Texas Instruments LM74500QDDFRQ1

Overview

LM74500QDDFRQ1 from Texas Instruments is an AEC-Q100 Grade 1 automotive reverse polarity protection controller that operates with an external N-channel MOSFET to provide low-loss input protection for 12-V, 24-V, and 48-V battery systems. It supports 3.2-V cold-crank startup, withstands –65-V reverse input voltage, delivers 15-V gate drive via integrated charge pump, and draws only 1 µA in shutdown mode - enabling robust protection in body control modules and infotainment power rails.

For engineers reviewing the LM74500QDDFRQ1 datasheet, LM74500QDDFRQ1 pinout, LM74500QDDFRQ1 application, or LM74500QDDFRQ1 equivalent, key selection criteria include its –65-V reverse voltage rating, 3.2-V minimum operating voltage, 80-µA typical quiescent current, SOT-23-8 package compatibility, and absence of reverse current blocking - critical for inductive load paths where regenerative energy must flow back to the battery.

Technical Context

The LM74500QDDFRQ1 implements a charge-pump–based gate driver architecture to bias the gate of an external N-channel MOSFET above SOURCE, achieving full enhancement down to 3.2 V. Its enable logic and VCAP UVLO (6.5 V release, 5.4 V falling threshold) coordinate gate activation only after stable charge pump voltage is established and EN exceeds 1.06 V.

It operates in two functional modes: shutdown (EN < 0.9 V, 1 µA IQ, GATE tied to SOURCE) and conduction (EN > 1.06 V, VCAP > 6.5 V, GATE driven to VCAP). The device lacks reverse-current blocking - intentionally designed for loads like wiper motors or relays that require freewheeling paths during turn-off to prevent voltage overshoot.

Key Specifications

Pinout & Package

LM74500QDDFRQ1 is housed in an 8-pin SOT-23 (DDF) package measuring 2.90 mm × 1.60 mm, optimized for space-constrained automotive PCBs. Thermal resistance R_θJA = 133.8°C/W supports operation up to +125°C ambient.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar reverse polarity protection applications.

Compared with LM74700QDBVRQ1 and TPS26600PWPR, the LM74500QDDFRQ1 uniquely combines –65-V reverse tolerance, 3.2-V cold-crank operation, and intentional lack of reverse-current blocking - making it the only qualified solution for BCM load-driving paths with inductive freewheeling requirements.

Availability

LM74500QDDFRQ1 is available at Aetrix Electronics and suitable for automotive body electronics, infotainment systems, and industrial PLC power inputs requiring stable component supply across extended temperature and transient-voltage conditions.

Supply support for LM74500QDDFRQ1 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

Texas Instruments is a global semiconductor company delivering analog and embedded processing solutions for automotive, industrial, personal electronics, and communications markets.

The LM74500-Q1 belongs to TI's automotive-grade power protection controller family, engineered specifically for reverse polarity protection in inductive-load applications where freewheeling current must be preserved - such as body control modules and motor-driven subsystems.

FAQ

What is the minimum input voltage required for LM74500QDDFRQ1 to start up and enable the gate driver?

The LM74500QDDFRQ1 has a power-on reset (POR) rising threshold of 3.9 V on the SOURCE pin, meaning it begins initialization and enables the charge pump only when SOURCE voltage exceeds 3.9 V. However, the device remains functional down to 3.2 V once enabled - supporting severe cold-crank conditions common in automotive systems. This 3.2-V operational floor is confirmed in Section 6.5 of the datasheet under VSOURCE operating input voltage.

Does LM74500QDDFRQ1 provide reverse current blocking, and why does it matter for my design?

No, LM74500QDDFRQ1 does not provide reverse current blocking. It is intentionally designed to allow current flow from output to input (e.g., from a wiper motor back to the battery) during turn-off. This prevents destructive voltage overshoot caused by inductive kickback - a critical requirement for BCM load-driving paths. If reverse-current blocking is needed (e.g., for protecting downstream DC/DC converters), LM74700QDBVRQ1 is the appropriate alternative.

Can I connect the EN pin directly to the SOURCE pin on LM74500QDDFRQ1, and what effect does that have?

Yes, the EN pin of LM74500QDDFRQ1 can be directly connected to the SOURCE pin. Because EN tolerates –65 V to +65 V and has an internal 3-µA sink current, tying it to SOURCE forces EN ≥ V_{EN_IH} (≥1.06 V) whenever SOURCE is powered - resulting in always-on operation. This eliminates the need for an external enable signal and simplifies schematics in applications requiring continuous protection.

What external components are mandatory for proper operation of LM74500QDDFRQ1?

Three external components are mandatory: (1) a 0.1-µF ceramic capacitor between VCAP and SOURCE pins for charge pump operation; (2) an N-channel MOSFET with V_GS rating ≥15 V and V_DS rating ≤60 V; and (3) a gate resistor (optional but recommended for EMI control). While a TVS diode is not required for basic functionality, TI recommends one for ISO 7637-2 Pulse 1 compliance in automotive environments.

How does LM74500QDDFRQ1 compare to a discrete P-channel MOSFET solution for reverse polarity protection?

LM74500QDDFRQ1 paired with an N-channel MOSFET delivers significantly lower conduction loss than a P-FET solution - especially below 4 V - because N-FETs offer lower R_DS(ON) and maintain enhancement down to 3.2 V. It also reduces solution size by ~75% (37.1 mm² vs. 140 mm²) and eliminates gate-bias complexity. Unlike self-biased P-FETs, LM74500QDDFRQ1 provides controlled gate timing and thermal-safe shutdown.