Analog Devices Inc./Maxim Integrated MAX7705ESA+

Overview

MAX7705ESA+ from Maxim Integrated is a microprocessor supervisory circuit that monitors +5V power supplies and asserts an active-low RESET signal during power-up, power-down, and brownout conditions. It features a precise 4.65V reset threshold, guaranteed 280ms power-on reset delay, operates down to VCC = 1V, and consumes only 65µA typical supply current. It replaces the TL7705 in µP systems without external components.

For engineers reviewing the MAX7705ESA+ datasheet, MAX7705ESA+ pinout, MAX7705ESA+ application, or MAX7705ESA+ equivalent, key selection criteria include guaranteed reset timeout over temperature, glitch immunity against sub-40µs VCC transients, low quiescent current for battery-backed systems, and compatibility with 8-pin SO footprint layouts.

Technical Context

The MAX7705ESA+ implements a precision bandgap-based voltage comparator with internal hysteresis to detect VCC crossing the 4.65V reset threshold. Its reset timing is generated by an on-chip oscillator-100% tested and guaranteed across –40°C to +85°C-ensuring deterministic 280ms delay after VCC rises above threshold.

RESET output is push-pull capable of sinking 3.2mA (0.4V max) and sourcing 800µA (VCC – 1.5V min), enabling direct interface to CMOS µP reset inputs. The device remains functional down to VCC = 1V, with RESET output becoming high-impedance below 1V.

Key Specifications

Pinout & Package

MAX7705ESA+ is housed in an 8-pin plastic small-outline (SO) package, 3.9mm × 4.9mm body, 1.27mm pitch, JEDEC MS-012 compliant. Pin 1 is VCC; pins 2–3 and 6–7 are no-connect; pin 4 is GND; pin 5 is active-low RESET output; pin 8 is VCC (dual-supply connection).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar microprocessor supervisory applications.

Compared with MAX706R and TL7705ACD, the MAX7705ESA+ delivers lower power, guaranteed timing, and zero-component simplicity specifically for +5V µP reset-making it optimal for cost-sensitive, industrial-grade 5V systems where watchdog capability is unnecessary.

Availability

MAX7705ESA+ is available at Aetrix Electronics and suitable for industrial PLC controllers, medical handheld diagnostics, automotive body control modules, and point-of-sale terminals requiring stable component supply and long-term manufacturability.

Supply support for MAX7705ESA+ 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

Maxim Integrated (now part of Analog Devices) designs precision analog, mixed-signal, and power management ICs for industrial, automotive, communications, and computing applications.

The MAX7705ESA+ belongs to Maxim's µP supervisory product line, engineered to replace legacy reset ICs like TL7705 with integrated timing, reduced external parts, and guaranteed performance across industrial temperature ranges.

FAQ

What is the guaranteed reset timeout specification for MAX7705ESA+ over temperature?

The MAX7705ESA+ guarantees a minimum reset timeout of 140ms and maximum of 560ms, with a typical value of 280ms across its full operating range of –40°C to +85°C. This timing is generated by an internal oscillator and 100% tested at final test - unlike RC-based alternatives, no derating or margining is required for thermal design. The MAX7705ESA+ datasheet specifies this parameter under "Reset Active Timeout Period" in the Electrical Characteristics table.

Can MAX7705ESA+ operate with a 3.3V supply rail?

No, the MAX7705ESA+ is specified for VCC from 1.2V to 5.5V but has a fixed 4.65V reset threshold optimized for +5V systems. At 3.3V, VCC remains below threshold continuously, causing RESET to stay asserted. For 3.3V applications, consider alternatives like MAX706R (2.63V threshold) or MAX708R (2.63V/2.93V/3.08V variants). The MAX7705ESA+ is intended exclusively for 5V µP supervision.

Does MAX7705ESA+ require a bypass capacitor on VCC?

Yes - a 0.1µF ceramic bypass capacitor mounted as close as possible to pin 2 (VCC) is recommended per the MAX7705ESA+ Applications Information section. This capacitor improves immunity to fast negative-going VCC transients and stabilizes internal reference operation. While the MAX7705ESA+ functions without it, omitting the capacitor reduces glitch immunity and may cause spurious resets during high-noise events.

How does MAX7705ESA+ behave when VCC falls below 1V?

When VCC drops below 1V, the MAX7705ESA+ RESET output transitions to high-impedance (Hi-Z) and no longer actively sinks or sources current. This is documented in the Applications Information section. In most systems, this is acceptable because µP and peripherals are nonfunctional below 1V. If a defined logic level is required down to 0V, a 100kΩ pull-down resistor from RESET to GND (as shown in Figure 2 of the MAX7705ESA+ datasheet) ensures RESET remains low.

Is MAX7705ESA+ pin-compatible with TL7705 in 8-pin SO packages?

Yes - the MAX7705ESA+ uses identical 8-pin SO pinout and footprint as the TL7705, with VCC on pins 1 and 8, GND on pin 4, and RESET on pin 5. Pins 2, 3, 6, and 7 are no-connect on both devices. This allows direct socket replacement in existing TL7705 designs, provided the external RC network is removed. The MAX7705ESA+ eliminates the need for the TL7705's pull-up resistor, timing capacitor, and reference bypass capacitor.