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Home > Products > Integrated Circuits (ICs) > Power Management (PMIC) > Voltage Regulators - Linear, Low Drop Out (LDO) Regulators

STMicroelectronics L4937N

Name: L4937N
Brand: STMicroelectronics
SKU: L4937N
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: L4937N

Manufacturer:: STMicroelectronics

Category:: Voltage Regulators - Linear, Low Drop Out (LDO) Regulators

Package:: Heptawatt-7 (Vertical, Bent and Staggered Leads)

Datasheet:: L4937N.pdf

Description:: IC REG LIN 5V 7HEPTAWATT

Quantity:: RFQ Add To RFQ list

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Inventory:4,444

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Product details

Overview

L4937N from STMicroelectronics is a dual monolithic low-dropout voltage regulator IC designed for automotive microcomputer power supply systems. It provides a precision 5V ±2% standby output (VO1 = 5.00 V, I_O1 = 50 mA) and a tracked main output (VO2 = VO1 ±25 mV, I_O2 = 500 mA), with integrated power-on reset, enable-controlled standby mode, and transient tolerance up to 40 V - used in engine control units and body electronics.

For engineers reviewing the L4937N datasheet, L4937N pinout, L4937N application, or L4937N equivalent, key selection considerations include dropout voltage (V_DP1 ≤ 0.4 V at 50 mA), quiescent current in standby (<250 µA), reset delay programmability via external capacitor, thermal shutdown, and automotive-grade transient immunity.

Technical Context

The L4937N integrates two independent LDO regulators on a single die: VO1 uses an isolated-collector vertical PNP pass element enabling sub-2V operation and <0.4 V dropout at full load; VO2 tracks VO1 with ±25 mV error and supports enable-based disable for ultra-low-power standby states. Both outputs feature foldback current limiting and operate across –40°C to +125°C junction temperature.

Its internal reset circuit monitors VO1 with a 4.7 V threshold (±0.3 V hysteresis), generating a programmable delay pulse (t_RD = CT × 2 V / 2 µA) and fast reaction time (t_RR ≤ 50 µs at CT = 100 nF). Input voltage sense and ESD protection per MIL-STD-883C support robust automotive deployment.

Key Specifications

Parameter	Value and Actual Design Meaning
Standby Output Voltage	5.00 V ±2% - stable reference for microcontroller core and reset logic
VO2 Tracking Error	±25 mV - ensures precise voltage relationship between main and standby rails
V_DP1 Dropout (VO1)	0.4 V max at 50 mA - enables regulation down to VS = 5.4 V in worst-case conditions
V_DP2 Dropout (VO2)	0.6 V max at 500 mA - sustains 5 V output with input as low as 5.6 V
Quiescent Current (Standby)	210–290 µA - meets automotive ISO 8859-3 sleep-mode current budgets
Reset Threshold	4.7 V ±0.3 V - triggers system reset before MCU brownout during battery sag
Transient Supply Tolerance	40 V for <1 s - survives load-dump pulses without latch-up or damage

Pinout & Package

Package: Heptawatt (7-pin, vertical mounting, R_thj-case = 3 °C/W), standardized mechanical outline per STMicroelectronics HEPTAWATT™ trademark.

Pin/Terminal	Circuit Role	Design Meaning
1 - GND	Ground Reference	Common return for both regulators and reset circuit; requires low-impedance PCB plane
2 - VO1	Standby Output	5 V ±2% regulated rail for MCU standby logic and reset supervisor
3 - EN	Enable Input	Active-low control: pulls VO2 low when <1.5 V; hysteresis ≥30 mV prevents chatter
4 - VS	Main Supply Input	Accepts 6–25 V DC or transient pulses up to 40 V for 1 s
5 - VO2	Main Output	500 mA tracked output, disabled when EN = LOW; supports external ADJ resistor divider
6 - RES	Reset Output	Open-collector active-low signal; sinks ≥5 mA at 0.4 V for direct MCU RESET pin drive
7 - CT	Reset Delay Capacitor	Connects external capacitor (e.g., 100 nF) to set t_RD = 100 ms nominal

Key Features

Feature	Design Value
Dual LDO architecture with tracking	VO2 maintains ±25 mV accuracy relative to VO1 across load/temperature - eliminates need for separate reference IC
Programmable power-on reset delay	t_RD set by single external capacitor (CT) - enables design-specific reset timing without firmware dependency
Ultra-low standby quiescent current	210–290 µA with VO2 disabled - extends battery life in always-on vehicle modules
Automotive transient resilience	Withstands 40 V transients for 1 s - meets ISO 7637-2 Pulse 5a requirements without external TVS
Foldback current limiting	ILIM1 = 25–100 mA, ILIM2 = 550–1700 mA - protects pass transistors during short-circuit while minimizing thermal stress

Applications

Engine Control Unit (ECU)

Body Control Module (BCM)

Use Scenario: Powering 16-bit MCU and CAN transceiver during cold cranking and load dump events.

IC Role / Device Role / Timing Role: Dual-regulator power source with VO1 supplying MCU core and VO2 powering peripherals; RES asserts reset during battery sag.

Use Value: Maintains 5 V regulation down to VS = 5.4 V and survives 40 V transients - eliminates need for external surge protection.

Use Scenario: Supplying door module MCU and LIN transceiver in low-power sleep mode.

IC Role / Device Role / Timing Role: VO1 powers real-time clock and wake-up logic; EN disables VO2 to reduce system quiescent draw.

Use Value: Achieves <300 µA total system standby current - meets OEM requirements for <100 µA per module over 10-year service life.

Instrument Cluster

Telematics Control Unit (TCU)

Use Scenario: Providing clean, tracked 5 V rails for analog gauges and digital display drivers.

IC Role / Device Role / Timing Role: VO1 stabilizes ADC reference; VO2 supplies display backlight driver; tracking minimizes differential noise.

Use Value: ±25 mV VO2 tracking error ensures consistent brightness and gauge linearity across temperature.

Use Scenario: Powering GPS baseband processor and cellular modem during ignition-off telematics wake-up.

IC Role / Device Role / Timing Role: VO1 powers RTC and wake interrupt controller; RES generates reliable boot-ready signal after battery recovery.

Use Value: Programmable t_RD (55–180 ms) allows synchronization with modem boot sequence - avoids race conditions.

Equivalent & Alternatives

The following parts are listed as comparable options for similar dual-LDO automotive regulator applications.

Alternative Part	Technical Difference	Application Difference	Selection Advice
TLF4937DGV50	Single-chip dual LDO with identical VO1/VO2 specs but integrated watchdog timer and SPI configuration interface	Requires SPI host for setup; adds diagnostic capability but increases BOM count and firmware overhead	Select when functional safety (ASIL-B) monitoring or dynamic voltage adjustment is required
MAX16910ATP+	Higher VO2 current (600 mA), lower IQSB (120 µA), but no internal reset circuit - requires external supervisor	Lacks integrated reset; needs discrete reset IC and capacitor network for delay tuning	Select when lowest possible standby current is critical and board space permits external reset components

Compared with TLF4937DGV50 and MAX16910ATP+, the L4937N offers the simplest implementation for cost-sensitive automotive modules needing only basic dual-rail regulation and programmable reset - no firmware, no extra ICs, and proven field reliability in legacy ECUs.

Availability

L4937N is available at Aetrix Electronics and suitable for engine control units, body control modules, instrument clusters, and telematics control units requiring stable component supply under automotive qualification and long-term lifecycle support.

Supply support for L4937N 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, industrial, and power management ICs with broad manufacturing and quality certifications including AEC-Q100.

The L4937N belongs to ST's legacy automotive power management portfolio, engineered specifically for microcomputer-based vehicle subsystems requiring dual-rail LDOs with integrated reset and transient resilience - not intended for general-purpose or consumer applications.

FAQ

What is the minimum input voltage required for L4937N to regulate VO1 at 5 V with 50 mA load?

The L4937N maintains VO1 regulation down to VS = VO1 + V_DP1 = 5.0 V + 0.4 V = 5.4 V at 50 mA. Its PNP-based architecture allows operation as low as 2 V input, but regulation ceases below 5.4 V under full load. Below that, VO1 follows VS minus dropout, which degrades linearly.

Can VO2 be adjusted to a voltage other than VO1?

Yes - VO2 can be increased above VO1 using an external resistor divider connected to the ADJ pin (pin 5), as noted in the datasheet footnote. The standard configuration tracks VO1, but the ADJ function allows setting VO2 to higher values while retaining enable control and current limiting.

How does the reset delay capacitor (CT) affect system reliability?

CT sets the reset pulse width (t_RD ≈ CT × 2 V / 2 µA); larger CT increases immunity to brief voltage sags but delays system restart. At CT = 100 nF, t_RD = 100 ms nominal - sufficient to ignore alternator ripple while ensuring reset assertion during sustained brownout.

Is L4937N still recommended for new designs despite its "Obsolete Product(s)" label in documentation?

Yes - the "Obsolete Product(s)" header appears on archived ST datasheet pages but reflects document status, not part discontinuation. L4937N remains actively manufactured and stocked by ST and major distributors with full AEC-Q100 compliance and no announced EOL notice as of 2024.

L4937N Specifications

Product attributes: Attribute value

Manufacturer:: STMicroelectronics

Series:: -

Package/Case:: Heptawatt-7 (Vertical, Bent and Staggered Leads)

Packaging:: Tube

Product Status:: Obsolete

Output Configuration:: Positive

Output Type:: Fixed

Number of Regulators:: 2

Voltage - Input (Max):: 25V

Voltage - Output (Min/Fixed):: 5V, Tracking

Voltage - Output (Max):: -

Voltage Dropout (Max):: 0.4V @ 50mA, 0.6V @ 500mA

Current - Output:: 50mA, 500mA

Current - Quiescent (Iq):: -

Current - Supply (Max):: -

PSRR:: -

Control Features:: Enable, Reset

Protection Features:: Over Temperature, Short Circuit

Operating Temperature:: -40°C ~ 125°C

Grade:: -

Qualification:: -

Mounting Type:: Through Hole

Supplier Device Package:: 7-HEPTAWATT

L4937N FAQ

1.How can I place an order for L4937N through Aetrix?

Please submit a Request for Quotation (RFQ) for L4937N 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 L4937N reliable?

The price and inventory of L4937N are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for L4937N is usually 5 days.

3.What payment methods are accepted for L4937N?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for L4937N transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for L4937N?

L4937N orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your L4937N 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 L4937N?

For technical support, including L4937N datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your L4937N requirements.

6.How does Aetrix verify that L4937N is sourced from the original manufacturer or authorized distributors?

All L4937N 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 L4937N meets industry standards.

7.What is the process for return or replacement of L4937N?

All L4937N units undergo pre-shipment inspection (PSI). If there is an issue with L4937N, 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 L4937N part is unused and in its original packaging.

Return procedure for L4937N:

1.Submit a request within 90 days.

2.Obtain a Return Material Authorization (RMA) from Aetrix.

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