Microchip Technology MIC79050-4.2YM-TR

Overview

MIC79050-4.2YM-TR from Microchip Technology is a fixed-output 4.2 V linear lithium-ion battery charger IC with ±0.75% voltage accuracy over –5°C to +60°C, 380 mV dropout at 500 mA, and integrated thermal shutdown/current-limit protection. It operates from 2.5 V to 16 V input and delivers up to 500 mA charging current in an 8-lead SOIC package with logic-controlled enable and feedback pins - used in compact portable Li-ion charging systems including cellular phones and PDAs.

For engineers reviewing the MIC79050-4.2YM-TR datasheet, MIC79050-4.2YM-TR pinout, MIC79050-4.2YM-TR application, or MIC79050-4.2YM-TR equivalent, this page provides verified technical context, real-world design meaning of key specs, validated pin functions, application-specific implementation guidance, and two confirmed alternative parts for Li-ion single-cell charging designs requiring high-accuracy termination and low-quiescent operation.

Technical Context

The MIC79050-4.2YM-TR implements a precision linear charging architecture using an internal PNP pass transistor controlled by a bandgap-referenced error amplifier. Its feedback (FB) and enable (EN) pins allow external control of regulation and shutdown - enabling pulse-charging topologies and end-of-charge detection via comparator circuits.

It supports both unregulated wall adapters (via load-line current limiting) and regulated sources, with line regulation of 0.009%/V and load regulation of 0.05% over 100 µA–500 mA. Thermal regulation is 0.05%/W, and reverse leakage is limited to ≤10 µA when input is floating or grounded.

Key Specifications

Pinout & Package

Package: 8-Lead SOIC (Small Outline Integrated Circuit), thermally enhanced with internally connected GND pins (pins 5–8) tied to die attach paddle for improved θ_JA = 63°C/W.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar lithium-ion single-cell charging applications.

Compared with MIC79050-4.2YM-TR, the MCP73831T-420I/OT offers tighter voltage accuracy but no enable or feedback control, while the BQ24075RGTR adds programmability and system power features at the cost of complexity and external dependencies - making MIC79050-4.2YM-TR optimal for simple, robust, pin-controlled Li-ion charging where minimal external components and zero-off current are critical.

Availability

MIC79050-4.2YM-TR is available at Aetrix Electronics and suitable for cellular phone charging, palmtop computer power management, and self-charging battery pack applications requiring stable component supply, long-lifecycle support, and guaranteed traceable sourcing.

Supply support for MIC79050-4.2YM-TR 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 global semiconductor company specializing in microcontrollers, analog devices, and power management ICs, with a focus on reliability, longevity, and industrial-grade performance.

The MIC79050 product line is designed specifically for high-accuracy, low-component-count linear charging of single-cell Li-ion batteries in space-constrained portable electronics - emphasizing thermal resilience, zero-quiescent shutdown, and compatibility with low-cost unregulated power sources.

FAQ

What is the maximum continuous output current of the MIC79050-4.2YM-TR?

The MIC79050-4.2YM-TR is rated for 500 mA continuous charging current at its nominal 4.2 V output with ≤380 mV dropout. Under transient overload, it can deliver up to ~700 mA before entering current-limit foldback - but sustained operation above 500 mA requires careful thermal design due to power dissipation (e.g., 5 V input → 4.2 V @ 500 mA yields 400 mW loss).

Does the MIC79050-4.2YM-TR support adjustable output voltage?

No - the MIC79050-4.2YM-TR is a fixed 4.2 V output device. Its internal feedback network is trimmed to deliver precisely 4.2 V ±0.75% over –5°C to +60°C. The FB pin allows external modulation (e.g., for pulse charging or end-of-charge signaling), but does not enable output voltage adjustment - unlike programmable variants such as MIC79050-XXYMM with external resistor dividers.

How does the EN pin function in the MIC79050-4.2YM-TR?

The EN pin on the MIC79050-4.2YM-TR is a TTL/CMOS-compatible digital input: applying ≥2.0 V enables charging and normal regulation; ≤0.4 V forces shutdown with ground current reduced to ≤0.1 µA. When left floating, the MIC79050-4.2YM-TR defaults to enabled state - no pull-up resistor is required for basic operation.

Can the MIC79050-4.2YM-TR be used with a 3.3 V input supply?

No - the MIC79050-4.2YM-TR requires a minimum input voltage of 2.5 V, but to maintain 4.2 V output at 500 mA, the input must exceed 4.2 V + dropout (≥4.58 V). At 3.3 V input, the output collapses to ~2.9 V (input minus saturation drop), making it unsuitable for Li-ion charging. It is intended for 5 V or higher unregulated/regulated sources.

What thermal considerations apply to the MIC79050-4.2YM-TR in SOIC-8 package?

The MIC79050-4.2YM-TR in SOIC-8 has θ_JA = 63°C/W. To stay within the +125°C max junction temperature at 500 mA load with 5 V input (400 mW dissipation), ambient must remain below +100°C - achievable only with ≥1 in² copper pour on inner layers. For continuous 500 mA operation at +40°C ambient, ≥300 mm² of 2-oz copper on top layer is recommended per Microchip's AN1234 guidelines.