NXP Semiconductors TDA3681J/N2C,112

Overview

TDA3681J/N2C,112 from NXP Semiconductors (formerly Philips) is a 4-output automotive voltage regulator IC with integrated power switch and ignition buffer, designed for car radio systems. It delivers regulated outputs of 8.5 V/600 mA (REG1), 5.0 V/300 mA (REG2), 5.0 V/1400 mA (REG3), 3.3 V/1 A (REG4), and features load dump protection up to 50 V, reverse polarity safety down to −18 V, and thermal shutdown at 150 °C.

For engineers reviewing the TDA3681J/N2C,112 datasheet, TDA3681J/N2C,112 pinout, TDA3681J/N2C,112 application, or TDA3681J/N2C,112 equivalent, this page provides verified functional specifications, validated pin assignments for DBS17P package, confirmed automotive-grade protections, and real-world design implications for microcontroller-supplied infotainment systems.

Technical Context

The TDA3681J/N2C,112 integrates four independent linear regulators with foldback current limiting, a protected high-current power switch (1.8 A continuous, 3 A peak), and a Schmitt-triggered ignition buffer with push-pull output. Regulators 1, 3, and 4 are VP-state controlled and share a combined enable input (EN1/3), while REG2 remains active during load dump and thermal shutdown to sustain microcontroller operation.

It employs dual supply inputs (VP1 and VP2): VP1 powers REG1, REG2, and the power switch; VP2 (≥6.5 V) supplies REG3 and REG4 to reduce dissipation. The HOLD output (open-collector, active LOW) aggregates fault conditions-including low VP, regulator undervoltage, thermal overload, and load dump-via internal OR logic with hysteresis.

Key Specifications

Pinout & Package

Package: DBS17P - plastic DIL-bent-SIL power package, 17-lead, lead length 7.7 mm (SOT243-3). Heat tab internally connected to GND (pin 13).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar multiple-output automotive regulator applications.

Compared with TLF35584QVVS1 and MAX16922ATP+, the TDA3681J/N2C,112 uniquely combines an 8.5 V analog supply rail, 1400 mA 5 V output, integrated power switch, and vehicle-ignition interface - making it irreplaceable in cost-sensitive, non-ASIL car radio platforms requiring full feature integration.

Availability

TDA3681J/N2C,112 is available at Aetrix Electronics and suitable for automotive infotainment, telematics control units, and premium audio amplifier power management requiring stable component supply across extended temperature (−40 °C to +85 °C), high-transient immunity, and long-lifecycle support.

Supply support for TDA3681J/N2C,112 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

NXP Semiconductors, formerly Philips Semiconductors, is a global leader in automotive and industrial semiconductors, with deep expertise in power management and automotive-grade reliability.

The TDA3681J/N2C,112 belongs to NXP's legacy automotive power management portfolio, specifically engineered for cost-optimized, high-reliability car radio and infotainment systems requiring multi-rail regulation, transient robustness, and vehicle-bus interface integration.

FAQ

What is the maximum continuous current capability of the power switch in TDA3681J/N2C,112?

The power switch in TDA3681J/N2C,112 delivers 1.8 A continuously when VP1 ≤ 16 V and V_SW = 13.5 V. At VP1 ≥ 17 V, clamping limits output to 16 V, and continuous current is reduced to maintain safe power dissipation. Peak current reaches 3 A for short durations before foldback activation, as confirmed in the Quick Reference Data table on page 3 of the datasheet.

How does the HOLD output behave when REG1 is disabled but REG3 and REG4 remain active in TDA3681J/N2C,112?

When REG1 is disabled via EN1/3, its internal hold-triggering circuit is deactivated, so undervoltage on REG1 does not assert HOLD. However, HOLD remains HIGH only if REG3 and REG4 are both in regulation, VP1 is ≥9.4 V (hysteresis), and no thermal or load dump event is active. If either REG3 or REG4 drops out of regulation, HOLD goes LOW - confirming per Fig.5 block diagram and Functional Description section on page 8.

Can TDA3681J/N2C,112 operate with VP2 disconnected while powering REG3 and REG4?

No. REG3 and REG4 require VP2 to be connected and ≥6.5 V to function - their internal pass transistors are sourced from VP2, not VP1. Disconnecting VP2 forces REG3 and REG4 outputs to collapse, triggering HOLD if enabled. This dependency is explicitly stated in the General Description (page 2) and confirmed in the Pinning table (page 6) where VP2 is labeled "second supply voltage" for REG3/REG4.

What is the purpose of the BU (backup) pin in TDA3681J/N2C,112, and how is it used in practice?

The BU pin provides a switched path to supply REG2 from an external backup capacitor during VP1 dropout. When VP1 falls below ~4.5 V, BU connects the capacitor to REG2, sustaining 5 V output for tens to hundreds of milliseconds depending on capacitor size (≥100 µF recommended). This enables microcontroller-controlled safe shutdown - a key requirement verified in the Functional Description (page 8) and Test Circuit Fig.10 (page 19).

Does TDA3681J/N2C,112 support simultaneous enable of all four regulators, and what are the sequencing constraints?

TDA3681J/N2C,112 does not support simultaneous enable of all four regulators via a single pin: REG1 and REG3 share EN1/3; REG4 uses EN4; REG2 is always active when VP1 ≥ 4 V. Sequencing must follow functional dependencies - e.g., REG2 must stabilize first to release RES before enabling REG1/REG3, as described in the Functional Description (page 8) and timing diagrams (Fig.6–7). No internal hardware sequencing logic exists.