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Texas Instruments LM2694SD
- Part No.:
- LM2694SD
- Manufacturer:
- Texas Instruments
- Package:
- 10-WFDFN Exposed Pad
- Datasheet:
-
LM2694SD.pdf
- Description:
- IC REG BUCK ADJ 600MA 10WSON
- Quantity:
- Payment:
- Shipping:
Inventory:3,193
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Product details
Overview
LM2694SD from Texas Instruments is a 30V, 600 mA step-down switching regulator with integrated N-channel buck switch and constant-on-time control architecture. It operates from 8V to 30V input, delivers adjustable output voltage via resistor divider feedback (2.5 V reference), and features valley current limiting at 0.62 A - used in high-voltage POL regulation for telecom secondary power supplies.
For engineers reviewing the LM2694SD datasheet, LM2694SD pinout, LM2694SD application, or LM2694SD equivalent, key selection considerations include its no-loop-compensation design, 1 MHz max switching frequency, thermal shutdown at 175°C, WSON-10 package with exposed pad, and RON/SD pin for programmable on-time and shutdown control.
Technical Context
The LM2694SD employs a constant-on-time control scheme where on-time is determined by VIN and an external RON resistor, enabling stable operating frequency across line and load variations. Its regulation relies on comparing FB voltage to a precision 2.5 V internal reference, with no external compensation required.
Current limiting is implemented via valley-sensing at the ISEN pin, triggering off-time extension when sensed current exceeds 0.62 A. The device integrates a startup regulator (VCC = 7.0 V ±0.4 V), bootstrap gate drive (BST–SW capacitor = 0.022 µF), and dual protection comparators: over-voltage (2.9 V threshold) and VCC under-voltage lockout (5.7 V rising).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 8 V to 30 V - supports wide-range industrial and telecom inputs without pre-regulation |
| Output Current Capability | 600 mA continuous - sufficient for point-of-load bias rails in FPGA, DSP, and ASIC core logic |
| Switching Frequency | Up to 1 MHz - enables compact magnetics and low-profile output capacitors |
| Feedback Reference | 2.5 V ±1.2% - sets output voltage via R1/R2 divider; enables precise, adjustable regulation |
| Valley Current Limit | 0.62 A ±12% - provides short-circuit protection with smooth transition to constant-current mode |
| Thermal Shutdown | 175°C activation - protects against sustained overload or poor heatsinking in enclosed systems |
| VCC Startup Regulator | 7.0 V ±0.4 V, 9 mA limit - powers internal circuitry directly from VIN; reduces need for external bias supply |
Pinout & Package
The LM2694SD is housed in a thermally enhanced 3 mm × 3 mm WSON-10 package with exposed pad (DSC0010A), optimized for high-power-density PCB layouts and efficient heat transfer to ground plane.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (SW) | Switching Node | Connects to inductor, freewheeling diode cathode, and BST capacitor - carries high dv/dt switching waveform |
| 2 (BST) | Bootstrap Supply | Drives high-side gate via 0.022 µF capacitor to SW - enables N-channel MOSFET operation without external charge pump |
| 3 (ISEN) | Current Sense Input | Senses recirculating inductor current during off-time - sets 0.62 A valley current limit |
| 4 (SGND) | Current Sense Ground | Return path for ISEN current - must be routed separately from power ground to avoid noise coupling |
| 5 (RTN) | Circuit Ground | Main analog/digital ground return - connects to system ground plane and output capacitor negative terminal |
| 6 (FB) | Voltage Feedback Input | Compares output voltage (via R1/R2 divider) to 2.5 V reference - determines regulation accuracy and transient response |
| 7 (SS) | Softstart Control | Charged by 12 µA internal current source - controls output ramp rate and inrush current during power-up |
| 8 (RON/SD) | On-Time Programming / Shutdown | Resistor-to-VIN sets on-time; grounding disables regulator - enables remote enable and frequency tuning |
| 9 (VCC) | Startup Regulator Output | 7.0 V regulated supply for internal logic and gate drive - bypassed with ≥0.1 µF ceramic capacitor |
| 10 (VIN) | Main Input Supply | Accepts 8–30 V DC input - requires local ceramic bypass (C1) near pin to suppress switching transients |
Key Features
| Feature | Design Value |
|---|---|
| No loop compensation required | Eliminates external RC network - simplifies layout, improves reliability, and ensures fast load transient response |
| Ultra-fast transient response | Regulates within microseconds of load step - critical for powering burst-mode digital loads like microcontrollers and FPGAs |
| Adjustable output voltage | Set via external R1/R2 divider - supports 3.3 V, 5 V, or custom outputs without changing IC |
| Integrated start-up regulator | Self-biases from VIN - removes need for auxiliary bias supply and reduces BOM count |
| Exposed thermal pad (WSON-10) | Enables direct connection to PCB ground plane - lowers θJA to 33°C/W for improved thermal performance |
Applications
| High-Efficiency Point-of-Load Regulator | Non-Isolated Telecom Buck Regulator |
|---|---|
Use Scenario: Powering FPGA I/O banks or microcontroller peripherals requiring tightly regulated 3.3 V or 5 V from a 12 V or 24 V backplane. IC Role / Device Role / Timing Role: Primary DC-DC converter delivering up to 600 mA with constant-on-time control and no external compensation. Use Value: Achieves >90% efficiency at full load while maintaining <1% output voltage deviation under 100 mA–600 mA dynamic load steps. | Use Scenario: Generating intermediate 5 V rail from 48 V telecom distribution bus for downstream DC-DC modules. IC Role / Device Role / Timing Role: High-input-voltage buck stage providing robust, low-noise bias for isolated converters. Use Value: Withstands 33 V transient surges and maintains regulation during 48 V bus dips down to 36 V due to wide 8–30 V input range. |
| Secondary High-Voltage Post Regulator | Industrial Sensor Bias Supply |
Use Scenario: Down-converting 24 V or 30 V industrial bus voltage to 12 V or 15 V for op-amp signal conditioning stages. IC Role / Device Role / Timing Role: Non-isolated post-regulator ensuring clean, stable supply despite noisy factory floor input. Use Value: Integrated VCC UVLO (5.7 V) and thermal shutdown (175°C) prevent latch-up during brownouts or ambient temperature excursions. | Use Scenario: Providing 3.3 V bias to analog sensors and ADC front-ends in programmable logic controllers (PLCs). IC Role / Device Role / Timing Role: Low-quiescent-current (0.8 mA typical) buck regulator supporting always-on sensor monitoring. Use Value: Softstart (SS pin) limits inrush current to <100 mA during cold boot, preventing system-wide voltage droop. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar step-down regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM2694MX/NOPB | TSSOP-14 package (vs. WSON-10); identical electrical specs and pinout mapping except NC pins | Better suited for through-hole prototyping or legacy TSSOP footprints; higher θJA (40°C/W) | Select when board space allows larger footprint and thermal margin is less constrained |
| TPS54202DRCT | 4.5–28 V input; 2 A output; integrated MOSFETs; 500 kHz fixed frequency; requires external compensation | Higher current capability but narrower input range; needs compensation network and larger inductor | Choose for designs needing >600 mA or tighter EMI control via fixed-frequency operation |
Compared with LM2694MX/NOPB, the LM2694SD offers superior thermal performance in space-constrained layouts; compared with TPS54202DRCT, it trades higher current for simpler design, wider input range, and no compensation - ideal for cost-sensitive, high-voltage POL applications.
Availability
LM2694SD is available at Aetrix Electronics and suitable for high-efficiency point-of-load regulation, non-isolated telecom buck conversion, and secondary high-voltage post-regulation requiring stable component supply and long-term industrial availability.
Supply support for LM2694SD 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
Texas Instruments is a global semiconductor leader specializing in analog, embedded processing, and power management technologies, with decades of expertise in high-reliability power conversion ICs.
The LM2694 product line delivers high-voltage, medium-current buck regulators for industrial, telecom, and automotive subsystems where simplicity, thermal efficiency, and input voltage robustness are critical.
FAQ
What is the maximum input voltage rating for the LM2694SD?
The LM2694SD has an absolute maximum input voltage (VIN to RTN) of 33 V, with recommended operating range from 8 V to 30 V. Exceeding 33 V risks permanent damage. The device includes built-in protection against transient overvoltage events common in telecom and industrial environments, making LM2694SD suitable for 24 V and 48 V bus-derived applications with appropriate input filtering.
How does the LM2694SD achieve no-loop-compensation operation?
The LM2694SD uses a constant-on-time control architecture that inherently stabilizes the feedback loop without external compensation components. By tying on-time directly to VIN and RON, the regulator maintains consistent frequency and phase margin across load and line variations - eliminating the need for RC networks on the FB pin. This design is validated in the LM2694SD datasheet and enables reliable operation with minimal external parts.
Can the LM2694SD be shut down remotely, and how is it implemented?
Yes, the LM2694SD supports remote shutdown via the RON/SD pin: pulling this pin below 0.8 V disables the buck switch, grounds the SS pin, and reduces bias current to 90–180 µA. Releasing the pin restores normal operation. This feature is fully specified in the LM2694SD Electrical Characteristics table and enables power sequencing, standby modes, and system-level fault response without additional logic.
What is the purpose of the ISEN and SGND pins on the LM2694SD?
The ISEN pin senses valley current during the off-time to enforce the 0.62 A current limit, while SGND provides the dedicated return path for that sensed current - separate from main circuit ground (RTN). This separation prevents noise from high di/dt switching currents from corrupting current-sense accuracy. Both pins are essential to the LM2694SD's valley-current-limiting protection scheme and must be routed with short, low-inductance traces per the LM2694SD layout guidelines.
Does the LM2694SD require a minimum output capacitor ESR, and why?
Yes, the LM2694SD requires ≥25 mVp-p ripple voltage at the FB pin for stable regulation, which translates to a minimum effective series resistance (ESR) on the output capacitor (C2). If the chosen capacitor's ESR is insufficient, a small series resistor (R3) must be added - as shown in the LM2694SD Typical Application Circuit - to generate the necessary ripple. This requirement ensures proper feedback loop dynamics in the absence of external compensation.
LM2694SD Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- 10-WFDFN Exposed Pad
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- Function:
- Step-Down
- Output Configuration:
- Positive
- Topology:
- Buck
- Output Type:
- Adjustable
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 8V
- Voltage - Input (Max):
- 30V
- Voltage - Output (Min/Fixed):
- 2.5V
- Voltage - Output (Max):
- 24V
- Current - Output:
- 600mA
- Frequency - Switching:
- 1MHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 10-WSON (3x3)
LM2694SD FAQ
1.How can I place an order for LM2694SD through Aetrix?
Please submit a Request for Quotation (RFQ) for LM2694SD 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 LM2694SD reliable?
The price and inventory of LM2694SD are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM2694SD is usually 5 days.
3.What payment methods are accepted for LM2694SD?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM2694SD transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM2694SD?
LM2694SD orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM2694SD 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 LM2694SD?
For technical support, including LM2694SD datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM2694SD requirements.
6.How does Aetrix verify that LM2694SD is sourced from the original manufacturer or authorized distributors?
All LM2694SD 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 LM2694SD meets industry standards.
7.What is the process for return or replacement of LM2694SD?
All LM2694SD units undergo pre-shipment inspection (PSI). If there is an issue with LM2694SD, 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 LM2694SD part is unused and in its original packaging.
Return procedure for LM2694SD:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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