3.3 Volt Ringing SLIC Family for Voice Over Broadband (VOB)

Product Status: Mass Production


The 3.3V family of ringing subscriber line interface circuits (SLIC) supports analog Plain Old Telephone Service (POTS) in short and medium loop length, wireless and wireline voice over broadband applications. Ideally suited for customer premise equipment, this family of products offers flexibility to designers with high ringing voltage and low power consumption system requirements.

The ISL5585 family is capable of operating with 100V ringing battery supply, which translates directly to the amount of ringing voltage supplied to the subscriber. With the high operating voltage, subscriber loop lengths can be extended to 500Ω (i.e., 5,000 feet) and beyond, allowing this family to serve emerging Fiber In The Loop (FITL) markets.

Other key features across the product family include: 3.3V VCC operation, low power consumption, ringing using sinusoidal or trapezoidal waveforms, robust auto-detection mechanisms for when subscribers go on or off hook, and minimal external discrete application components. Integrated test access features are also offered on selected products to support loopback testing as well as line measurement tests.

There are ten product offerings of the ISL5585 providing various grades of ringing battery voltage and longitudinal balance.


  • 3.3V Operation
  • Onboard Ringing Generation
  • Low Standby Power Consumption (75V, 65mW)
  • Programmable Transient Current Limit
  • Improved Off Hook Software Interface
  • Integrated MTU DC Characteristics
  • Low External Component Count
  • Silent Polarity Reversal
  • Pulse Metering and On Hook Transmission
  • Tip Open Ground Start Operation
  • Balanced and Unbalanced Ringing
  • Thermal Shutdown with Alarm Indicator
  • 28 Lead Surface Mount Packaging
  • QFN Package:
  • Compliant to JEDEC PUB95 MO-$220 QFN - Quad Flat No Leads - Package Outline
  • Near Chip Scale Package footprint, which improves PCB efficiency and has a thinner profile
  • Pb-Free Available (RoHS Compliant)


 Block Diagram


Basic Information
Production Status
Mass Production
Long. Balance
58/53 dB
High Battery Voltage
Loop Current (min)
15 mA
Loop Current (max)
45 mA
Integ. Battery Switch
Polarity Reversal
Qualification Level
Loop Current Range (mA)
15 to 45
Temperature Range
-40 to +85

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