STMicroelectronics L9222

Overview

L9222 from STMicroelectronics is a monolithic quad inverting transistor switch IC designed for high-voltage, high-current switching of inductive loads. It delivers up to 50 V output voltage, 1.2 A per channel output current, and features TTL-compatible inputs with integral clamp diodes. It is used to drive relays, solenoids, unipolar stepper motors, and LED arrays in industrial control modules.

For engineers reviewing the L9222 datasheet, L9222 pinout, L9222 application, or L9222 equivalent, key selection criteria include output sustaining voltage (46 V), saturation voltage at 0.6 A (0.8 V), enable-controlled quad-channel operation, and thermal resistance (90 °C/W junction-to-ambient).

Technical Context

The L9222 integrates four open-collector NPN transistors with integrated clamp diodes on a single die, each emitter tied to GND. Logic-level inputs (VIL ≤ 0.8 V, VIH ≥ 2.0 V) and a shared enable input allow synchronized channel control without external logic.

It operates with a logic supply voltage up to 7 V and sustains 50 V across outputs under inductive load conditions. Propagation delay is 20 µs (high-to-low and low-to-high) at 25 °C with 600 mA load, supporting reliable timing in relay-driving circuits.

Key Specifications

Pinout & Package

Available in Powerdip (12+2+2) and SO20L packages. The Powerdip variant has 16 pins with two isolated 2-pin auxiliary terminals (likely for GND/heat sink tab); SO20L is a 20-lead small-outline package.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar quad transistor switch applications.

Compared with ULN2803A, L9222 offers higher per-channel current (1.2 A vs. 0.5 A) and a dedicated enable pin for synchronized shutdown. Compared with TB6549FG, it provides simpler, lower-cost unidirectional switching without overhead of H-bridge control or communication interfaces.

Availability

L9222 is available at Aetrix Electronics and suitable for industrial relay control, solenoid actuation, unipolar stepper motor driving, and LED array management requiring stable component supply and long-term BOM continuity.

Supply support for L9222 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 power management, analog, microcontrollers, and automotive-grade ICs.

The L9222 belongs to ST's high-voltage industrial driver product line, engineered specifically for robust, cost-effective switching of inductive loads in factory automation, building controls, and electro-mechanical systems.

FAQ

What is the maximum continuous output current per channel for L9222?

The L9222 supports 1.2 A maximum output current per channel under specified conditions: V_IN = 0.4 V, R_LOAD = 10 Ω, V_S = 13 V, and T_j ≤ 125 °C. Derating is required above 25 °C ambient due to R_{th j-amb} = 90 °C/W; at 70 °C ambient, continuous current drops to approximately 0.75 A per channel with no heatsink.

Can L9222 outputs be paralleled to increase current capacity?

Yes - the datasheet explicitly states "The switches of the same device may be paralleled." This allows combining two or more channels to drive a single load requiring >1.2 A, provided layout symmetry and thermal balance are maintained. Total current remains limited by package thermal resistance and total power dissipation (P_D = ΣI_OUT × V_CE(sat)).

Does L9222 require external flyback diodes when driving relays?

No. Each output includes an integral clamp diode with 2.0 V forward voltage at 1.2 A. These diodes provide complete flyback energy recirculation for inductive loads, eliminating the need for external diodes in standard relay, solenoid, or stepper motor applications.

What is the function of the auxiliary pins (12–15) in the Powerdip (12+2+2) package?

In the Powerdip (12+2+2) variant, pins 12–15 are isolated GND/thermal pads - not electrically connected to internal circuitry. They serve mechanical anchoring and thermal conduction: soldering them to a large copper pour improves heat dissipation and board-level reliability, especially under sustained 1 A loads.