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Analog Devices Inc./Maxim Integrated DS1876T+
- Part No.:
- DS1876T+
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Category:
- Sensor and Detector Interfaces
- Package:
- 28-WFQFN Exposed Pad
- Datasheet:
-
DS1876T+.pdf
- Description:
- IC CTRLR SFP DUAL LDD 28TQFN
- Quantity:
- Payment:
- Shipping:
Inventory:2,006
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Product details
Overview
DS1876T+ from Maxim Integrated is a dual-channel SFP controller IC designed for optical transceiver modules with two independent laser driver interfaces. It integrates six 13-bit ADC channels (VCC, temperature, PMON1/2, BMON1/2), four 10-bit delta-sigma DAC outputs (MOD1/2, APC1/2), six quick-trip comparators for eye-safety shutdown, and I²C-compatible control per SFF-8472. It operates from +2.85V to +3.9V across –40°C to +95°C in 28-pin TQFN-EP packaging, targeting dual-Tx video SFP modules.
For engineers reviewing the DS1876T+ datasheet, DS1876T+ pinout, DS1876T+ application, or DS1876T+ equivalent, key selection criteria include dual-laser APC/modulation control, integrated eye-safety fault detection without external components, SFF-8472 register map compliance, temperature-indexed LUT-based DAC programming, and 28-pin TQFN package compatibility with SFP module PCB layouts.
Technical Context
The DS1876T+ implements a shared 13-bit successive-approximation ADC with round-robin sampling across six analog inputs (temperature, VCC, PMON1/2, BMON1/2), delivering 64–78ms update rate per channel. Its six quick-trip comparators operate on a time-multiplexed basis with 1.6μs sample timing, directly asserting TXFOUT on HTXP1/LTXP1/HBATH1/HTXP2/LTXP2/HBATH2 violations.
Four delta-sigma DACs (MOD1, MOD2, APC1, APC2) each use a 72-entry temperature lookup table (LUT) for closed-loop power/bias control; DAC output resolution is 10 bits with internal reference input (REFIN) supporting 0–VREFIN range. All DACs enter high-impedance state at power-up and transition to EEPROM-initialized values after tINIT = 20ms.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Main supply voltage | +2.85V to +3.9V - supports standard SFP module rail with ±10% margin at 3.3V nominal |
| Operating temperature | –40°C to +95°C - qualified for industrial-grade pluggable optical transceivers |
| ADC resolution & channels | 13-bit resolution across 6 channels (temp, VCC, PMON1/2, BMON1/2) - enables precise bias/power monitoring per laser |
| DAC outputs | Four 10-bit delta-sigma outputs (MOD1/2, APC1/2) - drive laser modulation and automatic power control loops |
| Quick-trip comparators | Six dedicated comparators (HTXP1/LTXP1/HBATH1/HTXP2/LTXP2/HBATH2) - hardware-level eye-safety shutdown with <10.5μs fault assert time |
| I²C interface | 400kHz fast-mode compatible, slave addresses A0h (aux), A2h (Tx1), B2h (Tx2) - matches SFF-8472 memory map partitioning |
| Package | 28-pin TQFN-EP (5mm × 5mm × 0.8mm) with exposed pad - optimized for thermal dissipation in compact SFP modules |
Pinout & Package
DS1876T+ uses a 28-pin thin quad flat no-lead package with exposed thermal pad (TQFN-EP, 5mm × 5mm × 0.8mm). Pin 1 is RSELOUT; pins 8, 18, and 21 are GND; pins 16 and 26 are VCC; pin 15 is N.C.; EP must be connected to GND for thermal and electrical integrity.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| RSELOUT (Pin 1) | Rate-select output | Drives external rate-select logic (e.g., RS1 in SFF-8431); open-drain, requires pull-up |
| SCL (Pin 2) | I²C clock input | Master-generated serial clock; supports 400kHz fast-mode timing per I²C spec |
| SDA (Pin 3) | I²C data I/O | Open-drain bidirectional bus line; shares address space across A0h/A2h/B2h slave addresses |
| TXFOUT (Pin 4) | Transmit fault output | Open-drain active-high fault indicator asserted on any of six quick-trip violations |
| PMON1 (Pin 13) | External monitor input | Measures photodiode current from TOSA1; used for HTXP1/LTXP1 quick-trip and ADC conversion |
| BMON1 (Pin 14) | External monitor input | Measures laser bias current from LDD1; used for HBATH1 quick-trip and ADC conversion |
| MOD1 (Pin 20) | Delta-sigma DAC output | 10-bit modulation control signal for LDD1; referenced to REFIN; supports RC filtering per Figure 6 |
| APC1 (Pin 25) | Delta-sigma DAC output | 10-bit automatic power control signal for LDD1; referenced to REFIN; enables closed-loop TX power stability |
Key Features
| Feature | Design Value |
|---|---|
| SFF-8472 compliance | Fully implements transmitter control/monitoring register map (A0h/A2h/B2h), enabling plug-and-play integration into SFP host systems |
| Integrated eye-safety architecture | Six hardware quick-trip comparators trigger TXFOUT within 10.5μs - eliminates need for external safety circuitry in Class 1 laser modules |
| Temperature-compensated DAC control | 72-entry LUT per DAC (MOD1/2, APC1/2) allows precise gain/offset compensation across –40°C to +95°C operating range |
| Dual independent monitoring paths | Separate PMON/BMON inputs and quick-trip thresholds for each laser channel - supports asymmetric TOSA/LDD configurations |
| Flexible security & memory | Two-level password scheme (three access tiers) and 256-byte auxiliary EEPROM at A0h - enables secure calibration and vendor-specific configuration storage |
Applications
| Dual-Tx Video SFP Modules | Bi-Directional CATV Optical Nodes |
|---|---|
Use Scenario: Dual-channel 1.25Gbps video transmission over single-fiber PON infrastructure with real-time laser health monitoring. IC Role / Device Role / Timing Role: DS1876T+ serves as primary SFP controller managing APC/MOD for two independent TOSAs while enforcing IEC 60825-1 eye-safety limits. Use Value: Eliminates discrete comparators and external DACs, reducing BOM count by ≥7 components and enabling full SFF-8472 compliance in <100mm² PCB area. |
Use Scenario: RF-over-fiber distribution in cable TV headends where upstream/downstream lasers require independent bias and power regulation. IC Role / Device Role / Timing Role: DS1876T+ performs simultaneous real-time monitoring of both transmit paths and triggers fail-safe shutdown if either laser exceeds Class 1M emission limits. Use Value: Six quick-trip comparators respond in <10.5μs - faster than microcontroller-based solutions - ensuring regulatory compliance under transient fault conditions. |
| Industrial Ethernet SFP Transceivers | Medical Imaging Fiber-Optic Links |
Use Scenario: Harsh-environment industrial switches requiring extended temperature operation (–40°C to +95°C) and robust laser fault handling. IC Role / Device Role / Timing Role: DS1876T+ provides deterministic, hardware-based laser shutdown independent of host firmware - critical for SIL-2 functional safety requirements. Use Value: Maskable laser shutdown capability allows selective disabling of one channel during maintenance while maintaining link integrity on the other. |
Use Scenario: Endoscopic imaging systems using dual-wavelength (e.g., 850nm/1310nm) fiber-optic illumination with strict laser safety certification. IC Role / Device Role / Timing Role: DS1876T+ continuously monitors HTXP/LTXP/BMATH thresholds per channel and asserts TXFOUT to cut laser drive within 10.5μs of violation. Use Value: Internal direct-to-digital temperature sensor eliminates external thermistor routing, improving layout reliability in miniaturized medical connectors. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar SFP controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MAX32664ETK+ | Single-channel SFP controller; lacks dual-LDD support, only four ADC inputs, no quick-trip comparators | Only suitable for single-transmitter modules; cannot replace DS1876T+ in dual-Tx designs without redesign | Select only when cost-sensitive single-channel applications require basic SFF-8472 compliance without eye-safety hardware |
| LMX2594RHBR | Wideband PLL synthesizer - not an SFP controller; no ADCs, DACs, I²C slave interface, or SFF-8472 register map | Designed for RF signal generation, not optical transceiver monitoring/control | Not a functional alternative; included only for context - DS1876T+ has no drop-in replacement among TI's portfolio |
Compared with MAX32664ETK+, DS1876T+ delivers dual-laser control, hardware eye-safety enforcement, and full SFF-8472 register mapping - essential for video SFPs. Compared with LMX2594RHBR, DS1876T+ is a purpose-built optical controller, not a frequency synthesizer, making it non-interchangeable in transceiver applications.
Availability
DS1876T+ is available at Aetrix Electronics and suitable for dual-Tx video SFP modules, industrial Ethernet transceivers, and medical fiber-optic links requiring stable component supply, RoHS-compliant packaging, and guaranteed long-term availability.
Supply support for DS1876T+ includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.
Manufacturer
Maxim Integrated, now part of Analog Devices, designs precision analog, mixed-signal, and digital ICs for industrial, communications, and computing applications.
The DS1876T+ belongs to Maxim's optical transceiver controller product line, engineered specifically to meet SFF-8472 requirements for dual-laser SFP modules with integrated safety-critical monitoring and closed-loop control.
FAQ
What is the function of the REFIN pin on the DS1876T+?
The REFIN pin on the DS1876T+ serves as the reference input for all four delta-sigma DACs (MOD1, MOD2, APC1, APC2). It accepts a stable voltage between 0.1×VCC and VCC, defining the full-scale output range (0 to VREFIN) for each DAC. Proper decoupling of REFIN is required to maintain DAC accuracy; the DS1876T+ datasheet specifies minimum 0.1μF ceramic capacitance to ground.
Does the DS1876T+ support both APC and modulation control for two independent lasers?
Yes, the DS1876T+ natively supports automatic power control (APC) and modulation control for two independent lasers via dedicated DAC outputs: APC1/MOD1 for transmitter 1 (accessed at I²C slave address A2h) and APC2/MOD2 for transmitter 2 (accessed at B2h). Each pair operates with its own 72-entry temperature lookup table, enabling independent, temperature-compensated control loops.
How does the DS1876T+ ensure laser eye safety compliance?
The DS1876T+ ensures laser eye safety compliance through six hardware quick-trip comparators that monitor HTXP1/LTXP1/HBATH1/HTXP2/LTXP2/HBATH2 in real time. Any violation asserts TXFOUT within 10.5μs and can optionally disable TXDOUT1/TXDOUT2 - all without host processor intervention. This meets IEC 60825-1 Class 1 requirements by eliminating software latency in safety-critical shutdown paths.
What I²C slave addresses does the DS1876T+ use and why are they significant?
The DS1876T+ uses three I²C slave addresses: A0h for auxiliary memory (256 bytes), A2h for transmitter 1 control/monitoring registers, and B2h for transmitter 2. This triple-address architecture directly implements the SFF-8472 memory map specification, allowing host systems to access per-channel data and shared configuration without address conflicts or bank-switching overhead.
Can the DS1876T+ operate with a 2.5V supply instead of the specified 2.85V–3.9V range?
No, the DS1876T+ is not rated for 2.5V operation. Its absolute minimum supply voltage is +2.85V, and the power-on reset (POA) threshold is 2.0V–2.75V. Operating below 2.85V risks undefined behavior, incomplete DAC initialization, or failure to meet SFF-8472 timing specifications. For 2.5V systems, a DC-DC boost or LDO regulator is required to meet the DS1876T+'s validated operating range.
DS1876T+ Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Package/Case:
- 28-WFQFN Exposed Pad
- Series:
- -
- Packaging:
- Tube
- Product Status:
- Active
- Programmable:
- Not Verified
- Type:
- SFP Laser Controller
- Input Type:
- Logic
- Output Type:
- Logic
- Current - Supply:
- 10 mA
- Operating Temperature:
- -40°C ~ 95°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 28-TQFN (5x5)
DS1876T+ FAQ
1.How can I place an order for DS1876T+ through Aetrix?
Please submit a Request for Quotation (RFQ) for DS1876T+ on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
2.Are the price and stock information for DS1876T+ reliable?
The price and inventory of DS1876T+ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for DS1876T+ is usually 5 days.
3.What payment methods are accepted for DS1876T+?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for DS1876T+ transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for DS1876T+?
DS1876T+ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your DS1876T+ order is processed, you will receive an email with the shipment details and tracking number.
Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.
5.How can I obtain technical support or documentation for DS1876T+?
For technical support, including DS1876T+ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your DS1876T+ requirements.
6.How does Aetrix verify that DS1876T+ is sourced from the original manufacturer or authorized distributors?
All DS1876T+ products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that DS1876T+ meets industry standards.
7.What is the process for return or replacement of DS1876T+?
All DS1876T+ units undergo pre-shipment inspection (PSI). If there is an issue with DS1876T+, returns or replacements are accepted under the following conditions:
1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.
2.The issue is reported within 90 days of delivery.
3.The DS1876T+ part is unused and in its original packaging.
Return procedure for DS1876T+:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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