Analog Devices Inc./Maxim Integrated MAX6338BUB+

Overview

MAX6338BUB from Maxim Integrated is a quad voltage monitor IC designed for multivoltage system supervision, monitoring +5.0V (−5% threshold), +3.3V (−5% threshold), +2.5V (−10% threshold), and an adjustable input with 1.23V internal reference. It delivers 25µA typical supply current, operates from +2.5V to +5.5V, and guarantees performance across −40°C to +85°C in a 10-pin µMAX package. Used in desktop computers and telecom equipment for reliable power-good signaling.

For engineers reviewing the MAX6338BUB datasheet, MAX6338BUB pinout, MAX6338BUB application, or MAX6338BUB equivalent, key selection criteria include factory-programmed trip thresholds per input, open-drain active-low outputs with internal 10µA pull-ups to VCC, undervoltage lockout below 2.5V, and support for wire-ORed "power good" logic without external components.

Technical Context

The MAX6338BUB integrates four independent comparators, each with a dedicated input and open-drain output. Inputs IN1–IN3 are factory-trimmed for +5.0V (−5%), +3.3V (−5%), and +2.5V (−10%) nominal supplies; IN4 is adjustable via external resistor divider referenced to the 1.23V bandgap. All comparators share a common 60ppm/°C threshold temperature coefficient and built-in 0.3% hysteresis.

Internal undervoltage lockout forces all outputs low when VCC drops below 2.5V. Outputs feature weak 10µA internal pull-ups to VCC-compatible with external pull-ups up to +5.5V-and support wire-OR configuration. The device uses BiCMOS process technology and requires no external components for basic operation.

Key Specifications

Pinout & Package

MAX6338BUB is housed in a 10-pin µMAX® package (3.0mm × 3.0mm, 0.6mm height, 0.5mm pitch), RoHS-compliant and available in lead-free format. Pin 1 is IN1; pin 5 is GND; pins 6–9 are OUT4–OUT1; pin 10 is VCC.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar quad voltage monitoring applications.

Compared with MAX6338BUB, MAX6337BUB+ omits the fourth monitor but retains identical accuracy and low ICC, while TPS3307-33DGNR trades integration for higher drive strength and vendor-specific toolchain alignment-neither offers pin compatibility or identical threshold programming.

Availability

MAX6338BUB is available at Aetrix Electronics and suitable for desktop computers, telecom line cards, and data storage controllers requiring stable component supply with guaranteed long-term manufacturability and consistent electrical performance.

Supply support for MAX6338BUB 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 industrial, computing, and communications markets, emphasizing low-power, high-reliability performance.

The MAX6338BUB belongs to Maxim's supervisory IC product line, engineered specifically for multivoltage system power integrity assurance in space-constrained, thermally demanding environments.

FAQ

What is the exact threshold voltage for the +2.5V input on MAX6338BUB?

The +2.5V input (IN3) on MAX6338BUB is factory-trimmed for a −10% tolerance, resulting in a typical trip threshold of 2.19V (range: 2.13V to 2.25V) as specified in the Electrical Characteristics table. This value is guaranteed over the full −40°C to +85°C operating temperature range and does not require external calibration. The MAX6338BUB uses an internal bandgap reference to maintain this accuracy without external components.

Does MAX6338BUB support monitoring a negative supply like −5.0V?

No, MAX6338BUB does not support −5.0V monitoring. Its IN1–IN3 inputs are configured for +5.0V (−5%), +3.3V (−5%), and +2.5V (−10%), and IN4 is adjustable only for positive voltages ≥1.23V. The −5.0V option appears in other variants (e.g., MAX6338MUB), but MAX6338BUB's Selector Guide entry explicitly lists IN3 as +2.5V† with 10% tolerance - confirming no negative input capability. Use MAX6338NUB for −5.0V support.

Can the outputs of MAX6338BUB be tied together for a single "power good" signal?

Yes, the four open-drain outputs (OUT1–OUT4) of MAX6338BUB can be wire-ORed using a single external pull-up resistor to VCC or another logic rail. Each output has a weak 10µA internal pull-up, but external pull-up ensures robust logic-high level and faster rise time. When any monitored supply fails, its corresponding output pulls low, asserting the combined signal - a standard implementation confirmed in the Applications Information section and Figure 2 of the datasheet.

What is the minimum VCC required for MAX6338BUB to function correctly?

MAX6338BUB requires a minimum VCC of +2.5V to operate. Below this level, the internal undervoltage lockout circuit forces all four outputs low regardless of input conditions - a hardwired safety feature. The device draws only 25µA typical current at +5V and remains functional down to +2.5V, with full specification compliance across the entire +2.5V to +5.5V range. Operation below +2.5V is undefined and not recommended.

How is the adjustable input (IN4) threshold set on MAX6338BUB?

The adjustable input (IN4) on MAX6338BUB uses an internal 1.23V bandgap reference. Threshold voltage V_INTH is set by an external resistor divider: R1 = R2 × (V_INTH/1.23 − 1). For example, to detect 4.5V, use R2 = 100kΩ and R1 = 265kΩ. The MAX6338BUB datasheet confirms this method in Figure 6 and the Auxiliary Input section, and specifies that unused IN4 must be tied to GND or VCC - floating is prohibited.