STMicroelectronics L604C

Overview

L604C from STMicroelectronics is an 8-channel high-voltage Darlington array with open-collector outputs, designed for interfacing CMOS logic (6–15 V) to inductive and resistive loads. Each channel delivers 400 mA continuous / 500 mA peak output current, supports 90 V V_CEX, and integrates clamp diodes. It is used in relay drivers, thermal printheads, and DC motor control in industrial control panels.

For engineers reviewing the L604C datasheet, L604C pinout, L604C application, or L604C equivalent, key selection factors include verified V_CE(sat) at 300 mA (2.0 V max), input voltage thresholds (ON ≤5 V, OFF ≥1 V), thermal resistance (70 °C/W), and DIP18 layout compatibility with opposite-pin input/output configuration.

Technical Context

The L604C implements eight independent NPN Darlington pairs with common-emitter outputs and integrated reverse-biased clamp diodes across each collector-emitter path. Input logic compatibility is defined by CMOS-level thresholds: VI(ON) ≤5 V and VI(OFF) ≥1 V at V_CE = 90 V.

Each channel operates with a guaranteed V_CE(sat) of ≤2.0 V at I_C = 300 mA and I_B = 500 µA, and exhibits I_EX ≤10 µA at V_CE = 90 V. Turn-on/turn-off delays are both ≤0.4 µs under specified load conditions.

Key Specifications

Pinout & Package

Package: 18-pin dual in-line package (DIP18), 0.3" wide, with through-hole mounting and standard 2.54 mm pitch. Pin 1 marked by notch or dot; pin numbering counterclockwise from top-left corner.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar Darlington array applications.

Compared with ULN2803A and TB6549FG, the L604C uniquely combines 90 V blocking, DIP18 through-hole compatibility, and native 6–15 V CMOS input support-making it optimal for legacy industrial boards upgrading from L603 while retaining 12 V logic interfaces.

Availability

L604C is available at Aetrix Electronics and suitable for industrial relay control, thermal printhead driving, and DC motor actuation requiring stable component supply across long-lifecycle equipment programs.

Supply support for L604C 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, designing and manufacturing analog, power, MCU, and sensor solutions for industrial, automotive, and consumer markets.

The L603/L604 series belongs to ST's legacy high-voltage interface portfolio, engineered specifically for robust electromechanical load control in harsh industrial environments with minimal external components.

FAQ

What is the maximum safe operating temperature for the L604C junction?

The absolute maximum junction temperature is 150 °C. Operation above 125 °C requires derating total power dissipation below 1.8 W using the 70 °C/W thermal resistance. Ambient temperature must be monitored in sealed enclosures, and heatsinking is recommended when >4 channels operate continuously above 200 mA.

Can L604C outputs be paralleled, and what design precautions apply?

Yes-outputs may be paralleled to increase current capacity. Ensure matched trace lengths and identical external load connections to avoid current imbalance. Derate total package power by 15% per additional paralleled channel beyond two, and verify V_CE(sat) matching across units if operating near 500 mA peak.

Does the L604C require external base resistors for CMOS input drive?

No-internal base resistor networks (7.2 kΩ + 3 kΩ per channel) are integrated. Direct connection to 6–15 V CMOS outputs is supported without external components. Input current draw is ~0.7 mA at 12 V, enabling direct drive from microcontroller GPIOs with sufficient sink capability.

How does the L604C's clamp diode differ from a standard external flyback diode?

The integrated diode connects cathode to V_CC and anode to collector, providing bidirectional clamping during inductive turn-off. Unlike discrete diodes, it shares thermal coupling with the Darlington junction, ensuring coordinated thermal response and eliminating solder joint reliability risks associated with discrete placements.