Analog Devices Inc./Maxim Integrated MAX5091AASA+

Overview

MAX5091AASA+ from Maxim Integrated is a high-voltage, low-quiescent-current linear regulator with integrated reset supervisor and power-fail comparator. It delivers a fixed +5V output at up to 100mA, operates from +5V to +28V input, withstands 40V transients, features 50mV max dropout at 100mA, and includes active-low open-drain RES and SO outputs. It serves as a primary power supply and system monitor in automotive body control modules.

For engineers reviewing the MAX5091AASA+ datasheet, MAX5091AASA+ pinout, MAX5091AASA+ application, or MAX5091AASA+ equivalent, key selection considerations include its -40°C to +125°C automotive temperature range, programmable reset timeout via external capacitor, uncommitted sense comparator for voltage monitoring, thermal shutdown at +165°C, and SO-EP package's 1.5W power dissipation at +70°C.

Technical Context

The MAX5091AASA+ integrates a PNP-based LDO pass element with factory-trimmed feedback for precise +5V regulation, an always-on reset circuit monitoring VOUT against 90% of nominal output (VRT = 90% × VOUT), and a separate uncommitted comparator with 1.16V threshold (VST) on SI input. Its CT pin enables adjustable reset delay using a single capacitor, while EN provides TTL-compatible enable/disable control with internal 3.6V pullup.

Regulator stability is ensured with only 10μF ceramic output capacitance (0603 case), and fault protection includes current limiting (260mA typ), short-circuit survival at VS ≤ 16V, and thermal shutdown with 20°C hysteresis. The SO-EP package's exposed paddle connects internally to GND and requires PCB copper attachment for thermal performance.

Key Specifications

Pinout & Package

The MAX5091AASA+ is housed in an 8-pin SO-EP (Small Outline–Exposed Pad) package with JEDEC MO-153AC outline, 1.5W thermal rating at +70°C, and θJA = 52°C/W. The exposed paddle (EP) must be soldered to PCB ground plane for effective heat dissipation and electrical grounding.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar high-voltage LDO with reset and supervision applications.

Compared with TPS7B6750QDGNRQ1 and LM2940T-5.0/NOPB, the MAX5091AASA+ uniquely combines 100mA LDO regulation, programmable reset timeout, and dual-supervision (RES + SO) in a single SO-EP package-reducing component count and PCB area where both power-good and power-fail detection are required.

Availability

MAX5091AASA+ is available at Aetrix Electronics and suitable for automotive body electronics, industrial PLC I/O modules, home security panels, and telecom remote terminal units requiring stable component supply across extended temperature and transient-voltage conditions.

Supply support for MAX5091AASA+ 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 automotive, industrial, and communications markets.

The MAX5091AASA+ belongs to Maxim's high-voltage LDO family engineered for automotive body electronics and industrial control systems requiring robust input transient handling, low IQ, and integrated power supervision.

FAQ

What is the maximum input voltage the MAX5091AASA+ can withstand without damage?

The MAX5091AASA+ withstands input transients up to +40V for durations ≤1 second, as specified in its Absolute Maximum Ratings. Continuous operation is rated from +5V to +28V. This 40V transient capability protects against automotive load-dump events. Exceeding +40V-even briefly-may cause permanent damage, so external clamping is recommended if higher transients are expected in the system design. The MAX5091AASA+'s internal protection does not extend beyond this limit.

How is the reset timeout period configured on the MAX5091AASA+?

The reset timeout period on the MAX5091AASA+ is set by connecting an external capacitor between the CT pin and GND. The delay follows tRD ≈ 35μs + (10⁶ × CCT), where CCT is in farads-for example, a 100nF capacitor yields ~100ms delay. CT is pulled high to VOUT during normal operation and driven low during reset, shutdown, or thermal fault. No resistor is required; only the capacitor determines timing. The MAX5091AASA+ datasheet provides the exact equation and tolerance band for production design.

Does the MAX5091AASA+ require an external pullup resistor on the RES pin?

Yes, the MAX5091AASA+ RES pin is an open-drain output and requires an external pullup resistor to VOUT. Typical values range from 10kΩ to 100kΩ, selected to ensure VRL ≤ 0.4V when sinking up to 825μA. The pullup establishes the high state (logic high) when the internal MOSFET is off; without it, RES remains floating and cannot signal reset completion. This requirement applies identically to the SO pin. The MAX5091AASA+ does not include internal pullups on either RES or SO.

Can the MAX5091AASA+ operate with a 3.3V input supply?

No, the MAX5091AASA+ cannot regulate from a 3.3V input. Its minimum input voltage is +5V for proper regulation, and its dropout voltage is 500mV at 100mA-so it requires at least 5.5V input to sustain 5V output under full load. At lower inputs (e.g., 4.75V), output collapses into dropout with increasing load. The device will not function below +5V, and attempting to operate it at 3.3V may result in undefined behavior or failure to start. For 3.3V input systems, a different regulator architecture is required. The MAX5091AASA+ is strictly a high-input LDO.

What is the thermal performance difference between the SO-EP and TDFN-EP packages for the MAX5091AASA+?

The MAX5091AASA+ uses the SO-EP package (θJA = 52°C/W, PD = 1.538W at +70°C), whereas the TDFN-EP variant (MAX5091AATA+T) offers superior thermal performance (θJA = 41°C/W, PD = 1.951W at +70°C). The SO-EP's higher junction-to-ambient resistance means it reaches thermal shutdown faster under identical load/ambient conditions. For designs requiring >100mA at elevated temperatures or limited PCB copper area, the TDFN-EP is preferred-but the MAX5091AASA+ itself is only offered in SO-EP, so thermal design must accommodate its 52°C/W rating.