Analog Devices Inc./Maxim Integrated MAX802LCPA

Overview

MAX802LCPA from Maxim Integrated is a microprocessor supervisory IC providing power-on reset, battery-backup switchover, watchdog timer, and power-fail detection in a single 8-pin DIP package. It asserts active-low RESET during power-up (VCC ≥ 1V), brownout (VCC < 4.65V), and watchdog timeout (1.6s), with 200ms reset pulse width and ±2% power-fail accuracy. Used in battery-powered controllers to preserve CMOS RAM during main supply failure.

For engineers reviewing the MAX802LCPA datasheet, MAX802LCPA pinout, MAX802LCPA application, or MAX802LCPA equivalent, key selection criteria include its 4.65V reset threshold, 200μA quiescent current, 50nA battery-backup mode current, guaranteed RESET assertion down to VCC = 1V, and compatibility with +5V μP systems requiring stable low-power supervision.

Technical Context

The MAX802LCPA integrates four independent functional blocks: a precision voltage monitor with 4.65V threshold and 40mV hysteresis, a 1.6s watchdog timer cleared by WDI edges or RESET assertion, a battery switchover circuit using an 80Ω PMOS switch when VCC falls below threshold and VBATT > VCC+20mV, and a 1.25V reference-based power-fail comparator driving PFO.

Its internal architecture ensures deterministic timing: RESET remains low for 200ms after VCC rises above 4.65V, and the watchdog disables automatically if WDI is floating or three-stated. The device operates from 1.0V to 5.5V on VCC or VBATT, with separate 5Ω (VCC-to-VOUT) and 80Ω (VBATT-to-VOUT) output switches enabling efficient RAM backup without external components.

Key Specifications

Pinout & Package

MAX802LCPA is housed in an 8-pin plastic DIP (PDIP) package with 0.3-inch width, RoHS-compliant lead finish, and standard through-hole mounting. Pin 1 is marked with a notch or dot; pin numbering follows counter-clockwise convention from top-left corner.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX802LCPA, MAX802LCSA offers identical functionality in a smaller footprint for modern SMT layouts, while MAX805LCPA serves distinct μP interface requirements with inverted reset polarity-neither is pin-compatible replacement without schematic or firmware adjustment.

Availability

MAX802LCPA is available at Aetrix Electronics and suitable for industrial data loggers, medical patient monitors, and smart energy meters requiring stable component supply across extended temperature ranges (0°C to +70°C).

Supply support for MAX802LCPA 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 applications.

The MAX802L series belongs to Maxim's microprocessor supervisory product line, designed specifically to replace discrete reset circuits and battery switchover diodes in +5V μP systems with guaranteed timing and low-power operation.

FAQ

What is the guaranteed reset threshold voltage for MAX802LCPA?

The MAX802LCPA has a guaranteed reset threshold of 4.65V with ±2% tolerance over temperature and supply variations. This value is specified for VCC falling conditions and ensures reliable reset assertion in +5V systems experiencing brownout. The threshold is internally trimmed and does not require external calibration. MAX802LCPA maintains this specification across its full operating temperature range of 0°C to +70°C.

How does the watchdog timer in MAX802LCPA operate?

The MAX802LCPA watchdog timer triggers a RESET pulse if the WDI pin remains static (high or low) for 1.6 seconds. It clears on any rising or falling edge at WDI, or when RESET is asserted. If WDI is left floating or connected to a high-impedance buffer, the watchdog disables automatically. The timer is not active during battery-backup mode unless WDI is driven. MAX802LCPA guarantees 1.6s timeout with ±37.5% variation (1.00s to 2.25s) over temperature and voltage.

Can MAX802LCPA operate with VCC below 4.65V and still assert RESET?

Yes, MAX802LCPA guarantees RESET assertion down to VCC = 1.0V, making it suitable for deep brownout conditions. As VCC drops below 4.65V, RESET goes low and remains low until VCC rises above the threshold plus 40mV hysteresis, then holds low for 200ms. Even at VCC = 1.0V, the output can sink 50μA while maintaining valid logic levels. This behavior is explicitly characterized and guaranteed in the MAX802LCPA datasheet.

What is the maximum allowable backup battery voltage for MAX802LCPA?

The maximum allowable backup battery voltage for MAX802LCPA is 4.80V, as specified in Table 2 of the datasheet. Exceeding this voltage risks forward-biasing the internal substrate diode (D1) when VCC approaches the reset threshold, causing unintended current flow from VBATT to VCC. Lithium batteries with open-circuit voltages of 3.0V–3.6V are ideal; higher-voltage sources require external regulation to stay within the 4.80V limit. MAX802LCPA enforces this constraint via internal design, not external components.

Does MAX802LCPA support power-fail warning for supplies other than +5V?

Yes, MAX802LCPA supports power-fail warning for non-+5V supplies using the PFI input and internal 1.25V reference. By configuring an external resistor divider, users can scale any positive supply (e.g., +3.3V, +12V) to produce 1.25V at PFI when the supply reaches its trip point. The PFI input draws only 25nA max, minimizing divider error. PFO then asserts low to signal impending failure. MAX802LCPA's ±2% power-fail accuracy applies to this function when used with properly calculated dividers.