SI2456-FT 56 kbps ISOModem Chipset | Silicon Laboratories
MPN： SI2456-FT ✓ 啟用中SI2456-FT 概覽
An ISOModem chipset is an integrated data-over-voice modem optimized for telephone and wide-area-network endpoints. Within the broader modem hierarchy, it combines signaling functions, data-link protocols, and telephone-line interface circuitry in one IC. This integration reduces the number of external interface components required in designs that need asynchronous or synchronous data transfer over an analog phone line.
The principal features of the SI2456-FT include a 3 V to 3.6 V supply range, 56 kbps maximum data rate, V.42bis and MNP2-5 error correction, automatic rate negotiation, parallel phone detection, and overcurrent protection. Its lead-free 24-TSSOP package supports conventional surface-mount assembly while exposing the device in the system-side modem format identified by the SI2456-FT ordering code.
Technically, the device combines modem signal processing with an integrated global DAA. The DAA provides the telephone-line termination and isolation functions required for connected-line operation, while protocol support covers the principal ITU-T and Bell modem recommendations listed for the component. Automatic rate negotiation allows the modem to select an appropriate bearer rate from the capabilities of the connected endpoint, and V.42bis/MNP2-5 support improves transmission reliability on noisy lines.
Typical uses include point-of-sale terminals, industrial data-collection equipment, remote telemetry systems, embedded telephone-network access, and legacy equipment requiring a Bell or ITU-T modem connection. The SI2456-FT is particularly appropriate where a compact surface-mount solution and integrated line isolation are more important than a high-speed broadband data interface.
Designers should verify the exact board layout, external network-interface components, and firmware requirements against the manufacturer datasheet before production. Because this is an integrated line-side modem chipset, PCB creepage, isolation, grounding, and telephone-network compliance require careful implementation; substitution should never be based on package appearance alone.
This page consolidates verified specifications, sourcing information, replacement guidance, and design considerations for the SI2456-FT. It also distinguishes a documented same-package family alternative from unverified substitutes, helping engineers make a defensible legacy-modem sourcing decision.
直接替換替代品，適用於 SI2456-FT — 相同封裝，腳位對腳位相容。需重新設計 PCB 的不同封裝零件不列入。
SI2457-D-FT
✅ 直接替換📋 參考替代品（不在目錄中）
SI2456-FT 規格
| Device Type | Modem / ISOModem chipset |
| Maximum Data Rate | 56 kbps |
| 供應電壓 | 3.3 V |
| Operating Voltage Range | 3 V to 3.6 V |
| 工作溫度範圍 | 0 °C to 70 °C |
| Package Type | TSSOP-24 |
| 腳位數 | 24 pins |
| 安裝類型 | Surface mount |
| Termination | Lead free |
| Data Access Arrangement | Integrated global DAA |
| Capacitive Isolation | More than 5000 V |
| Telephone-Line Interface | Globally compliant line interface |
| Phone Detection | Parallel phone detection |
| Protection | Overcurrent protection |
| ITU-T Protocol Support | V.21, V.22, V.23, V.32, V.32bis, V.34, V.42bis, V.90 |
| Bell Protocol Support | Bell 103 and Bell 212A |
| Error Correction | V.42bis and MNP2-5 |
| Rate Control | Automatic rate negotiation |
| RoHS 狀態 | Compliant |
SI2456-FT tssop-24 腳位配置指南
SI2456-FT（tssop-24 封裝）的腳位配置。 腳位編號、功能與連接圖定義於製造商資料手冊中。請參閱該手冊以取得確切的封裝尺寸與焊接指引。
無詳細腳位定義資料： SI2456-FT.
請參閱 資料表 以查看完整腳位配置。
典型應用
SI2456-FT 適用於 6 應用s: Point-of-Sale Terminal Connectivity, Industrial Telemetry Endpoint, Remote Monitoring System, Embedded Telephone-Network Access, Legacy Equipment Retrofit, Data Collection and Reporting Terminal.
Point-of-Sale Terminal Connectivity
The SI2456-FT fits point-of-sale terminals that must communicate with legacy remote systems over an analog telephone line. Its 56 kbps maximum rate is sufficient for transaction authorization and short data exchanges, while the integrated global DAA reduces the external line-interface burden. Automatic rate negotiation can select a compatible bearer rate during connection establishment, and parallel phone detection helps equipment recognize when an analog handset is already in use. The 24-TSSOP package also supports compact surface-mount hardware. Compared with a discrete modem and separate telephone interface, the chipset integrates line coupling and isolation functions, but engineers should still follow the manufacturer reference layout and verify regional network requirements.
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Industrial Telemetry Endpoint
The SI2456-FT is suitable for industrial telemetry equipment that periodically transfers readings over a telephone network rather than an Ethernet connection. The 56 kbps bearer rate supports compact reporting, and automatic rate negotiation improves interoperability with endpoints offering multiple Bell and ITU-T rates. The integrated global DAA, more than 5000 V capacitive isolation, overcurrent protection, and parallel phone detection make the chipset practical for unattended equipment connected to analog lines. Its specified 0 °C to 70 °C range suits commercial-temperature industrial enclosures, but harsher environments require a part with an explicitly wider rating. Firmware must support the intended protocols and line conditions before deployment.
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Remote Monitoring System
The SI2456-FT can connect a remote monitoring controller to a legacy central station through an analog telephone line. Bell and ITU-T protocol support covers common modem endpoints, while V.42bis and MNP2-5 error correction helps preserve data integrity over impaired connections. Automatic rate negotiation reduces configuration effort in installations where the available service varies. The integrated DAA removes the need for a separate basic telephone interface, helping reduce board area and assembly cost. Because the chipset is intended for legacy voice-band connectivity rather than broadband, it is best used where the remote endpoint already provides a modem service. Product developers should preserve the documented isolation and grounding arrangement to maintain network-side safety.
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Embedded Telephone-Network Access
The SI2456-FT supports embedded telephone-network access in equipment that must interoperate with conventional analog modem infrastructure. Its 3.3 V operating supply and 24-lead TSSOP package suit compact controller boards, while the integrated global DAA provides a consolidated modem and line-interface solution. Support for Bell 103, Bell 212A, V.21, V.22, V.23, V.32, V.32bis, V.34, V.42bis, and V.90 allows the host firmware to negotiate with widely deployed endpoints. Parallel phone detection can inform application logic when the line is occupied. The design must still account for surge, isolation, and printed-circuit-board spacing requirements, since a surface-mount package does not remove the need for a safe telephone-network interface.
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Legacy Equipment Retrofit
The SI2456-FT is appropriate for retrofitting legacy equipment that must retain Bell or ITU-T modem communication while modernizing only selected electronics. A replacement design can use the 56 kbps chipset without replacing an existing telephone connection or changing the host-facing communication strategy. Its integrated global DAA simplifies the analog line interface, and automatic rate negotiation supports deployment across varied endpoint capabilities. The lead-free 24-TSSOP package is compatible with conventional surface-mount assembly. SI2457-D-FT can be evaluated where the same package and pinout are desired along with improved ESD protection and diagnostics. Any retrofit should include line-rate, protocol, isolation, and firmware regression testing because a physical replacement does not automatically preserve every legacy behavior.
推薦
Data Collection and Reporting Terminal
The SI2456-FT fits compact terminals that collect local records and upload them through a modem service at scheduled intervals. A 56 kbps line can carry short reports efficiently, while V.42bis and MNP2-5 error correction improves reliability and automatic rate negotiation reduces connection setup complexity. Integrated line detection and DAA functions allow the terminal to remain compact without adding a separate basic telephone interface. The 3.3 V supply requirement is convenient for embedded systems using a regulated 3.3 V rail. Design teams should account for the commercial 0 °C to 70 °C rating, provide the specified bypass components, and preserve the manufacturer’s isolation layout. For field diagnostics, the SI2457-D-FT’s added status indicators and test points may improve troubleshooting.
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推薦產品摘要
工程參考資料，適用於 SI2456-FT — 比較、設計指引及合規資訊。
選型指南
與替代品比較
| 參數 | 本產品 | SI2457-D-FT |
|---|---|---|
| Brand | Silicon Laboratories | Silicon Laboratories |
| Package | TSSOP-24 | TSSOP-24 - same |
| Pin Compatibility | 24-pin ISOModem chipset | Same 24-TSSOP pinout |
| Diagnostic Capabilities | Standard device diagnostics | Enhanced diagnostics, test points, and status indicators |
主要差異化特點
- Documented pin-compatible upgrade path (對比SI2457-D-FT)
- Integrated global DAA (對比SI2457-D-FT)
- Broad legacy protocol support (對比SI2457-D-FT)
設計說明
Implement the SI2456-FT telephone interface using the manufacturer’s reference layout and preserve the documented isolation boundary between network-side and system-side circuitry. The integrated DAA does not remove the need for careful creepage, clearance, grounding, and high-voltage isolation analysis. Avoid placing sensitive analog or high-speed digital routes across the isolation boundary, and use a continuous ground strategy on the system side.
Power the SI2456-FT from a regulated 3.3 V rail within the verified 3 V to 3.6 V operating range. Place required bypass capacitors close to the supply and ground pins using the values and layout specified by the manufacturer datasheet. The current supply is 3.3 V nominal, but exact quiescent and peak-current requirements were not present in the supplied data and must be checked before sizing the upstream regulator.
Do not substitute a modem solely because it uses a 24-TSSOP package. The documented SI2457-D-FT candidate shares the SI2456-FT pinout, but added diagnostics can change firmware expectations, and other modem families may use different DAA, clock, or interface assignments. Review the complete pin table, protocol requirements, firmware dependencies, and country-specific telephone-network approvals before approving a replacement.
Route the modem and DAA sections separately from sensitive sensor, audio, and high-speed digital circuits. Maintain the recommended return-current path and avoid allowing telephone-interface currents to share narrow ground traces with precision circuitry. Because the SI2456-FT can operate up to 56 kbps, conventional low-frequency EMC filtering may be insufficient; validate radiated and conducted emissions with the final telephone-network interface and enclosure.
合規資訊
The verified component data identifies the SI2456-FT as lead-free with RoHS features. No explicit AEC-Q100 qualification was supplied; automotive qualification is therefore not asserted. REACH, halogen-free, and conflict-minerals information was not provided.
