Microchip Technology MIC39300-1.8BT

Overview

MIC39300-1.8BT from Microchip Technology is a 3A low-dropout linear regulator (LDO) delivering a fixed 1.8V output with 350mV dropout at full load, ±2% output voltage accuracy, and integrated thermal shutdown and current limiting. It serves as the primary post-regulation power stage for FPGA core supplies in industrial control modules.

For engineers reviewing the MIC39300-1.8BT datasheet, MIC39300-1.8BT pinout, MIC39300-1.8BT application, or MIC39300-1.8BT equivalent, key selection criteria include dropout voltage under 3A load, thermal performance in TO-263-5 package, stability with 10µF ceramic output capacitance, and compatibility with low-noise digital core rails.

Technical Context

The MIC39300-1.8BT employs a PNP pass transistor architecture enabling ultra-low dropout operation without requiring external compensation. Its internal reference and error amplifier maintain regulation across input voltages from 2.25V to 16V while rejecting line ripple up to 75dB at 120Hz.

It integrates foldback current limiting that reduces output current to ~0.5A during short-circuit events and activates thermal shutdown at 160°C junction temperature, with automatic recovery upon cooling below 140°C.

Key Specifications

Pinout & Package

Supplied in a thermally enhanced TO-263-5 (D²PAK) surface-mount package with exposed metal tab electrically connected to ground for improved heat dissipation.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TPS7A4700RGWR and NCP1117ST18T3G, the MIC39300-1.8BT uniquely balances 3A output capability, 350mV dropout, and integrated protection-making it the only viable fixed-1.8V LDO for thermally constrained, high-current digital core rails requiring no external compensation.

Availability

MIC39300-1.8BT is available at Aetrix Electronics and suitable for FPGA power delivery, industrial PLC CPU rails, and medical imaging sensor interfaces requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for MIC39300-1.8BT 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 is a U.S.-based semiconductor manufacturer specializing in microcontrollers, analog devices, FPGAs, and power management ICs for industrial, automotive, and communications markets.

The MIC39300 family was designed specifically for high-current, low-dropout regulation in space-constrained embedded systems where thermal performance and protection integration are critical.

FAQ

What is the minimum input voltage required for MIC39300-1.8BT to regulate 1.8V at 3A?

The MIC39300-1.8BT requires a minimum input voltage of 2.15V to maintain regulation at 3A load, based on its 350mV dropout specification. Below this threshold, the output voltage drops linearly with input. This value assumes typical junction temperature and proper PCB layout with adequate copper pour for thermal management. The MIC39300-1.8BT datasheet confirms this behavior across the full operating temperature range.

Does MIC39300-1.8BT require an external capacitor on the ADJ/SENSE pin?

No, the MIC39300-1.8BT does not require an external capacitor on the ADJ/SENSE pin because it is a fixed-output variant with internal feedback network. That pin is internally connected to the output and remains unused in standard operation. External components on ADJ/SENSE are only necessary for adjustable versions like MIC39302. The MIC39300-1.8BT datasheet explicitly states this configuration for the -1.8BT suffix part.

Can MIC39300-1.8BT be used in parallel to increase output current beyond 3A?

No, the MIC39300-1.8BT is not designed for parallel operation. Its internal error amplifier lacks current-sharing circuitry, and mismatched thermal gradients between devices would cause uneven current distribution and potential thermal runaway. For >3A applications, Microchip recommends using a single MIC39300-1.8BT with appropriate heatsinking or selecting a higher-current regulator. The MIC39300-1.8BT datasheet prohibits paralleling without explicit external control circuitry.

What is the thermal resistance (θ_JA) of MIC39300-1.8BT in TO-263-5 package with standard 2-layer PCB layout?

The MIC39300-1.8BT has a typical θ_JA of 45°C/W when mounted on a 2-layer PCB with 1-inch² copper pad connected to the exposed tab. This value assumes 1oz copper, no internal planes, and still air convection. With 4-layer boards and internal ground planes, θ_JA improves to ~32°C/W. These figures are measured per JEDEC JESD51-7 and documented in the MIC39300-1.8BT thermal characteristics table.

Is MIC39300-1.8BT compatible with 100% ceramic output capacitors?

Yes, the MIC39300-1.8BT is fully stable with 100% ceramic output capacitors rated ≥10µF and ESR ≤20mΩ. Unlike older LDOs, it does not require series resistance or tantalum/electrolytic types for phase margin. This eliminates capacitor aging concerns and reduces footprint. The MIC39300-1.8BT datasheet validates stability across the full temperature and load range using X5R/X7R MLCCs.