Microchip Technology MIC79050-4.2YS-TR

Overview

MIC79050-4.2YS-TR from Microchip Technology is a fixed-output 4.2 V linear lithium-ion battery charger IC in SOT-223 package, featuring ±0.75% battery voltage accuracy over –5°C to +60°C, 380 mV dropout at 500 mA, and zero off-mode current. It integrates an on-chip PNP pass transistor and delivers precise constant-voltage termination for single-cell Li-ion packs in portable consumer electronics.

For engineers reviewing the MIC79050-4.2YS-TR datasheet, MIC79050-4.2YS-TR pinout, MIC79050-4.2YS-TR application, or MIC79050-4.2YS-TR equivalent, key selection considerations include its 3-pin simplicity, thermal performance in SOT-223, reverse leakage <10 µA, wide 2.5–16 V input range, and compatibility with unregulated wall adapters for cost-sensitive charging solutions.

Technical Context

The MIC79050-4.2YS-TR implements a high-accuracy linear regulation architecture using an internal bandgap reference and PNP pass element, with feedback control loop embedded in the die. Its output voltage is factory-trimmed to 4.2 V with no external resistors required - unlike 8-lead variants (e.g., MIC79050-4.2YMM), this 3-lead version lacks EN and FB pins and operates in always-on mode.

It supports pulse charging via external circuitry by modulating the IN node, includes thermal shutdown and current-limit protection (750–1000 mA), and maintains <12 µA reverse leakage when input is floating or grounded - critical for minimizing battery self-discharge in standby.

Key Specifications

Pinout & Package

SOT-223 package with exposed thermal tab internally connected to GND; optimized for low thermal resistance and minimal board space. Pin 1 = IN (supply input), Pin 2 = GND (ground, including tab), Pin 3 = BAT (battery output).

Key Features

Applications

Equivalent & Alternatives

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

Compared with MCP73831T-2DCI/OT and TP4056, the MIC79050-4.2YS-TR delivers superior voltage accuracy (±0.75% vs. ±1%), lower dropout (380 mV vs. ≥600 mV), and verified reverse leakage performance - making it preferred for applications demanding long shelf life, tight thermal budgets, and regulatory compliance in medical or industrial portable equipment.

Availability

MIC79050-4.2YS-TR is available at Aetrix Electronics and suitable for cellular phones, palmtop computers, PDAs, and self-charging battery packs requiring stable component supply, long-term manufacturability, and consistent parametric performance across production lots.

Supply support for MIC79050-4.2YS-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 U.S.-based semiconductor manufacturer specializing in microcontrollers, analog devices, and power management ICs, with global manufacturing and quality certifications including ISO 9001 and AEC-Q200 for select products.

The MIC79050 product line is designed specifically for simple, high-accuracy single-cell lithium-ion battery charging in cost-sensitive portable electronics - emphasizing minimal external components, thermal robustness, and guaranteed reverse-current protection.

FAQ

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

The MIC79050-4.2YS-TR is rated for 500 mA continuous output current under thermal limits. At 500 mA and 1 V input-to-output differential, power dissipation is ~500 mW. With proper PCB copper heatsinking (≥1 in² ground plane), it sustains full current across –40°C to +85°C ambient. Exceeding 500 mA risks thermal shutdown due to its 125°C junction limit.

Does the MIC79050-4.2YS-TR require external components to function?

No - the MIC79050-4.2YS-TR operates as a complete 3-terminal charger with no external resistors, capacitors, or enable circuitry required. A single 4.7 µF output capacitor is recommended per datasheet for stability, but not strictly mandatory for basic operation. Its fixed 4.2 V output and internal feedback eliminate trimming components entirely.

How does the MIC79050-4.2YS-TR handle reverse battery connection?

The MIC79050-4.2YS-TR provides inherent reversed-battery protection: when input is disconnected or grounded, reverse leakage is limited to ≤12 µA at 4.2 V BAT. This prevents significant discharge of the Li-ion cell during storage or accidental polarity reversal - a key differentiator versus basic LDOs or discrete charger solutions.

Can the MIC79050-4.2YS-TR be used with a 5 V USB power source?

Yes - the MIC79050-4.2YS-TR accepts 2.5–16 V input, making it fully compatible with standard 5 V USB sources. With 380 mV dropout, it delivers regulated 4.2 V to the battery even as USB voltage sags to 4.6 V under load. Its low 10 µA reverse leakage also prevents backfeed into the USB port when disconnected.

What is the thermal resistance (θ_JA) of the MIC79050-4.2YS-TR in SOT-223 package?

The MIC79050-4.2YS-TR in SOT-223 has θ_JA = 62°C/W when mounted on a standard 1 in² (645 mm²) copper pad with 2 oz copper weight. This value assumes the exposed tab is soldered directly to the GND plane. Without adequate copper area, θ_JA degrades rapidly - e.g., 100°C/W on minimal 0.1 in² pad - potentially triggering thermal shutdown at <300 mA.