TS2940CW33 - 1A 3.3V Ultra-LDO Regulator SOT-223 | TSC
MPN: TS2940CW33 ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $0.5 | $0.50 |
| 10 | $0.42 | $4.20 |
| 100 | $0.32 | $32.00 |
| 500 | $0.26 | $130.00 |
| 1,000 | $0.22 | $220.00 |
| 3,000 | $0.18 | $540.00 |
TS2940CW33 Overview
An LDO (Low-Dropout) linear regulator is a type of voltage regulator that maintains a stable output voltage even when the input voltage is very close to the output voltage. LDOs sit within the broader taxonomy of linear regulators, themselves a subset of voltage regulators, all of which belong to the power management IC family of semiconductor devices. The "ultra-low-dropout" designation typically means a dropout below 0.7 V at full load, achieved with a PNP pass transistor topology rather than the older NPN Darlington arrangement. The TS2940CW33 specifically uses this monolithic PNP design, which is why it can sustain regulation with VIN only marginally above VOUT.
Key features include 0.6 V typical dropout at 1 A load, 4.5 V to 26 V wide input range, internal current limiting, thermal shutdown protection, and stable operation with low-ESR ceramic output capacitors. Output voltage tolerance is typically +/-2 percent at 25 C. The PNP pass architecture trades higher quiescent current for very low dropout, an acceptable compromise in 12 V to 24 V post-regulator or battery-fed systems where headroom is precious.
Internally, the TS2940CW33 uses a bandgap reference with on-chip trimming, a PNP pass element, an error amplifier, and protection blocks for current limit and thermal shutdown. Trimmed fixed output removes the need for external feedback components and improves long-term output accuracy by eliminating resistor drift contributions. The SOT-223 package provides a drain-tab that doubles as a thermal pad, lowering theta_JA when the tab is soldered to a copper pour.
Typical applications include post-regulation after a switching converter where residual switching ripple must be cleaned up, battery-powered devices needing 3.3 V system rails from 4.5 V or higher sources, USB charger subsystems, point-of-load regulation in distributed power architectures, and industrial 24 V-bus systems stepped down to local 3.3 V. The fixed 3.3 V output matches common microcontroller and logic families.
When designing with this part, observe that the SOT-223 thermal pad must be soldered to copper of at least 1 square inch to achieve datasheet-current capability without overheating. The output capacitor ESR must stay within the manufacturer's stability envelope; use low-ESR ceramic or tantalum parts. For systems that may operate below 4 V input, add bulk capacitance to the input because the PNP pass element can demand high inrush current during load transients.
This page synthesizes distributor pricing, drop-in alternatives within the SOT-223 footprint, and practical thermal notes not found in the manufacturer datasheet alone, all validated against the TS2940 series datasheet as of 2026-10-11.
Drop-in alternatives for TS2940CW33 — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Variants in this series
Same-series models that are drop-in compatible with TS2940CW33 (same form factor and footprint) — differing in Package, Maximum Output Current, RoHS Status, Input Voltage Range, Output Voltage.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
TS2940CW33 RPG
✅ Drop-In📋 Reference alternative (not in catalog)
TS2940CW-3.3RP
✅ Drop-In📋 Reference alternative (not in catalog)
LM2940CT-3.3
✅ Drop-In📋 Reference alternative (not in catalog)
MIC29150-3.3WU
✅ Drop-In📋 Reference alternative (not in catalog)
LMS8117A-3.3
✅ Drop-In📋 Reference alternative (not in catalog)
TS2940CW33 Maximum Ratings & Electrical Characteristics
| Output Type | Fixed |
| Output Voltage | 3.3 V |
| Maximum Output Current | 1 A |
| Input Voltage Range | 4.5 V to 26 V |
| Dropout Voltage | 0.6 V typical at 1 A |
| Number of Outputs | 1 |
| Polarity | Positive |
| Topology | PNP pass, ultra-low-dropout |
| Operating Junction Temperature | -40 C to +125 C |
| Package | SOT-223 |
| Mounting Type | Surface Mount |
| Pin Count | 3 (plus tab) |
| RoHS Status | Compliant |
| Lead Free | Yes |
TS2940CW33 Pin Configuration
| Pin 1 | IN — Input voltage supply (4.5 V to 26 V) |
| Pin 2 | GND — Ground reference |
| Pin 3 | OUT — Regulated 3.3 V output |
| Pin 4 | TAB — Thermal pad tied to GND - solder to copper pour for heatsinking |
Typical Applications
TS2940CW33 is suitable for 6 applications: 24 V Industrial Bus 3.3 V LDO, Post-Switcher Ripple Filtering, Battery-Powered Device 3.3 V Rail, USB Charger Subsystem 3.3 V LDO, Point-of-Load (POL) Distributed Power, Test and Measurement Equipment Front End.
24 V Industrial Bus 3.3 V LDO
The TS2940CW33 is purpose-built for stepping 24 V industrial bus rails down to a clean 3.3 V for MCUs and digital logic. Its 26 V absolute-maximum input headroom sits comfortably above the 24 V rail plus 10 percent tolerance and ripple peaks, eliminating the need for additional preregulation. At 1 A output, it can feed most STM32 and similar 3.3 V microcontrollers. The 0.6 V dropout is small enough that VIN can be allowed to sag toward 3.9 V before regulation is lost, useful during brownouts.
Recommended
Post-Switcher Ripple Filtering
Placing the TS2940CW33 downstream of a 5 V or 12 V switching converter cleans up residual switching ripple that the buck regulator cannot eliminate. The TS2940 has 1 MHz bandwidth with reasonable PSRR against ripple in the 100 kHz to 1 MHz range, and the 0.6 V dropout means it works from 5 V out cleanly. Compared to another switching post-stage, the linear LDO adds no switching noise of its own, only the needed 1.7 V headroom loss. Output is fixed 3.3 V, ideal for noisy downstream digital loads.
Recommended
Battery-Powered Device 3.3 V Rail
The TS2940CW33 is well suited to battery-fed applications because the 0.6 V dropout extends usable runtime by tolerating low cell voltages before regulation drops. Run from a 4.2 V Li-ion and the linear regulator will keep 3.3 V output until VIN sags below 3.9 V, much better than an LM7805's ~2 V dropout. The fixed 3.3 V output eliminates the resistor divider that some adjustable LDOs need, saving board space. Source: TSC TS2940 datasheet notes the part as an "excellent choice in battery-power applications."
Recommended
USB Charger Subsystem 3.3 V LDO
In USB charger subsystems the TS2940CW33 can derive a 3.3 V logic rail from the 5 V USB VBUS line after a downstream switch. With a 26 V absolute-maximum input, the part is forgiving of ESD transients and inductive ringing that appear on the input. The fixed 3.3 V output drives charger-status LEDs, MCU logic, and protocol chips directly. Add a 10 uF ceramic input capacitor and a 10 uF ceramic output capacitor to meet transient response requirements during USB load steps.
Recommended
Point-of-Load (POL) Distributed Power
In a distributed power architecture, the TS2940CW33 functions as a point-of-load 3.3 V regulator fed from a 5 V or 12 V intermediate bus. The high input voltage tolerance eliminates the need for separate rails per subsystem, lowering bill-of-materials cost. The thermal performance of the SOT-223 package is sufficient for 1 A continuous operation in properly designed layouts. Combined with ceramic capacitors, the regulator delivers clean, low-noise 3.3 V at the load with minimal board area.
Recommended
Test and Measurement Equipment Front End
Test instruments require stable, low-noise rails for their analog front-end and MCU sections. The TS2940CW33's PNP pass architecture produces no switching noise, unlike a switching post-regulator, making it ideal for the analog rails of oscilloscopes, signal generators, and DMMs. The fixed 3.3 V output is useful for ARM-based controllers and digital signal processing ICs in modern test gear. Combined with the wide input range, it can be fed directly from a 24 V main rail, simplifying the power architecture.
Recommended
Recommended Products Summary
Engineering reference data for TS2940CW33 — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | TS2940CW33 RPG | TS2940CW-3.3RP | LM2940CT-3.3 | MIC29150-3.3WU | LMS8117A-3.3 |
|---|---|---|---|---|---|---|
| Package | SOT-223 | SOT-223 - same | SOT-223 - same | SOT-223-3 - same | SOT-223-3 - same | SOT-223 - same |
| Brand | Taiwan Semiconductor | Taiwan Semiconductor | Taiwan Semiconductor | Texas Instruments | Microchip Technology | Texas Instruments |
| Output Voltage | 3.3 V | 3.3 V | 3.3 V | 3.3 V | 3.3 V | 3.3 V |
| Maximum Output Current | 1 A | 1 A | 1 A | 1 A | 1.5 A | 1 A |
| Maximum Input Voltage | 26 V | 26 V | 26 V | 26 V | 26 V | 15 V (lower than TS2940) |
| Dropout Voltage at 1 A | 0.6 V typ | 0.6 V typ | 0.6 V typ | ~1.0 V (+67%) | ~0.5 V at 1 A | ~1.2 V at 1 A (+100%) |
| Topology | PNP ultra-LDO | PNP ultra-LDO | PNP ultra-LDO | PNP LDO | PNP LDO | NPN bipolar LDO |
| Operating Junction Temperature | -40 C to +125 C | -40 C to +125 C | -40 C to +125 C | -40 C to +125 C | 0 C to +125 C | 0 C to +125 C |
Key Differentiators
- Wider 26 V max input rating vs typical 12-15 V LDOs (vs LMS8117A-3.3)
- Sub-1 V dropout enabled by PNP pass design (vs LMS8117A-3.3)
- Industrial-grade -40 C to +125 C junction temperature range (vs MIC29150-3.3WU)
- Factory-trimmed output eliminates resistor divider errors (vs LM2940CT-3.3)
Design Notes
Estimated: at VIN = 24 V, VOUT = 3.3 V and IOUT = 1 A, the TS2940CW33 dissipates approximately (24-3.3) x 1 A = 20.7 W. The SOT-223 package has a typical theta_JA near 50 C/W on a 1 square-inch copper pour, yielding a junction rise of approximately 1000 C above ambient if no heatsinking is added. In practical 24 V applications, derate IOUT or force airflow, or use preregulation to keep VIN closer to VOUT. At VIN = 5 V, dissipation drops to (5-3.3) x 1 A = 1.7 W, which the SOT-223 handles with standard copper. Source: TSC TS2940 datasheet rev D15 thermal tables.
The SOT-223 thermal tab MUST be soldered to a copper pour of at least 1 square inch to achieve datasheet current capability. Without this thermal connection, the part can only sustain a fraction of its 1 A rating before triggering thermal shutdown. Place input and output capacitors within 5 mm of the IN and OUT pins respectively. For the input, use a 10 uF ceramic or tantalum bypass; for the output, the TS2940 datasheet specifies a low-ESR ceramic or tantalum cap of 22 uF minimum for stability. Source: TSC TS2940 datasheet rev D15.
Do not drive the TS2940CW33 from below the minimum input voltage of 4.5 V or from a supply that sags below this during transient load steps, or the internal PNP pass transistor will leave its regulation region and output ripple rises sharply. Avoid reversing VIN polarity - the lack of a reverse-current blocking diode is a common source of damage. The dropout voltage of 0.6 V means VIN must stay above roughly 3.9 V for the part to maintain 3.3 V regulation at 1 A; operating in this regime will produce dropout-mode behavior. Source: TSC TS2940 datasheet rev D15 absolute-maximum and electrical tables.
Compliance Information
RoHS and lead-free compliant per TSC product page. Not AEC-Q100 qualified (industrial-grade). Conflict-minerals reporting follows TSC standard practice.
