Texas Instruments TL7705ACP

Overview

TL7705ACP from Texas Instruments is a precision supply-voltage supervisor IC designed as a reset controller for 5-V microcomputer systems. It features a 4.55-V threshold voltage (V_IT−), wide 3.5–18-V operating supply range, temperature-compensated 2.53-V reference output, and externally adjustable reset pulse duration via CT pin. It delivers active-high and active-low complementary reset signals (RESET/RESET) for reliable microprocessor initialization in embedded power management.

For engineers reviewing the TL7705ACP datasheet, TL7705ACP pinout, TL7705ACP application, or TL7705ACP equivalent, key selection considerations include its fixed 4.55-V undervoltage detection threshold, dual open-collector reset outputs, SOIC-8/PDIP-8 package compatibility, and use of external timing capacitor for configurable delay - critical for TTL-compatible system reset timing compliance.

Technical Context

The TL7705ACP implements a precision bandgap-based voltage reference with ±10 mV stability over 3.5–18 V supply and ±16 mV variation across –40°C to +85°C. Its internal comparator monitors SENSE input against the trimmed 4.55-V threshold with 15-mV hysteresis to prevent chatter during brownout recovery.

Reset assertion is triggered when SENSE falls below V_IT−; deassertion occurs after a programmable delay (t_d = 1.3×10⁴ × C_T) once SENSE exceeds V_IT+. The REF pin provides a stable 2.53-V output usable for external biasing, while RESIN allows manual reset override.

Key Specifications

Pinout & Package

TL7705ACP is packaged in an 8-pin PDIP (Plastic Dual In-line Package) with 9.81 mm × 6.35 mm body size and through-hole mounting. Pin spacing is 2.54 mm standard.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar supply-voltage supervision applications.

Compared with TL7705ACP, TPS3808G33 offers tighter threshold tolerance but narrower supply range and no reference output, while MAX692CPA+ adds watchdog functionality at the cost of reduced supply flexibility and loss of timing capacitor adjustment - making TL7705ACP optimal for fixed 5-V systems requiring design simplicity and analog reference reuse.

Availability

TL7705ACP is available at Aetrix Electronics and suitable for microprocessor reset, industrial PLC power sequencing, and embedded networking equipment requiring stable component supply and long-term obsolescence planning.

Supply support for TL7705ACP 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 TL77xxA product line was engineered specifically for robust, low-cost reset control in microcomputer and microprocessor systems - emphasizing precision threshold accuracy, wide supply tolerance, and flexible timing for legacy and modern 5-V designs.

FAQ

What is the exact undervoltage detection threshold voltage of the TL7705ACP?

The TL7705ACP has a nominal negative-going input threshold voltage (V_IT−) of 4.55 V at 25°C, with a typical range of 4.5 V to 4.6 V across the 0°C to +70°C operating temperature range. This threshold is factory-trimmed and applies specifically to the TL7705ACP variant within the TL77xxA family, enabling precise supervision of standard 5-V logic supplies.

Does the TL7705ACP require an external capacitor on the REF pin, and why?

Yes, the TL7705ACP requires a 0.1-µF capacitor connected between REF (Pin 1) and GND. This capacitor stabilizes the internal 2.53-V reference voltage against fast supply transients and reduces noise coupling, ensuring accurate threshold comparison and preventing false resets. Omitting it risks erratic behavior during power-up or load switching events.

Can the TL7705ACP be used to monitor a 3.3-V supply rail?

No, the TL7705ACP is not suitable for direct 3.3-V rail monitoring because its fixed 4.55-V threshold exceeds 3.3 V. Attempting to use it would result in permanent reset assertion. For 3.3-V systems, select a supervisor with matching threshold (e.g., TL7703ACP or TPS3808G33), or use an external resistor divider on the SENSE input - though TL7705ACP's internal design does not support adjustable thresholds.

What is the function of the CT pin on the TL7705ACP, and how is it sized?

The CT (Capacitor Timing) pin on the TL7705ACP sets the reset pulse duration using the formula t_d = 1.3 × 10⁴ × C_T, where C_T is in farads and t_d in seconds. A 0.1-µF capacitor yields ~1.3 ms delay - commonly used to meet microprocessor reset timing requirements. Capacitor tolerance directly impacts delay accuracy, so X7R or C0G dielectrics are recommended.

Is the TL7705ACP pin-compatible with other TL77xxA variants like TL7702ACP or TL7709ACP?

Yes, all TL77xxA variants including TL7705ACP, TL7702ACP, and TL7709ACP share identical 8-pin PDIP (P) and SOIC (D) footprints and pinouts. They differ only in factory-trimmed threshold voltages (2.5 V, 4.55 V, 7.6 V respectively) and internal resistor networks - allowing drop-in replacement when the application's supply rail matches the variant's specified V_IT−.