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STMicroelectronics LF33CPT
- Part No.:
- LF33CPT
- Manufacturer:
- STMicroelectronics
- Package:
- TO-252-5, DPAK (4 Leads + Tab), TO-252AD
- Datasheet:
-
LF33CPT.pdf
- Description:
- IC REG LINEAR 3.3V 500MA PPAK
- Quantity:
- Payment:
- Shipping:
Inventory:3,362
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Product details
Overview
LF33CPT from STMicroelectronics is a 3.3 V, ±2% tolerance, 500 mA low-dropout linear voltage regulator in PENTAWATT-5 package with TTL-compatible shutdown control (pin 2), 0.4 V dropout at 500 mA, and 50 µA quiescent current in OFF mode-designed for battery-powered microcontroller subsystems requiring stable local regulation and standby power management.
For engineers reviewing the LF33CPT datasheet, LF33CPT pinout, LF33CPT application, or LF33CPT equivalent, this page delivers verified electrical specs, thermal performance data, real-world use cases in portable instrumentation and automotive body electronics, and validated alternative options with precise functional trade-offs.
Technical Context
The LF33CPT implements a fixed-output, NPN-based LDO architecture with internal current limiting, thermal shutdown, and logic-controlled inhibit function. Its 5-pin PENTAWATT configuration separates IN, OUT, GND, SHUTDOWN, and ADJ (NC) terminals to enable board-level power sequencing and partial-system sleep modes.
It operates across –40°C to +125°C junction temperature, supports input voltages up to 16 V, and maintains output stability with only a 2.2 µF ceramic output capacitor (ESR 0.1–10 Ω), eliminating need for electrolytic or tantalum types.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | 3.3 V ±2% at 25°C (min 3.234 V, max 3.366 V); ensures compatibility with 3.3 V logic families under full temperature and load range. |
| Dropout Voltage | 0.4 V at 500 mA load; enables regulation from 3.7 V input-critical for single-cell Li-ion or dual-cell alkaline systems. |
| Quiescent Current | 50 µA in OFF mode, 500 µA in ON mode; minimizes standby drain in always-on sensor nodes and remote controls. |
| Output Current | 500 mA continuous; sufficient for powering ARM Cortex-M0+ MCUs, CAN transceivers, and small LCD controllers. |
| Supply Rejection | 80 dB at 120 Hz; suppresses ripple from noisy DC-DC pre-regulators in mixed-signal industrial modules. |
| Thermal Resistance | RthJC = 3°C/W (PENTAWATT); allows >3 W dissipation with modest heatsinking-supports 12 V→3.3 V conversion at 500 mA without derating. |
| Noise Voltage | 50 µV RMS (10 Hz–100 kHz); suitable for analog front-ends in precision ADC reference supplies. |
Pinout & Package
PENTAWATT-5 (vertical mount, 5-pin) package with integrated heat slug; pin 1 = Input, pin 2 = Shutdown (TTL-compatible), pin 3 = Ground, pin 4 = Output, pin 5 = NC (not connected, internally unused).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (IN) | Input voltage supply | Accepts 4.3–16 V DC; requires 0.1 µF ceramic bypass close to pin for high-frequency stability. |
| 2 (SHDN) | Logic-controlled inhibit | TTL-low (≤0.8 V) disables output; TTL-high (≥2 V) enables regulation-enables system-level power gating. |
| 3 (GND) | Power ground reference | Low-impedance return path; must be routed separately from digital ground to avoid noise coupling into regulated output. |
| 4 (OUT) | Regulated output | Delivers 3.3 V ±2% to load; requires 2.2 µF ceramic capacitor (X7R, ESR ≤10 Ω) directly at pin for loop stability. |
| 5 (NC) | No connection | Internally unconnected; must remain floating-no external tie or pull-up/pull-down required. |
Key Features
| Feature | Design Value |
|---|---|
| Very low dropout | 0.4 V at full 500 mA load-enables operation from marginal input sources like partially discharged batteries. |
| Ultra-low OFF-mode IQ | 50 µA shutdown current-extends shelf life of sealed battery-powered devices beyond 10 years. |
| Single-capacitor stability | Stable with only 2.2 µF ceramic output cap (no ESR requirement)-reduces BOM count and PCB area vs. legacy LDOs. |
| Wide operating temperature | –40°C to +125°C junction range-qualified for under-hood automotive and industrial motor control environments. |
| Integrated protection | Current limit + thermal shutdown-prevents damage during short-circuit or overload without external circuitry. |
Applications
| Portable Medical Sensors | Automotive Body Control Modules |
|---|---|
Use Scenario: Wearable ECG patch with Bluetooth LE MCU and analog signal chain powered by coin cell. IC Role / Device Role / Timing Role: Local 3.3 V regulator for MCU core, RF transceiver, and precision op-amps-enabled/disabled via host GPIO. Use Value: 50 µA OFF current extends 200 mAh CR2032 battery life to >2 years in sleep mode; 0.4 V dropout allows usable runtime down to 3.5 V input. |
Use Scenario: Door module controlling window lift, mirror fold, and interior lighting in 12 V vehicle system. IC Role / Device Role / Timing Role: Dedicated 3.3 V supply for LIN transceiver and microcontroller-shut down when ignition is off. Use Value: Logic-controlled shutdown reduces parasitic drain below 100 µA, meeting ISO 19453-3 quiescent current requirements. |
| Industrial IoT Edge Nodes | Smart Metering Subsystems |
Use Scenario: Battery-backed LoRaWAN node monitoring temperature/humidity in remote utility cabinets. IC Role / Device Role / Timing Role: Primary regulator for ultra-low-power MCU and sensor interface-activated only during measurement cycles. Use Value: 500 µA ON-mode IQ minimizes active-phase consumption; 80 dB PSRR rejects switching noise from shared DC-DC converter. |
Use Scenario: Electricity meter with isolated RS-485 communication and metrology ADC requiring clean 3.3 V reference. IC Role / Device Role / Timing Role: Low-noise post-regulator for ADC reference and digital isolator side-decoupled from main 5 V rail. Use Value: 50 µV RMS output noise prevents quantization errors in 24-bit sigma-delta ADCs; ±2% accuracy meets IEC 62053-21 Class 0.2. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar fixed-output LDO regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LD33CV | Same 3.3 V/500 mA output, but TO-220 package (no shutdown pin); RthJA = 50°C/W vs. 50°C/W (PENTAWATT); no logic control. | Suitable where board space permits TO-220 and system-level shutdown is handled externally. | Select LD33CV only if shutdown functionality is unnecessary and thermal design accommodates higher ambient rise. |
| TLV73333PDBVR | 3.3 V/300 mA, SOT-23-5, 120 µA IQ in ON mode, 0.25 V dropout at 300 mA; no thermal shutdown. | Better for space-constrained designs with lower current needs; lacks automotive temp rating and overtemperature protection. | Choose TLV73333PDBVR for compact consumer wearables-not for industrial or automotive deployments requiring robustness. |
Compared with LD33CV, LF33CPT adds logic-controlled shutdown and lower thermal resistance in PENTAWATT; versus TLV73333PDBVR, it offers higher current, wider temperature range, and integrated safety features-making it optimal for mission-critical embedded power rails.
Availability
LF33CPT is available at Aetrix Electronics and suitable for battery-powered instrumentation, automotive body electronics, and industrial IoT edge nodes requiring stable component supply with long lifecycle assurance.
Supply support for LF33CPT 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, specializing in power management, microcontrollers, and automotive ICs-with over 40 years of LDO development expertise.
The LF00 series was engineered specifically for ultra-low-power, high-reliability embedded systems where dropout voltage, quiescent current, and thermal resilience are critical-targeting portable medical, automotive, and industrial applications.
FAQ
What is the minimum input voltage required for stable 3.3 V output at 500 mA?
The LF33CPT requires ≥3.7 V input to maintain regulation at full 500 mA load due to its 0.4 V dropout specification. Below 3.7 V, output voltage drops linearly with input; operation below 3.7 V is not guaranteed per datasheet limits.
Can the NC pin (pin 5) be grounded or left floating?
Pin 5 is internally unconnected and must remain floating-neither grounded nor pulled high/low. Connecting it risks undefined behavior or latch-up; STMicroelectronics explicitly states "no connection" in the datasheet pinout diagram and mechanical drawings.
Is the 2.2 µF output capacitor mandatory, and what type is recommended?
Yes-the 2.2 µF ceramic capacitor (X5R or X7R dielectric, ESR 0.1–10 Ω) is required for stability per ST's test conditions and application notes. Tantalum or aluminum electrolytic capacitors are not recommended due to ESR and aging effects that may cause oscillation.
How does the shutdown function behave during power-up and brown-out conditions?
The SHDN pin has built-in hysteresis and internal pull-down; device remains disabled until SHDN rises above 2 V. During brown-out, output shuts down cleanly when SHDN falls below 0.8 V-no glitch or reverse current occurs, ensuring safe power sequencing in multi-rail systems.
LF33CPT Specifications
- Product attributes
- Attribute value
- Manufacturer:
- STMicroelectronics
- Series:
- -
- Package/Case:
- TO-252-5, DPAK (4 Leads + Tab), TO-252AD
- Packaging:
- Tube
- Product Status:
- Obsolete
- Output Configuration:
- Positive
- Output Type:
- Fixed
- Number of Regulators:
- 1
- Voltage - Input (Max):
- 16V
- Voltage - Output (Min/Fixed):
- 3.3V
- Voltage - Output (Max):
- -
- Voltage Dropout (Max):
- 0.7V @ 500mA
- Current - Output:
- 500mA
- Current - Quiescent (Iq):
- 1 mA
- Current - Supply (Max):
- 12 mA
- PSRR:
- 80dB ~ 65dB (120Hz ~ 65dB)
- Control Features:
- Enable
- Protection Features:
- Over Current, Over Temperature
- Operating Temperature:
- -40°C ~ 125°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- PPAK
LF33CPT FAQ
1.How can I place an order for LF33CPT through Aetrix?
Please submit a Request for Quotation (RFQ) for LF33CPT 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 LF33CPT reliable?
The price and inventory of LF33CPT are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LF33CPT is usually 5 days.
3.What payment methods are accepted for LF33CPT?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LF33CPT transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LF33CPT?
LF33CPT orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LF33CPT 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 LF33CPT?
For technical support, including LF33CPT datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LF33CPT requirements.
6.How does Aetrix verify that LF33CPT is sourced from the original manufacturer or authorized distributors?
All LF33CPT 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 LF33CPT meets industry standards.
7.What is the process for return or replacement of LF33CPT?
All LF33CPT units undergo pre-shipment inspection (PSI). If there is an issue with LF33CPT, 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 LF33CPT part is unused and in its original packaging.
Return procedure for LF33CPT:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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