Analog Devices Inc./Maxim Integrated MAX6304CSA+T

Overview

MAX6304CSA+T from Maxim Integrated is an active-high, push-pull microprocessor supervisory circuit with adjustable reset threshold (≥1.22V), adjustable reset timeout (2.8–5.2 ms with 1500pF), and adjustable watchdog timeout (2.8–5.2 ms normal mode / 1.4–2.6 s extended mode). It features 4µA supply current, power-supply transient immunity, and operates from 1.31V to 5.5V - used in battery-powered medical instruments and embedded controllers requiring reliable brownout detection and software hang protection.

For engineers reviewing the MAX6304CSA+T datasheet, MAX6304CSA+T pinout, MAX6304CSA+T application, or MAX6304CSA+T equivalent, this page delivers verified electrical parameters, SO-8 package layout guidance, real-world timing behavior under temperature and voltage variation, and validated alternative options for reset/watchdog supervision in low-power µP systems.

Technical Context

The MAX6304CSA+T implements a precision bandgap reference (1.22V ±25mV) feeding a comparator that monitors RESET IN via external resistor divider. Its reset assertion is guaranteed valid down to VCC = 1.31V, with hysteresis of 20mV and input leakage <±1nA. The device uses two independent precision current sources (500nA) at SRT and SWT pins to generate timing intervals linearly proportional to capacitor values.

Watchdog operation supports dual modes: normal (WDS = GND) yields µs-range timeouts; extended mode (WDS = VCC) multiplies timeout by 500× using internal counter scaling. WDI accepts 30ns pulses and exhibits 100pA leakage in normal mode, rising to ±70µA when driven high in extended mode. Reset deassertion occurs after programmable tRP delay following VIN > VRST.

Key Specifications

Pinout & Package

MAX6304CSA+T is housed in an 8-pin SO (Small Outline) package per JEDEC MS-012, with 1.27mm pitch, body size 4.9mm × 6.0mm, and RoHS-compliant lead-free finish (+ suffix). Pin 1 is marked by beveled corner or dot.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX6304CSA+T, MAX6302CSA+T offers identical timing adjustability but requires external biasing for RESET, while TPS3808G33DBVR sacrifices configurability for ultra-low current and small size - making MAX6304CSA+T the sole option supporting both adjustable reset threshold and 500× watchdog extension in SO-8.

Availability

MAX6304CSA+T is available at Aetrix Electronics and suitable for medical portable monitors, industrial embedded controllers, set-top box power management, and intelligent sensor nodes requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for MAX6304CSA+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) designs precision analog and mixed-signal ICs for power, sensing, and interface applications - known for high-reliability, low-power solutions in demanding environments.

The MAX6301–MAX6304 family was engineered specifically for µP supervision in battery-constrained and noise-prone systems, emphasizing adjustable thresholds, ultra-low ICC, and robust timing control without external crystals or complex configuration.

FAQ

What is the minimum VCC required for MAX6304CSA+T to assert a valid RESET signal?

The MAX6304CSA+T guarantees active-high RESET assertion for VCC ≥ 1.31V. Below this voltage, output drive capability degrades; however, the device remains functional down to VCC = 1V with reduced sink/source current. For applications requiring valid RESET down to 0V, a 100kΩ pullup from RESET to VCC is recommended per Figure 10 in the datasheet - ensuring MAX6304CSA+T maintains defined logic state across full power collapse.

How do I calculate the resistor values for a 3.3V reset threshold using MAX6304CSA+T?

To set VRST = 3.3V, use the formula VRST = 1.22 × (R1 + R2)/R2. Select R2 = 1MΩ (standard high-impedance value), then solve: 3.3 = 1.22 × (R1 + 1M)/1M → R1 ≈ 1.72MΩ. Use 1.72MΩ (or nearest E96 value 1.74MΩ) for R1. Both resistors should be ≤1% tolerance metal film types to maintain threshold accuracy within ±25mV over temperature.

Can MAX6304CSA+T monitor a 1.8V supply rail?

Yes - MAX6304CSA+T can monitor any voltage ≥1.22V using the RESET IN pin and external resistor divider. For a 1.8V rail, configure R1 and R2 such that VRST = 1.22 × (R1 + R2)/R2 = 1.8V. Example: with R2 = 1MΩ, R1 = 470kΩ yields VRST ≈ 1.80V. Ensure the divider draws <100nA to avoid loading effects, and verify timing capacitor leakage <10nA for accurate tRP/tWD.

What happens to the watchdog timer when WDS is toggled during operation?

Toggling WDS resets the watchdog timer to zero regardless of current state - this is explicitly documented in the Pin Description section. If WDS transitions from GND to VCC, the device enters extended mode and restarts timing with ×500 scaling; if WDS transitions from VCC to GND, it reverts to normal mode and restarts with base timeout. This behavior enables dynamic wake-up/sleep mode switching, as demonstrated in Figure 5 using an 80C51.

Is MAX6304CSA+T pin-compatible with other devices in the MAX6301–MAX6304 family?

Yes - all MAX6301–MAX6304 variants share identical 8-pin SO, PDIP, and µMAX packages and pinouts. The MAX6304CSA+T differs only in output polarity (active-high) and drive type (push-pull), matching the pin mapping shown in the Typical Operating Circuit diagram. No PCB redesign is needed when substituting within this family, though RESET logic polarity and external pull-up requirements must be verified in system firmware and schematic.