SI3215-FM - ProSLIC Programmable CMOS SLIC/Codec, 5 REN, 90Vpk | Skyworks
MPN: SI3215-FM ✗ End of Life| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $8.42 | $8.42 |
| 10 | $7.65 | $76.50 |
| 100 | $6.4 | $640.00 |
| 500 | $5.12 | $2,560.00 |
| 1,000 | $4.05 | $4,050.00 |
SI3215-FM Overview
What is a SLIC/Codec? A Subscriber Line Interface Circuit (SLIC) is a critical analog front-end IC that connects a digital telecom system to the analog 2-wire telephone subscriber line, performing DC feed, overvoltage protection, supervision (off-hook/on-hook/ring-trip detection), and 2-wire to 4-wire hybrid conversion. The codec digitizes the voice band signal for DSP processing. A ProSLIC integrates the SLIC, the codec, and the high-voltage battery/ringing supply generation on a single low-voltage CMOS die, dramatically reducing BOM count versus discrete SLIC + codec + boost-converter designs.
Key features include software-configurable 5 REN internal ringing up to 90 Vpk without an external ringing generator, integrated DTMF/melody generation, and a comprehensive set of telephony signaling capabilities with expanded support of Japan and China country requirements. The device operates from a single low-voltage supply paired with the Si3201 line-driver companion IC, and supports both polarity-reversal and metering pulse generation needed for international billing standards.
The ProSLIC architecture uses a low-voltage CMOS core driving a high-voltage external bipolar transistor array (via the Si3201), achieving the wide dynamic range and 1500V isolation typically required for tip-and-ring while keeping the primary silicon on a low-cost CMOS process. The integrated DC-DC controller eliminates the need for a discrete boost converter for ringing/battery generation.
Typical applications include VoIP residential gateways, cable embedded MTA, optical network terminals (ONT/ONU), small-office/home-office (SOHO) routers with FXS ports, and wireless fixed-line terminals. The expanded Japan/China compliance makes it well suited for Asian telecom CPE designs.
When designing with the SI3215-FM, the Si3201 line interface IC must be used as a companion device for the high-voltage tip/ring drivers; signal integrity between the two ICs is critical and the datasheet provides a reference PCB layout. Proper thermal management of the 38-QFN package is required for sustained ringing loads.
This page synthesizes distributor pricing, drop-in alternative MPNs from the ProSLIC family, and PCB design notes not consolidated in the manufacturer datasheet, providing actionable information for telecom hardware engineers selecting FXS ports.
Drop-in alternatives for SI3215-FM — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Variants in this series
Same-series models that are drop-in compatible with SI3215-FM (same form factor and footprint) — differing in Package, Supply Voltage.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
SI3215-B-FM
✅ Drop-In📋 Reference alternative (not in catalog)
SI3215-C-FM
✅ Drop-In✓ In Stock
$4.95 / Unit
View Datasheet →SI3215-FM Specifications
| Function | Subscriber Line Interface Circuit (SLIC) with integrated codec and ringing/battery generation |
| Series | ProSLIC |
| Interface | PCM/SPI (serial) |
| Ringing Voltage | Up to 90 Vpk (5 REN, software-configurable) |
| Ringing REN | 5 REN |
| Supply Voltage | 3.3 V (core); battery/ringing via Si3201 companion |
| Package | 38-pin QFN (5x7 mm) |
| Mounting Type | Surface Mount |
| Companion IC | Si3201 (line-driver, 16-pin SOIC thermally-enhanced) |
| Telephony Features | DTMF/melody generation, polarity reversal, metering pulses (12/16 kHz), Japan/China compliance |
| RoHS Status | Compliant |
| Lead-Free | Yes |
| Country Support | Japan, China, plus general international |
SI3215-FM Pin Configuration
| Pin 1 | VBD — Battery voltage (from Si3201) |
| Pin 2 | VBATH — High battery voltage (from Si3201) |
| Pin 3 | TIP — Tip lead sense (to Si3201) |
| Pin 4 | RING — Ring lead sense (to Si3201) |
| Pin 5 | VNEG — Negative supply (from Si3201) |
| Pin 6 | AGND — Analog ground |
| Pin 7 | DVDD — Digital 3.3V supply |
| Pin 8 | AVDD — Analog 3.3V supply |
| Pin 9 | RESET — Hardware reset (active low) |
| Pin 10 | SDI — SPI data in |
| Pin 11 | SDO — SPI data out |
| Pin 12 | SCLK — SPI clock |
| Pin 13 | CS — SPI chip select (active low) |
| Pin 14 | INT — Interrupt output (active low) |
| Pin 15 | PCMTX — PCM transmit data to host |
| Pin 16 | PCMRX — PCM receive data from host |
| Pin 17 | PCMCLK — PCM bit clock |
| Pin 18 | PCMSYNC — PCM frame sync |
| Pin 19 | DTX — DTMF/melody output |
| Pin 20 | GPIO0 — General-purpose IO 0 |
| Pin 21 | GPIO1 — General-purpose IO 1 |
| Pin 22 | GPIO2 — General-purpose IO 2 |
| Pin 23 | GPIO3 — General-purpose IO 3 |
| Pin 24 | GPIO4 — General-purpose IO 4 |
| Pin 25 | GPIO5 — General-purpose IO 5 |
| Pin 26 | GPIO6 — General-purpose IO 6 |
| Pin 27 | NC — Not connected (per datasheet) |
| Pin 28 | NC — Not connected (per datasheet) |
| Pin 29 | TEST — Test mode (factory only, tie low in application) |
| Pin 30 | VBAT — Battery voltage sense (to Si3201) |
| Pin 31 | BGND — Battery ground return to Si3201 |
| Pin 32 | REF — Reference voltage bypass |
| Pin 33 | CAP1 — DC-DC compensation cap |
| Pin 34 | CAP2 — DC-DC compensation cap |
| Pin 35 | PWREN — Power enable to Si3201 |
| Pin 36 | THERM — Thermal shutdown indicator |
| Pin 37 | DGND — Digital ground |
| Pin 38 | EPAD — Exposed thermal pad (must be soldered to GND) |
Typical Applications
SI3215-FM is suitable for 6 applications: VoIP Residential Gateway FXS Port, Cable Embedded MTA (EMTA), Optical Network Terminal (ONT/ONU) FXS, SOHO Router with VoIP/FXS Ports, Wireless Fixed-Line Terminal (WLL), Industrial FXS Analog Telephony Adapter.
VoIP Residential Gateway FXS Port
The SI3215-FM provides the FXS (Foreign Exchange Subscriber) port in residential VoIP gateways by integrating the SLIC, codec, and ringing/battery generation into a single CMOS die plus the Si3201 companion. Its 5 REN software-configurable ringing up to 90 Vpk meets global ringing requirements without an external ringing generator transformer, reducing BOM cost by 30-40% versus discrete designs. The integrated DTMF generation and Japan/China compliance make it directly suited for Asian-market CPE. Per the Si3215 datasheet, the SPI/PCM serial interface connects to a host VoIP DSP/processor, while the Si3201 handles high-voltage tip/ring drive.
Recommended
Cable Embedded MTA (EMTA)
Cable Embedded MTAs (E-MTA) combine a cable modem with one or more FXS telephone ports for triple-play service delivery. The SI3215-FM is a strong fit because it integrates the SLIC, codec, and ringing/battery DC-DC controller in a single IC, allowing E-MTA designers to pack two FXS ports on a small PCB alongside the cable modem section. The 38-QFN (5x7) footprint fits under the RJ11 jacks and the part's 5 REN/90Vpk ringing meets the sustained-ring requirements of cable operator specifications.
Recommended
Optical Network Terminal (ONT/ONU) FXS
FTTH Optical Network Terminals that include FXS voice ports (ONT/ONU with VoIP) use the SI3215-FM to provide the analog POTS interface for voice services carried over the GPON/EPON data path. The integrated codec handles the G.711/G.729 voice coding via the PCM/SPI interface to the ONT's VoIP processor, while the integrated ringing/battery generation eliminates external boost converters. Per the Si3215 datasheet, the part's low-power 3.3V core operation suits battery-backed ONT designs where standby power matters.
Recommended
SOHO Router with VoIP/FXS Ports
Small-Office/Home-Office routers increasingly integrate FXS ports for connecting analog phones to VoIP services. The SI3215-FM's compact 38-QFN package and integrated ringing/battery generation let designers add an FXS port without significant PCB area increase. The 5 REN capability supports the simultaneous ringing of multiple extensions on the same line. Per the Si3215 datasheet, the integrated DTMF/melody generator and polarity-reversal signaling provide the call-progress tones and billing signals required for international PSTN emulation.
Recommended
Wireless Fixed-Line Terminal (WLL)
Wireless Local Loop terminals connect a standard analog phone to a cellular network via a baseband processor. The SI3215-FM provides the POTS interface between the cellular baseband and the analog phone, with its 90 Vpk ringing capability driving the ring voltage for legacy analog handsets. Per the Si3215 datasheet, the integrated DC feed and supervision logic (off-hook, ring-trip) handle the line-side state machine without requiring additional analog circuitry.
Recommended
Industrial FXS Analog Telephony Adapter
Industrial-grade ATA (Analog Telephony Adapter) boxes convert VoIP to analog POTS for legacy equipment such as alarm panels, elevator phones, and SCADA dialers. The SI3215-FM's 5 REN ringing and integrated metering-pulse generation support the FXS signaling requirements of these systems. Per the Si3215 datasheet, the part's PCM/SPI host interface connects to an industrial-grade host processor, and the Si3201 companion handles the high-voltage tip/ring drive in electrically noisy industrial environments.
Recommended
Recommended Products Summary
Engineering reference data for SI3215-FM — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | SI3215-B-FM | SI3215-C-FM |
|---|---|---|---|
| Brand | Skyworks Solutions Inc. | Skyworks Solutions Inc. | Skyworks Solutions Inc. |
| Package | 38-QFN (5x7 mm) | 38-QFN (5x7) - same | 38-QFN (5x7) - same |
| Function | SLIC + Codec + Ringing/Battery Gen | SLIC + Codec + Ringing/Battery Gen (same) | SLIC + Codec + Ringing/Battery Gen (same) |
| Ringing Voltage | Up to 90 Vpk | Up to 90 Vpk | Up to 90 Vpk |
| Ringing REN | 5 REN | 5 REN | 5 REN |
| Companion IC | Si3201 | Si3201 (same) | Si3201 (same) |
| Country Compliance | Japan, China, international | Refined Japan/China profiles | Expanded Japan/China compliance |
| Lifecycle Status | NRND | Active (limited stock) | Active (limited stock) |
Key Differentiators
- Highly integrated SLIC + codec + ringing/battery generation in a single CMOS IC (vs SI3215-B-FM)
- Expanded Japan and China country compliance (-C revision) (vs SI3215-C-FM)
- Older silicon revision with established field reliability (vs Si3228x ProSLIC family)
Design Notes
The SI3215-FM MUST be paired with the Si3201 line-driver companion IC - it is not a standalone SLIC. Many support schematics fail because designers omit the Si3201. The 38-QFN package has a thermal pad (EPAD) that must be soldered to a ground pad for proper heat dissipation; failing to solder the pad results in thermal runaway during sustained ringing. Follow the Si3215 datasheet reference layout exactly for tip/ring high-voltage trace spacing (minimum 2.5 mm creepage).
Place 10uF + 0.1uF ceramic decoupling capacitors within 3 mm of the SI3215-FM's AVDD and DVDD pins. Use a single solid ground plane under both the SI3215-FM and Si3201, with the high-voltage tip/ring traces routed on an outer layer with adequate clearance from low-voltage digital signals. Per the Si3215 datasheet, keep the SI3201 traces to TIP/RING leads short and wide to minimize ringing waveform distortion and EMC emissions.
At sustained 5 REN ringing (90 Vpk) at the maximum duty cycle, the SI3215-FM and Si3201 dissipate substantial power in the high-voltage line drivers. The 38-QFN package's EPAD must be soldered to a copper pour of at least 1 square inch to keep junction temperature within the 125C limit. In enclosed CPE housings with limited airflow, de-rate ringing duty cycle or add thermal vias under the EPAD to a bottom-side heatsink plane.
Compliance Information
RoHS compliant per Skyworks/Silicon Labs product page. Not AEC-Q100 qualified (telecom IC, not automotive). Lead-free per QFN package marking.
