ISL6308A Three-Phase Buck PWM Controller with High Current Integrated MOSFET Drivers

The ISL6308A is a three-phase PWM control integrated circuit (IC) equipped with built-in MOSFET drivers. It delivers precise voltage regulation suitable for various applications, including high current low voltage point-of-load converters, embedded systems, and other general low voltage medium to high current applications. The incorporation of power MOSFET drivers into the controller IC represents a shift from the traditional separate PWM controller and driver configuration seen in previous multi-phase product families. This integration reduces the number of external components required, resulting in a more cost-effective and space-efficient power management solution. The output voltage can be set using an on-chip digital-to-analog converter (DAC) or an external precision reference. A two-bit code selects the DAC reference from four possible values (0.6V, 0.9V, 1.2V, and 1.5V). Additionally, a unity gain differential amplifier is included for remote voltage sensing, allowing compensation for any voltage differences between remote and local grounds. The output voltage can also be adjusted using a single external resistor. An optional droop function is available and can be disabled for applications with less stringent output voltage variation requirements or less severe transient loads. A distinctive feature of the ISL6308A is its dual approach to current sensing, utilizing both DCR and rDS(ON) methods. Load line voltage positioning and overcurrent protection are achieved through continuous inductor DCR current sensing, while rDS(ON) current sensing ensures accurate channel-current balance. This combination leverages the advantages of both techniques. The controller IC includes advanced protection features such as sophisticated overvoltage and overcurrent protection. In the event of overvoltage, the converter activates the lower MOSFETs to clamp the rising output voltage and safeguard the load. An overvoltage protection (OVP) output is also available to drive an optional crowbar device. The overcurrent protection threshold is adjustable via a single external resistor. Additional protection mechanisms include safeguards against open circuits on the remote sensing inputs, collectively providing robust protection for the output load.

The ISL6308A is designed to enhance the efficiency and reliability of power management systems. Its three-phase PWM control architecture allows for smooth operation across various load conditions, making it ideal for applications requiring high efficiency and performance. The use of integrated MOSFET drivers minimizes the need for external components, which simplifies the design and reduces the overall footprint of the power management solution.

The programmable output voltage feature, facilitated by the on-chip DAC, allows for flexibility in design, accommodating a range of output requirements with precision. The remote voltage sensing capability ensures that voltage regulation remains accurate even when significant distances exist between the power supply and the load, thus enhancing the performance in distributed power systems.

The dual current sensing technique is particularly noteworthy, as it not only improves the accuracy of current measurement but also enhances the overall stability of the power supply. The combination of DCR and rDS(ON) sensing allows for effective load balancing among multiple phases, which is crucial in multi-phase applications where uneven current distribution can lead to overheating and potential failure.

The comprehensive protection features embedded in the ISL6308A ensure that both the power supply and the connected load are safeguarded against potential faults. The overvoltage protection mechanism is crucial for preventing damage to sensitive components, while the adjustable overcurrent protection allows designers to tailor the system to their specific needs. The inclusion of protections against open circuits in the sensing inputs further enhances the reliability of the system, making the ISL6308A a robust choice for modern power management applications.The ISL6308A is a three-phase PWM control IC with integrated MOSFET drivers. It provides a precision voltage regulation system for multiple applications including, but not limited to, high current low voltage point-of-load converters, embedded applications and other general purpose low voltage medium to high current applications. The integration of power MOSFET drivers into the controller IC marks a departure from the separate PWM controller and driver configuration of previous multi-phase product families. By reducing the number of external parts, this integration allows for a cost and space saving power management solution.

Output voltage can be programmed using the on-chip DAC or an external precision reference. A two bit code programs the DAC reference to one of 4 possible values (0. 6V, 0. 9V, 1. 2V and 1. 5V). A unity gain, differential amplifier is provided for remote voltage sensing, compensating for any potential difference between remote and local grounds. The output voltage can also be offset through the use of single external resistor. An optional droop function is also implemented and can be disabled for applications having less stringent output voltage variation requirements or experiencing less severe step loads.

A unique feature of the ISL6308A is the combined use of both DCR and rDS(ON) current sensing. Load line voltage positioning and overcurrent protection are accomplished through continuous inductor DCR current sensing, while rDS(ON) current sensing is used for accurate channel-current balance. Using both methods of current sampling utilizes the best advantages of each technique. Protection features of this controller IC include a set of sophisticated overvoltage and overcurrent protection.

Overvoltage results in the converter turning the lower MOSFETs ON to clamp the rising output voltage and protect the load. An OVP output is also provided to drive an optional crowbar device. The overcurrent protection level is set through a single external resistor. Other protection features include protection against an open circuit on the remote sensing inputs. Combined, these features provide advanced protection for the output load. 🔗 External reference