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STMicroelectronics LD2979M50TR
- Part No.:
- LD2979M50TR
- Manufacturer:
- STMicroelectronics
- Package:
- SC-74A, SOT-753
- Datasheet:
-
LD2979M50TR.pdf
- Description:
- IC REG LINEAR 5V 50MA SOT23-5
- Quantity:
- Payment:
- Shipping:
Inventory:3,361
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Product details
Overview
LD2979M50TR from STMicroelectronics is a 5.0 V fixed-output, very low dropout (LDO) linear voltage regulator in SOT23-5L package, delivering up to 50 mA with 0.2 V typical dropout at full load, 500 µA typical quiescent current, and 63 dB supply voltage rejection - designed for local regulation in battery-powered and low-noise embedded systems.
For engineers reviewing the LD2979M50TR datasheet, LD2979M50TR pinout, LD2979M50TR application, or LD2979M50TR equivalent, key selection criteria include logic-controlled inhibit functionality, 1 µF minimum output capacitance stability, -25 °C to 125 °C operating junction temperature, TTL-compatible shutdown input, and internal thermal/current limiting for robust operation in space-constrained designs.
Technical Context
The LD2979M50TR implements a PMOS pass transistor architecture enabling ultra-low dropout voltage and minimal quiescent current across load and temperature. Its inhibit pin (Pin 3) accepts TTL-level logic control (VIH ≥ 2 V, VIL ≤ 0.18 V) to enable/disable regulation without external circuitry.
Stability is guaranteed with only 1 µF ceramic output capacitor (ESR < 1 Ω), and internal protection includes current limiting, thermal shutdown, and reverse-current blocking. The device maintains ±2% output voltage accuracy over -25 °C to 125 °C and load currents from 1 mA to 50 mA.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | 5.0 V ±2% over -25 °C to 125 °C and 1–50 mA load - ensures stable MCU core or sensor biasing without external feedback. |
| Dropout Voltage | 0.2 V typ. at 50 mA - enables operation from 5.2 V input, critical for single-cell Li-ion or 5 V rail margining. |
| Quiescent Current | 500 µA typ. at 50 mA load - minimizes standby power in always-on IoT nodes and wearables. |
| Supply Rejection | 63 dB typ. at 120 Hz - suppresses ripple from noisy DC/DC converters feeding the LDO input. |
| Shutdown Control | TTL-compatible inhibit pin (Pin 3) - allows precise system-level power sequencing and partial board sleep modes. |
| Stability Capacitor | 1 µF ceramic (ESR < 1 Ω) - eliminates need for bulky tantalum or electrolytic capacitors, reducing PCB area. |
| Operating Temp | -25 °C to 125 °C junction - supports industrial and under-hood automotive auxiliary circuits. |
Pinout & Package
SOT23-5L is a 5-pin, surface-mount plastic package (3.0 × 1.75 × 1.3 mm) with exposed pad for thermal enhancement, RoHS-compliant and ECOPACK® certified.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Pin 1 (VI) | Input voltage supply | Accepts 5.2–16 V DC; must be ≥ VO + Vd for regulation; decoupling required near pin. |
| Pin 2 (GND) | Power ground reference | Low-impedance return path for input/output current; connects to PCB ground plane. |
| Pin 3 (INHIBIT) | Logic-controlled enable/disable | High ≥ 2 V enables output; low ≤ 0.18 V disables regulator and reduces IQ to 0 µA. |
| Pin 4 (NC) | No connect | Internally unconnected; must remain floating or grounded - not tied to any signal. |
| Pin 5 (VO) | Regulated output | Delivers 5.0 V ±2% to load; requires 1 µF ceramic capacitor placed adjacent to this pin. |
Key Features
| Feature | Design Value |
|---|---|
| Ultra-low dropout | 0.2 V typ. at 50 mA enables use with minimal input headroom - extends battery runtime in 3.7 V Li-ion systems. |
| Logic-controlled shutdown | Inhibit pin directly interfaces with MCU GPIO without level-shifting - simplifies power-state management in portable devices. |
| Low-noise regulation | 160 µV RMS output noise (300 Hz–50 kHz) supports precision analog sensors and ADC references. |
| Thermal & current protection | Internal foldback current limit and thermal shutdown prevent damage during overload or ambient overheating. |
| Minimal external components | Only one 1 µF ceramic capacitor needed for stability - reduces BOM count and layout complexity. |
Applications
| Portable Medical Sensors | Industrial PLC I/O Modules |
|---|---|
Use Scenario: Wearable ECG front-end powered by coin cell or rechargeable Li-ion battery. IC Role / Device Role / Timing Role: Local 5.0 V regulator for op-amp signal conditioning and low-power MCU core supply. Use Value: 500 µA quiescent current and 0.2 V dropout extend battery life >30% vs standard LDOs; 1 µF capacitor fits tight wearable form factor. | Use Scenario: Isolated digital input module in factory automation cabinet with wide ambient temperature swing. IC Role / Device Role / Timing Role: Post-regulator supplying isolated interface ICs and optocoupler LEDs from 12–24 V bus. Use Value: -25 °C to 125 °C operation ensures reliability in uncontrolled enclosures; 63 dB SVR rejects switching noise from nearby SMPS. |
| Smart Meter RF Subsystems | Automotive Body Control Units |
Use Scenario: Powering sub-GHz RF transceiver (e.g., CC1120) and microcontroller in AMI meter with long shelf life. IC Role / Device Role / Timing Role: Always-on 5.0 V rail for RTC and wake-up logic, with shutdown during transmit bursts. Use Value: Inhibit pin enables dynamic power gating - cuts idle current to zero during deep sleep, meeting 10-year battery life targets. | Use Scenario: Interior lighting control module mounted near dashboard with ambient temperatures up to 85 °C. IC Role / Device Role / Timing Role: Secondary regulator for LED driver ICs and CAN transceiver bias from 12 V battery rail. Use Value: Internal thermal shutdown prevents latch-up during hot-cranking events; 5.0 V output matches legacy logic interface requirements. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar low-dropout, logic-controlled regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| AP2112K-5.0 | 0.4 V dropout at 50 mA; 65 µA quiescent current; no inhibit pin - uses EN pin with internal pull-up. | Lacks true logic-compatible inhibit; requires external pull-down for disable; lower IQ but higher dropout. | Prefer when ultra-low IQ dominates design priority and shutdown timing is non-critical. |
| MCP1700T-5002E | 0.6 V dropout at 250 mA; 1.6 µA IQ; fixed 5.0 V; active-high EN; no thermal shutdown. | Higher dropout limits use with low-input rails; lacks thermal protection; rated for 250 mA but larger package. | Choose only if higher output current is required and thermal stress is managed externally. |
Compared with AP2112K-5.0 and MCP1700T-5002E, the LD2979M50TR uniquely balances ultra-low dropout (0.2 V), TTL-compatible inhibit control, and integrated thermal/current protection in SOT23-5L - making it optimal for thermally constrained, battery-sensitive applications where precise enable timing and safety margins are essential.
Availability
LD2979M50TR is available at Aetrix Electronics and suitable for portable medical sensors, industrial PLC I/O modules, smart meter RF subsystems, and automotive body control units requiring stable component supply with consistent lead times and full traceability.
Supply support for LD2979M50TR 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 microcontrollers, power management ICs, analog chips, and MEMS sensors for industrial, automotive, and consumer markets.
The LD2979 series belongs to ST's high-efficiency linear regulator product line, engineered specifically for ultra-low-power, space-constrained applications where dropout voltage, quiescent current, and logic-controlled shutdown are critical system-level requirements.
FAQ
What is the minimum input voltage required for regulation at 50 mA load?
The LD2979M50TR requires VI ≥ VO + Vd = 5.0 V + 0.4 V (max at 50 mA, -25 °C to 125 °C) = 5.4 V to maintain regulation. At room temperature, 5.2 V suffices due to 0.2 V typical dropout. Input below this threshold causes output to droop linearly with input.
Can Pin 4 (NC) be connected to ground or left floating?
Pin 4 is internally unconnected and must remain floating - connecting it to ground or any signal may cause unpredictable behavior or damage. ST's datasheet explicitly states "Not to be connected" and warns against routing traces to this pin on PCB layouts.
Does the LD2979M50TR support reverse current protection?
Yes - the PMOS pass transistor architecture inherently blocks reverse current flow from VO to VI when the input is removed or falls below the output. This prevents backfeeding into upstream supplies and protects source rails during hot-swap or fault conditions.
Is an input capacitor required for stable operation?
An input capacitor is not mandatory for stability per datasheet, but a 1 µF ceramic capacitor placed close to Pin 1 (VI) is strongly recommended to suppress high-frequency noise and transient spikes from the source, especially when fed from a switching regulator or long PCB traces.
LD2979M50TR Specifications
- Product attributes
- Attribute value
- Manufacturer:
- STMicroelectronics
- Series:
- -
- Package/Case:
- SC-74A, SOT-753
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- Output Configuration:
- Positive
- Output Type:
- Fixed
- Number of Regulators:
- 1
- Voltage - Input (Max):
- 16V
- Voltage - Output (Min/Fixed):
- 5V
- Voltage - Output (Max):
- -
- Voltage Dropout (Max):
- 0.6V @ 50mA
- Current - Output:
- 50mA
- Current - Quiescent (Iq):
- 170 µA
- Current - Supply (Max):
- 13 mA
- PSRR:
- 63dB (120Hz)
- Control Features:
- Enable
- Protection Features:
- Over Current, Over Temperature
- Operating Temperature:
- -25°C ~ 125°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- SOT-23-5
LD2979M50TR FAQ
1.How can I place an order for LD2979M50TR through Aetrix?
Please submit a Request for Quotation (RFQ) for LD2979M50TR on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
2.Are the price and stock information for LD2979M50TR reliable?
The price and inventory of LD2979M50TR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LD2979M50TR is usually 5 days.
3.What payment methods are accepted for LD2979M50TR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LD2979M50TR transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LD2979M50TR?
LD2979M50TR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LD2979M50TR order is processed, you will receive an email with the shipment details and tracking number.
Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.
5.How can I obtain technical support or documentation for LD2979M50TR?
For technical support, including LD2979M50TR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LD2979M50TR requirements.
6.How does Aetrix verify that LD2979M50TR is sourced from the original manufacturer or authorized distributors?
All LD2979M50TR products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that LD2979M50TR meets industry standards.
7.What is the process for return or replacement of LD2979M50TR?
All LD2979M50TR units undergo pre-shipment inspection (PSI). If there is an issue with LD2979M50TR, returns or replacements are accepted under the following conditions:
1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.
2.The issue is reported within 90 days of delivery.
3.The LD2979M50TR part is unused and in its original packaging.
Return procedure for LD2979M50TR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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