Texas Instruments TPS78408BQWDRBRQ1

Overview

TPS78408BQWDRBRQ1 from Texas Instruments is an AEC-Q100 Grade 1 automotive LDO voltage regulator delivering 300 mA output current with 0.5% typical output accuracy, 115-mV dropout at 300 mA (3.3 V_OUT), and 50-dB PSRR up to 100 kHz. It operates from 1.65 V to 6.0 V input and supports fixed 0.8-V output, enabling power supply for low-voltage analog rails in safety-critical vehicle systems.

For engineers reviewing the TPS78408BQWDRBRQ1 datasheet, TPS78408BQWDRBRQ1 pinout, TPS78408BQWDRBRQ1 application, or TPS78408BQWDRBRQ1 equivalent, key selection criteria include its ultra-low quiescent current (25 µA typ), active output discharge, functional safety documentation support, and wettable-flank VSON-8 packaging for automated optical inspection in automotive PCB assembly.

Technical Context

The TPS78408BQWDRBRQ1 integrates a precision bandgap reference, error amplifier, and foldback current-limit protection to maintain regulation under transient load steps and overcurrent conditions. Its internal 500-µs soft-start reduces inrush current and allows use of smaller input capacitance without compromising stability.

Designed for post-regulation in multi-rail automotive subsystems, it features enable-controlled sequencing, active pulldown on disable, and thermal shutdown with 170°C trip and 155°C reset hysteresis - all validated across –40°C to +125°C ambient (–40°C to +150°C junction).

Key Specifications

Pinout & Package

TPS78408BQWDRBRQ1 uses the wettable flank VSON-8 (DRB) package (3.00 mm × 3.00 mm), optimized for solder joint inspection and thermal performance (R_θJA = 61.8°C/W). The thermal pad is electrically connected to GND and must be soldered to a large ground plane.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar LDO regulator applications.

Compared with TPS7B8701QKVURQ1 and TLV73308PQDBVRQ1, the TPS78408BQWDRBRQ1 uniquely balances ultra-low dropout, active output discharge, and full functional safety support - making it optimal for ASIL-B-compliant 0.8-V core rail generation where both efficiency and fail-safe behavior are mandatory.

Availability

TPS78408BQWDRBRQ1 is available at Aetrix Electronics and suitable for automotive head units, hybrid instrument clusters, and telematics control units requiring stable component supply with full AEC-Q100 traceability and long-term production support.

Supply support for TPS78408BQWDRBRQ1 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 leader specializing in analog and embedded processing technologies, with deep expertise in automotive-grade power management solutions.

The TPS784-Q1 product line delivers high-accuracy, low-noise LDOs engineered specifically for ASIL-B automotive subsystems demanding robustness, low quiescent current, and functional safety compliance.

FAQ

What is the output voltage of the TPS78408BQWDRBRQ1?

The TPS78408BQWDRBRQ1 is a fixed-output LDO with a nominal output voltage of 0.8 V. This value is factory-trimmed and guaranteed across temperature and load conditions, with ±1.7% maximum deviation over –40°C to +150°C junction temperature. The 0.8-V rail is intended for powering low-voltage digital cores and I/O interfaces in modern automotive microcontrollers and SoCs.

Does the TPS78408BQWDRBRQ1 support automotive qualification standards?

Yes, the TPS78408BQWDRBRQ1 is AEC-Q100 qualified for Grade 1 operation (–40°C to +125°C ambient), with a junction temperature range of –40°C to +150°C. It also includes functional safety documentation - such as FIT rate, failure mode effects analysis (FMEA), and diagnostic coverage metrics - to support ISO 26262 ASIL-B system-level certification.

What package type does the TPS78408BQWDRBRQ1 use, and why is it significant?

The TPS78408BQWDRBRQ1 uses the wettable flank VSON-8 (DRB) package (3.00 mm × 3.00 mm). Its side-wettable flanks enable automated optical inspection (AOI) of solder joints - a critical requirement for zero-defect automotive manufacturing. The exposed thermal pad improves thermal resistance (R_θJB = 34.3°C/W) and supports reliable operation under sustained 300-mA loads.

How does the enable (EN) pin function on the TPS78408BQWDRBRQ1?

The EN pin on the TPS78408BQWDRBRQ1 is an active-high logic input. The device enables when EN ≥ 0.85 V and disables when EN ≤ 0.425 V. It must never be left floating; if unused, TI recommends connecting EN directly to IN. During disable, the TPS78408BQWDRBRQ1 activates its internal pulldown circuit (~120 Ω at 3.3 V) to discharge the output capacitor rapidly.

What is the dropout voltage specification for the TPS78408BQWDRBRQ1 at full load?

At 300 mA output current and 3.3 V output, the TPS78408BQWDRBRQ1 has a maximum dropout voltage of 115 mV. For its fixed 0.8-V output variant, dropout is specified at 900 mV (max) under the same 300-mA load - reflecting the higher relative voltage drop required to regulate very low output voltages. This value is measured at V_OUT = 0.95 × V_OUT(nom) and TJ = 25°C.