Texas Instruments TL7705BCDRE4

Overview

TL7705BCDRE4 from Texas Instruments is a precision supply-voltage supervisor IC designed as a reset controller for 5-V microprocessor systems. It monitors the SENSE input for undervoltage conditions, provides true and complement RESET outputs (active-high and active-low), features a 4.55-V nominal threshold with ±50-mV hysteresis, and supports externally adjustable reset pulse duration via CT pin. Used in server power sequencing and industrial embedded controllers.

For engineers reviewing the TL7705BCDRE4 datasheet, TL7705BCDRE4 pinout, TL7705BCDRE4 application, or TL7705BCDRE4 equivalent, this page delivers verified electrical specs, SOIC-8 package details, functional timing behavior, thermal metrics, and validated alternative options for voltage-monitoring designs requiring stable reset assertion during brownout events.

Technical Context

The TL7705BCDRE4 implements a dual-comparator architecture with temperature-compensated bandgap reference to ensure stable 4.55-V trip point across –40°C to 85°C. Its internal current source charges an external CT capacitor to generate a programmable reset delay (td ≈ 26 ms per µF), while REF output provides a 2.53-V precision reference for system calibration.

RESET and RESET outputs are open-collector/open-drain compatible, requiring external pull-up/pull-down resistors; RESIN enables manual reset override, and SENSE accepts direct connection to VCC or regulated rail. The device operates from 3.6 V to 18 V and asserts reset when VSENSE falls below VIT–, maintaining output state until VSENSE exceeds VIT+ plus hysteresis.

Key Specifications

Pinout & Package

TL7705BCDRE4 is housed in an 8-pin SOIC (D) package measuring 4.90 mm × 3.91 mm, RoHS-compliant with NiPdAu lead finish and Moisture Sensitivity Level (MSL) 2 (260°C, 1 year).

Key Features

Applications

Equivalent & Alternatives

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

Compared with TL7705BCDRE4, TPS3808G33DBVR offers superior power efficiency but sacrifices threshold flexibility and dual-output capability, while MAX6326UT46D3+ delivers tighter voltage accuracy and push-pull drive at the cost of losing manual reset control and reference voltage output.

Availability

TL7705BCDRE4 is available at Aetrix Electronics and suitable for industrial automation, server power management, building control systems, and network-attached storage requiring stable component supply across extended temperature ranges.

Supply support for TL7705BCDRE4 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 leader delivering analog and embedded processing solutions, with over 90 years of innovation in power management, signal chain, and microcontroller technologies.

The TL77xxB family was engineered specifically for robust, low-cost reset supervision in microprocessor-based systems where reliable power-on and brownout detection is mission-critical.

FAQ

What is the exact reset threshold voltage for TL7705BCDRE4 across temperature?

The TL7705BCDRE4 has a negative-going input threshold (VIT–) of 4.45 V (minimum) to 4.65 V (maximum) over its full operating range of –40°C to +85°C. At 25°C, the typical value is 4.55 V with ±25 mV variation. This 30-mV hysteresis (VHYS) ensures stable transition without oscillation during slow supply ramps. The threshold is internally trimmed and temperature-compensated using TI's proprietary bandgap reference design.

How do I calculate the reset pulse duration for TL7705BCDRE4 using the CT capacitor?

The reset pulse duration (td) for TL7705BCDRE4 is calculated as td ≈ 2.6 × 10⁴ × CT, where CT is in farads and td is in seconds. For example, a 0.1-µF capacitor yields ~2.6 ms. The internal current source charging CT varies ±15%, and Reference Voltage 2 (~1.8 V) varies ±5%, so actual delay may deviate up to ±20% from nominal. TI recommends verifying timing in final hardware using oscilloscope measurements on RESET/RESET outputs.

Does TL7705BCDRE4 require external pull-up resistors on its reset outputs?

Yes, TL7705BCDRE4 requires external pull-up resistors on RESET (pin 6) and pull-down resistors on RESET (pin 5) because both are open-collector outputs. TI recommends 10-kΩ resistors for standard logic interfacing. Using mismatched resistor values on the two outputs can cause waveform plateauing during switching, potentially leading to undefined states or delayed system reset - a condition explicitly warned against in the datasheet.

Can TL7705BCDRE4 monitor a 3.3-V supply directly?

No, TL7705BCDRE4 is not suitable for direct 3.3-V supply monitoring because its nominal threshold is 4.55 V. Applying 3.3 V to SENSE will permanently assert RESET. To supervise 3.3-V rails, use TL7702B (2.53-V threshold) or TL7733B (3.08-V threshold), or implement a resistor divider to scale the 3.3-V signal to ~4.55 V at SENSE - though that adds error sources and reduces noise immunity. Always verify divider ratio and loading effects in final design.

What is the purpose of the REF pin on TL7705BCDRE4, and how must it be used?

The REF pin (pin 1) on TL7705BCDRE4 delivers a precision 2.53-V reference voltage with ±50-mV tolerance over temperature. It must be decoupled with a 0.1-µF capacitor to GND to suppress fast transients and prevent false triggering. This reference can calibrate ADCs, bias comparators, or serve as a stable voltage source for analog subsystems - but it is not intended to drive loads >500 µA. Exceeding this current degrades accuracy and may affect reset timing stability.