Analog Devices Inc./Maxim Integrated DS1858B-050

Overview

DS1858B-050 from Maxim Integrated is a dual temperature-controlled nonvolatile variable resistor IC with integrated analog monitoring and digital temperature sensing. It features two 50kΩ, 256-position linear resistors, three external analog monitor inputs (MON1–MON3), an internal direct-to-digital temperature sensor, and a 2-wire serial interface - all in a 16-ball CSBGA package. It enables precise, temperature-compensated bias control in optical transceiver laser driver circuits.

For engineers reviewing the DS1858B-050 datasheet, DS1858B-050 pinout, DS1858B-050 application, or DS1858B-050 equivalent, this page delivers verified technical context, real-world use cases for optical diagnostics, confirmed resistor linearity and thermal coefficient specs, and validated alternative parts for SFF-8472-compliant designs.

Technical Context

The DS1858B-050 implements a temperature-indexed lookup table architecture where each of its two 50kΩ resistors is assigned a unique 256-position value per 2°C increment across –40°C to +102°C. Resistor settings are stored in EEPROM and updated via I²C-compatible 2-wire bus (SCL/SDA) at up to 400kHz.

It integrates five monitored channels - internal temperature, VCC, and three external analog inputs - each digitized to 12-bit accuracy (16-bit left-justified format) with programmable high/low alarm thresholds and interrupt flags. Two open-drain buffers (OUT1/OUT2) support Tx fault and loss-of-signal signaling in optical modules.

Key Specifications

Pinout & Package

DS1858B-050 is housed in a 16-ball Chip Scale Ball Grid Array (CSBGA) package measuring 4mm × 4mm with 1.0mm ball pitch. The package supports surface-mount reflow assembly and provides compact integration for space-constrained optical module PCBs.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar dual-variable-resistor-with-monitoring applications.

Compared with DS1858B-050, DS1858E-050 offers identical performance in a TSSOP package for easier assembly, while MAX31723 provides standalone temperature sensing but lacks resistive and multi-channel analog monitoring capabilities - making it a partial functional substitute requiring significant external circuitry.

Availability

DS1858B-050 is available at Aetrix Electronics and suitable for optical transceiver manufacturing, industrial temperature-compensated instrumentation, and RF power amplifier design requiring stable component supply and long-term lifecycle support.

Supply support for DS1858B-050 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 power management ICs for demanding industrial, communications, and computing applications.

The DS1858B-050 belongs to Maxim's SFF-8472-compliant digital diagnostic monitoring product line, engineered specifically for temperature-aware bias control and real-time health monitoring in hot-pluggable optical modules.

FAQ

What is the primary function of the DS1858B-050 in optical transceiver designs?

The DS1858B-050 serves as a dual temperature-compensated resistor and multi-channel monitor IC in optical transceivers. It replaces manual potentiometers and discrete thermistors by providing two 50kΩ nonvolatile variable resistors whose values change automatically every 2°C - ensuring stable laser bias and modulation voltage across temperature. Its MON1–MON3 inputs and internal temperature sensor feed diagnostic data into the host controller via I²C, fulfilling SFF-8472 compliance requirements. DS1858B-050 integrates these functions in a single 4mm × 4mm CSBGA package optimized for pluggable optics.

How does the DS1858B-050 implement temperature compensation for its resistors?

The DS1858B-050 uses a temperature-indexed lookup table architecture: each of its two 50kΩ resistors has a dedicated 256-position table, with one entry assigned per 2°C increment from –40°C to +102°C. The internal temperature sensor reads ambient temperature, selects the corresponding table index, and applies the stored resistance value - all without host intervention. This eliminates need for external thermistors or MCU-based interpolation. DS1858B-050 stores these tables in EEPROM, allowing factory or field programming for application-specific compensation curves.

Can the DS1858B-050 operate on both 3.3V and 5V supplies?

Yes, the DS1858B-050 operates over a supply range of 3.0V to 5.5V, making it compatible with both 3.3V and 5V systems. Its I/O pins (SDA, SCL, WPEN, IN1, IN2) meet TTL/CMOS logic thresholds across this range, and its analog monitors (MON1–MON3) maintain 0–2.5V full-scale input range regardless of VCC. The device draws 1–2mA typical supply current and includes separate analog and digital power-on reset thresholds (POA = 2.0–2.6V, POD = 1.0–2.2V) to ensure reliable initialization. DS1858B-050's dual-supply compatibility simplifies integration into mixed-voltage optical module designs.

What are the key differences between DS1858B-050 and DS1858E-050?

The DS1858B-050 and DS1858E-050 share identical electrical specifications, register maps, and functional behavior - differing only in package type and thermal characteristics. DS1858B-050 uses a 16-ball CSBGA (4mm × 4mm), optimized for high-density optical module PCBs and automated reflow assembly. DS1858E-050 uses a 16-pin TSSOP package, better suited for prototyping, manual soldering, and applications where board area is less constrained. Both operate from –40°C to +95°C and support the same I²C addressing and monitoring features. DS1858B-050 is the preferred choice for production optical transceivers.

Does the DS1858B-050 support interrupt-driven monitoring?

Yes, the DS1858B-050 supports interrupt-driven monitoring via its MINT (Monitor Interrupt) output, which is mapped to the OUT1 pin when configured. Each monitored channel (temperature, VCC, MON1–MON3) has dedicated high/low alarm flags in SRAM registers 70h and 71h. These flags can be masked individually using configuration byte 88h, and the resulting OR'ed interrupt signal appears on OUT1. This allows host systems to respond asynchronously to out-of-limit conditions without polling - critical for real-time fault handling in optical links. DS1858B-050's interrupt architecture is fully SFF-8472 compliant.