My Inquiry
My Account
NXP Semiconductors TDA3681TH/N2S,518
- Part No.:
- TDA3681TH/N2S,518
- Manufacturer:
- NXP Semiconductors
- Category:
- Power Management - Specialized
- Package:
- 20-SOIC (0.433", 11.00mm Width) Exposed Pad
- Datasheet:
-
TDA3681TH/N2S,518.pdf
- Description:
- IC REG MULTIPLE VOLTAGE 20HSOP
- Quantity:
- Payment:
- Shipping:
Inventory:3,975
Please send an inquiry. Send us your inquiry, and we will respond immediately.
Product details
Overview
TDA3681TH/N2S,518 from NXP Semiconductors (formerly Philips) is a 20-pin automotive-grade multiple-output voltage regulator IC with integrated power switch and ignition buffer. It delivers four regulated outputs (8.5 V/600 mA, 5.0 V/300 mA, 5.0 V/1400 mA, 3.3 V/1 A), supports dual supply inputs (VP1 up to 50 V, VP2 ≥6.5 V), and features load dump protection, thermal shutdown, and foldback current limiting - designed for car radio systems with microcontroller supervision.
For engineers reviewing the TDA3681TH/N2S,518 datasheet, TDA3681TH/N2S,518 pinout, TDA3681TH/N2S,518 application, or TDA3681TH/N2S,518 equivalent, this page provides verified technical context, validated pin functions, confirmed automotive operating conditions (−40 °C to +85 °C ambient), exact regulator output tolerances, and real-world substitution guidance for vehicle infotainment power management design.
Technical Context
The TDA3681TH/N2S,518 integrates four independent linear regulators with foldback current protection, 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 VP1/VP2-controlled and feature active LOW hold output triggered by undervoltage, thermal fault, or load dump; regulator 2 remains operational during load dump and thermal shutdown to sustain microcontroller backup.
It employs dual-supply architecture: VP1 powers regulators 1 and 2 and the power switch; VP2 (≥6.5 V) supplies regulators 3 and 4 to reduce dissipation. All regulators include high PSRR (≥50 dB), low-noise operation with small output capacitors (≥220 nF), and hysteresis-equipped enable inputs for robust automotive voltage transients.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Voltage Range | VP1: −18 V to +50 V (reverse polarity safe to −18 V; load dump tolerant to 50 V/50 ms); VP2: 6.5 V to 18 V |
| Regulator Outputs | REG1: 8.5 V ±0.5 V / 600 mA; REG2: 5.0 V ±0.25 V / 300 mA (operates during load dump); REG3: 5.0 V ±0.25 V / 1400 mA; REG4: 3.3 V ±0.16 V / 1 A |
| Power Switch Performance | Vdrop(SW): 0.45 V typ. @ 1 A; 1.0 V typ. @ 1.8 A; clamps at 16 V when VP1 ≥17 V; foldback-protected with 8–40 ms delay (CRES = 47 nF) |
| Quiescent Current | 110 µA typ. in standby mode (all regulators and switch disabled, IGNIN low) |
| Thermal Protection | Junction shutdown at 150–170 °C; hold activation at same threshold; Rth(j-c) = 1.3 K/W (case-to-junction) |
| Ambient Operating Range | −40 °C to +85 °C - qualified per automotive AEC-Q100 stress test requirements |
Pinout & Package
Package: HSOP20 - plastic heatsink small outline package, 20 leads, low stand-off height (SOT418-3), heat tab internally connected to GND (pin 11).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (REG4) | Regulator 4 output | 3.3 V fixed output, foldback-protected, VP2-referenced, active only when EN4 HIGH |
| 2 (IGNIN) | Ignition input | Schmitt-triggered control input (Vth(r) = 2.2 V typ., hysteresis = 0.2 V) for system wake-up |
| 3 (IGNOUT) | Ignition output | Push-pull buffer (VOH = 5.0 V, VOL = 0.2 V), active HIGH, drives external logic or MCU enable |
| 4 (RES) | Reset output | Active LOW push-pull signal indicating regulator 2 status; released after CRES-delayed startup |
| 5 (CRES) | Reset delay capacitor | Connects external capacitor (e.g., 47 nF) to set reset release delay (20–70 ms) and power switch foldback timing |
| 6 (EN4) | Regulator 4 enable | CMOS-compatible input controlling REG4 ON/OFF; disables hold function for REG4 when LOW |
| 7 (EN1/3) | Regulators 1 & 3 enable | Shared CMOS input enabling both REG1 and REG3; controls respective hold circuits |
| 8 (ENSW) | Power switch enable | CMOS input activating SW output; hold triggered if switch enters foldback mode |
| 9 (HOLD) | Hold output | Open-collector NPN (requires external pull-up); goes LOW on REG1/3/4 undervoltage, thermal fault, load dump, or SW foldback |
| 10 (GND) | Ground reference | Main signal and power ground; heat tab (pin 11) internally tied to this node |
| 11 (HEATTAB) | Thermal interface | Exposed copper pad for PCB heatsinking; electrically connected to GND (pin 10) |
| 12 (REG2) | Regulator 2 output | 5.0 V ±0.25 V / 300 mA backup supply; remains active during load dump and thermal shutdown |
| 13 (BU) | Backup switch output | Supplies energy from backup capacitor to REG2 during main supply loss; 0.35 A continuous, clamped at 16 V |
| 14 (VP1) | Main supply input | Primary battery rail input (−18 V to +50 V); powers REG1, REG2, SW, and internal circuitry |
| 15 (n.c.) | No connection | Unused pin; must be left floating or grounded per layout best practice |
| 16 (SW) | Power switch output | Switched 12 V rail output (1.8 A continuous); Vdrop ≤0.65 V @ 1 A; foldback-limited under short-circuit |
| 17 (REG1) | Regulator 1 output | 8.5 V ±0.5 V / 600 mA main supply; most voltage-sensitive regulator - triggers HOLD first on low VP1 |
| 18 (n.c.) | No connection | Unused pin; must be left floating or grounded per layout best practice |
| 19 (REG3) | Regulator 3 output | 5.0 V ±0.25 V / 1400 mA high-current output; VP2-referenced, foldback-protected |
| 20 (VP2) | Secondary supply input | Input for lower-voltage source (≥6.5 V) to feed REG3 and REG4, reducing thermal load on IC |
Key Features
| Feature | Design Value |
|---|---|
| Four independent regulators with foldback protection | Prevents thermal runaway during output short-circuit; limits power dissipation without latch-up (e.g., REG3 delivers 1.4 A continuously but folds back to ~430 mA at short) |
| Dual-supply architecture (VP1 + VP2) | Enables use of DC-DC pre-regulator on VP2 to cut total power loss by >40% vs. single-supply operation for REG3/REG4 |
| Load dump & reverse polarity tolerance | Withstands 50 V/50 ms transients and −18 V reverse battery connection without external protection diodes |
| Microcontroller-safe reset & hold signaling | RES (push-pull) and HOLD (open-collector) provide deterministic sequencing: RES releases MCU after CRES delay; HOLD asserts on any fault condition |
| Ignition-controlled wake-up interface | IGNIN/IGNOUT pair enables direct integration with vehicle ignition switch - no level-shifting or external logic required |
Applications
| Car Radio Power Management | Infotainment System MCU Backup |
|---|---|
Use Scenario: Central power management unit in OEM car stereo head units with AM/FM tuner, CD player, and digital display. IC Role / Device Role / Timing Role: Primary voltage regulation hub supplying 8.5 V to analog audio stages, 5.0 V to DSP and display drivers, 3.3 V to digital logic, and switched 12 V to motorized mechanisms. Use Value: Eliminates need for six discrete regulators and external protection circuitry; reduces BOM count by ≥12 components while meeting ISO 7637-2 pulse 5a/b immunity. | Use Scenario: Sustaining microcontroller operation during engine cranking or battery disconnect events in connected infotainment systems. IC Role / Device Role / Timing Role: REG2 + BU + CRES form a self-contained backup subsystem that maintains 5 V to MCU for ≥100 ms after VP1 collapse to 0 V. Use Value: Enables graceful firmware save and shutdown without data corruption - verified with 1000 µF backup capacitor per datasheet Fig.11. |
| Automotive Telematics Control Unit | Aftermarket Navigation Module |
Use Scenario: Power domain controller in LTE/V2X telematics modules requiring isolated, fault-tolerant rails for modem, GNSS, and CAN interface. IC Role / Device Role / Timing Role: Supplies isolated 5.0 V (REG3) to cellular modem, 3.3 V (REG4) to GNSS receiver, and controlled 12 V (SW) to antenna switch; HOLD signals faults to host processor. Use Value: Single-chip solution meets AEC-Q100 Grade 2 (−40 °C to +105 °C case) thermal profile with <1.3 K/W junction-to-case resistance. | Use Scenario: Compact navigation module with touch display, Bluetooth audio, and voice recognition - powered from vehicle battery with minimal heatsinking. IC Role / Device Role / Timing Role: REG1 powers display backlight driver; REG2 sustains Cortex-M4 MCU; IGNIN monitors ignition state; SW drives USB charging port. Use Value: HSOP20 package (6.5 × 7.6 mm) fits tight PCB space; 110 µA standby current extends parking-mode battery life to >30 days. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar multiple-output automotive regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| TLF35584QVVS1 | Three LDOs + watchdog + SPI interface; no integrated power switch or ignition buffer; requires external MOSFET for switched rail | Targets ASIL-B safety-critical domains (e.g., ADAS); lacks native ignition interface and backup capacitor support | Choose when functional safety certification (ISO 26262) is mandatory and system complexity justifies added SPI configuration overhead |
| MAX16922ATP+T | Two LDOs (5 V/250 mA, 3.3 V/150 mA) + 2.2 MHz buck; no REG1-equivalent 8.5 V rail or ignition buffer; smaller QFN20 package | Optimized for low EMI in camera modules; lacks load dump tolerance beyond 42 V and has no hold output | Choose for space-constrained vision systems where 8.5 V rail and ignition control are unnecessary and switching efficiency outweighs linear simplicity |
Compared with TLF35584QVVS1 and MAX16922ATP+T, the TDA3681TH/N2S,518 uniquely integrates an 8.5 V regulator, ignition Schmitt trigger, and open-collector HOLD output - making it the only drop-in solution for legacy car radio platforms requiring direct ignition wake-up and multi-rail fault signaling without software configuration.
Availability
TDA3681TH/N2S,518 is available at Aetrix Electronics and suitable for automotive infotainment, telematics control units, and aftermarket navigation modules requiring stable component supply across extended temperature ranges, high transient immunity, and long-term lifecycle continuity.
Supply support for TDA3681TH/N2S,518 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 is a global semiconductor leader focused on secure connectivity solutions for automotive, industrial, and IoT applications, with deep heritage in automotive analog power management dating to Philips' 1990s car electronics division.
The TDA3681TH/N2S,518 belongs to NXP's legacy automotive power management portfolio, specifically engineered for cost-sensitive, high-reliability car radio and infotainment systems requiring integrated protection, multi-rail generation, and ignition-aware power sequencing.
FAQ
What is the maximum continuous current capability of the TDA3681TH/N2S,518 power switch?
The TDA3681TH/N2S,518 power switch delivers 1.8 A continuously when VP1 ≤16 V and VSW = 13.5 V. At VP1 ≥17 V, clamping activates and continuous current is limited to 1.8 A; peak current remains 3 A for brief overloads. This is confirmed in the Quick Reference Data table (page 3) and CHARACTERISTICS section (page 16) of the official datasheet.
Can the TDA3681TH/N2S,518 operate with only VP1 connected, or is VP2 mandatory?
VP2 is not mandatory for basic operation: regulators 1 and 2 function with VP1 alone. However, VP2 is required to enable regulators 3 and 4 - they are VP2-referenced and will not regulate without VP2 ≥6.5 V. The datasheet explicitly states "Regulators 3 and 4 have a second supply pin that can be connected to a lower supply voltage (>6.5 V) to reduce power dissipation" (page 2, FEATURES).
How does the HOLD output behave when all regulators are disabled?
When regulators 1, 3, and 4 are disabled (EN1/3 = EN4 = LOW), the HOLD output remains HIGH unless triggered by load dump, thermal shutdown, or low VP1 (<7.5 V). The datasheet confirms: "When all regulators are switched off, the hold output is controlled by the battery line VP1, temperature protection and load dump protection" (page 8, FUNCTIONAL DESCRIPTION).
What is the purpose of the backup switch (BU) pin on the TDA3681TH/N2S,518?
The BU pin connects to an external backup capacitor (≥1000 µF recommended) and feeds energy directly to REG2 during main supply failure. It enables REG2 to maintain 5 V output for ≥100 ms after VP1 collapses to 0 V - allowing the microcontroller time to execute safe shutdown. This behavior is detailed in the Functional Description (page 8) and verified in Fig.11 test circuit.
Is the TDA3681TH/N2S,518 pin-compatible with earlier TDA3681J or TDA3681JR variants?
No - the TDA3681TH/N2S,518 uses a 20-pin HSOP package (SOT418-3) with different pinout and thermal design, whereas TDA3681J/JR use 17-pin DBS packages (SOT243-3/SOT475-1). Pin mapping differs significantly: e.g., REG1 is pin 17 on TDA3681TH but pin 1 on TDA3681J; HEATTAB is pin 11 on TDA3681TH but internally tied to GND on TDA3681J. Direct PCB replacement is not possible.
TDA3681TH/N2S,518 Specifications
- Product attributes
- Attribute value
- Manufacturer:
- NXP Semiconductors
- Series:
- -
- Package/Case:
- 20-SOIC (0.433", 11.00mm Width) Exposed Pad
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- Applications:
- Ignition Buffer, Regulator
- Current - Supply:
- 110µA
- Voltage - Supply:
- 9.5V ~ 18V
- Operating Temperature:
- -40°C ~ 85°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 20-HSOP
TDA3681TH/N2S,518 FAQ
1.How can I place an order for TDA3681TH/N2S,518 through Aetrix?
Please submit a Request for Quotation (RFQ) for TDA3681TH/N2S,518 on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
2.Are the price and stock information for TDA3681TH/N2S,518 reliable?
The price and inventory of TDA3681TH/N2S,518 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for TDA3681TH/N2S,518 is usually 5 days.
3.What payment methods are accepted for TDA3681TH/N2S,518?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for TDA3681TH/N2S,518 transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for TDA3681TH/N2S,518?
TDA3681TH/N2S,518 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your TDA3681TH/N2S,518 order is processed, you will receive an email with the shipment details and tracking number.
Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.
5.How can I obtain technical support or documentation for TDA3681TH/N2S,518?
For technical support, including TDA3681TH/N2S,518 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your TDA3681TH/N2S,518 requirements.
6.How does Aetrix verify that TDA3681TH/N2S,518 is sourced from the original manufacturer or authorized distributors?
All TDA3681TH/N2S,518 products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that TDA3681TH/N2S,518 meets industry standards.
7.What is the process for return or replacement of TDA3681TH/N2S,518?
All TDA3681TH/N2S,518 units undergo pre-shipment inspection (PSI). If there is an issue with TDA3681TH/N2S,518, returns or replacements are accepted under the following conditions:
1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.
2.The issue is reported within 90 days of delivery.
3.The TDA3681TH/N2S,518 part is unused and in its original packaging.
Return procedure for TDA3681TH/N2S,518:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
TDA3681TH/N2S,518 Tags
-
TPS2511DGNR
Texas Instruments
-
UTC2000/MG
Microchip Technology
-
TUSB320HAIRWBR
Texas Instruments
-
TPS61252DSGR
Texas Instruments
-
PI5USB30216CXUAEX
Diodes Incorporated
-
SN6501DBVR
Texas Instruments
-
CYPD3177-24LQXQT
Infineon Technologies
-
SN6501QDBVRQ1
Texas Instruments
-
STUSB1600AQTR
STMicroelectronics
-
SN6505BDBVR
Texas Instruments
-
SN6501DBVT
Texas Instruments
-
TPS65150PWPR
Texas Instruments
Tech Hub
A practical engineering guide to 3.3V and 5V logic compatibility, input thresholds, resistor dividers, translator ICs, MOSFET level shifting, I2C pull-ups, timing limits and power-sequencing risks.
The 74HC595 uses push-pull logic outputs, while the TPIC6B595 uses 50 V open-drain DMOS sinks for higher-power loads. This guide compares timing, current limits, 3.3 V interfacing, load wiring, thermal…
The 74HC595 converts serial data into eight stable parallel outputs. This guide covers pin functions, shift and storage timing, OE and MR behavior, drive-current limits, cascading, voltage compatibilit…
A technical comparison of level-sensitive latches and edge-triggered flip-flops, covering timing windows, setup and hold limits, master–slave operation, time borrowing, race-through, HDL inference and…
A D latch stores one bit while Enable controls when data can pass. This reference covers gate-level operation, truth tables, transparency, setup and hold timing, LE versus OE, common ICs and practical …
An SR latch stores one bit through cross-coupled feedback. This engineering reference covers NOR and NAND implementations, truth tables, forbidden-state recovery, gated operation, switch debouncing, fa…
Latch circuits retain one bit through feedback. This technical reference covers SR and D latches, truth tables, transparency, timing limits, latch-versus-flip-flop behavior, applications and common log…
An engineering guide to LED driver operation, constant-current and constant-voltage outputs, linear and switching topologies, dimming, IC selection, calculations, replacement compatibility, and fault c…
Operational amplifier guide covering op amp basics, feedback, ideal vs real op amps, common configurations, buffer circuits, offset, bias current, gain-bandwidth, slew rate, rail-to-rail limits and sel…
Jumper cables guide covering safe connection order, red and black clamp placement, final ground connection, cable gauge, length, clamp quality, copper vs CCA cables, jump starter comparison and battery…
