Analog Devices Inc./Maxim Integrated MAX693MLP

Overview

MAX693MLP from Maxim Integrated is a 16-pin microprocessor supervisory circuit providing battery backup switchover, adjustable reset and watchdog timeout, CMOS RAM write protection, power-fail warning, and low-V_CC detection. It features a 4.4V reset threshold, 1.3V PFI comparator, 1µA battery-backup supply current, and operates across –40°C to +85°C. Used in industrial controllers and automotive ECUs for reliable µP power monitoring and data retention.

For engineers reviewing the MAX693MLP datasheet, MAX693MLP pinout, MAX693MLP application, or MAX693MLP equivalent, key selection considerations include its 16-pin SO package, dual-mode watchdog (100ms/1.6s), CE gating logic, BATT ON output for external transistor drive, and compatibility with 4.4V-reset systems requiring brownout immunity and nonvolatile memory protection.

Technical Context

The MAX693MLP integrates a precision 4.4V reset comparator with 40mV hysteresis, a 1.3V power-fail detector with automatic disable when V_CC < V_BATT, and a dual-source watchdog timer configurable via OSC SEL and OSC IN pins. Its CE IN/CE OUT pair implements active-high chip-enable gating with 50ns propagation delay and forced high output during undervoltage.

Battery switchover uses internal PNP and MOSFET paths: V_OUT connects to V_CC above VBATT+70mV (rising) or VBATT+50mV (falling), with 20mV hysteresis; below V_CC = 0V, it delivers 250µA at V_BATT–0.1V while drawing only 1µA standby current. BATT ON sinks 25mA and drives external PNP bases directly.

Key Specifications

Pinout & Package

MAX693MLP is housed in a 16-pin SOIC (Small Outline Integrated Circuit) package with 1.27mm pitch, JEDEC MS-012AC compliant, and rated for surface-mount reflow assembly.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX693MLP, MAX693CSA+ offers identical supervision functionality with updated environmental compliance, while TPS3823MPW provides simplified reset-only capability at lower cost but omits critical features like CE gating, BATT ON, and battery switchover-making it unsuitable for RAM-backed systems.

Availability

MAX693MLP is available at Aetrix Electronics and suitable for industrial controllers, automotive body electronics, medical infusion pumps, and ruggedized data loggers requiring stable component supply, long-lifecycle support, and guaranteed –40°C to +85°C operation.

Supply support for MAX693MLP 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, and computing applications.

The MAX690–MAX695 family, including MAX693MLP, was engineered specifically for µP-based systems needing integrated power monitoring, battery backup, and memory protection - reducing discrete count and improving reliability over separate reset, watchdog, and switchover circuits.

FAQ

What is the reset threshold voltage of the MAX693MLP?

The MAX693MLP has a guaranteed reset threshold of 4.4V, with a minimum of 4.25V and maximum of 4.5V across temperature and supply variations. This 4.4V threshold is specifically designed for compatibility with ±10% 5V power rails and provides robust brownout immunity. The MAX693MLP's reset comparator includes 40mV hysteresis to prevent chatter during slow V_CC transitions. This value is fixed and not adjustable - unlike some members of the MAX690 family, the MAX693MLP does not support external resistor programming of the reset point.

Does the MAX693MLP support battery backup switchover, and what are the voltage limits?

Yes, the MAX693MLP supports automatic battery backup switchover between V_CC and V_BATT. It operates with V_BATT in the 2.0V to 4.0V range and switches V_OUT to the higher of the two supplies. Switchover occurs at V_CC = V_BATT + 70mV (rising) or V_BATT + 50mV (falling), with 20mV hysteresis. In battery mode, V_OUT delivers up to 250µA at V_BATT – 0.1V while consuming only 1µA quiescent current - making the MAX693MLP ideal for long-term CMOS RAM or RTC backup using coin cells or lithium batteries.

How does the CE gating function work on the MAX693MLP?

The MAX693MLP implements CE gating using CE IN and CE OUT pins: when V_CC is above the 4.4V reset threshold, CE OUT follows CE IN with ≤200ns propagation delay; if V_CC falls below 4.4V, CE OUT is forced high regardless of CE IN state. This prevents spurious writes to battery-backed CMOS RAM or EEPROM during power-up, brownout, or shutdown. The MAX693MLP's CE gating is hardware-enforced and requires no firmware intervention - a key differentiator from software-based write-protection schemes that may fail under lockup conditions.

Can the watchdog timeout period of the MAX693MLP be adjusted, and how?

Yes, the MAX693MLP watchdog timeout is fully configurable. With OSC SEL floating or high, setting OSC IN low selects 100ms timeout; leaving OSC IN floating selects 1.6s. With OSC SEL low, OSC IN accepts an external clock (0–250kHz) or a capacitor (e.g., 47pF yields ~400ms/1.6s depending on variant). All configurations retain the 50ms reset pulse width (except MAX695 variants). This flexibility allows tuning to match firmware execution cycles - critical for safety-critical applications where watchdog response must align with task deadlines.

What is the purpose of the BATT ON pin on the MAX693MLP?

The BATT ON pin on the MAX693MLP is an active-high, 25mA-sinking output that signals when V_OUT is sourced from V_BATT. It directly drives the base of an external PNP transistor to boost backup current beyond the 50mA limit of the internal V_OUT switch. This eliminates the need for discrete level-shifting or current-amplification circuitry. In designs requiring >50mA RAM/RTC backup - such as those with multiple SRAM banks or real-time clocks with alarm circuitry - the BATT ON pin enables simple, reliable high-current battery switchover without adding complexity or failure points.