Texas Instruments TL7705BQDRG4

Overview

TL7705BQDRG4 from Texas Instruments is a precision supply-voltage supervisor IC designed as a reset controller for microprocessor and microcontroller systems. It monitors the SENSE input for undervoltage conditions, provides true and complement reset outputs (RESET and RESET), features an externally adjustable reset pulse duration via CT capacitor, and operates across –40°C to 125°C with a 4.55 V nominal threshold voltage. It is used in automotive-grade embedded control modules requiring high-temperature reliability.

For engineers reviewing the TL7705BQDRG4 datasheet, TL7705BQDRG4 pinout, TL7705BQDRG4 application, or TL7705BQDRG4 equivalent, key selection criteria include its Q-suffix industrial temperature grade (–40°C to 125°C), SOIC-8 package, dual active-high/active-low reset outputs, adjustable timing via external capacitor, and precision 4.55 V ±50 mV threshold with hysteresis.

Technical Context

The TL7705BQDRG4 implements a precision bandgap-based voltage reference and comparator architecture to detect supply drops at the SENSE pin. Its internal timing circuit uses a current source charging an external CT capacitor to generate a user-defined reset pulse width (td ≈ 2.6 × 10⁴ × CT).

It supports three functional modes: automatic reset on undervoltage, manual reset override via RESIN, and power-on reset activation below 1 V VCC. The REF output provides a stable 2.53 V reference for external use, and both RESET outputs are open-collector, requiring external pull-up/pull-down resistors.

Key Specifications

Pinout & Package

TL7705BQDRG4 is housed in an 8-pin SOIC (D) package, 4.90 mm × 3.91 mm body size, RoHS-compliant with NiPdAu lead finish and Level-1 MSL rating.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar voltage supervisor applications.

Compared with TPS3808G33DBVR and MAX6326UT46D3+T, the TL7705BQDRG4 uniquely combines Q-grade temperature operation, dual complementary open-collector outputs, adjustable timing, and a buffered reference output-making it optimal for high-reliability industrial and automotive reset control where flexibility and extended environmental robustness are required.

Availability

TL7705BQDRG4 is available at Aetrix Electronics and suitable for automotive engine control units, industrial PLC modules, telecom base station power management, and medical diagnostic imaging controllers requiring stable component supply across extended temperature ranges.

Supply support for TL7705BQDRG4 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 specializing in analog, embedded processing, and connectivity technologies with over 90 years of innovation in power management and signal conditioning.

The TL77xxB family was developed specifically for robust, precision supply-voltage supervision in microprocessor-based systems demanding high-temperature reliability, configurable timing, and dual-reset signaling-targeting automotive, industrial, and communications infrastructure markets.

FAQ

What is the operating temperature range specified for the TL7705BQDRG4?

The TL7705BQDRG4 is characterized for operation from –40°C to 125°C, as indicated by the "Q" suffix in its part number. This qualifies it for under-hood automotive applications and high-temperature industrial environments where standard commercial or industrial grade supervisors would fail. The datasheet confirms this range applies specifically to the TL7705BQ variant, not the BC or BI versions.

How does the CT pin function in the TL7705BQDRG4?

The CT pin on the TL7705BQDRG4 connects to an external capacitor that sets the reset pulse duration. An internal current source charges the capacitor until it reaches a threshold, determining the time delay before RESET and RESET deactivate after a supply recovery. The relationship is td ≈ 2.6 × 10⁴ × C_T, so a 0.1 µF capacitor yields ~2.6 ms. TL7705BQDRG4 requires this capacitor for proper reset timing behavior.

Why does the TL7705BQDRG4 provide both RESET and RESET outputs?

The TL7705BQDRG4 provides complementary open-collector outputs (RESET active-high, RESET active-low) to directly interface with diverse logic families without external inversion. This eliminates the need for additional gate logic in systems requiring simultaneous assertion of both polarities-for example, resetting an FPGA (active-low) while enabling a watchdog timer (active-high). Both outputs are synchronized and share identical timing characteristics.

What is the purpose of the REF pin on the TL7705BQDRG4?

The REF pin on the TL7705BQDRG4 delivers a precision 2.53 V (typ), temperature-compensated reference voltage with ±50 mV tolerance over –40°C to 125°C. It is intended for use as a stable voltage source in external circuits-such as ADC references, comparator thresholds, or sensor biasing-reducing system BOM count and improving overall voltage monitoring accuracy. A 0.1 µF capacitor to GND is mandatory for noise immunity.

Can the TL7705BQDRG4 be used to monitor voltages other than 5 V?

Yes, the TL7705BQDRG4 can supervise any supply between 3.6 V and 18 V by scaling the SENSE input with an external resistor divider. Its 4.55 V threshold is fixed, so for non-5 V rails (e.g., 12 V or 3.3 V), a divider sets the voltage at SENSE to 4.55 V when the monitored rail reaches the desired trip point. The TL7705BQDRG4's wide supply range and precision reference support accurate scaled supervision across multiple rail voltages.