STMicroelectronics L9825

Overview

L9825 from STMicroelectronics is an octal low-side driver IC designed for automotive resistive and inductive load control, featuring 8 independent power outputs with R_DS(on) ≤ 0.75 Ω at T_J = 25°C, intrinsic 50 V output voltage clamping, and dual-control architecture supporting both SPI (outputs 1–8) and parallel inputs (outputs 1 & 2). It delivers up to 2.05 A per output (1–6) and integrates overcurrent shutdown, thermal protection, and open-load diagnostics.

For engineers reviewing the L9825 datasheet, L9825 pinout, L9825 application, or L9825 equivalent, key selection considerations include its PowerSO-20 package thermal resistance (R_thjc-all = 1.6 °C/W), diagnostic threshold at 0.32·V_CC, and dual-mode control enabling PWM-capable parallel operation for outputs 1 and 2 alongside serial configuration for full 8-channel management.

Technical Context

The L9825 implements a hybrid control architecture: outputs 1 and 2 accept direct parallel logic via NON1/NON2 pins with internal pull-up resistors (50–250 kΩ), while all eight outputs are configurable via SPI (3 MHz max clock, 8-bit shift register with NCS-synchronized latching). The device uses dedicated fault latches for outputs 1–2 and real-time status reporting via SDO for all outputs.

Its protection system applies differentiated strategies: outputs 1–6 trigger immediate overcurrent shutdown (I_SC = 1.4 A typ), whereas outputs 7–8 enter current-limit regulation (I_LIM = 1.4 A typ) before thermal shutdown (T_JSC = 165 °C) - optimized for lamp loads with high inrush. Diagnostic detection includes open-load sensing (I_OL = 20–100 µA sink) and short-to-V_BAT detection using a 0.32·V_CC threshold comparator.

Key Specifications

Pinout & Package

Package: PowerSO-20 (JEDEC MO-166), thermally enhanced surface-mount package with exposed lead slug for low R_thjc (1.6 °C/W for all outputs).

Key Features

Applications

Equivalent & Alternatives

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

Compared with TLE6240GP and VN808CM, the L9825 uniquely combines parallel/PWM-ready control for two channels, built-in 50 V flyback clamping, and differentiated protection modes - making it optimal for cost-sensitive automotive modules requiring both flexibility and robustness without external protection components.

Availability

L9825 is available at Aetrix Electronics and suitable for automotive body control modules, LED headlamp drivers, engine bay solenoid controllers, and commercial vehicle lighting hubs requiring stable component supply across extended temperature ranges and high-reliability operation.

Supply support for L9825 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-grade analog, power, and microcontroller solutions with broad AEC-Q100 qualification coverage.

The L9825 belongs to ST's automotive power driver product line, engineered specifically for intelligent load switching in 12 V vehicle electrical systems - emphasizing integrated protection, diagnostic capability, and thermal resilience in compact packages.

FAQ

Can L9825 drive inductive loads without external flyback diodes?

Yes. The L9825 features intrinsic output voltage clamping at typ. 50 V, which safely recirculates flyback current from inductive loads such as solenoids and relays. This eliminates the need for external freewheeling diodes in standard 12 V automotive applications, reducing PCB area and component count while maintaining robust transient suppression.

How does L9825 handle lamp loads with high inrush current?

Outputs 7 and 8 implement current-limit regulation instead of hard shutdown during overcurrent events, allowing controlled current delivery during lamp cold-start. When current exceeds 1.4 A (typ), the output enters regulation mode - dissipating power until thermal shutdown (165 °C) activates if sustained - preventing nuisance tripping while protecting the device.

What is the diagnostic accuracy for open-load detection?

The L9825 uses a dedicated 60 µA diagnostic sink current per output and compares output voltage to a 0.32·V_CC threshold. At V_CC = 5 V, this yields a 1.6 V detection threshold, enabling reliable open-load identification even with wiring resistance up to 26 Ω (1.6 V / 60 µA), covering typical harness lengths in automotive platforms.

Is parallel operation of outputs supported for higher current?

Yes. The datasheet explicitly permits paralleling outputs of the same type (e.g., OUT1 + OUT2) to double current capacity. However, total flyback energy must remain within the 20 mJ limit specified per output, and thermal design must account for combined power dissipation - validated via R_thjc-all = 1.6 °C/W for simultaneous full-load operation.