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EOL Products:
A certain prescribed period of time has passed since EOL was announced for these products, and production has been discontinued.

2.5A Regulator with Integrated High-Side MOSFET for Synchronous Buck or Boost Buck Converter


The ISL85402 is a synchronous buck controller with a 125mΩ high-side MOSFET and low-side driver integrated. The ISL85402 supports a wide input range of 3V to 36V in buck mode. It supports 2.5A continuous load under conditions of 5V VOUT , VIN range of 8V to 36V, 500kHz and +105°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 14 for more details.

The ISL85402 has a 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 2.5V or lower (Refer to “Typical Application Schematic III - Boost Buck Converter” on page 5).

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.


  • Buck Mode: Input Voltage Range 3V to 36V (Refer to “Input Voltage” on page 13 for more details)
  • Boost Mode Expands Operating Input Voltage Lower Than 2.5V (Refer to “Input Voltage” on page 13 for more details)
  • Selectable Forced PWM Mode or PFM Mode
  • 300µA IC Quiescent Current (PFM, No Load); 180µA Input Quiescent Current (PFM, No Load, VOUT Connected to AUXVCC)
  • Less than 3µA Shut Down 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)


 Block Diagram


Basic Information
Production Status
iSim Model
Buck or Boost
# of Outputs
Input Voltage Min (V)
Input Voltage Max (V)
Output Voltage Min (V)
Output Voltage Max (V)
Output Current Max (A)
0.3 mA
Switching Freq. (max) (MHz)
Switching Freq. (min) (MHz)
Max Duty Cycle (%)
Qualification Level
Peak Efficiency (%)
SYNCH Capability
Control Type
Current Mode
Switching Frequency Range (MHz)
0.2 to 2.2
Temperature Range
-40 to +85

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