Texas Instruments DS3680D

Overview

DS3680D from Texas Instruments is a quad telephone relay driver IC designed to interface –48-V relay systems with TTL/CMOS logic in telecom central office and line card applications. It delivers 50-mA output current per channel from –52-V battery supply, features ±20-V common-mode input range referenced to battery ground, and includes built-in clamp diodes for relay coil transient suppression.

For engineers reviewing the DS3680D datasheet, DS3680D pinout, DS3680D application, or DS3680D equivalent, key selection criteria include negative-supply relay driving capability, high-impedance differential inputs compatible with bipolar/negative logic, fail-safe disconnect behavior, and SOIC-14 packaging for space-constrained telephony hardware.

Technical Context

The DS3680D implements four independent high-side driver channels, each with complementary differential inputs (IN+, IN–) and open-collector outputs referenced to BAT NEG. Its input stage operates with ±20-V common-mode range relative to BAT GND, enabling direct connection to diverse signaling sources without level-shifting.

Each channel integrates a clamp diode network to limit inductive kickback from relay coils up to 5 H, and employs fail-safe logic where an open-circuit output forces the driver into OFF state. The device draws ≤100 µA high-level input current at VID = 2 V and supports turn-on/off times of 1–10 µs under 1-kΩ resistive load.

Key Specifications

Pinout & Package

DS3680D is housed in a 14-pin SOIC (D) package with 1.27-mm lead pitch, 8.55–8.75 mm body width, and 1.75-mm maximum height-optimized for automated assembly and thermal management in telecom PCBs.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar quad relay driver applications.

Compared with DS3680N, DS3680D offers identical performance in a surface-mount package optimized for automated manufacturing and thermal dissipation, while SN75LBC176 serves a fundamentally different interface role and cannot substitute for relay driving functionality.

Availability

DS3680D is available at Aetrix Electronics and suitable for central office line cards, loop-start telephone interfaces, and PBX station interfaces requiring stable component supply and long-term lifecycle support.

Supply support for DS3680D 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 headquartered in Dallas, Texas, delivering analog and embedded processing solutions for industrial, automotive, and communications markets.

The DS3680D belongs to TI's legacy telecom interface product line, engineered specifically for –48-V relay control in PSTN infrastructure-prioritizing noise immunity, fail-safe behavior, and direct battery-rail compatibility over general-purpose logic interfacing.

FAQ

What is the maximum inductive load the DS3680D can drive per channel?

The DS3680D is rated for 50 mA continuous output current into inductive loads, with a specified maximum inductance of 5 H per relay coil. This rating ensures reliable operation with standard telecom relays while maintaining clamp diode effectiveness and thermal stability within the SOIC-14 package's 608-mW power limit at 70°C ambient.

Does the DS3680D support negative logic input signaling?

Yes, the DS3680D supports negative logic inputs due to its high-impedance differential architecture and wide common-mode input range (–20 V to +20 V referenced to BAT GND). When IN– is held more positive than IN+, the output turns OFF-enabling direct interface with legacy negative-logic supervisory circuits without external inverters or level shifters.

How does the fail-safe disconnect feature work in the DS3680D?

The DS3680D implements fail-safe disconnect by using complementary inputs: if either IN+ or IN– becomes open-circuited, the internal comparator forces the output into the OFF state. This prevents unintended relay activation during cable faults, connector disconnection, or microcontroller reset events-ensuring safety-critical telecom systems default to a known safe condition.

Can the DS3680D be used with a +5-V logic supply while driving –52-V relays?

Yes, the DS3680D isolates logic-level inputs from the –52-V battery domain via its ±20-V common-mode input range referenced to BAT GND. A +5-V microcontroller can directly drive the IN+/IN– pins without level-shifting, as long as its ground is referenced to BAT GND or coupled through appropriate isolation-enabling mixed-voltage system integration without additional interface ICs.

What is the purpose of the BAT GND pin on the DS3680D?

The BAT GND pin on the DS3680D serves as the reference node for the input stage's common-mode voltage range, not as a power return. It allows the inputs to operate with ±20 V tolerance relative to the battery ground-reducing sensitivity to IR drop and noise between logic ground and battery ground. It must be connected to the system's battery ground plane, not the digital logic ground.