SI3225-FQ Dual-Channel SLIC/Codec IC | Silicon Labs
MPN: SI3225-FQ ✓ ActiveSI3225-FQ Overview
A SLIC/codec, also called a ProSLIC, combines the line-driving and voice-processing functions required at the network edge. Within the product hierarchy, a SLIC/codec is a telecommunications interface IC, a mixed-signal semiconductor, and a system-level interface between a voice codec and the analog telephone line. The integrated architecture reduces the number of separate analog components while centralizing line supervision, voice processing, and diagnostic functions.
The SI3225-FQ supports two independent analog channels in a single device, making it suitable for dual-channel line cards, voice gateways, embedded telephony systems, and customer-premises equipment. Its internal diagnostics assist development and troubleshooting, while external ringing support extends the available line-function capabilities without requiring the same external support arrangement for every design.
The SI3225 series is described as a low-voltage CMOS dual ProSLIC platform designed for complete dual-channel analog telephone interfaces. The SI3225 family is associated with LSSGR, ITU, and ETSI interface requirements. Because line-card designs remain sensitive to codec behavior, ringing voltage, impedance, and channel configuration, engineers should preserve the silicon revision, device variant, and firmware configuration associated with the original qualified design.
Typical deployments include two-channel analog adapters, voice-over-IP terminal equipment, digital transport cards, and legacy telephone interface equipment being modernized around an existing analog line. Two integrated channels can also reduce routing density and component count when the board must terminate two analog lines in a constrained area, although the line interface still requires the appropriate protection, isolation, and network-side components specified by the system design.
During design review, check the SI3225 pin-description table in the manufacturer datasheet before assigning PCB tracks, and validate the external ringing network against the selected line-country configuration. Use the same variant and software configuration for production units, because changing ringing, impedance, or codec behavior may require renewed line-interface qualification even when the package and board footprint remain unchanged.
Drop-in alternatives for SI3225-FQ — 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 SI3225-FQ (same form factor and footprint) — differing in Package, Product Type.
SI3225-A-FQ
✅ Drop-In ⚠️ Specs Unverified📋 Reference alternative (not in catalog)
SI3225-B-FQ
✅ Drop-In ⚠️ Specs Unverified📋 Reference alternative (not in catalog)
SI3225-C-FQ
✅ Drop-In ⚠️ Specs Unverified📋 Reference alternative (not in catalog)
SI3225-F-FQ
✅ Drop-In ⚠️ Specs Unverified📋 Reference alternative (not in catalog)
SI3225-G-FQ
✅ Drop-In ⚠️ Specs Unverified📋 Reference alternative (not in catalog)
SI3225-FQ Specifications
| Product Type | Dual-channel SLIC/codec IC |
| Number of Channels | 2 channels |
| Line Interface Functions | SLIC and codec integrated in one IC |
| Ringing Support | External ringing support |
| Diagnostic Features | Internal diagnostics |
| Technology | Low-voltage CMOS |
| Package | 64-lead TQFP |
| Mounting Type | Surface mount |
| Terminal Configuration | Lead-free |
| Interface Standards | LSSGR, ITU, and ETSI specifications |
SI3225-FQ 64-lead tqfp Pin Configuration Guide
Pin configuration for SI3225-FQ (64-lead tqfp package). Pin numbering, functions, and connection diagrams are defined in the manufacturer datasheet. Refer to it for the exact footprint and soldering guidelines.
No detailed pinout data available for SI3225-FQ.
Refer to the datasheet for full pin configuration.
Typical Applications
SI3225-FQ is suitable for 6 applications: Dual-Channel Voice Gateway, Analog Line Card, Customer Premises Equipment, Voice-over-IP Terminal, Digital Transport Equipment, Telephony Test and Diagnostics.
Dual-Channel Voice Gateway
The SI3225-FQ fits a voice gateway that must terminate two analog telephone lines while using a limited component count. Its two integrated SLIC/codec channels, external ringing support, and internal diagnostics consolidate line-interface and voice-processing functions into one 64-lead TQFP device. This can simplify board partitioning compared with two separate line-interface channels. The design must still implement the required line protection, isolation, filtering, and ringing network. Engineers should select the software and device configuration that matches the gateway's target line standard, impedance, ring cadence, and codec behavior before production release.
Recommended
Analog Line Card
A two-channel analog line card can use the SI3225-FQ to combine the Subscriber Line Interface Circuit and codec functions for each channel. The dual-channel architecture reduces the number of dedicated telephone-interface ICs, while external ringing support permits the required ringing arrangement to be implemented around the device. Internal diagnostics provide useful status and troubleshooting functions during board bring-up and field service. The line card designer must follow the exact SI3225 application circuit for protection, impedance networks, ring detection, supply filtering, and keep the analog and digital return paths arranged to minimize noise coupling.
Recommended
Customer Premises Equipment
The SI3225-FQ is suitable for customer-premises equipment requiring an integrated analog telephone interface and voice codec. By placing two SLIC/codec channels in a single low-voltage CMOS device, the equipment can reduce external component count without separating the line interface from codec conversion. External ringing support and internal diagnostics support both incoming-call signaling and service diagnostics. Product engineers should verify regional line behavior, impedance configuration, ring voltage requirements, and codec timing for every target country before fixing the production configuration.
Recommended
Voice-over-IP Terminal
In a voice-over-IP terminal, the SI3225-FQ can provide the analog telephone-network side of the voice path while the terminal's digital processing handles packetized speech. Integrating the SLIC and codec functions permits a compact implementation for two analog lines, and internal diagnostics help identify line-interface problems during installation. The performance trade-off is that this device handles the analog line interface rather than replacing the terminal's speech codec or packet engine. Keep the digital and analog sections separated carefully, validate line-side timing, and confirm that the selected SI3225 variant supports the required country-specific line parameters.
Recommended
Digital Transport Equipment
The SI3225-FQ can support legacy analog access on a digital transport card that must bridge two telephone channels into modern transport electronics. Its 64-lead TQFP package provides a defined surface-mount integration point, while the dual-channel architecture consolidates the SLIC and codec sections. External ringing support covers line-signaling needs that cannot be satisfied by the basic codec path alone. The card designer should budget board area for the external line networks and protection components, verify thermal behavior of the complete assembly, and use the manufacturer's reference layout to preserve signal and return-path integrity.
Recommended
Telephony Test and Diagnostics
The SI3225-FQ is useful in telephone-interface test equipment because its internal diagnostics and integrated SLIC/codec channels can simplify line-state monitoring. Two channels allow a test fixture to evaluate analog line behavior without implementing two separate interface devices, while external ringing support supports tests involving incoming ring signals. The equipment must still reproduce the protection and impedance conditions of the intended line so that measurements represent real network behavior. Engineers should use the manufacturer's diagnostic procedures, define pass/fail limits for each target line standard, and confirm the operating configuration for every country or carrier supported by the tester.
Recommended
Recommended Products Summary
Engineering reference data for SI3225-FQ — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | SI3225-A-FQ | SI3225-B-FQ | SI3225-C-FQ | SI3225-F-FQ | SI3225-G-FQ |
|---|---|---|---|---|---|---|
| Brand | Silicon Labs | Silicon Labs | Silicon Labs | Silicon Labs | Silicon Labs | Silicon Labs |
| Package | 64-lead TQFP | 64-lead TQFP | 64-lead TQFP | 64-lead TQFP | 64-lead TQFP | 64-lead TQFP |
| SLIC/Codec Integration | Integrated | Integrated | Integrated | Integrated | Integrated | Integrated |
| Technology | Low-voltage CMOS | Low-voltage CMOS | Low-voltage CMOS | Low-voltage CMOS | Low-voltage CMOS | Low-voltage CMOS |
| Line Interface Standards | LSSGR, ITU, and ETSI specifications | LSSGR, ITU, and ETSI specifications | LSSGR, ITU, and ETSI specifications | LSSGR, ITU, and ETSI specifications | LSSGR, ITU, and ETSI specifications | LSSGR, ITU, and ETSI specifications |
| Terminal Configuration | Lead-free | Lead-free | Lead-free | Lead-free | Lead-free | Lead-free |
Key Differentiators
- Two integrated line channels in one package (vs SI3225-A-FQ)
- Closely related same-family package option (vs SI3225-F-FQ)
- External ringing support with internal diagnostics (vs SI3225-B-FQ)
Design Notes
Follow the SI3225 reference layout and place the device close to the analog line-network and codec-support components. Keep the analog line paths compact, provide an uninterrupted return path, and separate the digital interface from high-impedance line nodes. PCB signal integrity is especially important around ringing and codec signals, so preserve the manufacturer's recommended component placement and grounding topology rather than routing by convenience.
Do not infer the supply limits or bypass requirements from a generic low-voltage CMOS description. Use the exact electrical-characteristics and application-circuit sections for the selected SI3225 variant, including input-voltage tolerance, supply sequencing, and decoupling values. Place the required bypass capacitors at their specified pins and verify startup behavior across minimum, nominal, and maximum input conditions.
A shared TQFP footprint does not by itself make every SI3225 variant interchangeable. Confirm pin assignments, supported impedance, ring configuration, codec behavior, diagnostics, and software support before substituting a different suffix. Production changes should also preserve the qualified device revision and firmware configuration because telephone-interface behavior can differ even when the board outline is unchanged.
Compliance Information
The product is identified as lead-free. No explicit RoHS, REACH, halogen-free, conflict-minerals, or automotive qualification statement is available.
