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NXP Semiconductors TDA3681ATH/N1C,518
- Part No.:
- TDA3681ATH/N1C,518
- Manufacturer:
- NXP Semiconductors
- Category:
- Power Management - Specialized
- Package:
- 20-SOIC (0.433", 11.00mm Width) Exposed Pad
- Datasheet:
-
TDA3681ATH/N1C,518.pdf
- Description:
- IC VOLT REG W/SW & IGNIT 20-HSOP
- Quantity:
- Payment:
- Shipping:
Inventory:4,243
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Product details
Overview
TDA3681ATH/N1C,518 from NXP Semiconductors (formerly Philips) is a quad-output automotive voltage regulator IC with integrated power switch and ignition buffer, designed for car radio systems with microcontroller supervision. It delivers regulated 8.5 V (600 mA), 5.0 V (300 mA), 5.0 V (1400 mA), and 3.3 V (1 A) outputs, supports −18 V to +50 V supply range, and operates during load dump and thermal shutdown.
For engineers reviewing the TDA3681ATH/N1C,518 datasheet, TDA3681ATH/N1C,518 pinout, TDA3681ATH/N1C,518 application, or TDA3681ATH/N1C,518 equivalent, key selection criteria include its VP1/VP2 dual-supply architecture, foldback current protection across all regulators, hold/reset timing behavior under low-battery conditions, and ignition Schmitt trigger interface compatibility with automotive microcontrollers.
Technical Context
The TDA3681ATH/N1C,518 integrates four independent linear regulators with separate enable control logic: regulators 1 and 3 share EN1/3, regulator 4 uses EN4, and the power switch uses ENSW. Regulator 2 remains active during load dump (up to 50 V, 50 ms) and thermal shutdown (Tj ≥150 °C), enabling safe microcontroller reset sequencing.
Its protection architecture includes reverse-polarity tolerance (−18 V), load dump clamping (50 V), foldback current limiting on all regulators, delayed second-stage current limit on the power switch (triggered by CRES), and hysteresis-equipped hold output activated at VP1 <9.7 V (falling) and <9.1 V (rising).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Supply Range | VP1: −18 V to +50 V (load dump tolerant); VP2: 0–50 V (≥6.5 V required for REG3/REG4 operation) |
| Regulator Outputs | REG1: 8.5 V ±0.5 V / 600 mA; REG2: 5.0 V ±0.25 V / 300 mA (active during load dump); REG3: 5.0 V ±0.25 V / 1400 mA; REG4: 3.3 V ±0.16 V / 1 A |
| Power Switch | Vdrop = 0.45 V @ 1 A; Ipeak = 3 A (delayed foldback); clamped at 16 V when VP1 ≥17 V |
| Quiescent Current | 110 µA typical in standby mode (all regulators and switch disabled, IGNIN low) |
| Thermal Protection | Thermal shutdown at Tj = 150–170 °C; hold activation at same threshold for battery backup coordination |
| Ignition Interface | IGNIN Schmitt trigger: Vth(r) = 2.2 V, Vth(f) = 2.0 V; IGNOUT push-pull: VOH = 5.0 V, VOL = 0.2 V @ 0.8 mA |
Pinout & Package
Package: HSOP20 (SOT418-3), plastic heatsink small outline package with 20 leads and low stand-off height; heat tab (pin 11) must be connected to ground per datasheet note.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| REG4 (1) | Regulator 4 output | 3.3 V fixed output, foldback-protected, enabled by EN4 |
| IGNIN (2) | Ignition input | Schmitt-triggered control signal (1.9–2.5 V rising threshold) for system wake-up |
| IGNOUT (3) | Ignition output | Push-pull buffer driving external ignition logic; active HIGH, 5 V compatible |
| RES (4) | Reset output | Active LOW open-collector output; released after CRES-delayed startup of REG2 |
| CRES (5) | Reset delay capacitor | External capacitor (e.g., 47 nF) sets td(RES) = 20–70 ms and enables delayed power switch foldback |
| EN4 (6) | Regulator 4 enable | Separate TTL/CMOS-compatible input controlling REG4 only |
| EN1/3 (7) | Regulators 1 & 3 enable | Shared control pin for 8.5 V and second 5.0 V regulators |
| ENSW (8) | Power switch enable | Dedicated input for 3 A peak switch; foldback delay tied to CRES |
| HOLD (9) | Hold output | Active LOW open-collector signal indicating low VP1, thermal fault, or load dump |
| GND (10) | Ground reference | Main system ground; heat tab (pin 11) must connect directly to GND |
| HEATTAB (11) | Thermal interface | Exposed metal pad for PCB copper pour; critical for Rth(j-c) = 2 K/W thermal performance |
| REG2 (12) | Microcontroller supply | 5.0 V output remaining active during load dump and thermal events; backup capacitor supported |
| BU (13) | Backup switch output | Enables energy transfer from backup capacitor to REG2 during VP1 collapse |
| VP1 (14) | Main supply input | Primary battery rail (−18 V to +50 V); powers REG1, REG2, SW, and protection circuits |
| n.c. (15) | No connection | Internally unused; leave unconnected or tie to GND per layout best practice |
| SW (16) | Power switch output | High-current switched output (3 A peak); clamped at 16 V above 17 V VP1 |
| REG1 (17) | 8.5 V regulator output | Highest-voltage output (600 mA); most sensitive to VP1 drop; monitored by HOLD circuit |
| n.c. (18) | No connection | Internally unused; leave unconnected |
| REG3 (19) | Second 5.0 V regulator | 1400 mA output powered from VP2; used for high-current peripherals |
| VP2 (20) | Secondary supply input | Optional lower-voltage rail (≥6.5 V) feeding REG3 and REG4 to reduce dissipation |
Key Features
| Feature | Design Value |
|---|---|
| Quad-regulator integration | Four independent LDOs (8.5 V/600 mA, 5.0 V/300 mA, 5.0 V/1400 mA, 3.3 V/1 A) with shared and discrete enable control |
| Automotive-grade protection | Reverse polarity (−18 V), load dump (50 V/50 ms), thermal shutdown (150–170 °C), and foldback current limiting on all outputs |
| Microcontroller-safe sequencing | REG2 remains active during faults; RES and HOLD outputs provide deterministic reset/hold timing via external CRES |
| Dual-supply architecture | VP2 input allows REG3/REG4 to be powered from DC-DC converter (≥6.5 V), reducing total power dissipation by >40% vs. single-rail operation |
| Ignition interface | Integrated Schmitt-triggered IGNIN and push-pull IGNOUT eliminate need for external level-shifting or buffering in 12 V automotive systems |
Applications
| Car Radio Power Management | Microcontroller Supervision System |
|---|---|
Use Scenario: Central power management unit in OEM car radios with AM/FM/DAB tuners, DSP, and display. IC Role / Device Role / Timing Role: TDA3681ATH/N1C,518 supplies all subsystem rails (8.5 V tuner, 5.0 V MCU, 3.3 V interface), sequences startup via CRES-delayed reset, and maintains REG2 during engine cranking. Use Value: Eliminates discrete LDOs and protection ICs; reduces BOM count by ≥7 components while guaranteeing fault resilience per ISO 7637-2 Pulse 5a. | Use Scenario: Safety-critical reset coordination in infotainment head units with ARM-based SoCs. IC Role / Device Role / Timing Role: TDA3681ATH/N1C,518 acts as system supervisor: REG2 powers the SoC core, HOLD asserts on battery sag (<9.7 V), and RES releases the SoC only after stable 5 V is confirmed. Use Value: Prevents brown-out lockup during cold-cranking; ensures deterministic boot sequence without software intervention. |
| Automotive Ignition Interface | Load-Dump-Tolerant Audio Amplifier Supply |
Use Scenario: Wake-up signaling between vehicle body controller and infotainment module. IC Role / Device Role / Timing Role: TDA3681ATH/N1C,518 receives 12 V ignition signal via IGNIN Schmitt trigger and drives IGNOUT to enable audio subsystem power rails. Use Value: Replaces external comparator + MOSFET driver; provides noise-immune edge detection (0.2 V hysteresis) and 5 V logic-level output compatible with MCU GPIOs. | Use Scenario: Powering Class D audio amplifiers in premium car audio systems exposed to alternator transients. IC Role / Device Role / Timing Role: TDA3681ATH/N1C,518 supplies 5.0 V/1400 mA (REG3) to amplifier bias rails and remains operational during 50 V/50 ms load dump pulses. Use Value: Enables continuous audio playback during engine restart; avoids amplifier mute artifacts caused by conventional LDO dropout. |
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 5 V regulators + watchdog timer; no 8.5 V or 3.3 V outputs; SPI interface for configuration | Requires external 8.5 V LDO and 3.3 V regulator; suited for ASIL-B safety-critical clusters, not cost-sensitive radios | Select if functional safety (ISO 26262) and programmability outweigh need for integrated 8.5 V/3.3 V rails |
| MAX16922ATP+T | Single 5 V/300 mA regulator + 200 mA switch; no multi-rail capability; smaller 20-pin TQFN | Lacks REG1/REG3/REG4 and ignition buffer; requires companion ICs for full TDA3681ATH/N1C,518 functionality | Select only for space-constrained designs where only REG2-level supply and basic switching are needed |
Compared with TLF35584QVVS1 and MAX16922ATP+T, the TDA3681ATH/N1C,518 uniquely integrates four precisely matched automotive LDOs, dual-supply flexibility, and ignition interface in one HSOP20 package-reducing board area by 35% and eliminating inter-IC communication overhead in car radio designs.
Availability
TDA3681ATH/N1C,518 is available at Aetrix Electronics and suitable for automotive infotainment, car radio power management, microcontroller supervision, and ignition interface applications requiring stable component supply across extended temperature and transient-voltage conditions.
Supply support for TDA3681ATH/N1C,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 specializing in secure connectivity solutions for automotive, industrial, and IoT markets, with deep heritage in Philips' analog and power management IP.
The TDA3681ATH/N1C,518 belongs to NXP's legacy automotive power management portfolio, engineered specifically for cost-sensitive, high-reliability car radio platforms requiring integrated multi-rail regulation, load-dump resilience, and microcontroller coexistence.
FAQ
What is the maximum continuous current capability of the power switch in TDA3681ATH/N1C,518?
The power switch in TDA3681ATH/N1C,518 delivers 1.8 A continuous current at VP1 = 16 V and VSW = 13.5 V. At VP1 ≥17 V, it clamps at 16 V and limits current to 1.8 A; peak current reaches 3 A for short durations before foldback activation. This is verified in the Quick Reference Data table (page 3) and CHARACTERISTICS section (page 13) of the datasheet.
How does the TDA3681ATH/N1C,518 handle load dump events while powering a microcontroller?
The TDA3681ATH/N1C,518 maintains regulator 2 (5.0 V output) during load dump pulses up to 50 V for 50 ms, ensuring uninterrupted microcontroller operation. Simultaneously, it asserts the HOLD output (active LOW) and disables regulators 1, 3, and 4 to protect downstream circuitry. The reset output remains asserted until VP1 stabilizes and CRES charges, preventing premature MCU release.
Can the TDA3681ATH/N1C,518 operate with only one supply voltage, or is VP2 mandatory?
VP2 is not mandatory for basic operation: the TDA3681ATH/N1C,518 functions with VP1 alone for regulators 1 and 2 and the power switch. However, VP2 is required to enable regulators 3 and 4 - they will not regulate if VP2 <6.5 V. Using VP2 (e.g., from a DC-DC converter) reduces thermal stress and improves efficiency, especially under high-load conditions.
What is the purpose of the BU (backup switch) pin on the TDA3681ATH/N1C,518?
The BU pin on the TDA3681ATH/N1C,518 controls energy transfer from an external backup capacitor to regulator 2 during VP1 collapse (e.g., engine stop). When VP1 drops below ~4.5 V, the BU switch closes, allowing stored charge to sustain REG2's 5.0 V output long enough for the microcontroller to execute safe shutdown routines - a critical feature for non-volatile memory preservation.
Is the TDA3681ATH/N1C,518 pin-compatible with earlier TDA3681 variants like TDA3681T/N1,518?
Yes, the TDA3681ATH/N1C,518 is pin-compatible with the original TDA3681T/N1,518 and TDA3681AH/N1,518 variants. All share identical HSOP20 (SOT418-3) packaging, pin numbering, electrical characteristics, and functional block diagram per Philips' 2003 datasheet revision. No PCB layout changes are required when upgrading to the /N1C,518 version, which reflects updated traceability and packaging markings.
TDA3681ATH/N1C,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
TDA3681ATH/N1C,518 FAQ
1.How can I place an order for TDA3681ATH/N1C,518 through Aetrix?
Please submit a Request for Quotation (RFQ) for TDA3681ATH/N1C,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 TDA3681ATH/N1C,518 reliable?
The price and inventory of TDA3681ATH/N1C,518 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for TDA3681ATH/N1C,518 is usually 5 days.
3.What payment methods are accepted for TDA3681ATH/N1C,518?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for TDA3681ATH/N1C,518 transactions.
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4.How is shipping managed for TDA3681ATH/N1C,518?
TDA3681ATH/N1C,518 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your TDA3681ATH/N1C,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 TDA3681ATH/N1C,518?
For technical support, including TDA3681ATH/N1C,518 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your TDA3681ATH/N1C,518 requirements.
6.How does Aetrix verify that TDA3681ATH/N1C,518 is sourced from the original manufacturer or authorized distributors?
All TDA3681ATH/N1C,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 TDA3681ATH/N1C,518 meets industry standards.
7.What is the process for return or replacement of TDA3681ATH/N1C,518?
All TDA3681ATH/N1C,518 units undergo pre-shipment inspection (PSI). If there is an issue with TDA3681ATH/N1C,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 TDA3681ATH/N1C,518 part is unused and in its original packaging.
Return procedure for TDA3681ATH/N1C,518:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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