The ISL85402 is a synchronous buck controller with a 125mΩ high-side MOSFET and low-side driver integrated. The ISL85402 supports a wide input voltage range from 3V to 36V. Regarding the output current capability from the thermal perspective, the ISL85402 can typically support continuous load of 2.5A under conditions of 5V VOUT, VIN range of 8V to 30V, 500kHz, +85°C ambient temperature with still air. For any specific application, the actual maximum output current depends upon the die temperature not exceeding +125°C with the power dissipated in the IC, which is related to input voltage, output voltage, duty cycle, switching frequency, board layout and ambient temperature, etc. Refer to “Output Current” on page 13 for more details.
The ISL85402 has flexible selection of operation modes of forced PWM mode and PFM mode. In PFM mode, the quiescent input current is as low as 180µA (AUXVCC connected to VOUT). The load boundary between PFM and PWM can be programmed to cover wide applications.
The low-side driver can be either used to drive an external low-side MOSFET for a synchronous buck, or left unused for a standard non-synchronous buck. The low-side driver can also be used to drive a boost converter as a pre-regulator followed by a buck controlled by the same IC, which greatly expands the operating input voltage range down to 3V or lower .
The ISL85402 offers the most robust current protections. It uses peak current mode control with cycle-by-cycle current limiting. It is implemented with frequency foldback under current limit condition; besides that, the hiccup overcurrent mode is also implemented to guarantee reliable operations under harsh short conditions.
The ISL85402 has comprehensive protections against various faults including overvoltage and over-temperature protections, etc.
Features
• Ultra Wide Input Voltage Range 3V to 36V
• Optional Mode Operation - Forced PWM Mode - Selectable PFM with Programmable PFM/PWM Boundary
• 300µA IC Quiescent Current (PFM, No Load); 180µA Input Quiescent Current (PFM, No Load, VOUT Connected to AUXVCC)
• Less than 3µA Standby Input Current (IC Disabled)
• Operational Topologies - Synchronous Buck - Non-Synchronous Buck - Two-Stage Boost Buck
• Programmable Frequency from 200kHz to 2.2MHz and Frequency Synchronization Capability
• ±1% Tight Voltage Regulation Accuracy
• Reliable Overcurrent Protection - Temperature Compensated Current Sense - Cycle-by-Cycle Current Limiting with Frequency Foldback - Hiccup Mode for Worst Case Short Condition
• 20 Ld 4x4 QFN Package
• Pb-Free (RoHS Compliant)
Applications
• General Purpose
• 24V Bus Power
• Battery Power
• Point of Load
• Embedded Processor and I/O Supplies
(Picture: Pinout)
