5 QFN. A 28 Ld EPSOIC package is coming soon.