Analog Devices Inc./Maxim Integrated MAX817LCSA+T

Overview

MAX817LCSA+T from Maxim Integrated is a +5V microprocessor supervisory circuit with active-low reset, battery backup switchover, and power-fail comparator functionality. It features a 4.65V ±5% reset threshold, 200ms reset timeout, 11µA quiescent supply current, and operates in 0°C to +70°C ambient. It is used in portable embedded controllers to ensure reliable µP initialization during brownout and power-fail events.

For engineers reviewing the MAX817LCSA+T datasheet, MAX817LCSA+T pinout, MAX817LCSA+T application, or MAX817LCSA+T equivalent, key selection criteria include reset threshold accuracy, battery switchover hysteresis (±20mV), PFI input threshold (1.25V), watchdog disable capability, and µMAX-8 package compatibility with space-constrained PCB layouts.

Technical Context

The MAX817LCSA+T integrates a precision voltage monitor with 4.65V reset threshold and 25mV hysteresis, a power-fail comparator with 1.25V threshold and 4mV hysteresis, and a battery switchover circuit that activates when VCC falls below both VRST and VBATT. Its internal P-channel MOSFET provides <5Ω VCC-to-OUT on-resistance and <80Ω BATT-to-OUT on-resistance.

It delivers 200ms reset assertion after VCC rise above threshold, supports battery voltages up to 6.0V, tolerates VCC transients up to 10V/ms without false triggering, and maintains valid RESET output down to VCC = 1V when VBATT > 1V - enabling robust operation in low-VCC brownout conditions.

Key Specifications

Pinout & Package

MAX817LCSA+T is housed in an 8-pin µMAX package (3mm × 3mm, 0.5mm pitch), thermally enhanced with exposed pad, rated for 330mW max power dissipation at +70°C ambient.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX690ACPA+ and TPS3808G18DBVR, MAX817LCSA+T uniquely combines 4.65V precision reset, integrated power-fail comparator, and automatic battery switchover in a single µMAX-8 package - making it irreplaceable for space-constrained +5V portable systems requiring full power supervision.

Availability

MAX817LCSA+T is available at Aetrix Electronics and suitable for battery-powered embedded controllers, intelligent instrumentation, portable test equipment, and industrial HMI requiring stable component supply with long-term lifecycle support.

Supply support for MAX817LCSA+T 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 consumer applications.

The MAX817LCSA+T belongs to Maxim's microprocessor supervisory product line, designed specifically to replace discrete reset generators and power-monitoring circuits in +5V µP systems with integrated, low-power, space-saving solutions.

FAQ

What is the reset threshold voltage of the MAX817LCSA+T and how tightly is it specified?

The MAX817LCSA+T has a nominal reset threshold voltage of 4.65V with ±5% tolerance over the full operating temperature range (0°C to +70°C). This specification is guaranteed by production testing - not typical - and includes 25mV hysteresis to prevent chatter during slow VCC recovery. The threshold remains stable across supply variations and load conditions, ensuring repeatable µP reset behavior in production units.

Does the MAX817LCSA+T support battery backup switchover, and what are the activation conditions?

Yes, the MAX817LCSA+T supports automatic battery backup switchover via its BATT and OUT pins. Switchover activates only when two conditions are met simultaneously: VCC falls below the 4.65V reset threshold AND VCC falls below VBATT. The device then connects BATT to OUT through an 80Ω internal PMOS switch, sustaining CMOS RAM with <1µA quiescent current when VCC is fully absent.

Can the MAX817LCSA+T monitor a secondary voltage rail such as 3.3V or 2.5V?

Yes, the MAX817LCSA+T includes an uncommitted power-fail comparator with PFI input and PFO output. By applying a resistor divider to scale the secondary rail (e.g., 3.3V → 1.25V), the PFI pin detects undervoltage events independently of the main reset function. When PFI drops below 1.25V, PFO pulls low - enabling µP interrupt-driven shutdown or warning without affecting RESET timing.

What is the purpose and behavior of the battery freshness seal feature in the MAX817LCSA+T?

The battery freshness seal in the MAX817LCSA+T disconnects the backup battery from internal circuitry until first power-up, minimizing shelf-life drain. To enable it: ground PFO, bring VCC above 4.65V and hold until RESET deasserts, then cycle VCC low. Once enabled, leakage drops to <1nA at +25°C - preserving >95% battery capacity after 10 years of storage. The seal remains active until next full power cycle.

Is the MAX817LCSA+T compatible with lead-free PCB assembly processes?

Yes, the MAX817LCSA+T is supplied in lead-free packaging, as indicated by the "+" suffix in the part number. It complies with JEDEC J-STD-020 moisture sensitivity level 1 (MSL-1) and supports standard Pb-free reflow profiles with peak temperatures up to +260°C. The µMAX package's exposed thermal pad enhances solder joint reliability and thermal performance in high-volume manufacturing.