Analog Devices Inc./Maxim Integrated MAX705CSA

Overview

MAX705CSA from Maxim Integrated is a low-cost microprocessor supervisory circuit in 8-pin SO package, providing active-low reset output, 1.6s watchdog timer, 4.65V supply-voltage monitoring, and 1.25V power-fail comparator input for +5V systems. It guarantees RESET validity down to VCC = 1V and delivers a 200ms reset pulse width during power-up, brownout, or manual reset - used in embedded controllers and industrial instrumentation requiring reliable power sequencing.

For engineers reviewing the MAX705CSA datasheet, MAX705CSA pinout, MAX705CSA application, or MAX705CSA equivalent, key selection criteria include its 4.65V reset threshold, watchdog timeout tolerance (±37.5%), PFI comparator accuracy (±0.05V), MR debounced timing (≥150ns), and guaranteed operation across 0°C to +70°C ambient.

Technical Context

The MAX705CSA integrates four core supervisory functions on a single die: a precision bandgap-based voltage monitor with 40mV hysteresis, a monostable watchdog timer triggered by WDI edge transitions, a dedicated 1.25V reference comparator for external power-fail detection, and a TTL/CMOS-compatible manual-reset input with internal 250µA pull-up. All logic outputs are push-pull with defined sink/source drive capability.

Its reset generator uses an internal RC timing network to ensure 200ms minimum pulse width after VCC rise above threshold or MR release; the watchdog timeout is factory-trimmed to 1.6s ±37.5% at VCC = 5V and TA = +25°C, with no external components required. The PFI comparator features <25nA input bias current and 400ns response time for fast power-fail assertion.

Key Specifications

Pinout & Package

MAX705CSA is housed in an 8-pin SO (Small Outline) package, 3.9mm × 4.9mm body, 1.27mm pitch, RoHS-compliant with lead-free option available (add '+' suffix). Thermal resistance θJA = 170°C/W; max continuous power dissipation at +70°C is 471mW.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX706CSA and MAX813LCSA, the MAX705CSA offers the industry-standard 4.65V reset point for legacy +5V designs, preserves watchdog functionality for runtime fault recovery, and maintains full compatibility with existing layouts using 8-pin SO footprint - making it the default choice for new designs targeting broad µP compatibility.

Availability

MAX705CSA is available at Aetrix Electronics and suitable for industrial controllers, embedded instrumentation, computing peripherals, and critical μP power monitoring requiring stable component supply across extended production lifecycles.

Supply support for MAX705CSA 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) is a semiconductor company specializing in high-performance analog, mixed-signal, and power-management ICs for industrial, communications, and computing markets.

The MAX705–MAX708/MAX813L family was designed specifically to replace discrete reset generators and watchdog circuits in cost-sensitive microprocessor systems - delivering integrated reliability with minimal external components.

FAQ

What is the reset threshold voltage for MAX705CSA?

The MAX705CSA has a nominal reset threshold of 4.65V with ±150mV tolerance, meaning RESET asserts when VCC drops below 4.50V and releases after VCC rises above 4.75V. This threshold is factory-trimmed and guaranteed over temperature and supply variations, ensuring consistent behavior in +5V systems where regulation tightness is critical. The MAX705CSA's 40mV hysteresis prevents chatter during slow supply ramps.

Does MAX705CSA support operation below 1.0V VCC?

No, the MAX705CSA specifies a minimum operating VCC of 1.0V. Below this voltage, internal circuitry cannot guarantee correct logic states or output drive strength. However, the device does guarantee RESET output validity down to VCC = 1.0V - meaning RESET remains a valid logic low (≤0.4V) until VCC falls below that point, enabling safe system shutdown sequencing. Operation below 1.0V is not characterized or supported.

Can the watchdog timer in MAX705CSA be disabled?

Yes, the watchdog timer in MAX705CSA is disabled by leaving the WDI pin unconnected (floating) or driving it with a high-impedance three-state buffer. When WDI is floating, the internal watchdog timer remains cleared and WDO stays high unless VCC falls below the reset threshold. This allows use of MAX705CSA's reset and power-fail functions without watchdog supervision - confirmed in the datasheet's Pin Description and Detailed Description sections.

What is the maximum load the RESET output of MAX705CSA can drive?

The RESET output of MAX705CSA can sink up to 3.2mA while maintaining ≤0.4V output voltage, and source up to 800µA while staying within VCC −1.5V. This drive capability supports direct connection to most µP reset inputs without external buffering. For heavier loads or long traces, a series resistor (e.g., 4.7kΩ) is recommended to prevent contention with bidirectional reset pins, as documented in the Applications Information section.

Is MAX705CSA RoHS-compliant and lead-free?

Yes, MAX705CSA is available in RoHS-compliant, lead-free packaging. Maxim Integrated offers both leaded and lead-free versions of the 8-pin SO package; the lead-free variant is ordered by adding a '+' suffix to the part number (e.g., MAX705CSA+). The datasheet confirms RoHS status via package code notation and specifies soldering profiles for lead-free reflow at +260°C peak temperature.