Microchip Technology MCP1791-3002E/ET

Overview

MCP1791-3002E/ET from Microchip Technology is a 5-pin, fixed-output 3.0V low-dropout linear regulator designed for automotive and industrial 12/24VDC systems. It delivers up to 70 mA at +125°C junction temperature, features 48V load dump protection (<500 ms), ±2.5% output voltage tolerance over -40°C to +125°C, and integrates shutdown control (SHDN) and power-good indication (PWRGD). It powers microcontrollers in fire alarm sensors and HVAC controls.

For engineers reviewing the MCP1791-3002E/ET datasheet, MCP1791-3002E/ET pinout, MCP1791-3002E/ET application, or MCP1791-3002E/ET equivalent, key selection criteria include its 30V max continuous input, 70 µA typical quiescent current, thermal shutdown at 157°C, short-circuit foldback at 2.7V (for 3.0V output), and compatibility with 4.7 µF ceramic or 1 µF tantalum output capacitors.

Technical Context

The MCP1791-3002E/ET implements a CMOS-based LDO architecture with internal reference, error amplifier, and pass transistor. Its VIN monitoring circuit enforces 6.0V minimum startup voltage and includes undervoltage lockout independent of SHDN control.

It integrates dual protection: thermal shutdown (157°C trip, 20°C hysteresis) and short-circuit current limiting (99 mA typical foldback for 3.0V output), plus PSRR of -90 dB at 100 Hz. The PWRGD open-drain output asserts when VOUT reaches 88–92% of nominal (3.0V), with 30 µs rise delay and 235 µs fall delay.

Key Specifications

Pinout & Package

SOT-223-5 package with exposed GND tab; pin 1 = SHDN (active-low enable), pin 2 = VIN, pin 3 = GND (tab), pin 4 = VOUT, pin 5 = PWRGD (open-drain). Tab must be soldered to PCB ground plane for thermal and electrical integrity.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar LDO regulator applications.

Compared with NCP163AMX300TBG and TPS7B6733QPWPRQ1, the MCP1791-3002E/ET uniquely combines 3.0V output, integrated SHDN/PWRGD, 48V load dump protection, and SOT-223-5 packaging - making it optimal for space-constrained, cost-sensitive automotive and fire safety modules where precise 3.0V regulation and built-in sequencing are mandatory.

Availability

MCP1791-3002E/ET is available at Aetrix Electronics and suitable for automotive accessory adapters, electronic thermostat controls, low-voltage fire alarm sensors, microcontroller power rails, and HVAC control systems requiring stable component supply across extended temperature and transient conditions.

Supply support for MCP1791-3002E/ET 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

Microchip Technology Inc. is a leading provider of microcontrollers, analog devices, and Flash-IP solutions, serving automotive, industrial, communications, and consumer markets with high-reliability silicon and development tools.

The MCP1790/MCP1791 product line was engineered specifically for harsh-environment power management - delivering robust 3.0V/3.3V/5.0V regulation in automotive 12/24VDC and commercial 24VAC fire alarm systems where load dump survival and ultra-low quiescent current are non-negotiable.

FAQ

What is the maximum input voltage the MCP1791-3002E/ET can withstand continuously?

The MCP1791-3002E/ET supports a continuous input voltage range of 6.0V to 30.0V. Its absolute maximum rating is +48.0V for transient events only - specifically designed to survive FORD Test Pulse G (43.5V ±10%) load dump transients lasting under 500 ms with a 30-second repetition rate. Continuous operation above 30V violates specification and risks permanent damage.

Does the MCP1791-3002E/ET require an external pull-up resistor on the PWRGD pin?

Yes, the MCP1791-3002E/ET PWRGD pin is an open-drain output and requires an external pull-up resistor to VOUT (3.0V) or another compatible rail. Typical values range from 10 kΩ to 100 kΩ. Without this pull-up, PWRGD cannot assert a valid high state, breaking power sequencing functionality in systems relying on this signal for reset or enable timing.

Can the MCP1791-3002E/ET operate with a 1 µF ceramic output capacitor?

No - the MCP1791-3002E/ET requires a minimum of 4.7 µF ceramic output capacitance (X7R/X5R) for stability. A 1 µF ceramic capacitor will cause oscillation unless a 0.3 Ω series resistor is added. For 1 µF output capacitance, use tantalum or aluminum electrolytic types instead, which meet the stability requirement per datasheet Section 4.7.

What is the thermal shutdown behavior of the MCP1791-3002E/ET?

The MCP1791-3002E/ET triggers thermal shutdown at a typical junction temperature of +157°C and recovers when temperature falls to approximately +137°C due to 20°C hysteresis. During shutdown, output is disabled and quiescent current drops to ~10 µA. Recovery is automatic and does not require cycling VIN or SHDN - but sustained overload will cause repeated cycling if PCB thermal design cannot dissipate heat.

How does the SHDN pin behave when left unconnected?

When the SHDN pin of the MCP1791-3002E/ET is left floating, its internal pull-down resistor forces it below 0.8V, placing the device into shutdown mode with 10 µA quiescent current. To enable normal operation, SHDN must be actively driven to ≥2.4V (e.g., via MCU GPIO or resistor divider from VIN). This fail-safe behavior prevents unintended power-up in noisy or undriven systems.