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STMicroelectronics L6902D
- Part No.:
- L6902D
- Manufacturer:
- STMicroelectronics
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
L6902D.pdf
- Description:
- IC REG BUCK ADJ 1A 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:2,226
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Product details
Overview
L6902D from STMicroelectronics is a voltage-mode step-down switching regulator with integrated P-channel DMOS power switch, adjustable current limit (±5% accuracy), 1 A continuous output current capability, 8–36 V input range, and 1.235–34 V adjustable output voltage. It serves as a constant-voltage/constant-current controller in battery charging and distributed power supply systems.
For engineers reviewing the L6902D datasheet, L6902D pinout, L6902D application, or L6902D equivalent, key selection considerations include its 250 kHz fixed switching frequency, internal 3.3 V ±2% reference, zero-load operation, thermal shutdown at 150°C, and SO-8 package compatibility with compact DC/DC layouts.
Technical Context
The L6902D implements a voltage-mode control architecture with dual error amplifiers-one for voltage regulation (FB input, 1.235 V reference) and one for current regulation (CS+/CS− inputs). Its internal oscillator fixes switching at 250 kHz, and voltage feedforward improves line transient response.
Current limiting is programmable via external sense resistor or on-chip 100 mΩ sense path, enabling precise NiCd/NiMH battery charging. Protection features include latched overcurrent (2.5 A typ.), feedback disconnection detection, overvoltage clamp, and thermal shutdown with 20°C hysteresis.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 8 V to 36 V - supports automotive and industrial unregulated rails without pre-regulation |
| Output Current | Up to 1 A continuous - sufficient for subnotebook PRMs and battery charge stages |
| Reference Voltage | 3.3 V ±2% - enables accurate feedback loop design and stable 1.235 V base output |
| Current Limit Accuracy | ±5% - ensures repeatable charge termination and short-circuit protection behavior |
| Switching Frequency | 250 kHz fixed - allows use of small, low-ESR ceramic output capacitors and compact magnetics |
| Dropout Voltage | 0.25 V typ. at 1 A - maintains regulation down to low VIN, critical for high-current preregulation |
| Thermal Shutdown | 150°C with 20°C hysteresis - prevents latch-up during sustained overload or poor heatsinking |
Pinout & Package
Package: SO-8 (ECOPACK® compliant), surface-mount, 1.27 mm pitch, 5.0 × 4.0 mm footprint, Rth j-amb = 110°C/W (board-mounted).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 OUT | Power output node | Drives inductor and output filter; connects directly to P-channel DMOS drain |
| 2 CS+ | High-side current sense input | Accepts voltage from top of external sense resistor or internal 100 mΩ path |
| 3 CS− | Low-side current sense input | Ground-referenced sense return; enables bidirectional current monitoring |
| 4 COMP | Error amplifier compensation node | External RC network sets loop stability; interfaces with both voltage and current EA outputs |
| 5 FB | Voltage feedback input | Sets output via resistive divider; 1.235 V threshold defines base regulation point |
| 6 VREF | Internal 3.3 V reference output | Stable, loadable reference for external circuitry; no capacitor required |
| 7 GND | Analog and power ground | Common return for feedback, sense, and reference circuits; must be low-impedance |
| 8 VCC | Unregulated input supply | Power source for internal logic and gate drive; operates up to 40 V absolute max |
Key Features
| Feature | Design Value |
|---|---|
| Integrated P-channel DMOS | 250 mΩ typical RDS(on) - reduces conduction loss and eliminates external high-side switch |
| Zero-load operation | Continuous regulation at IOUT = 0 A - supports always-on systems without burst-mode noise |
| Voltage feedforward | Direct VIN scaling in PWM comparator - improves line regulation and transient rejection |
| Feedback disconnection protection | Automatic shutdown if FB pin floats - prevents uncontrolled overvoltage during open-loop faults |
| Adjustable current limit | Programmable via external Rsense or internal path - enables flexible charge current or current-source design |
Applications
| NiCd/NiMH Battery Charger | Preregulator for Li-ion Systems |
|---|---|
Use Scenario: Charging multi-cell NiCd/NiMH packs in portable medical devices or cordless tools. IC Role / Device Role / Timing Role: Constant-current/constant-voltage controller with precise 1 A charge current and thermal foldback. Use Value: ±5% current accuracy ensures consistent cell capacity and cycle life; 250 kHz switching minimizes EMI in handheld enclosures. | Use Scenario: Generating stable 5 V intermediate rail from 12–24 V vehicle battery for Li-ion protection ICs. IC Role / Device Role / Timing Role: High-efficiency preregulator with adjustable current limit to protect downstream battery management ICs. Use Value: 0.25 V dropout at 1 A enables operation during cold-crank transients; SO-8 footprint simplifies layout in space-constrained automotive modules. |
| Adjustable Current Generator | Distributed Power Supply Node |
Use Scenario: Providing programmable bias current for optical transceivers or sensor excitation in industrial IoT nodes. IC Role / Device Role / Timing Role: Precision current source using CS+/CS− differential sensing and internal error amplifier. Use Value: Eliminates need for op-amp-based current mirrors; ±5% accuracy replaces calibration steps in production test. | Use Scenario: Local 3.3 V or 5 V conversion in modular telecom equipment with multiple isolated subsystems. IC Role / Device Role / Timing Role: Compact, self-contained DC/DC converter with built-in protections for board-level power domains. Use Value: Thermal shutdown and latched overcurrent prevent cascading failures across distributed loads; 110°C/W Rth supports natural convection cooling. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar step-down regulator with current-limit applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM2596-ADJ | Fixed 150 kHz frequency; no integrated current-sense amplifier; requires external current sense amp for CC mode | Primarily CV-only; CC operation adds complexity and board area | Choose when cost sensitivity outweighs current accuracy and integration needs |
| TPS5430 | 3.5 A rating; external N-MOSFET drive; no internal current-sense amplifier or dedicated CS pins | Higher current but lacks native constant-current architecture for battery charging | Prefer for higher-power CV applications where external current control is acceptable |
Compared with LM2596-ADJ and TPS5430, the L6902D uniquely integrates dual error amplifiers and dedicated CS+/CS− pins for true single-chip constant-current regulation-critical for battery charge safety and precision without added components.
Availability
L6902D is available at Aetrix Electronics and suitable for battery chargers, mobile PC power supplies, and distributed power supply nodes requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.
Supply support for L6902D 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, designing and manufacturing analog, microcontroller, power, and sensor solutions for industrial, automotive, and consumer markets.
The L6902D belongs to ST's legacy power management IC portfolio targeting simple, robust DC/DC conversion in cost-sensitive and space-constrained applications such as portable computing and battery-powered instrumentation.
FAQ
What is the minimum output voltage achievable with the L6902D?
The L6902D achieves a minimum output voltage of 1.235 V when the FB pin is connected directly to the output. This value is set by the internal voltage reference and is specified with ±1.5% tolerance across temperature and line conditions. No external resistor divider is needed for this configuration, making it ideal for low-voltage logic supply generation.
Can the L6902D operate without an external current sense resistor?
Yes - the L6902D supports current limiting using its internal 100 mΩ sense path between CS+ and CS− pins. When configured this way, it delivers ±5% current accuracy at 1 A without any external resistor. However, for higher accuracy or different current thresholds, an external sense resistor is recommended and connected across CS+ and CS−.
How does the L6902D handle feedback disconnection?
The L6902D monitors the FB pin voltage and disables the power stage if FB rises above 1.8 V while VCC is valid - indicating an open feedback loop. This prevents uncontrolled output overvoltage. The device remains latched off until VCC is cycled or the fault condition is corrected, ensuring system-level safety in mission-critical power paths.
Is the L6902D suitable for automotive applications?
The L6902D is not qualified as AEC-Q100 automotive grade, though its 8–36 V input range and -40°C to +150°C junction temperature range align with many automotive subsystem requirements. ST explicitly states non-automotive qualification in its datasheet disclaimer; users must perform full system-level validation for safety-critical vehicle functions.
L6902D Specifications
- Product attributes
- Attribute value
- Manufacturer:
- STMicroelectronics
- Series:
- -
- Package/Case:
- 8-SOIC (0.154", 3.90mm Width)
- Packaging:
- Tube
- Product Status:
- Active
- Function:
- Step-Down
- Output Configuration:
- Positive
- Topology:
- Buck
- Output Type:
- Adjustable
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 8V
- Voltage - Input (Max):
- 36V
- Voltage - Output (Min/Fixed):
- 1.235V
- Voltage - Output (Max):
- 34V
- Current - Output:
- 1A
- Frequency - Switching:
- 250kHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- -40°C ~ 150°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-SOIC
L6902D FAQ
1.How can I place an order for L6902D through Aetrix?
Please submit a Request for Quotation (RFQ) for L6902D 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 L6902D reliable?
The price and inventory of L6902D are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for L6902D is usually 5 days.
3.What payment methods are accepted for L6902D?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for L6902D transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for L6902D?
L6902D orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your L6902D 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 L6902D?
For technical support, including L6902D datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your L6902D requirements.
6.How does Aetrix verify that L6902D is sourced from the original manufacturer or authorized distributors?
All L6902D 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 L6902D meets industry standards.
7.What is the process for return or replacement of L6902D?
All L6902D units undergo pre-shipment inspection (PSI). If there is an issue with L6902D, 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 L6902D part is unused and in its original packaging.
Return procedure for L6902D:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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