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STMicroelectronics L5970D
- Part No.:
- L5970D
- Manufacturer:
- STMicroelectronics
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
L5970D.pdf
- Description:
- IC REG BUCK ADJ 1A 8SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:3,516
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Product details
Overview
L5970D from STMicroelectronics is a monolithic step-down switching regulator with an integrated P-channel D-MOS transistor (RDS(on) = 250 mΩ), delivering up to 1 A output current across an adjustable output voltage range of 1.2 V to 35 V. It operates from 4.4 V to 36 V input, features internal 250 kHz fixed-frequency PWM control, and supports zero-load operation with 100% duty cycle capability-ideal for 5 V bus-powered computer peripherals and industrial DC-DC converters.
For engineers reviewing the L5970D datasheet, L5970D pinout, L5970D application, or L5970D equivalent, key selection considerations include its 3.3 V ±2% reference accuracy, pulse-by-pulse current limiting, synchronization capability, thermal shutdown protection, and SO8 package compatibility with standard PCB layout practices for high-efficiency buck conversion.
Technical Context
The L5970D implements voltage-mode PWM control with feedforward compensation, using an internal error amplifier (65 dB open-loop gain, 2.3 mS transconductance) and COMP pin for external frequency compensation. Its feedback loop references a precision 3.3 V bandgap (±2% over temperature), with FB pin threshold at 1.235 V for adjustable output configurations.
Switching is governed by a fixed 250 kHz oscillator (±12% over temperature), enabling predictable EMI filtering and inductor sizing. The device integrates inhibit logic (active-high INH), SYNC input for master-slave operation, and robust protection including thermal shutdown, feedback disconnection detection, and internal current limiting (1.87 A typical).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output current | Up to 1 A continuous; supports pulse-by-pulse current limiting up to 2.25 A for short-circuit protection. |
| Input voltage range | 4.4 V to 36 V; enables direct use on 5 V, 12 V, and 24 V industrial/computer buses. |
| Output voltage range | 1.2 V to 35 V; set via external resistor divider on FB pin referencing 1.235 V internal threshold. |
| Switching frequency | 250 kHz fixed (212–280 kHz over temp); balances efficiency, size, and EMI for mid-power buck designs. |
| RDS(on) | 250 mΩ typical; reduces conduction loss and thermal stress in the integrated P-MOSFET switch. |
| Reference voltage | 3.3 V ±2% (3.234–3.366 V); stable over -40°C to +125°C, used for internal regulation and FB comparator. |
| Quiescent current | 3–5 mA operating; drops to 50–150 µA in inhibit mode-critical for low-power standby systems. |
Pinout & Package
Package: SO8 (Small Outline, 8-pin, ECOPACK® lead-free). Dimensions per JEDEC MS-012, body width 3.9 mm, pitch 1.27 mm, max height 1.65 mm.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| OUT (Pin 1) | Regulator output node | Switching node connecting to external inductor; carries pulsed current and requires low-inductance layout. |
| SYNC (Pin 2) | Synchronization input/output | Accepts external clock (2.5 V high, 0.74 V low) or outputs synchronized pulse for multi-regulator timing alignment. |
| INH (Pin 3) | Inhibit control | Active-high enable; open-circuit disables regulator via internal pull-up; grounded for always-on operation. |
| COMP (Pin 4) | Error amplifier output | Connects to RC network for loop compensation; sets phase margin and transient response of feedback loop. |
| FB (Pin 5) | Feedback input | High-impedance input referenced to 1.235 V; senses output via resistive divider to regulate voltage precisely. |
| VREF (Pin 6) | Internal reference output | Provides stable 3.3 V ±2% reference; no external capacitor required-simplifies auxiliary bias design. |
| GND (Pin 7) | Power and signal ground | Common return for power path, feedback, and control circuitry; must be low-impedance and star-connected. |
| VCC (Pin 8) | Unregulated input supply | Power source for internal circuitry; must be bypassed with ceramic capacitor close to pin for noise immunity. |
Key Features
| Feature | Design Value |
|---|---|
| Voltage feedforward | Compensates for input voltage variations in real time, improving line regulation and transient response without additional components. |
| Zero-load operation | Maintains regulation down to 0 A output current via adaptive biasing-enables always-on monitoring circuits. |
| Low dropout mode | Supports 100% duty cycle operation, allowing VOUT ≈ VIN − IOUT × RDS(on) for minimal headroom applications. |
| Internal current limiting | Pulse-by-pulse peak current limit (1.87 A typ.) prevents MOSFET failure during overload or short-circuit events. |
| Thermal shutdown | Activates at TJ ≥ 150°C with hysteresis; protects silicon under sustained overload or poor heatsinking. |
Applications
| Consumer Audio Power Supply | Industrial DC-DC Converter |
|---|---|
|
Use Scenario: Powering analog audio stages and DACs in car radios and LCD monitors requiring clean, low-noise 3.3 V or 5 V rails. IC Role / Device Role / Timing Role: Primary buck regulator providing regulated output with <15 mV load regulation and 10 mV line regulation. Use Value: Integrated 3.3 V reference and feedforward control minimize output ripple (<10 mVpp) without external LDO post-regulation. |
Use Scenario: Generating 12 V or 24 V intermediate rails from wide-input 36 V battery or industrial bus systems. IC Role / Device Role / Timing Role: High-voltage step-down controller supporting 4.4–36 V input and delivering up to 1 A with thermal fault recovery. Use Value: 250 mΩ RDS(on) and 90% peak efficiency at 5 V/1 A reduce heatsink requirements in enclosed enclosures. |
| Networking Modem Power | Computer Peripheral Regulator |
|
Use Scenario: Supplying isolated 3.3 V logic and 1.8 V core voltages in DSL modems and xDSL line cards with tight space constraints. IC Role / Device Role / Timing Role: Compact SO8-based buck converter enabling dual-output designs using auxiliary winding or cascaded topology. Use Value: Synchronization pin allows precise phase alignment with other regulators to reduce input ripple and simplify EMI filter design. |
Use Scenario: Providing stable 3.3 V or 5 V power to graphics/audio cards and optical storage controllers in desktop PCs. IC Role / Device Role / Timing Role: Bus-compatible regulator optimized for 5 V input operation with fast transient response to dynamic load steps. Use Value: 100% duty cycle capability ensures regulation even as input decays near 5 V-critical for brown-out resilience. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar step-down regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM2596-ADJ | Fixed 150 kHz frequency, higher RDS(on) (~300 mΩ), no SYNC or INH pins, wider VIN (4.5–40 V). | Lacks synchronization and inhibit control; less suitable for multi-rail coordinated power sequencing. | Prefer when cost sensitivity outweighs need for advanced control features and thermal performance is secondary. |
| MP1584EN-LF-Z | Higher switching frequency (1.5 MHz), lower quiescent current (2.5 mA), but no integrated VREF output or feedforward. | Better for compact designs needing small inductors; lacks 3.3 V reference for auxiliary bias generation. | Choose when board space is constrained and external reference is available; avoid if VREF pin simplification is critical. |
Compared with LM2596-ADJ and MP1584EN-LF-Z, the L5970D uniquely combines feedforward control, a buffered 3.3 V reference, and synchronization-all in SO8-making it optimal for multi-rail, thermally sensitive, or reference-sharing applications where layout simplicity and system-level coordination matter.
Availability
L5970D is available at Aetrix Electronics and suitable for consumer audio power supplies, industrial DC-DC converters, and networking modem power systems requiring stable component supply, long-lifecycle support, and consistent SO8 packaging.
Supply support for L5970D 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 analog, microcontroller, power, and sensor solutions for industrial, automotive, and consumer markets.
The L5970D belongs to ST's monolithic DC-DC converter product line, engineered specifically for high-efficiency, wide-input-voltage buck regulation in space-constrained and thermally demanding applications-from computing peripherals to automotive infotainment subsystems.
FAQ
What is the minimum input voltage required for L5970D to regulate a 3.3 V output?
The L5970D requires a minimum input voltage of 4.4 V to maintain regulation at any output voltage, including 3.3 V. This is due to internal headroom requirements for the P-channel MOSFET gate drive and error amplifier operation. Below 4.4 V, the device enters dropout mode and cannot sustain regulation-even with 100% duty cycle-because VCC itself falls below operational thresholds.
Can the L5970D generate negative output voltages?
No, the L5970D is a synchronous step-down (buck) regulator only and cannot produce negative outputs directly. However, application note figures (e.g., Figure 19) show it used in inverting buck-boost configurations with external components-including a second diode, inductor winding, and polarity-reversal layout-to achieve negative rails like –12 V. Such topologies require careful stability analysis and are not supported natively by the IC's control architecture.
How does the INH pin behave when left unconnected?
When the INH pin is left floating, an internal pull-up resistor forces it high, disabling the L5970D. To enable normal operation, INH must be actively pulled low (≤0.8 V) via a direct connection to GND or an open-drain driver. Leaving it unconnected is a valid hardware disable method but precludes remote enable control unless inverted logic is added externally.
Is external compensation mandatory for stable operation?
Yes, external compensation via the COMP pin is mandatory. The L5970D's error amplifier is intentionally uncompensated; stability depends on an external RC network (e.g., 4.7 kΩ + 22 nF) between COMP and FB. Omitting this network causes oscillation or erratic regulation, as confirmed in Figure 14's demo board schematic and Section 5 of the datasheet.
L5970D 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):
- 4.4V
- Voltage - Input (Max):
- 36V
- Voltage - Output (Min/Fixed):
- 1.2V
- Voltage - Output (Max):
- 35V
- 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
L5970D FAQ
1.How can I place an order for L5970D through Aetrix?
Please submit a Request for Quotation (RFQ) for L5970D 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 L5970D reliable?
The price and inventory of L5970D are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for L5970D is usually 5 days.
3.What payment methods are accepted for L5970D?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for L5970D transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for L5970D?
L5970D orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your L5970D 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 L5970D?
For technical support, including L5970D datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your L5970D requirements.
6.How does Aetrix verify that L5970D is sourced from the original manufacturer or authorized distributors?
All L5970D 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 L5970D meets industry standards.
7.What is the process for return or replacement of L5970D?
All L5970D units undergo pre-shipment inspection (PSI). If there is an issue with L5970D, 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 L5970D part is unused and in its original packaging.
Return procedure for L5970D:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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