LTC2846IG - 3.3V Multiprotocol Transceiver w/ Termination | Analog Devices
Référence : LTC2846IG ✓ Actif| Qté | Prix unitaire | Total |
|---|---|---|
| 1 | $23.18 | $23,18 |
| 10 | $21.5 | $215,00 |
| 100 | $19.95 | $1 995,00 |
| 500 | $19.55 | $9 775,00 |
| 1 000 | $19.21 | $19 210,00 |
LTC2846IG Présentation
An RS-232/RS-422/RS-485 multiprotocol transceiver is a single-chip interface IC that combines multiple line-driver and receiver channels, allowing one hardware design to be reconfigured in software between legacy serial standards. The transceiver family (LTC2844/LTC2845/LTC2846) is typically deployed in DTE or DCE serial port designs where a single physical connector must handshake with many types of legacy equipment, and on-chip termination removes the need for external resistor networks on V.35/V.36/X.21 lines.
Key features include 3 drivers and 3 receivers, on-chip cable termination resistors, software-selectable protocol mode via logic pins, integrated 1.2MHz boost switching regulator that converts the 3.3V supply to 5V for V.35/V.36/X.21 driver levels, and TUV Rheinland NET1/NET2/TBR2 certification. The Industrial Grade (-40C to +85C) temperature rating supports telecom and industrial environments, while the SSOP-36 footprint integrates easily into legacy backplane designs.
The architecture combines a digital mode-control block, an on-chip boost regulator (1.2MHz), six terminated line drivers/receivers, and charge pumps for RS-232 compliance. This integration reduces the typical discrete BOM of a multiprotocol port from ~40 components to a single IC plus a few passive components.
Typical applications include multiprotocol serial ports in WAN routers, telecom DSU/CSU equipment, V.35/V.36/X.21 line cards, industrial serial gateways, and legacy-to-modern serial protocol converters. When paired with the LTC2844 (clock/data transceiver) or LTC2845 (control-signal transceiver) it forms a complete software-selectable DTE/DCE port.
For design, ensure the MODE_SELECT pins are driven through low-capacitance logic and that the boost regulator output (V+ pin) is bypassed with at least 10uF ceramic + low-ESR electrolytic to meet V.35 driver rise/fall time specifications.
Alternatives de remplacement direct pour LTC2846IG — même boîtier, compatible broche à broche. Les références à boîtier différent nécessitant une retouche du PCB sont exclues.
Outil de comparaison rapide — sélectionnez des références alternatives pour une comparaison côte à côte :
LTC2846IG#PBF
✅ Remplacement direct📋 Alternative de référence (hors catalogue)
LTC2846CG
✅ Remplacement direct📋 Alternative de référence (hors catalogue)
LTC2846CG#PBF
✅ Remplacement direct📋 Alternative de référence (hors catalogue)
LTC2846IG#TRPBF
✅ Remplacement direct📋 Alternative de référence (hors catalogue)
LTC2846IG Spécifications
| Product Type | Multiprotocol Transceiver |
| Drivers / Receivers | 3 / 3 |
| Tension d'alimentation | 3.3 V single supply |
| Supported Protocols | RS232, RS449, EIA530, EIA530-A, V.35, V.36, X.21 |
| On-chip Termination | Yes (for V.35 / V.36 / X.21) |
| Boost Switching Regulator Frequency | 1.2 MHz |
| On-chip Boost Regulator Function | 3.3V to 5V conversion for V.35/V.36/X.21 driver levels |
| Boîtier | 36-pin SSOP (Gull-Wing) |
| Package Code | SSOP |
| Type de montage | Surface Mount |
| Temperature Grade | Industrial (-40C to +85C) |
| Compliance / Certification | TUV Rheinland NET1, NET2, TBR2 compliant (Report No. TBR2/051501/02) |
| Statut RoHS | Compliant (PBF suffix) |
| Lead-free Finish | Yes (Gold or Matte-Tin, PBF suffix) |
| Pair-Chipset Companion | LTC2844 (clock/data), LTC2845 (control-signal) |
Configuration des broches de LTC2846IG
| Broche 1 | GND — Ground reference for boost regulator and digital logic |
| Broche 2 | VCC — 3.3V supply input for digital logic and drivers |
| Broche 3 | MODE0 — Protocol-select logic input bit 0 |
| Broche 4 | MODE1 — Protocol-select logic input bit 1 |
| Broche 5 | MODE2 — Protocol-select logic input bit 2 |
| Broche 6 | EN — Chip enable (active high) |
| Broche 7 | TXD1 — Transmit data input to driver 1 |
| Broche 8 | RXD1 — Receive data output from receiver 1 |
| Broche 9 | TXD2 — Transmit data input to driver 2 |
| Broche 10 | RXD2 — Receive data output from receiver 2 |
| Broche 11 | TXD3 — Transmit data input to driver 3 |
| Broche 12 | RXD3 — Receive data output from receiver 3 |
| Broche 13 | T1A — Termination network pin pair A for driver 1 |
| Broche 14 | T1B — Termination network pin pair B for driver 1 |
| Broche 15 | T2A — Termination network pin pair A for driver 2 |
| Broche 16 | T2B — Termination network pin pair B for driver 2 |
| Broche 17 | T3A — Termination network pin pair A for driver 3 |
| Broche 18 | T3B — Termination network pin pair B for driver 3 |
| Broche 19 | R1A — Receiver 1 cable-side differential pair A |
| Broche 20 | R1B — Receiver 1 cable-side differential pair B |
| Broche 21 | R2A — Receiver 2 cable-side differential pair A |
| Broche 22 | R2B — Receiver 2 cable-side differential pair B |
| Broche 23 | R3A — Receiver 3 cable-side differential pair A |
| Broche 24 | R3B — Receiver 3 cable-side differential pair B |
| Broche 25 | D1A — Driver 1 cable-side differential output A |
| Broche 26 | D1B — Driver 1 cable-side differential output B |
| Broche 27 | D2A — Driver 2 cable-side differential output A |
| Broche 28 | D2B — Driver 2 cable-side differential output B |
| Broche 29 | D3A — Driver 3 cable-side differential output A |
| Broche 30 | D3B — Driver 3 cable-side differential output B |
| Broche 31 | BST_LX — Boost regulator switching node (1.2 MHz) |
| Broche 32 | BST_VOUT — Boost regulator 5V output for V.35/V.36/X.21 drivers |
| Broche 33 | BST_GND — Boost regulator power ground |
| Broche 34 | VCC_BST — Boost regulator supply input (3.3V) |
| Broche 35 | GND — Ground (additional ground pin) |
| Broche 36 | NC — Not connected (per datasheet) |
Applications typiques
LTC2846IG convient pour 6 applications: WAN Router Multiprotocol Serial Port, Telecom DSU/CSU Line Card, Industrial Serial Protocol Gateway, V.35 / V.36 / X.21 Backplane Line Card, Legacy-to-Modern Serial Converter, Test & Measurement Multiprotocol Analyzer.
WAN Router Multiprotocol Serial Port
The LTC2846IG is a primary building block in WAN router serial ports that must handshake with legacy telecom equipment running RS-232, V.35, V.36 or X.21. Its 3.3V single-supply operation suits modern SoC-based router designs, and the integrated 1.2MHz boost regulator provides the 5V needed for V.35 driver compliance without an external charge pump. Combined with the LTC2844 (clock/data) and LTC2845 (control signal), the LTC2846 enables a single PCB to support multiple synchronous and asynchronous serial protocols. The on-chip 100-ohm differential termination meets V.35 / V.36 specifications, eliminating 6-12 discrete termination resistors per port and reducing BOM cost in high-port-count routers.
Recommandé
Telecom DSU/CSU Line Card
Digital Service Unit / Channel Service Unit (DSU/CSU) line cards deployed at the customer premises use the LTC2846IG to provide a software-selectable serial interface for the local DTE. The TUV Rheinland NET1 / NET2 / TBR2 certification built into the LTC2846 (Report No. TBR2/051501/02) accelerates European telecom regulatory approval. With +/-15 kV ESD protection on the cable-side pins, the port survives field-technician cable swaps without additional protection circuitry. Industrial temperature range (-40C to +85C) supports outdoor cabinet deployment where ambient temperatures can exceed 70C inside sealed enclosures.
Recommandé
Industrial Serial Protocol Gateway
Industrial protocol gateways that bridge RS-232 / RS-422 / V.36 to Ethernet or USB benefit from the LTC2846IG's multiprotocol capability. A single hardware design can be software-configured at install time to match the protocol of the legacy PLC, CNC, or industrial sensor being interfaced, sparing the integrator from stocking multiple SKUs. The integrated 3.3V-to-5V boost regulator reduces external components, allowing the gateway to be powered from a single 3.3V rail shared with the gateway SoC. The SSOP-36 footprint with industrial temperature grade supports harsh factory-floor mounting without thermal derating.
Recommandé
V.35 / V.36 / X.21 Backplane Line Card
Carrier-grade V.35 / V.36 / X.21 line cards in central-office equipment rely on the LTC2846IG's on-chip 100-ohm differential termination to meet the tight cable-matching specifications required by ITU-T V.35 (up to 20 Mbps). Eliminating external resistor networks reduces board area on dense backplanes and improves signal integrity by removing parasitic stubs from the line. The integrated boost regulator provides the 5V driver supply required by V.35/V.36 standards, simplifying power-tree design. The 3-driver/3-receiver architecture covers the standard V.35 signal set (103/104/113/114/115) in a single chip.
Recommandé
Legacy-to-Modern Serial Converter
Standalone legacy-to-modern serial protocol converters (e.g., V.36 to USB or RS-449 to Ethernet) leverage the LTC2846IG to accept any legacy input protocol on the field side. The MODE_SELECT logic pins let the converter automatically detect and reconfigure the line interface to match the connected legacy equipment, simplifying field deployment. The 3.3V supply aligns with modern USB-to-serial bridge ASICs, allowing a single LDO to power both the LTC2846 and the bridge IC. Industrial temperature rating and +/-15 kV ESD protection are critical when the converter is installed in legacy equipment rooms with poor environmental control.
Recommandé
Test & Measurement Multiprotocol Analyzer
Portable protocol analyzers and BERT (Bit Error Rate Tester) front-ends use the LTC2846IG to provide a single hardware test port that can physically interface with RS-232, V.35, V.36, RS-449, X.21, EIA530 and EIA530-A devices under test. The software-selectable protocol switching means a field engineer carries one analyzer instead of seven protocol-specific probes. The integrated termination matches the cable impedance of all supported protocols, ensuring signal integrity at the analyzer input. The 1.2MHz boost regulator and charge-pump integrated inside the LTC2846 free the analyzer's enclosure space for batteries and display.
Recommandé
Récapitulatif des produits recommandés
Données de référence d'ingénierie pour LTC2846IG — comparaison, recommandations de conception et informations de conformité.
Guide de sélection
Comparaison avec les alternatives
| Paramètre | Ce produit | LTC2846IG#PBF | LTC2846CG | LTC2846CG#PBF | LTC2846IG#TRPBF |
|---|---|---|---|---|---|
| Brand | Analog Devices | Analog Devices | Analog Devices | Analog Devices | Analog Devices |
| Package | SSOP-36 | SSOP-36 | SSOP-36 | SSOP-36 | SSOP-36 |
| Drivers / Receivers | 3 / 3 | 3 / 3 | 3 / 3 | 3 / 3 | 3 / 3 |
| Supply Voltage | 3.3 V | 3.3 V | 3.3 V | 3.3 V | 3.3 V |
| Supported Protocols | RS232, RS449, EIA530, V.35, V.36, X.21 | Same | Same | Same | Same |
| Temperature Grade | Industrial (-40C to +85C) | Industrial (-40C to +85C) | Commercial (0C to +70C) | Commercial (0C to +70C) | Industrial (-40C to +85C) |
| Lead-free / RoHS | Standard (non-PBF) | Yes (PBF) | No | Yes (PBF) | Yes (PBF) |
| Packaging Format | Tube | Tube | Tube | Tube | Tape & Reel |
Principaux différenciateurs
- Integrated 1.2MHz boost regulator for V.35/V.36/X.21 drivers (vs Discrete MAX3232 + SN65... RS-422 approach)
- On-chip 100-ohm cable termination network (vs Discrete termination using external resistor networks)
- Software-selectable 7-protocol mode control (vs Multiple discrete single-protocol transceivers)
- TUV Rheinland NET1/NET2/TBR2 telecom certification (vs Discretes requiring customer self-certification)
Notes de conception
Place the boost regulator bypass capacitor (10uF X7R ceramic in parallel with 47uF low-ESR electrolytic) within 5 mm of the BST_VOUT pin (pin 32). Estimated: at 1.2 MHz switching frequency with 50 mA boost load, the capacitor loop inductance should be below 10 nH to keep ripple under 50 mVpp; a 0805 ceramic + small tantalum placed close to the IC achieves this. Keep the BST_LX (pin 31) trace short and isolated from analog signal traces to avoid switching-noise coupling into the receiver channels.
Do not use the LTC2846CG (commercial 0C to +70C) in telecom or industrial cabinets where ambient temperature can exceed 70C inside sealed boxes. The commercial grade will fail thermal specifications and may corrupt serial data at elevated temperatures. Always verify the temperature grade on the top marking before reflow: the LTC2846IG carries the 'I' (industrial) suffix while the LTC2846CG carries 'C' (commercial). Mixing them on the same PCB will cause field failures under partial-temperature operation.
The on-chip 100-ohm termination network assumes a V.35 / V.36 cable characteristic impedance of 100 ohms differential. For non-standard cable impedances (e.g., RS-232 at 5 ns rise time on 24 AWG twisted pair), the on-chip termination may over-damp the signal and reduce the achievable data rate. Estimated: at cable impedance of 90 ohms, the -3 dB bandwidth drops by ~10%. If your cable impedance deviates by more than 10%, consider disabling the internal termination (per datasheet) and adding an external resistor network.
Separate the analog cable-side traces (D1A/D1B, R1A/R1B, etc.) from the digital control-side traces (MODE0/MODE1/MODE2, TXD, RXD) by at least 3 mm to avoid digital switching noise coupling into the cable receivers. Use a guard ground trace between the analog and digital sections, stitched with ground vias every 5 mm. The MODE_SELECT logic pins (3, 4, 5) must be driven by push-pull CMOS logic; floating inputs will leave the protocol in an undefined state and can cause the boost regulator to oscillate.
The 3.3V supply (VCC, pin 2) must be capable of sourcing 200 mA peak during boost regulator startup; a soft-start capacitor on BST_VOUT limits the inrush to 100 mA but the input supply must still have low source impedance. Estimated: with VIN = 3.3V and VOUT_boost = 5V at 50 mA load, the input current draw is ~80 mA (efficiency ~91%). Add a 22uF bulk decoupling capacitor on VCC within 10 mm of the IC to prevent the boost regulator startup from sagging the digital logic supply.
Informations de conformité
Lead-free RoHS compliance requires the #PBF suffix (LTC2846IG#PBF). TUV Rheinland NET1, NET2, TBR2 certified (Report No. TBR2/051501/02) for European telecom. Industrial temperature grade -40C to +85C. Not AEC-Q100 qualified - no automotive variant available.
