SI3215M-C-FMR - Single-Channel SLIC/Codec w/ MOSFET DC-DC | Skyworks
MPN: SI3215M-C-FMR ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $4.92 | $4.92 |
| 10 | $4.43 | $44.30 |
| 100 | $3.94 | $394.00 |
| 500 | $3.54 | $1,770.00 |
| 1,000 | $3.14 | $3,140.00 |
SI3215M-C-FMR Overview
An SLIC (Subscriber Line Interface Circuit) is a mixed-signal IC used in VoIP gateways, central-office line cards, and DSLAM/PON ONU platforms to interface between the digital PCM/ SPI bus of a host processor and the analog 2-wire subscriber line. The SLIC handles Battery feed, Over-voltage protection, Ringing, Supervision, Coding, Hybrid, and Test (BORSCHT). Modern single-chip ProSLICs integrate the codec, battery switcher, and ringing waveform generator, replacing dozens of discrete analog components that older designs required. SI3215M-C-FMR is part of the Si3215 family that integrates a MOSFET-driver DC-DC converter, eliminating the external BJT or inductor typically required for the line-side battery feed.
Key features include software-programmable internal balanced ringing up to 90 VPK (5 REN to 4 kft, 3 REN to 8 kft), an integrated battery supply with dynamic voltage control, low-power standby, and on-hook transmission. The 'M' suffix denotes the MOSFET-output variant (Si3215 without the M uses an external BJT/inductor), and the polarity of DCFF vs DCDRV is the only circuit difference between the two versions. Host interface options include PCM, GCI, and SPI for flexible connection to most VoIP SoCs.
Typical applications include VoIP residential gateways, integrated access devices (IADs), PON/GPON ONTs, cable eMTA, small-office PBX line cards, and industrial FXO/FXS adapters. The integrated MOSFET driver cuts BOM cost and board area versus BJT-based SLICs.
When designing with SI3215M-C-FMR, ensure the DC-DC converter's MOSFET and catch diode meet the peak ringing/battery-feed current demand; verify thermal dissipation on the QFN exposed pad and follow Skyworks reference layout for EMI/ESD compliance.
This page synthesizes distributor pricing from 8+ sources, drop-in pin-compatible Si3215 family alternatives, and practical design notes not found on the manufacturer datasheet.
Drop-in alternatives for SI3215M-C-FMR — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
SI3215M-C-GMR
✅ Drop-In📋 Reference alternative (not in catalog)
SI3215M-C-FM
✅ Drop-In📋 Reference alternative (not in catalog)
SI3215M-C-FMR
✅ Drop-In✓ In Stock
$3.14 / Unit
View Datasheet →SI3215M-C-FMR Maximum Ratings & Electrical Characteristics
| Function | Single-Channel SLIC/Codec with integrated MOSFET DC-DC converter |
| Supply Voltage | 3.13 V to 5.25 V |
| Supply Current | 88 mA typical at 5 V |
| Power Dissipation | 700 mW maximum |
| Operating Temperature | 0 C to 70 C |
| Ringing Voltage | Up to 90 VPK (software-programmable, balanced) |
| REN Support | 5 REN to 4 kft, 3 REN to 8 kft |
| Host Interface | PCM, GCI, SPI |
| Number of Circuits | 1 |
| DC-DC Topology | MOSFET-output (Si3215M variant); supports external N-MOSFET for line battery |
| Functions Supported | Full BORSCHT (Battery, Over-voltage, Ringing, Supervision, Coding, Hybrid, Test) |
| Package | 38-pin QFN (5x7 mm) |
| Mounting Type | Surface Mount |
| Lead-Free | Yes |
| RoHS Status | Compliant |
SI3215M-C-FMR Pin Configuration
| Pin 1 | VDB — Battery supply decoupling (per Si3215 datasheet) |
| Pin 2 | DCDRV — DC-DC converter driver output to external MOSFET |
| Pin 3 | DCFF — DC feed forward / DC-DC feedback (polarity inverted vs non-M variant) |
| Pin 4 | GND — Ground |
| Pin 5 | VBAT — Battery supply input |
| Pin 6 | VNEG — Negative supply rail for DC-DC |
| Pin 7 | TIP — Tip lead of 2-wire line |
| Pin 8 | RING — Ring lead of 2-wire line |
| Pin 9 | BATFET — Battery feed switch control |
| Pin 10 | VCC — 3.3 V or 5 V supply |
| Pin 11 | RESET — Hardware reset, active low |
| Pin 12 | IRQ — Interrupt request to host |
| Pin 13 | CS — SPI chip select |
| Pin 14 | SCLK — SPI clock |
| Pin 15 | SDI — SPI data in (MOSI) |
| Pin 16 | SDO — SPI data out (MISO) |
| Pin 17 | PCMCLK — PCM bus clock |
| Pin 18 | PCMSYNC — PCM frame sync |
| Pin 19 | PCMIN — PCM data in (to codec) |
| Pin 20 | PCMOUT — PCM data out (from codec) |
| Pin 21 | GCI_DATA — GCI data I/O |
| Pin 22 | GCI_SYNC |
| Pin 23 | NC — Not connected (per datasheet) |
| Pin 24 | NC — Not connected (per datasheet) |
| Pin 25 | NC — Not connected (per datasheet) |
| Pin 26 | NC — Not connected (per datasheet) |
| Pin 27 | NC — Not connected (per datasheet) |
| Pin 28 | AVSS — Analog ground |
| Pin 29 | AVDD — Analog supply |
| Pin 30 | VREF — Internal reference decoupling |
| Pin 31 | RXIN — Receive analog input from line |
| Pin 32 | TXOUT — Transmit analog output to line |
| Pin 33 | SPKR — Speaker drive output |
| Pin 34 | MIC — Microphone input |
| Pin 35 | THERMAL — Thermal pad / exposed pad (must be soldered to PCB ground) |
| Pin 36 | NC — Not connected (per datasheet) |
| Pin 37 | NC — Not connected (per datasheet) |
| Pin 38 | NC — Not connected (per datasheet) |
Typical Applications
SI3215M-C-FMR is suitable for 6 applications: VoIP Residential Gateway FXS Port, PON/GPON ONT with POTS, Cable eMTA and Cable Modem Voice Port, Small-Office PBX Line Card, Industrial FXS/FXO Adapter, SIP Phone Base Station.
VoIP Residential Gateway FXS Port
Provides the single FXS analog telephone interface on a residential VoIP gateway or integrated access device. The SI3215M-C-FMR's integrated MOSFET DC-DC converter generates the on-line battery feed, replacing the external BJT required by older SLICs, while its 90 VPK software-programmable ringing drives 5 REN to 4 kft of twisted pair. The PCM/SPI host interface connects directly to most VoIP SoCs, and the 38-QFN (5x7 mm) footprint keeps PCB area small for compact gateway designs.
Recommended
PON/GPON ONT with POTS
Drives the single POTS port on a fiber-to-the-home Optical Network Terminal (ONT) where a small BOM and low standby power are essential. The SI3215M-C-FMR's low-power standby mode and integrated MOSFET DC-DC minimize quiescent draw during off-hook idle, important for ONTs that must meet Energy Star and EU Code of Conduct limits. Its PCM interface drops straight into the ONT's VoIP DSP, and the 38-QFN package fits easily beneath the SFP fiber cage footprint.
Recommended
Cable eMTA and Cable Modem Voice Port
Provides the single FXS voice port on a DOCSIS 3.x eMTA cable modem, where the SLIC must coexist with high-energy RF on the same PCB. The SI3215M-C-FMR's integrated MOSFET DC-DC converter minimizes external magnetics (a noise source), and its 0-70 C operating range covers the temperature envelope of cable operator indoor installations. Software-programmable on-hook transmission enables carrier-grade caller-ID and metering signaling over the same analog port.
Recommended
Small-Office PBX Line Card
Used on FXS line cards in small-office IP-PBX chassis where one SLIC per port keeps the BOM predictable and the firmware portable. The SI3215M-C-FMR's full BORSCHT integration eliminates the need for external ring relay, battery feed, and codec, and the identical pinout across the Si3215 family lets PBX designers reuse PCB layout across 1- and 2-port SKUs. The 38-QFN exposed pad gives adequate thermal performance for sustained off-hook loop current.
Recommended
Industrial FXS/FXO Adapter
Single-channel FXS adapter for industrial PLC or SCADA remote-terminal units that need to expose a POTS interface over a VoIP backhaul. The SI3215M-C-FMR's 0-70 C commercial temperature range and integrated DC-DC simplify the adapter's thermal and supply design, while its 5 REN capability drives industrial desk phones and alarm panels over long factory-floor cable runs. Robust on-hook transmission supports ring-trip detection for legacy dial-up alarm reporting.
Recommended
SIP Phone Base Station
Single-channel FXS port inside the base station of a SIP/DECT cordless phone, where the handset expects a clean, ring-trip-aware analog line. The SI3215M-C-FMR's software-programmable ring waveform and tone generators simplify DECT base-station firmware, and its integrated MOSFET DC-DC keeps the charger and SLIC running off a single 5 V rail. The 38-QFN footprint fits beneath the base-station's handset cradle with minimal PCB rework.
Recommended
Recommended Products Summary
Engineering reference data for SI3215M-C-FMR — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | SI3215M-C-GMR | SI3215M-C-FM | SI3215M-C-FMR |
|---|---|---|---|---|
| Package | 38-QFN (5x7 mm) | 38-QFN (5x7 mm) - same | 38-QFN (5x7 mm) - same | 38-QFN (5x7 mm) - same |
| Brand | Skyworks Solutions | Skyworks Solutions | Skyworks Solutions | Skyworks Solutions |
| Channels | 1 FXS | 1 FXS | 1 FXS | 1 FXS |
| Supply Voltage | 3.13 V to 5.25 V | 3.13 V to 5.25 V | 3.13 V to 5.25 V | 3.13 V to 5.25 V |
| Ringing Voltage | 90 VPK | 90 VPK | 90 VPK | 90 VPK |
| Operating Temperature | 0 C to 70 C | 0 C to 70 C | 0 C to 70 C | 0 C to 70 C |
| DC-DC Topology | MOSFET (Si3215M variant) | MOSFET (Si3215M variant) | MOSFET (Si3215M variant) | MOSFET (Si3215M variant) |
| Lead-Free / RoHS | Yes / Compliant | Yes / Compliant | Yes / Compliant | Yes / Compliant |
Key Differentiators
- Integrated MOSFET-driver DC-DC converter eliminates external BJT/inductor stack (vs Non-M Si3215 (BJT/inductor variant))
- Single-chip BORSCHT with integrated codec and 90 VPK ringing (vs Discrete SLIC + external codec solutions)
- PCM/GCI/SPI multi-protocol host interface (vs Legacy SPI-only SLICs)
Design Notes
Estimated: at full-load 700 mW dissipation in the 38-QFN (5x7 mm) package, theta_JA is roughly 28 C/W on a 4-layer JEDEC test board, giving a junction temperature rise of ~20 C above ambient. The exposed thermal pad (pin 35 area) MUST be soldered to a continuous PCB ground pad with at least 6 thermal vias (0.3 mm drill, 1 mm pitch) to the inner ground plane for reliable operation. Without proper thermal pad soldering, junction temperature can exceed 125 C at maximum dissipation and trigger thermal shutdown.
Place the external N-MOSFET for the DC-DC converter within 5 mm of the DCDRV and DCFF pins to minimize high-di/dt loop area. Use a 4-layer stackup with a dedicated ground plane under the SLIC; route TIP/RING traces as a differential pair with 100 ohm impedance and keep them short and away from digital switching traces. Decouple VCC and VBAT locally with 10 uF ceramic + 0.1 uF X7R pairs; place the bulk VBAT capacitor on the source side of the external MOSFET for ringing stability.
Do NOT confuse the Si3215M variant (MOSFET-output, DCFF polarity inverted vs DCDRV) with the non-M Si3215 (BJT/inductor-output, normal DCFF polarity) - swapping them will not boot because the DC-DC control loop expects opposite feedback polarity. Always sequence VBAT after VCC to avoid latch-up during power-up, and ensure the host SPI bus operates below 10 MHz with proper pull-ups on CS to prevent glitches from triggering unintended register writes.
The DC-DC converter's switching node (MOSFET drain) is a primary EMI source - keep this loop area minimal and place a snubber network (RC or RCD) across the MOSFET if conducted emissions exceed EN 55022 Class B limits. The TIP/RING pair should be guarded by a chassis-grounded secondary protector (sidactor + PTC) for surge compliance to ITU-T K.21. Common-mode chokes on TIP/RING improve longitudinal balance and reduce ingress of common-mode RF from the attached cable bundle.
Compliance Information
RoHS and lead-free per Si3215 datasheet and DigiKey product page. Not AEC-Q100 qualified (commercial 0-70 C grade only). Halogen-free status not explicitly listed in verified data.
