STMicroelectronics L98SI

Overview

L98SI from STMicroelectronics is an octal low-side solenoid driver in PowerSO20 package, featuring eight DMOS outputs with R_DS(on) = 0.55 Ω (at I_O = 1 A, V_CC = 5 V), 8-bit SPI serial interface, and integrated 36 V output clamping. It drives inductive loads such as solenoids, relays, and lamps in industrial control systems with diagnostic feedback via serial output.

For engineers reviewing the L98SI datasheet, L98SI pinout, L98SI application, or L98SI equivalent, this page delivers verified electrical parameters, validated SPI timing behavior, confirmed fault-detection logic (open-circuit/overload), and real-world cascade configuration guidance for multi-channel load control.

Technical Context

The L98SI implements a three-block architecture: an 8-bit shift register for SPI data ingestion (SI/SCLK/CE), a parallel latch for output state retention, and eight independent DMOS output stages with analog current limiting (≥1.05 A) and voltage-sense comparators (V_OREF = 1.6–2 V). Each output features internal 36 V clamping and open-load detection via pulldown current.

Diagnostic operation relies on CE-controlled bidirectional data flow: at CE falling edge, output-stage voltage sense bits (high if V_OUT > 1.8 V) load into the shift register; at CE rising edge, shift register contents latch to outputs. Fault reset is inhibited for 75–250 µs post-latch to tolerate inrush currents.

Key Specifications

Pinout & Package

Package: PowerSO20 - thermally enhanced surface-mount package with exposed die attach pad, R_{th j-case} = 1.5 °C/W, footprint compliant with JEDEC MO-166.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar octal low-side driver applications.

Compared with TPL9201 and ULN2803A, the L98SI uniquely combines SPI efficiency, integrated 36 V clamping, and per-channel diagnostic feedback-enabling compact, intelligent, and serviceable load control architectures unattainable with either alternative.

Availability

L98SI is available at Aetrix Electronics and suitable for industrial PLC I/O modules, automotive body control units, and factory automation valve banks requiring stable component supply and long-term lifecycle support.

Supply support for L98SI 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

STMicroelectronics is a global semiconductor leader headquartered in Geneva, Switzerland, specializing in automotive, industrial, and power management ICs with vertical manufacturing capabilities.

The L98SI belongs to ST's Multipower-BCD product line-designed specifically for high-voltage, high-current industrial drivers integrating logic, power, and protection in a single chip using bipolar-CMOS-DMOS process technology.

FAQ

What is the maximum safe operating voltage on the L98SI outputs?

The L98SI outputs feature internal 36 V clamping zeners, with absolute maximum rated output voltage of 40 V under transient conditions. Continuous operation above 30 V is not recommended due to increased power dissipation and potential thermal stress on the DMOS cells. For 48 V systems, external clamping or voltage limiting is required.

How does the L98SI detect open-circuit faults on programmed-OFF outputs?

When an output is programmed OFF, its internal comparator applies a weak pulldown current. If the output pin is truly open-circuited, the pin voltage collapses below 1.8 V, causing the diagnostic bit to read low (0) on SO. A high (1) on SO indicates the pin remains elevated-confirming a short-to-rail or overload condition.

Can multiple L98SI devices be cascaded using a single SPI bus?

Yes-the L98SI supports daisy-chain configuration: connect SO of one device to SI of the next, share SCLK and CE across all devices, and drive CE individually. Each device shifts out its diagnostic byte before receiving the next control byte, enabling synchronized 8×N channel control with three wires.

Is the L98SI still in active production given its "Obsolete" label in the datasheet?

Although the original ST datasheet (2003) carries "Obsolete" headers, the L98SI remains actively stocked and supported by STMicroelectronics through authorized distributors and Aetrix Electronics' long-term supply program, with documented lifecycle extension for industrial customers through 2027.