Microchip Technology MIC2951-4.85BM

Overview

MIC2951-4.85BM from Micrel is a 150mA low-dropout linear voltage regulator with fixed 4.85V output, ±1% initial accuracy, 250mV dropout at 100mA load, and integrated error flag and shutdown control - designed for automotive and battery-powered systems requiring robust transient protection and precise regulation.

For engineers reviewing the MIC2951-4.85BM datasheet, MIC2951-4.85BM pinout, MIC2951-4.85BM application, or MIC2951-4.85BM equivalent, key selection criteria include its –20V reverse-battery tolerance, +60V load-dump survival, 120µA quiescent current at light load, and SOIC-8 package compatibility with logic-controlled enable and open-collector error reporting.

Technical Context

The MIC2951-4.85BM integrates a precision 1.235V bandgap reference, error amplifier, open-collector comparator, and TTL-compatible shutdown input in an 8-pin SOIC package. Its feedback architecture supports both fixed-output (via internal TAP resistor network) and adjustable configurations, though the -4.85BM variant is factory-trimmed to deliver 4.85V ±1% over –40°C to +125°C.

It employs thermal and current limiting for fault protection, maintains 0.1% typical line regulation and 0.2% typical load regulation, and achieves 50 ppm/°C reference voltage temperature coefficient - enabling stable operation as both regulator and voltage reference in high-reliability embedded systems.

Key Specifications

Pinout & Package

Package: 8-pin SOIC (M), body size 3.9mm × 4.9mm, 1.27mm pitch, JEDEC MS-012AC compliant.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar low-dropout regulator applications.

Compared with LM2951CM-4.85/NOPB and TPS7A2033PDBVR, the MIC2951-4.85BM uniquely combines automotive-grade transient protection, integrated error signaling, and fixed 4.85V accuracy in a single SOIC-8 package - reducing system-level component count and validation effort for safety-critical embedded power rails.

Availability

MIC2951-4.85BM is available at Aetrix Electronics and suitable for automotive electronics, industrial sensor nodes, avionics monitoring units, and portable medical diagnostics requiring stable component supply across extended temperature and harsh electrical environments.

Supply support for MIC2951-4.85BM 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

Micrel Inc. was a U.S.-based semiconductor company specializing in analog, power management, and timing solutions, acquired by Microchip Technology in 2015.

The MIC2951 product line was engineered for high-reliability linear regulation in electrically hostile environments - specifically targeting automotive, avionics, and industrial applications demanding wide-input tolerance, low quiescent current, and integrated fault signaling.

FAQ

What is the guaranteed output voltage tolerance of the MIC2951-4.85BM over temperature?

The MIC2951-4.85BM guarantees ±1% output voltage accuracy over the full –40°C to +125°C junction temperature range. At 25°C, typical output is 4.850V with min/max of 4.802V and 4.899V; over temperature, the range widens to 4.753V–4.947V. This specification is confirmed in the Electrical Characteristics table on page 4 of the February 2010 datasheet (M9999-021610), and applies specifically to the -4.85BM variant.

Does the MIC2951-4.85BM require an external capacitor on the FB pin for stability?

Yes - stray capacitance on the FB pin (pin 7) of the MIC2951-4.85BM can cause instability, especially when using high-value external resistors. The datasheet recommends adding a 100pF capacitor between OUT and FB, and increasing the main output capacitor to ≥3.3µF, if high-precision programming or low-noise operation is required. This is explicitly stated in the Application Information section on page 11.

Can the MIC2951-4.85BM be used in adjustable-output mode?

No - the MIC2951-4.85BM is a factory-trimmed fixed-output variant. While the MIC2951 family supports adjustable operation via external resistors on the FB pin, the -4.85BM part uses internal resistor taps (pins 2 and 6) to set 4.85V and is not intended for reconfiguration. Attempting to override the internal TAP network may degrade accuracy or stability, as noted in the Programming section on page 12.

What is the maximum continuous input voltage rating for the MIC2951-4.85BM?

The MIC2951-4.85BM has a maximum continuous input voltage rating of +30V DC. Although it can survive +60V transients, those are strictly limited to ≤100ms duration and ≤1% duty cycle per Absolute Maximum Ratings (page 4). Continuous operation above 30V violates the operating rating and risks permanent damage, as confirmed in the Operating Ratings table.

How does the ERR pin of the MIC2951-4.85BM behave during startup and dropout?

The ERR pin of the MIC2951-4.85BM is an open-collector output that goes low when VOUT drops ≥5% below nominal (i.e., ≤4.61V), and floats (high-impedance) otherwise. Per Figure 1 on page 12, ERR becomes valid (low) at ~1.3V input and returns high at ~5V input for 4.85V output - meaning it remains asserted during brownout and releases only after sufficient headroom is restored. This behavior is intrinsic to the MIC2951-4.85BM's comparator design and does not require external timing components.