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Analog Devices Inc./Maxim Integrated DS1856B-020/T&R
- Part No.:
- DS1856B-020/T&R
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Category:
- Digital Potentiometers
- Package:
- 16-LBGA, CSPBGA
- Datasheet:
-
DS1856B-020/T&R.pdf
- Description:
- DUAL TEMP-CONTROLLED RESISTOR
- Quantity:
- Payment:
- Shipping:
Inventory:2,500
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Product details
Overview
DS1856B-020/T&R from Maxim Integrated is a dual, temperature-controlled, nonvolatile variable resistor IC with integrated 12-bit analog monitoring (VCC, MON1–MON3, internal temperature), password-protected EEPROM, and SFF-8472-compliant diagnostics for optical transceivers. It features two 256-position linear resistors, three external analog inputs, and operates from 2.85V to 5.5V across –40°C to +95°C.
For engineers reviewing the DS1856B-020/T&R datasheet, DS1856B-020/T&R pinout, DS1856B-020/T&R application, or DS1856B-020/T&R equivalent, this device serves as a calibrated, secure, temperature-compensated biasing solution in SFF-8472-compliant optical modules requiring real-time diagnostic monitoring and nonvolatile resistor tuning.
Technical Context
The DS1856B-020/T&R implements a dual-resistor architecture where each 256-step resistor is mapped via temperature-indexed look-up tables (–40°C to +102°C, 2°C resolution), enabling automatic resistance adjustment based on measured die temperature. Its 2-wire interface supports both standard (100kHz) and fast-mode (400kHz) operation with programmable slave addresses (A2h default, configurable via ADFIX).
Monitoring is performed by a shared 12-bit ADC with left-justified output: VCC uses 100µV/LSB scaling (0–6.5536V full-scale), MON1–MON3 use 38.147µV/LSB (0–2.5V), and temperature is reported in two's complement format (±128°C, 1/256°C resolution). Alarm/warning flags and interrupt outputs (OUT1/OUT2) are generated autonomously per channel.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Resistor Values | 20kΩ per channel (DS1856B-020); position 00h = 0.2–0.4kΩ, position FFh = 15–25kΩ at +25°C |
| Temperature Resolution | 2°C step granularity for resistor look-up table indexing across –40°C to +102°C range |
| Monitor Accuracy | ±0.5% FS for VCC/MON1–MON3; ±3.0°C thermometer error over full operating range |
| Supply Range | 2.85V to 5.5V - supports both 3.3V and 5V systems without level-shifting |
| Interface Speed | Up to 400kHz I²C fast-mode - enables rapid configuration and telemetry polling in high-speed optical links |
| EEPROM Endurance | 50,000 write cycles at +70°C - sufficient for field calibration and lifetime parameter updates |
| Security Levels | Three-tier password protection (User / Level 1 / Level 2) controlling access to monitoring, EEPROM, and configuration registers |
Pinout & Package
DS1856B-020/T&R is housed in a 16-ball CSBGA package (4mm × 4mm, 1.0mm pitch), optimized for space-constrained optical module PCBs.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| SDA | 2-wire serial data I/O | Open-drain bidirectional bus line; requires external pull-up; supports multi-drop I²C topology |
| SCL | 2-wire serial clock input | Master-generated clock; timing-critical for 100/400kHz operation; rise/fall time ≤300ns @ 400pF load |
| OUT1 / OUT2 | Open-drain buffer outputs | Configurable fault/warning indicators (e.g., Tx Fault, LOS); sink up to 6mA; TTL/CMOS-compatible logic levels |
| IN1 / IN2 | TTL/CMOS buffer inputs | Direct connection to host logic; used for external signal assertion (e.g., laser enable, reset) |
| MON1 / MON2 / MON3 | External analog monitor inputs | High-impedance (≥1MΩ) inputs supporting factory-calibrated 0–2.5V full-scale range; scalable dynamic range |
| L0 / H0 / L1 / H1 | Resistor terminal connections | Four dedicated terminals for dual potentiometric networks; no polarity constraint - voltage must stay within GND–VCC |
| VCC / GND | Power supply pins | Single-supply operation; decoupling capacitor (0.1µF) required at VCC pin per layout guidelines |
Key Features
| Feature | Design Value |
|---|---|
| SFF-8472 Compliance | Fully implements digital diagnostic monitoring interface for optical transceivers - eliminates need for external microcontroller-based monitoring |
| Temperature-Indexed Resistors | Each resistor independently programmed per 2°C increment across –40°C to +102°C - enables precise thermal compensation of laser bias and modulation currents |
| Five-Channel Monitoring | Simultaneous real-time measurement of VCC, temperature, and three external analog signals - supports closed-loop control and alarm generation without host intervention |
| Password-Protected EEPROM | Three-tier security (User/Level 1/Level 2) prevents unauthorized access to calibration data, limits, and resistor tables - critical for OEM IP protection |
| Dual Buffer Outputs | OUT1/OUT2 support hardware-level fault signaling (e.g., Tx Fault, LOS) and can be asserted automatically when monitored values exceed user-defined thresholds |
Applications
| Optical Transceivers | RF Power Amplifiers |
|---|---|
Use Scenario: Embedded in SFP/SFP+ modules for real-time monitoring and bias control of VCSEL/DFB lasers. IC Role / Device Role / Timing Role: Dual-resistor network sets laser bias and modulation current while temperature sensor auto-adjusts settings to maintain optical output stability. Use Value: Enables compliance with SFF-8472 diagnostic requirements and reduces BOM count by integrating monitoring, compensation, and secure storage in one IC. |
Use Scenario: Biasing and thermal stabilization of GaN/GaAs RF power amplifier stages in base station front-ends. IC Role / Device Role / Timing Role: Resistor R0 adjusts gate bias voltage; R1 tunes drain current; internal temperature sensor triggers dynamic compensation every 2°C step. Use Value: Maintains amplifier linearity and efficiency across ambient temperature swings without external MCU intervention or calibration routines. |
| Instrumentation Systems | Industrial Laser Drivers |
Use Scenario: Precision current/voltage reference trimming in portable test equipment with battery-powered operation. IC Role / Device Role / Timing Role: Nonvolatile resistor pair provides stable, temperature-compensated gain/offset correction; monitors VCC and sensor supply rails. Use Value: Eliminates manual potentiometer adjustments and drift-related recalibration; EEPROM retains settings through power cycles and field updates. |
Use Scenario: Closed-loop thermal management in fiber-coupled diode laser drivers used in medical and material processing systems. IC Role / Device Role / Timing Role: MON1–MON3 monitor thermistor, heatsink voltage, and driver supply; DS1856B-020/T&R adjusts bias resistors to maintain constant optical power. Use Value: Prevents thermal runaway and extends laser diode lifetime by enforcing tight temperature-dependent current limits with hardware-level response. |
Availability
DS1856B-020/T&R is available at Aetrix Electronics and suitable for optical transceiver manufacturing, RF power amplifier design, instrumentation calibration, and industrial laser driver development requiring stable component supply and long-term lifecycle support.
Supply support for DS1856B-020/T&R 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 and mixed-signal ICs for demanding applications in communications, computing, and industrial systems.
The DS1856B-020/T&R belongs to Maxim's SFF-8472-compliant digital diagnostic monitoring product line, engineered specifically for optical module manufacturers needing integrated, secure, temperature-aware bias control and telemetry.
FAQ
What is the resistance tolerance and temperature coefficient of DS1856B-020/T&R at position FFh?
At position FFh and +25°C, DS1856B-020/T&R exhibits a resistance of 15kΩ to 25kΩ (±25% typical). Its temperature coefficient is specified at 50ppm/°C across the full resistor setting range, ensuring predictable drift behavior during thermal compensation in optical bias circuits.
How does DS1856B-020/T&R handle password entry and security escalation?
DS1856B-020/T&R implements three access tiers: User (default, read-only monitoring), Level 1 (requires Password 1, enables auxiliary EEPROM access), and Level 2 (requires Password 2, unlocks full register write capability). Passwords are entered into PWE bytes (7Bh–7Eh); PW1/PW2 are stored in protected locations (B0h–B3h, B4h–B7h) and never readable.
Can DS1856B-020/T&R operate on a 3.3V supply while maintaining full specification compliance?
Yes - DS1856B-020/T&R is fully specified from 2.85V to 5.5V. At 3.3V, it maintains all key performance parameters: 400kHz I²C operation, ±0.5% FS monitor accuracy, 2°C resistor indexing resolution, and guaranteed functionality across –40°C to +95°C, making it ideal for modern low-voltage optical modules.
What is the update rate for monitored channels like MON1 and temperature in DS1856B-020/T&R?
DS1856B-020/T&R performs round-robin conversion of all five monitored channels (VCC, Temp, MON1–MON3) with a frame time of 47ms to 60ms. Each channel's 16-bit result is updated at this rate, and corresponding alarm/warning flags are asserted within one frame after threshold violation detection.
Does DS1856B-020/T&R support multiple devices on the same I²C bus, and how is addressing managed?
Yes - DS1856B-020/T&R supports up to 128 devices on one I²C bus. Its default main address is 0xA2, but the Chip Address byte (Table 03, 8Ch) allows reprogramming. ADEN and ADFIX bits configure dual-address mode (A0h/A2h) or single-address mapping (Auxiliary memory relocated to Tables 00h/01h), enhancing compatibility with legacy DS1852/DS1859 systems.
DS1856B-020/T&R Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc./Maxim Integrated
- Series:
- -
- Package/Case:
- 16-LBGA, CSPBGA
- Packaging:
- Bulk
- Product Status:
- Active
- Programmable:
- -
- Taper:
- Linear
- Configuration:
- Rheostat
- Number of Circuits:
- 2
- Number of Taps:
- 256
- Resistance (Ohms):
- 20k
- Interface:
- I2C
- Memory Type:
- Non-Volatile
- Voltage - Supply:
- 2.85V ~ 5.5V
- Features:
- Temperature Sensor
- Tolerance:
- -
- Temperature Coefficient (Typ):
- 50ppm/°C
- Mounting Type:
- Surface Mount
- Grade:
- -
- Qualification:
- -
- Supplier Device Package:
- 16-CSBGA (4x4)
- Operating Temperature:
- -40°C ~ 95°C
- Resistance - Wiper (Ohms) (Typ):
- -
DS1856B-020/T&R FAQ
1.How can I place an order for DS1856B-020/T&R through Aetrix?
Please submit a Request for Quotation (RFQ) for DS1856B-020/T&R 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 DS1856B-020/T&R reliable?
The price and inventory of DS1856B-020/T&R are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for DS1856B-020/T&R is usually 5 days.
3.What payment methods are accepted for DS1856B-020/T&R?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for DS1856B-020/T&R transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for DS1856B-020/T&R?
DS1856B-020/T&R orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your DS1856B-020/T&R 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 DS1856B-020/T&R?
For technical support, including DS1856B-020/T&R datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your DS1856B-020/T&R requirements.
6.How does Aetrix verify that DS1856B-020/T&R is sourced from the original manufacturer or authorized distributors?
All DS1856B-020/T&R 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 DS1856B-020/T&R meets industry standards.
7.What is the process for return or replacement of DS1856B-020/T&R?
All DS1856B-020/T&R units undergo pre-shipment inspection (PSI). If there is an issue with DS1856B-020/T&R, 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 DS1856B-020/T&R part is unused and in its original packaging.
Return procedure for DS1856B-020/T&R:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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