Microchip Technology MIC79110-4.2YML-TR

Overview

MIC79110-4.2YML-TR from Micrel is a fixed-output 4.2V, 1.2A linear lithium-ion battery charger IC with ±0.75% voltage accuracy over –5°C to +60°C, ±5% current limit accuracy, and integrated reverse-polarity protection. It operates from 2.5V–16V input, delivers low dropout (550mV at 700mA), and targets single-cell Li-ion charging in portable consumer electronics.

For engineers reviewing the MIC79110-4.2YML-TR datasheet, MIC79110-4.2YML-TR pinout, MIC79110-4.2YML-TR application, or MIC79110-4.2YML-TR equivalent, key selection criteria include fixed 4.2V output compliance with standard Li-ion chemistry, programmable end-of-charge threshold via REOC, analog current monitoring via ACHG, thermal shutdown, and DFN-10 package compatibility for space-constrained designs.

Technical Context

The MIC79110-4.2YML-TR implements constant-current/constant-voltage (CC/CV) charging with internal pass transistor control, precision voltage regulation using bandgap reference, and external resistor-programmed current limits (RSET) and end-of-charge thresholds (REOC). Its shutdown pin (SD) provides active-low enable/disable with 60mV hysteresis.

It features dual status outputs: an open-drain digital end-of-charge flag (DEOC) and a proportional analog current source (ACHG = IBAT/1000). Reverse-current protection limits VBAT-to-VIN leakage to ≤20µA when VIN is disconnected, and thermal shutdown activates at TJ ≥ +125°C.

Key Specifications

Pinout & Package

Package: 10-pin 3mm × 3mm leadless DFN (ML), exposed thermal pad, RoHS-compliant, moisture sensitivity level 1.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar lithium-ion linear charger applications.

Compared with TP4056 and BQ24075, the MIC79110-4.2YML-TR uniquely integrates reverse-polarity protection, analog current monitoring (ACHG), and fully programmable end-of-charge threshold (REOC) in a 3mm × 3mm DFN - reducing component count and enabling higher diagnostic fidelity without increasing PCB area.

Availability

MIC79110-4.2YML-TR is available at Aetrix Electronics and suitable for cellular phones, digital cameras, notebook PC cradles, and portable meters requiring stable component supply, long-term lifecycle support, and consistent parametric performance across production batches.

Supply support for MIC79110-4.2YML-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

Micrel Inc. was a U.S.-based analog and mixed-signal semiconductor company founded in 1978, acquired by Microchip Technology in 2015. Known for high-reliability power management and timing solutions.

The MIC79110 product line was designed specifically for cost-sensitive, space-constrained single-cell Li-ion charging applications requiring precision voltage regulation, programmable current control, and integrated safety features - targeting portable consumer electronics before acquisition.

FAQ

What is the maximum input voltage rating for the MIC79110-4.2YML-TR?

The MIC79110-4.2YML-TR has an absolute maximum input voltage rating of 18V on the VIN pins, with a recommended operating range of 2.5V to 16V. Exceeding 18V may cause permanent damage. The device maintains regulation down to 2.5V input, enabling compatibility with low-headroom sources such as partially discharged USB supplies or 3.3V auxiliary rails used in auto-shutdown circuits.

How does the MIC79110-4.2YML-TR implement end-of-charge detection?

The MIC79110-4.2YML-TR uses the REOC pin to set a precise end-of-charge current threshold via an external resistor. When battery charge current falls below IEOC = (0.2V / REOC) × 1000, the DEOC pin transitions from LOW to high-impedance state. This digital flag can drive an LED or microcontroller interrupt without external logic, and its accuracy is maintained across –40°C to +125°C.

Can the MIC79110-4.2YML-TR be used with batteries other than 4.2V Li-ion?

No - the MIC79110-4.2YML-TR is factory-trimmed for fixed 4.2V output and is not adjustable. It is intended exclusively for standard single-cell lithium-ion or lithium-polymer batteries with 4.2V nominal full-charge voltage. For other voltages, the adjustable variant MIC79110YML must be used with external feedback resistors on the ADJ pin.

What thermal protection mechanisms does the MIC79110-4.2YML-TR include?

The MIC79110-4.2YML-TR incorporates thermal shutdown that disables the output when junction temperature exceeds +125°C, with automatic recovery once temperature falls below hysteresis threshold. Its 3mm × 3mm DFN package includes an exposed thermal pad for PCB copper pour attachment, and θJC = 2°C/W enables efficient heat transfer to the board - critical for sustaining 1.2A charge current in enclosed handheld devices.

Does the MIC79110-4.2YML-TR provide reverse-current protection when input is disconnected?

Yes - the MIC79110-4.2YML-TR limits reverse current from battery to input to ≤20µA when VIN is floating or grounded, eliminating need for external blocking diodes. This protection remains active regardless of SD pin state and is inherent to the internal architecture, preserving battery charge during standby or adapter removal in cradle-style applications.