REG104GA-3.3/2K5G4 - 1A, 3.3V SOT-223 LDO Regulator | Texas Instruments
MPN: REG104GA-3.3-2K5G4 ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $2.85 | $2.85 |
| 10 | $2.55 | $25.50 |
| 100 | $2.18 | $218.00 |
| 500 | $1.95 | $975.00 |
| 1,000 | $1.72 | $1,720.00 |
REG104GA-3.3-2K5G4 Overview
A Low-Dropout (LDO) linear regulator is a type of voltage regulator that maintains a stable output voltage even when the input voltage approaches the output voltage, by using a low-resistance pass transistor. LDOs sit within the broader hierarchy of linear regulators -> voltage regulators -> power management ICs -> semiconductors. Compared to switching regulators, LDOs introduce no switching noise onto the output rail, which is critical for analog and RF loads, at the cost of dissipating (VIN - VOUT) x IOUT as heat.
Key features of the REG104GA-3.3/2K5G4 include a low ground-pin current that minimizes quiescent loss, a low-dropout voltage enabled by the DMOS pass element, internal current limiting and thermal shutdown for fault protection, and stable operation with low-ESR ceramic output capacitors. The fixed 3.3 V output removes the need for an external feedback divider and reduces external component count. The SOT-223 package provides a thermal pad that allows the tab to be soldered to a copper pour for improved power dissipation.
Architecturally, the REG104 uses TI's DMOS topology, which delivers significantly lower dropout than the legacy PNP LDO family (e.g., REG1117) and improves PSRR at high frequencies. The reference, error amplifier, and DMOS pass device are integrated into a single die, with the die attached to the SOT-223 tab for direct thermal conduction to the PCB.
Typical applications include post-regulation following a 5 V or 12 V switching converter for 3.3 V digital loads, USB/peripheral power, industrial 24 V -> 3.3 V intermediate rails, FPGA/CPLD auxiliary supplies, and microcontroller power rails in point-of-load designs. In each of these, the LDO cleans up ripple that the switching converter cannot fully reject at its switching frequency harmonics.
When designing with the REG104GA-3.3/2K5G4, ensure adequate PCB copper area on the SOT-223 tab to keep junction temperature within the -40 C to +85 C operating range under worst-case load. Verify input-to-output differential and total power dissipation against the thermal resistance, since LDOs are most often derated thermally rather than electrically.
This page synthesizes distributor pricing for the REG104GA-3.3/2K5G4, drop-in same-package alternatives from the same TI REG104 family, and practical design notes not found on the manufacturer product page.
Drop-in alternatives for REG104GA-3.3-2K5G4 — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
REG104GA-3.3/2K5
✅ Drop-In ⚠️ Specs Unverified📋 Reference alternative (not in catalog)
REG104FA-3.3/2K5G4
✅ Drop-In ⚠️ Specs Unverified📋 Reference alternative (not in catalog)
REG104GA-3.3G4
✅ Drop-In📋 Reference alternative (not in catalog)
REG104GA-5.0/2K5G4
✅ Drop-In ⚠️ Specs Unverified📋 Reference alternative (not in catalog)
REG104GA-2.5/2K5G4
✅ Drop-In ⚠️ Specs Unverified📋 Reference alternative (not in catalog)
REG104GA-A.2K5G4
✅ Drop-In ⚠️ Specs Unverified📋 Reference alternative (not in catalog)
REG104GA-3.3-2K5G4 Maximum Ratings & Electrical Characteristics
| Topology | Low-Dropout (LDO) Linear Regulator |
| Pass Element | DMOS |
| Output Type | Fixed |
| Output Voltage | 3.3 V |
| Output Voltage Tolerance | 2 % |
| Maximum Output Current | 1 A |
| Maximum Input Voltage Absolute | 16 V |
| Nominal Input Voltage | 15 V |
| Operating Temperature Range | -40 C to +85 C |
| Package | SOT-223-6 (DCQ) |
| Number of Pins | 6 |
| Terminal Form | Gull Wing |
| Enable Feature | Yes (per REG104 family) |
| Protection Features | Current Limit, Thermal Shutdown |
| Mounting Type | Surface Mount |
| RoHS Status | Compliant (per distributor listings) |
| Lead Free | Yes |
| Packaging | Tape & Reel, 2,500-piece reel (/2K5) |
REG104GA-3.3-2K5G4 Pin Configuration
| Pin 1 | IN — Input supply voltage |
| Pin 2 | GND — Ground |
| Pin 3 | IN — Input supply voltage (parallel pin for lower impedance) |
| Pin 4 | NC — Not connected (per datasheet; some order codes tie to EN) |
| Pin 5 | OUT — Regulated output voltage (3.3 V) |
| Pin 6 | OUT — Regulated output voltage (parallel pin for lower impedance) |
Typical Applications
REG104GA-3.3-2K5G4 is suitable for 6 applications: Post-Regulation After 5V Switching Converter, Industrial 24V to 3.3V Intermediate Rail, USB Peripheral 3.3V Supply, FPGA/CPLD Auxiliary 3.3V Rail, Audio Codec Power Rail, Sensor Node and IoT Power Conditioning.
Post-Regulation After 5V Switching Converter
The REG104GA-3.3/2K5G4 is placed downstream of a 5 V switching converter to deliver a clean 3.3 V rail for digital ICs. With its DMOS pass element and 1 A output capability, the LDO strips residual switching ripple from the upstream converter, producing a low-noise rail suitable for microcontrollers, FPGAs, and CPLDs. The fixed 3.3 V output eliminates the feedback divider, simplifying the BOM. At a 5 V -> 3.3 V conversion, dropout is minimal and the part dissipates only ~1.7 W at 1 A, which the SOT-223-6 (DCQ) tab handles with a modest copper pour. This topology is favored over a second switching converter because the LDO adds no EMI to the 3.3 V rail.
Recommended
Industrial 24V to 3.3V Intermediate Rail
In industrial PLC and factory-automation boards, a 24 V backplane rail must be stepped down to 3.3 V for logic and sensor interfaces. The REG104GA-3.3/2K5G4, with its 15 V nominal / 16 V absolute maximum input, requires a small upstream pre-regulator (e.g., 24 V -> 12 V switcher) before the LDO. Once the input is in range, the DMOS pass element maintains regulation with low dropout, and the part's -40 C to +85 C operating range covers the industrial temperature envelope. The 6-pin SOT-223 (DCQ) footprint makes it easy to place near each point-of-load. Designers should add input TVS protection and verify thermal dissipation at maximum load.
Recommended
USB Peripheral 3.3V Supply
USB-powered peripherals (USB-to-serial, USB audio, USB MCU boards) often need a regulated 3.3 V rail from a 5 V USB VBUS input. The REG104GA-3.3/2K5G4 can deliver up to 1 A at 3.3 V from a 5 V input, exceeding the 500 mA USB 2.0 limit and supporting USB 3.0 peripheral loads. The DMOS topology ensures low dropout across the 5 V -> 3.3 V step, and the LDO's clean output is ideal for downstream RF or analog blocks. Add input protection (TVS, PTC) on VBUS to handle hot-plug transients that exceed the 16 V absolute maximum.
Recommended
FPGA/CPLD Auxiliary 3.3V Rail
FPGAs and CPLDs typically require a quiet 3.3 V auxiliary rail in addition to their core supplies. Placing a REG104GA-3.3/2K5G4 at each point-of-load cleans up ripple from the upstream converter and provides 1 A continuous current for I/O banks, configuration logic, and housekeeping circuitry. The SOT-223-6 (DCQ) tab solders to a copper pour for thermal relief. Compared to a switching regulator, this LDO adds no high-frequency noise to the 3.3 V rail, which improves FPGA I/O timing margins and reduces EMI emissions from the board.
Recommended
Audio Codec Power Rail
Audio codecs and DACs require a quiet analog supply to preserve dynamic range and SNR. The REG104GA-3.3/2K5G4's DMOS pass element provides high PSRR at audio-band frequencies, rejecting ripple from upstream switchers that would otherwise modulate the audio output. With 1 A capability, it can supply both the codec's analog and digital sections from a single 3.3 V rail. The fixed output removes the feedback-divider noise injection that plagues some adjustable LDOs in low-level audio stages.
Recommended
Sensor Node and IoT Power Conditioning
Battery-powered sensor nodes and IoT endpoints often stack a switching charger with a final LDO to power noise-sensitive analog front-ends and radios. The REG104GA-3.3/2K5G4 can deliver 3.3 V at up to 1 A from a higher-voltage rail, with low quiescent current minimizing sleep-mode loss. The -40 C to +85 C operating range covers outdoor and industrial sensor deployments. In a typical 12 V -> 3.3 V configuration, the DMOS pass element's low dropout preserves usable input headroom as the supply droops, extending battery runtime.
Recommended
Recommended Products Summary
Engineering reference data for REG104GA-3.3-2K5G4 — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | REG104GA-3.3/2K5 | REG104FA-3.3/2K5G4 | REG104GA-3.3G4 | REG104GA-5.0/2K5G4 | REG104GA-2.5/2K5G4 | REG104GA-A.2K5G4 |
|---|---|---|---|---|---|---|---|
| Package | SOT-223-6 (DCQ) | SOT-223-6 (DCQ) - same | SOT-223-6 (DCQ) - same | SOT-223-6 (DCQ) - same | SOT-223-6 (DCQ) - same | SOT-223-6 (DCQ) - same | SOT-223-6 (DCQ) - same |
| Brand | Texas Instruments | Texas Instruments | Texas Instruments | Texas Instruments | Texas Instruments | Texas Instruments | Texas Instruments |
| Output Voltage | 3.3 V fixed | 3.3 V fixed | 3.3 V fixed | 3.3 V fixed | 5.0 V fixed | 2.5 V fixed | Adjustable |
| Maximum Output Current | 1 A | 1 A | 1 A | 1 A | 1 A | 1 A | 1 A |
| Maximum Input Voltage | 16 V absolute / 15 V nominal | 16 V absolute / 15 V nominal | 16 V absolute / 15 V nominal | 16 V absolute / 15 V nominal | 16 V absolute / 15 V nominal | 16 V absolute / 15 V nominal | 16 V absolute / 15 V nominal |
| Pass Element | DMOS | DMOS | DMOS | DMOS | DMOS | DMOS | DMOS |
| Operating Temperature Range | -40 C to +85 C | -40 C to +85 C | -40 C to +85 C | -40 C to +85 C | -40 C to +85 C | -40 C to +85 C | -40 C to +85 C |
| Packaging / Reel Quantity | 2,500-piece T&R (/2K5G4) | 2,500-piece T&R (/2K5) | 2,500-piece T&R (F-reel code) | G4 finish code, quantity per datasheet | 2,500-piece T&R (/2K5G4) | 2,500-piece T&R (/2K5G4) | 2,500-piece T&R (/2K5G4) |
| RoHS / Lead Free | Yes (G4 suffix) | Yes (lead-free finish) | Yes (G4 finish code) | Yes (G4 finish code) | Yes (G4 suffix) | Yes (G4 suffix) | Yes (G4 suffix) |
Key Differentiators
- Fixed 3.3 V output eliminates feedback divider (vs REG104GA-A.2K5G4 (adjustable))
- Lower output voltage option in same footprint (vs REG104GA-5.0/2K5G4)
- Higher output voltage option in same footprint (vs REG104GA-2.5/2K5G4)
- G4 lead-free finish code on 2,500-piece reel (vs REG104GA-3.3 (base order code))
Design Notes
Estimated: at VIN = 5 V, VOUT = 3.3 V, and IOUT = 1 A, the part dissipates (5 V - 3.3 V) x 1 A = 1.7 W. With the SOT-223-6 (DCQ) tab soldered to roughly 1 square inch of 1 oz copper (theta_JA around 35 C/W per the REG104 datasheet thermal table), junction temperature rises ~60 C above ambient. At higher VIN-VOUT differentials, the same 1 A load produces proportionally more heat. Keep total dissipation under approximately 1.5 W for reliable -40 C to +85 C operation without a dedicated heatsup; derate further in enclosed or high-ambient environments.
Place the input and output ceramic capacitors as close as possible to the IN and OUT pins to minimize high-frequency loop inductance. Use a 1 uF or greater X5R/X7R ceramic on the input and a similar value on the output; the REG104 datasheet specifies the ESR range needed for output stability. The SOT-223 tab should be soldered to a copper pour that is stitched with thermal vias to the opposite board side or inner plane to spread heat.
Do not exceed the 16 V absolute maximum on the input - add a TVS diode or Zener clamp if the upstream rail can spike above this during transients. Verify the enable pin (if used on this order code) is properly driven; floating EN can leave the regulator in an undefined state on some variants. Avoid placing the part near high-power switching FETs that could couple switching noise into the feedback loop and degrade PSRR.
Route the GND pin directly to a low-impedance ground plane via a short, wide trace - the ground pin carries the part's quiescent current plus load return current and must not share impedance with noisy digital returns. If the layout requires the input/output capacitors on the opposite side of the board, use vias with minimal inductance (multiple parallel vias) rather than single-via connections.
Compliance Information
RoHS compliance and lead-free finish confirmed via the G4 suffix and distributor listings (Mouser, DigiKey). AEC-Q100 not qualified - this is an industrial/consumer part, not automotive grade. Halogen-free status not explicitly stated in the verified data.
