SI-8105Q: Step-Down Switching Regulator with Current-Mode Control

The SI-8105QL is a step-down switching regulator IC, designed as an output voltage regulator at the secondary stage of switch mode power supplies. The current-mode control system permits small ceramic capacitors to be used as output capacitors. Together with the compact DIP8 package, this allows reduction of regulator circuitry area on the PCB by approximately 50% in comparison with conventional topologies.

Designed to save power, losses in the SI-8105QL are reduced by controlling the maximum on-resistance of a built-in output MOSFET to as low as 165 mΩ. Furthermore, die miniaturization has been accomplished through a proprietary BCD process.

The SI-8105QL supplies an output current of 3.5 A and an output voltage that is variable from 0.5 to 24 V, which is set simply to a voltage compatible with the diverse reduced power supply voltages required by signal processing ICs. Accepting a wide input voltage range, from 4.75 to 28 V, the SI-8105QL can be driven directly by a 24 V power supply.

Applications include power supplies for signal processing ICs for memories and microcomputers used in plasma display panel (PDP) TVs, liquid crystal display (LCD) TVs, computer hard drives, and DVD recorders.

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  • Current-mode control system employed
  • Excellent line regulation (60 mV maximum)
  • 165 mΩ maximum on-resistance of built-in MOSFET
  • Output current 3.5 A
  • Wide range of input voltages (4.75 to 28 V), supports 24 V direct drive
  • Output voltage 0.5 to 24 V, compatible with various IC power supply voltages, through low VREF of 0.5 V.
  • High efficiency, 94% maximum at VIN = 8 V, VO = 5 V, and IO = 0.5 A
  • Operating frequency 350 kHz, supports downsizing of smoothing choke coil
  • Soft start and output on/off functions built-in
  • Built-in protection:
    • Drooping overcurrent protection
    • Overtemperature protection
    • Undervoltage lockout (UVLO)

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Functional Block Diagram Package

Part Number Specifications and Availability

Part Number Package Type Temperature RoHS
Part Composition /
RoHS Data
Comments Samples Check
Distributor Stock
SI-8105QL-TL 8-lead DIP -20°C to 85°C Yes View Data New Contact your
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