STMicroelectronics LD49300PT12R

Overview

LD49300PT12R from STMicroelectronics is a 3.0 A, very low-dropout linear voltage regulator with dual-supply architecture (VIN = 1.4–5.5 V, VBIAS = 3–6 V), fixed 1.2 V output, ±1.5% initial tolerance, 400 mV max dropout at 3 A, and 10 MHz bandwidth for fast transient response. It powers microprocessor core voltages in PC add-in cards and graphics processors where ultra-low input voltage and high current stability are critical.

For engineers reviewing the LD49300PT12R datasheet, LD49300PT12R pinout, LD49300PT12R application, or LD49300PT12R equivalent, key selection criteria include dual-rail supply compatibility, ceramic-capacitor stability, thermal shutdown protection, logic-controlled enable, and PPAK package thermal performance in high-density PCB layouts.

Technical Context

The LD49300PT12R implements a dual-input architecture: main VIN supplies output power while separate VBIAS powers internal control circuitry, enabling operation down to 1.4 V on VIN and ensuring ultra-low output impedance. Its bandgap reference (0.8 V typ.) and error amplifier drive a PMOS pass device with 10 MHz closed-loop bandwidth.

It features active-high EN pin with 0.4 V/1.4 V hysteresis thresholds, integrated thermal shutdown (150 °C typical), current limiting (4.5 A), and stable operation with ≥1 µF ceramic output capacitance - no minimum load required and ESR-insensitive compensation.

Key Specifications

Pinout & Package

LD49300PT12R uses the PPAK (Power Package) surface-mount package: 6-pin, exposed thermal pad (tab connected to GND), 6.0 × 6.4 mm footprint, 2.4 mm height, optimized for PCB copper plane heatsinking.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar high-current, low-dropout LDO applications.

Compared with TPS7A8300RGRT and NCP1117ST12T3G, LD49300PT12R uniquely combines 3 A output, 1.4 V minimum VIN, dual-supply architecture, and 10 MHz bandwidth - making it the only option capable of powering modern GPU cores directly from low-voltage SMPS rails without compromising transient performance or thermal density.

Availability

LD49300PT12R is available at Aetrix Electronics and suitable for graphics processor core supplies, PC add-in card power systems, and microprocessor core voltage applications requiring stable component supply, long-term lifecycle support, and traceable sourcing.

Supply support for LD49300PT12R 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

STMicroelectronics is a global semiconductor leader headquartered in Geneva, Switzerland, designing and manufacturing analog, MCU, power, and sensor solutions for industrial, automotive, and consumer markets.

The LD49300 belongs to ST's high-performance LDO family engineered specifically for high-current, low-noise core voltage regulation in graphics, computing, and FPGA platforms - emphasizing ultra-low dropout, fast transient response, and robust thermal management in compact packages.

FAQ

What is the minimum input voltage required for LD49300PT12R to regulate 1.2 V output?

The LD49300PT12R requires a minimum main input voltage (VIN) of 1.4 V, enabled by its dual-supply architecture: VIN supplies the output stage while VBIAS (3–6 V) powers the control circuitry. At 3 A load, dropout is 400 mV, so VIN must be ≥1.6 V for stable 1.2 V regulation. This allows operation from low-headroom sources such as 1.8 V SMPS rails or partially discharged batteries.

Can LD49300PT12R operate without an external VBIAS supply?

No. LD49300PT12R requires a dedicated VBIAS supply between 3 V and 6 V to power its internal reference, error amplifier, and driver circuitry. The VBIAS pin draws only 3–5 mA but is mandatory for regulation - connecting VIN to VBIAS is not permitted per datasheet absolute maximum ratings (VBIAS must not exceed 7 V, and VIN–VBIAS differential is undefined). Omitting VBIAS causes complete functional failure.

What is the recommended output capacitor for optimal transient performance?

For optimal transient performance, ST recommends a 10 µF X7R ceramic capacitor placed adjacent to the VOUT pin. While 1 µF satisfies minimum stability requirements, 10 µF reduces output voltage deviation during 3 A load steps by >40% and improves recovery time by ~3×. The capacitor must have low ESR (<10 mΩ) and be mounted with short, wide traces to minimize parasitic inductance - critical for maintaining 10 MHz bandwidth.

How does the PPAK package affect thermal design in high-power applications?

The PPAK package uses an exposed GND tab soldered directly to the PCB's internal or bottom-layer ground plane, serving as the primary thermal path. With ≥200 mm² of 2-oz copper connected to the tab, θJA drops below 100 °C/W - allowing full 3 A operation at 70 °C ambient without a heatsink. Thermal vias (≥6 × 0.3 mm) from the tab to inner GND layers further reduce θJC by up to 30%, enabling sustained power dissipation up to 2.5 W in compact layouts.