Evaluation Board For Advanced Single Synchronous Buck Pulse-Width Modulation Controller

The ISL6420B simplifies the implementation of a complete control and protection scheme for a high-performance DC/DC buck converter. It is designed to drive N-Channel MOSFETs in a synchronous rectified buck topology. The ISL6420B integrates control, output adjustment, monitoring and protection functions into a single package. Additionally, the IC features an external reference voltage tracking mode for externally referenced buck converter applications and DDR termination supplies, as well as a voltage margining mode for system testing in networking DC/DC converter applications. The operating frequency is fully adjustable from 100kHz to 1.4MHz. High frequency operation offers cost and space savings. The ISL6420B monitors the output voltage and generates a PGOOD (power good) signal when soft-start sequence is complete and the output is within regulation. A built-in overvoltage protection circuit prevents the output voltage from going above typically 115% of the set point. Protection from overcurrent conditions is provided by monitoring the rDS(ON) of the upper MOSFET to inhibit the PWM operation appropriately. This approach simplifies the implementation and improves efficiency by eliminating the need for a current sensing resistor.

• Operates From:
  • 4.5V to 5.5V Input
  • 5.5V to 28V Input
• 0.6V Internal Reference Voltage
  • ±2.0% Reference Accuracy
• Resistor-Selectable Switching Frequency
  • 100kHz to 1.4MHz
• Voltage Margining and External Reference Tracking Modes
• Output can Sink or Source Current
• Lossless, Programmable Overcurrent Protection
  • Uses Upper MOSFET’s rDS(ON)
• Programmable Soft-Start
• Drives N-Channel MOSFETs
• Simple Single-Loop Control Design
  • Voltage-Mode PWM Control
• Fast Transient Response
  • High-Bandwidth Error Amplifier
  • Full 0% to 100% Duty Cycle
• Extensive Circuit Protection Functions
  • PGOOD, Overvoltage, Overcurrent, Shutdown
• Diode Emulation during Startup for Pre-Biased Load Applications
• Offered in 20 Ld QFN and QSOP Packages
• QFN (4 x 4) Package
  • QFN compliant to JEDEC PUB95 MO-220 QFN -Quad Flat No Leads - Product Outline
  • QFN Near Chip Scale Package Footprint; Improves PCB Efficiency, Thinner in Profile
• Pb-Free (RoHS Compliant)