STMicroelectronics L6370QTR

Overview

L6370QTR from STMicroelectronics is a 2.5 A single high-side smart power switch in VFQFPN48 (7 × 7 mm) package, designed for industrial load switching with integrated current limiting, thermal shutdown, open-load detection, and dual diagnostic outputs. It operates from 9.5 V to 35 V supply, features R_DS(on) = 0.1 Ω, internal demagnetization clamping (V_demag = V_S − 50 V), and supports resistive, capacitive, and inductive loads in PLC I/O modules.

For engineers reviewing the L6370QTR datasheet, L6370QTR pinout, L6370QTR application, or L6370QTR equivalent, key selection criteria include its non-dissipative short-circuit protection (t_ON programmable via external capacitor), differential input stage with ±7 V common-mode range and 1.4 V offset, dual open-drain diagnostics (DIAG1/DIAG2), and IEC61000-4-4/4-5 transient immunity-critical for rugged industrial control designs.

Technical Context

The L6370QTR integrates a high-side NDMOS power switch with embedded charge-pump driver, current-sense resistor (R_SC), and analog diagnostic logic. Its differential input stage uses a 1.4 V internal offset and 400 mV hysteresis to reject noise in noisy industrial environments, while the ON-DELAY pin enables programmable t_ON (1.28 μs/pF, 2.56 ms to 64 ms) for inrush-tolerant capacitive/filament load driving.

Short-circuit response employs non-dissipative linear-mode current limiting at 3.2 A (typ.), followed by automatic off-time (t_OFF = 64 × t_ON) and retry cycling-avoiding thermal shutdown during sustained faults. Internal Zener clamping (V_CL = 48–58 V) enables fast inductive demagnetization without external diodes, and open-load detection triggers when output current falls below 3 mA (typ.) at V_IN+ > V_IN−.

Key Specifications

Pinout & Package

VFQFPN48 (7 mm × 7 mm × 1.0 mm) thermally enhanced QFN package with exposed thermal pad (pin 41 = GND) and 48 terminals. Pin 1–2, 10–11 are paralleled OUTPUT pins; pins 5–8 are paralleled VS inputs; pin 38 (OUTSTATUS) provides 2–4 mA LED drive current for visual status indication.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar high-side smart switch applications.

Compared with VND5E025AKTR-E and TPS27081AQPWPRQ1, the L6370QTR uniquely combines differential noise-immune inputs, programmable non-dissipative short-circuit recovery, and full IEC industrial transient immunity-making it the sole option for high-reliability PLC and CNC applications requiring both robustness and diagnostic precision.

Availability

L6370QTR is available at Aetrix Electronics and suitable for programmable logic controllers, industrial PC peripheral I/O, numerical control machines, and high-reliability load switching applications requiring stable component supply across extended product lifecycles.

Supply support for L6370QTR 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, and microcontroller solutions for industrial, automotive, and consumer markets.

The L6370QTR belongs to ST's VIPower™ M0-7 family of high-voltage intelligent power switches, engineered specifically for industrial automation systems demanding high integration, fault resilience, and long-term supply stability.

FAQ

What is the maximum safe operating junction temperature for the L6370QTR?

The L6370QTR features overtemperature protection triggered at a junction temperature threshold (Θ_lim) of 135 °C (typical), with 20 °C hysteresis. Operation above this point shuts off the output and asserts DIAG2 low. Thermal resistance junction-to-ambient is 50 °C/W on a 2-layer PCB with thermal vias-so at 2.5 A and 24 V, ambient must stay below ~75 °C for continuous use without forced cooling.

How does the ON-DELAY pin affect short-circuit behavior?

Connecting a capacitor (50 pF to 2 nF) between ON-DELAY and GND sets t_ON = 1.28 μs/pF, defining the duration the device sources 3.2 A during a ground fault before entering off-time (t_OFF = 64 × t_ON). Grounding ON-DELAY disables this feature, reverting to thermal shutdown-useful for testing but not recommended for production inductive loads.

Can the L6370QTR drive inductive loads without external components?

Yes-the L6370QTR integrates an internal Zener clamp (V_CL = 48–58 V) that safely absorbs demagnetization energy from inductive loads like solenoids and relays. This eliminates the need for external flyback diodes or RC snubbers, verified per IEC61000-4-5 surge testing up to 2 kV, and supports energy absorption up to 6.0 J at 125 °C.

What diagnostic conditions are reported by DIAG1 and DIAG2?

DIAG1 and DIAG2 jointly encode six conditions via their logic levels: normal operation, open load (I_OUT < 3 mA), short-to-V_S, short-to-ground, overtemperature, and undervoltage. Table 7 in the datasheet defines all combinations-e.g., DIAG1 = low + DIAG2 = low indicates undervoltage, while DIAG1 = high + DIAG2 = low signals short-to-ground with ON-DELAY grounded.