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STMicroelectronics L4938EPD
- Part No.:
- L4938EPD
- Manufacturer:
- STMicroelectronics
- Package:
- 20-SOIC (0.433", 11.00mm Width) Exposed Pad
- Datasheet:
-
L4938EPD.pdf
- Description:
- IC REG LINEAR POS ADJ POWERSO20
- Quantity:
- Payment:
- Shipping:
Inventory:1,432
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Product details
Overview
L4938EPD from STMicroelectronics is a monolithic dual-voltage regulator IC designed for microcomputer-controlled automotive systems, featuring two low-dropout outputs (5 V ±1% @ 100 mA and 5 V ±2% @ 400 mA), programmable reset threshold (3.8–4.7 V), and protected enable/sense inputs tolerant to –5 V transients.
For engineers reviewing the L4938EPD datasheet, L4938EPD pinout, L4938EPD application, or L4938EPD equivalent, this device supports critical power sequencing, voltage supervision, and transient-robust 5 V rail generation in engine control units, body controllers, and ADAS domain modules requiring stable dual-rail supply with integrated reset and sense functions.
Technical Context
The L4938EPD integrates two independent LDO regulators: OUT1 uses an isolated-collector vertical PNP transistor enabling dropout operation down to 3 V input while maintaining 5 V ±1% regulation up to 40 V transients; OUT2 employs identical topology rated for 400 mA, with ADJ pin allowing fixed 5 V or externally adjustable output via resistor divider.
Its supervisory circuitry includes a reset generator powered by OUT1 (not VS), enabling reliable reset assertion even during main supply loss; a sense comparator with 1.16 V typ threshold monitors external voltage rails; and EN/SI inputs hardened against –5 V negative transients with ±1 mA current limiting.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| OUT1 Voltage | 5 V ±1% at 100 mA load - ensures stable MCU core supply under full automotive temperature range (–40 °C to 150 °C). |
| OUT2 Voltage | 5 V ±2% at 400 mA load when ADJ tied to OUT2 - powers peripheral ICs, CAN transceivers, or sensors with high-current capability. |
| Quiescent Current | 65 µA in standby mode (EN high) - enables ultra-low-power sleep states in always-on vehicle modules. |
| Reset Threshold | Adjustable 3.8 V to 4.7 V via PR-to-GND resistor - allows precise brown-out detection aligned with MCU VDD requirements. |
| Supply Range | 5 V to 28 V DC operating; withstands 40 V transients <400 ms - compatible with 12 V automotive battery systems including load-dump conditions. |
| Thermal Shutdown | Output 2 disables ~10 K before Output 1 at TJ ≈ 165 °C - prevents thermal runaway while preserving critical core supply. |
| Input Protection | EN and SI pins tolerate –5 V transients - eliminates need for external clamping diodes in harsh ECU environments. |
Pinout & Package
Package: PowerSO-20 - thermally enhanced surface-mount package with exposed die attach pad for improved heat dissipation in automotive PCB layouts.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VS1 | Supply for OUT1, reset, and sense circuits | Primary 5–28 V input powering 100 mA regulator and supervisory logic; must be decoupled near pin. |
| VS2 | Supply for OUT2 regulator | Dedicated input for 400 mA regulator; enables independent supply routing and transient isolation from VS1. |
| OUT1 | 100 mA regulated output | Stable 5 V ±1% rail for microcontroller core or real-time clock; low dropout maintains regulation down to 3 V input. |
| OUT2 | 400 mA regulated output | Main system rail for peripherals; disable via EN pin reduces total system quiescent current to 65 µA. |
| ADJ | Feedback node for OUT2 | Connect to OUT2 for fixed 5 V; use external resistor divider to set custom output voltage (e.g., 3.3 V) with RADJ = 60–150 kΩ. |
| EN | Active-low enable for OUT2 | Pulling low activates 400 mA regulator; hysteresis (20–60 mV) prevents chatter during slow-rising control signals. |
| SI | Sense input for comparator | Monitors external voltage (e.g., battery pre-ignition); comparator triggers SO output at 1.16 V threshold with 30 mV hysteresis. |
| RES | Open-drain reset output | Asserts low when OUT1 drops below programmed threshold; sourced from OUT1, not VS - ensures reset validity during supply faults. |
| PR | Reset threshold programming | Resistor to GND sets reset point from 3.8 V to 4.7 V; calculation uses RPR = (22k / VRT) − 1 − 92.9k formula. |
| CT | Reset delay capacitor connection | 47 nF capacitor sets nominal reset pulse delay of 100 ms; charge current from OUT1 enables accurate timing without external bias. |
Key Features
| Feature | Design Value |
|---|---|
| Standby quiescent current | 65 µA enables >10-year battery backup in always-on telematics modules without compromising wake-up responsiveness. |
| Dual independent LDOs | OUT1 (100 mA) and OUT2 (400 mA) operate with separate inputs (VS1/VS2), allowing optimized PCB layout and fault containment. |
| Reset generation from OUT1 | Self-powered reset circuit remains functional even if main VS supply fails - guarantees deterministic MCU reset on brown-out. |
| Negative transient protection | EN and SI pins withstand –5 V pulses without external components - reduces BOM count and board space in cost-sensitive ECUs. |
| Thermal de-rating coordination | OUT2 shuts down ~10 K before OUT1, preserving core logic supply while shedding non-critical load during overheating. |
Applications
| Engine Control Unit (ECU) | Body Control Module (BCM) |
|---|---|
Use Scenario: Real-time combustion timing and fuel injection control under wide temperature and vibration conditions. IC Role / Device Role / Timing Role: Dual-rail power manager providing isolated 5 V supplies for MCU core (OUT1) and actuator drivers (OUT2), with reset synchronized to VDD integrity. Use Value: Maintains 5 V ±1% core supply down to 3 V input during cranking, preventing MCU lockup while delivering 400 mA to solenoid drivers during transient-rich engine start-stop cycles. | Use Scenario: Centralized lighting, door lock, and window control with CAN communication and low-power sleep modes. IC Role / Device Role / Timing Role: System power supervisor generating wake-up reset signal and monitoring battery voltage via SI pin for low-battery warning. Use Value: Enables <100 µA system sleep current via EN-controlled OUT2 shutdown, while SI-driven SO output alerts MCU to battery voltage sag before critical undervoltage occurs. |
| Advanced Driver Assistance Systems (ADAS) | Infotainment Domain Controller |
Use Scenario: Radar sensor fusion processing with strict thermal and voltage stability requirements in front bumper location. IC Role / Device Role / Timing Role: Dual-output regulator supplying 5 V to radar SoC (OUT1) and 5 V to CAN FD transceiver (OUT2), with thermal shutdown prioritizing SoC supply. Use Value: Coordinated thermal protection disables only transceiver rail (OUT2) at 155 °C, preserving radar processing continuity while shedding non-critical communication load. | Use Scenario: Multi-display head unit with audio DSP, touchscreen controller, and USB peripherals requiring clean, sequenced 5 V rails. IC Role / Device Role / Timing Role: Power sequencer using RES output to hold application processor in reset until both OUT1 and OUT2 stabilize within tolerance. Use Value: Programmable reset threshold (3.8–4.7 V) aligns precisely with infotainment SoC's VDD min specification, eliminating false resets during cold-cranking voltage dips. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar dual-output automotive LDO regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| TLF35584QKV | Triple-output (3× 5 V) with integrated watchdog and SPI interface; higher quiescent current (120 µA) | Requires SPI configuration and supports ASIL-B functional safety; lacks adjustable reset threshold | Select when system-level diagnostics, multi-rail flexibility, or ISO 26262 compliance are required over simple dual-LDO operation. |
| MAX16910ATA+ | Single 5 V output (250 mA) with reset and watchdog; no second regulator or sense comparator | Smaller SO-8 package; lower thermal capability; no SI/SENSE functionality | Select for space-constrained applications where only one regulated rail and basic reset are needed, not dual-rail + supervision. |
Compared with TLF35584QKV and MAX16910ATA+, the L4938EPD uniquely combines dual independent LDOs, programmable reset, and dedicated sense comparator in PowerSO-20 - making it optimal for cost-sensitive, non-safety-critical automotive modules needing minimal external components and proven thermal robustness without digital overhead.
Availability
L4938EPD is available at Aetrix Electronics and suitable for engine control units, body control modules, ADAS sensor hubs, and infotainment domain controllers requiring stable component supply across extended automotive temperature ranges and long production lifecycles.
Supply support for L4938EPD 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, specializing in automotive-grade analog, power, and microcontroller solutions with broad AEC-Q100 qualification coverage.
The L4938EPD belongs to ST's automotive power management IC portfolio, engineered specifically for robust dual-rail voltage regulation and system supervision in engine, chassis, and body electronics where reliability under extreme electrical stress is mandatory.
FAQ
What is the maximum allowable transient voltage on VS1 and VS2 pins?
The L4938EPD supports transient supply voltages up to 40 V on both VS1 and VS2 for durations less than 400 ms, per absolute maximum ratings. This withstand capability covers standard automotive load-dump events without requiring external TVS diodes, provided proper PCB layout and local decoupling are implemented.
Can OUT2 be configured for an output voltage other than 5 V?
Yes - by disconnecting ADJ from OUT2 and connecting an external resistor divider between OUT2, ADJ, and GND, the L4938EPD supports adjustable OUT2 voltages. The formula is VOUT2 = VOUT1 × (1 + R1E/R2E), with RADJ (60–150 kΩ) forming part of the feedback network; temperature coefficient (2000 ppm/°C) must be considered for precision designs.
How does the sense comparator function without an external power supply?
The SI pin connects to an internal comparator referenced to a 1.16 V bandgap voltage. It draws ≤±1 µA, enabling direct monitoring of battery or pre-regulator voltage via external resistive divider. The SO output is open-drain and requires a pull-up to VOUT1 or another 5 V rail - no separate bias supply is needed.
Is thermal shutdown behavior different between OUT1 and OUT2?
Yes - thermal shutdown is staged: OUT2 disables approximately 10 K before OUT1 reaches its 165 °C junction limit. This design preserves the critical 100 mA OUT1 rail (e.g., for MCU core) while shedding the higher-current OUT2 load (e.g., actuators or interfaces), allowing controlled thermal recovery without full system reset.
L4938EPD Specifications
- Product attributes
- Attribute value
- Manufacturer:
- STMicroelectronics
- Series:
- -
- Package/Case:
- 20-SOIC (0.433", 11.00mm Width) Exposed Pad
- Packaging:
- Tube
- Product Status:
- Active
- Output Configuration:
- Positive
- Output Type:
- Adjustable (Fixed)
- Number of Regulators:
- 2
- Voltage - Input (Max):
- 28V
- Voltage - Output (Min/Fixed):
- 4.9V (5V)
- Voltage - Output (Max):
- 5.1V
- Voltage Dropout (Max):
- 0.4V @ 100mA, 0.6V @ 400mA
- Current - Output:
- 100mA, 400mA
- Current - Quiescent (Iq):
- -
- Current - Supply (Max):
- -
- PSRR:
- -
- Control Features:
- Enable, Reset
- Protection Features:
- Over Temperature
- Operating Temperature:
- -40°C ~ 150°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- PowerSO-20
L4938EPD FAQ
1.How can I place an order for L4938EPD through Aetrix?
Please submit a Request for Quotation (RFQ) for L4938EPD 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 L4938EPD reliable?
The price and inventory of L4938EPD are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for L4938EPD is usually 5 days.
3.What payment methods are accepted for L4938EPD?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for L4938EPD transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for L4938EPD?
L4938EPD orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your L4938EPD 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 L4938EPD?
For technical support, including L4938EPD datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your L4938EPD requirements.
6.How does Aetrix verify that L4938EPD is sourced from the original manufacturer or authorized distributors?
All L4938EPD 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 L4938EPD meets industry standards.
7.What is the process for return or replacement of L4938EPD?
All L4938EPD units undergo pre-shipment inspection (PSI). If there is an issue with L4938EPD, 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 L4938EPD part is unused and in its original packaging.
Return procedure for L4938EPD:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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