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Texas Instruments LM25574QMT/NOPB
- Part No.:
- LM25574QMT/NOPB
- Manufacturer:
- Texas Instruments
- Package:
- 16-TSSOP (0.173", 4.40mm Width)
- Datasheet:
-
LM25574QMT/NOPB.pdf
- Description:
- IC REG BUCK ADJ 500MA 16TSSOP
- Quantity:
- Payment:
- Shipping:
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Product details
Overview
LM25574QMT/NOPB from Texas Instruments is a 42-V, 0.5-A synchronous step-down DC/DC switching regulator with integrated 750-mΩ N-channel MOSFET, emulated current-mode control, adjustable 50 kHz–1 MHz switching frequency, and 1.225 V feedback reference. It delivers robust industrial power conversion from 6 V to 42 V input to stable low-voltage rails in space-constrained designs.
For engineers reviewing the LM25574QMT/NOPB datasheet, LM25574QMT/NOPB pinout, LM25574QMT/NOPB application, or LM25574QMT/NOPB equivalent, key selection considerations include its TSSOP-16 package, cycle-by-cycle current limiting, thermal shutdown, adjustable soft-start, master/slave synchronization capability, and compatibility with WEBENCH® Power Designer for rapid design validation.
Technical Context
The LM25574QMT/NOPB implements emulated current-mode control using a reconstructed ramp signal-derived from an internal diode-current sample-and-hold circuit plus a voltage-controlled current source (IRAMP = (10 µA × (VIN − VOUT)) + 50 µA)-eliminating leading-edge spikes and enabling stable operation at very low duty cycles. Its dual-mode VCC regulator maintains ~7 V bias supply above 9 V VIN while tracking VIN below that threshold.
Functional modes include three-level SD pin control (shutdown <0.7 V, standby 0.7–1.225 V, operational >1.225 V), programmable oscillator via RT resistor, SYNC pin for multi-device synchronization or external clock locking, and built-in protections: cycle-by-cycle current limit (0.7 A typ), thermal shutdown (165 °C), and UVLO on VCC (5.35 V).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 6 V to 42 V - supports wide industrial bus voltages including 12 V, 24 V, and 36 V nominal systems without pre-regulation. |
| Output Current | 0.5 A continuous - sufficient for powering microcontrollers, sensors, and interface ICs in embedded systems. |
| Feedback Reference | 1.225 V ±1.5% - enables precise output regulation down to 1.225 V and supports common 3.3 V, 2.5 V, and 1.8 V rails via resistor divider. |
| Switching Frequency | 50 kHz to 1 MHz - adjustable via single RT resistor; higher frequencies reduce inductor size but increase switching losses. |
| Integrated MOSFET RDS(on) | 750 mΩ max - reduces external component count and improves efficiency in mid-power buck applications. |
| Thermal Shutdown | 165 °C with 25 °C hysteresis - prevents permanent damage during overload or poor heatsinking conditions. |
| Soft-Start Current | 10 µA typ - sets controlled output ramp time with external SS capacitor; avoids inrush current stress on input supply. |
Pinout & Package
TSSOP-16 package (5.00 mm × 4.40 mm), thermally enhanced with exposed PGND pad; suitable for automated assembly and moderate-power density PCB layouts.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VIN | Main input supply connection | Accepts 6–42 V unregulated input; absolute max 45 V - requires local ceramic bypassing to PGND. |
| VCC | Bias regulator output | Supplies internal circuitry; regulated to ~7 V above 9 V VIN; requires 0.1–1 µF ceramic decoupling to AGND. |
| SW | Switching node | Drives external Schottky diode and buck inductor; connects directly to BST capacitor and PRE pin for bootstrap assist. |
| BST | Bootstrap capacitor connection | Charged via internal diode during SW off-time; requires 0.022 µF ceramic between BST and SW pins. |
| PGND | Power ground return | Low-side reference for IS sense resistor and PRE switch; must be routed separately from AGND to minimize noise coupling. |
| AGND | Analog ground reference | Reference for FB, COMP, RAMP, RT, and SS; should connect to PGND at single point near device. |
| FB | Feedback input | Connects to resistor divider from OUT; internal 1.225 V reference enables accurate output voltage setting. |
| COMP | Error amplifier output | Interface for type-II compensation network between COMP and FB; determines loop stability and transient response. |
| RT | Oscillator frequency set | Resistor to AGND programs switching frequency from 50 kHz to 1 MHz; value calculated per TI Equation 1. |
| RAMP | Emulated current ramp control | External capacitor to AGND sets ramp slope; critical for current-mode stability and subharmonic oscillation prevention. |
| IS | Diode current sense input | Connects to Schottky diode anode; enables accurate DC level reconstruction of inductor current for emulated ramp. |
| SD | Shutdown/standby control | Three-state logic: <0.7 V = shutdown, 0.7–1.225 V = standby, >1.225 V = active; includes 5 µA internal pull-up. |
| SYNC | Oscillator sync I/O | Open-drain capable; allows master-slave synchronization across multiple LM25574QMT/NOPB devices or external clock locking. |
| SS | Soft-start timing | 10 µA internal current source charges external capacitor; controls output voltage ramp rate and inrush current. |
| PRE | Bootstrap pre-charge assist | Open-drain output pulsed 250 ns before each SW on-time; improves light-load bootstrap capacitor charging. |
| OUT | Regulated output connection | High-current path to output capacitor; must be low-inductance and low-ESR for stable regulation and transient response. |
Key Features
| Feature | Design Value |
|---|---|
| Emulated current-mode architecture | Eliminates need for current-sense resistor and associated noise filtering; enables stable operation at <10% duty cycle in high-VIN/low-VOUT applications. |
| Adjustable soft-start | Programmable rise time via external SS capacitor prevents input inrush and output overshoot during power-up. |
| Frequency synchronization | Multi-device synchronization or external clock locking via SYNC pin reduces EMI and eliminates beat frequencies in multi-rail systems. |
| Integrated protection suite | Cycle-by-cycle current limit (0.7 A), thermal shutdown (165 °C), VCC UVLO (5.35 V), and remote shutdown ensure robust field operation. |
| Dual-mode VCC regulator | Tracks VIN below 9 V and regulates to 7 V above - minimizes internal power dissipation and extends efficiency across full input range. |
Applications
| Industrial PLC I/O Module | Automotive Body Control Unit |
|---|---|
Use Scenario: Powers isolated analog sensor interfaces and digital I/O drivers in DIN-rail mounted programmable logic controllers operating from 24 V DC industrial bus. IC Role / Device Role / Timing Role: Primary buck regulator delivering 3.3 V/0.5 A to MCU, ADC, and CAN transceiver; synchronized to system clock via SYNC pin. Use Value: Wide 6–42 V input range accommodates brownouts and load-dump transients; thermal shutdown ensures reliability in enclosed enclosures. | Use Scenario: Supplies 5 V rail to microcontroller, LIN transceiver, and LED drivers in automotive door modules powered from 12 V battery with cold-crank tolerance. IC Role / Device Role / Timing Role: Input-stage buck converter stepping down battery voltage; uses SD pin for ignition-controlled enable/disable and soft-start to avoid headlight flicker. Use Value: 0.7 A current limit protects against shorted loads; 1.225 V reference enables precise 5.0 V output with ±1% tolerance over temperature. |
| Telecom Remote Radio Unit | Factory Automation Sensor Node |
Use Scenario: Generates 1.8 V core supply for FPGA and RF front-end ICs in outdoor small-cell base stations powered from 48 V PoE-derived input. IC Role / Device Role / Timing Role: High-efficiency intermediate regulator converting 48 V to 1.8 V; operates at 600 kHz to minimize inductor size and EMI filter footprint. Use Value: Emulated current mode enables stable regulation at 3.75% duty cycle (1.8 V/48 V); RAMP pin allows slope compensation for high-VOUT stability. | Use Scenario: Powers ultra-low-power wireless sensor SoCs (e.g., CC2652) in predictive maintenance nodes deployed on rotating machinery with 24 V fieldbus input. IC Role / Device Role / Timing Role: Standby-aware power manager: enters low-IQ shutdown (<70 µA) when SD pin pulled low by host MCU during sleep cycles. Use Value: Three-level SD control enables seamless transition between active, standby, and shutdown states without external logic; TSSOP-16 fits compact PCB footprints. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar buck regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM25576QMH/NOPB | Higher 1.5-A output current, same 42-V input, identical pinout and feature set except increased current capability. | Suitable where future-proofing for higher load or parallel operation is required; requires larger inductor and output capacitor. | Select LM25576QMH/NOPB if peak load exceeds 0.5 A or margin for aging/temperature derating is needed. |
| TPS54340DDAR | 42-V, 3.5-A buck regulator with integrated FET; different pinout, no RAMP or IS pins; uses traditional current-sense resistor instead of emulated ramp. | Better suited for higher-current applications (>0.5 A) but lacks diode-current sensing and emulated ramp architecture. | Choose TPS54340DDAR only when higher output current is mandatory and layout can accommodate external sense resistor and revised compensation. |
Compared with LM25576QMH/NOPB, the LM25574QMT/NOPB offers lower quiescent current and smaller solution size for ≤0.5 A loads; versus TPS54340DDAR, it provides superior light-load efficiency and simplified EMI filtering due to emulated current-mode architecture-but at lower maximum output current.
Availability
LM25574QMT/NOPB is available at Aetrix Electronics and suitable for industrial PLC I/O modules, automotive body control units, telecom remote radio units, and factory automation sensor nodes requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for LM25574QMT/NOPB 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 designing analog ICs, embedded processors, and system-on-chip solutions for industrial, automotive, and communications markets.
The LM25574QMT/NOPB belongs to TI's high-voltage buck regulator product line, engineered specifically for robust, low-component-count DC/DC conversion in harsh environments with wide input voltage ranges and stringent reliability requirements.
FAQ
What is the maximum input voltage rating for the LM25574QMT/NOPB?
The LM25574QMT/NOPB has an absolute maximum VIN rating of 45 V. Operation must remain within the recommended 6 V to 42 V range. Exceeding 45 V-even transiently-can cause permanent damage. Layout best practices include placing low-ESR ceramic capacitors close to VIN and PGND to suppress ringing during load or line transients.
How does the LM25574QMT/NOPB achieve current-mode control without a sense resistor?
The LM25574QMT/NOPB uses emulated current-mode control: it reconstructs the inductor current ramp using a voltage-controlled current source (IRAMP = (10 µA × (VIN − VOUT)) + 50 µA) and a DC level sampled from the re-circulating diode current at the IS pin. This eliminates external sense resistors, reduces noise sensitivity, and enables stable operation at very low duty cycles.
Can the LM25574QMT/NOPB synchronize to an external clock?
Yes, the LM25574QMT/NOPB supports external clock synchronization via the SYNC pin. An open-drain external clock source with pulse width ≥15 ns and frequency higher than the free-running oscillator (set by RT) can lock the internal switching frequency. Multiple LM25574QMT/NOPB devices can also self-synchronize by connecting their SYNC pins together.
What is the purpose of the PRE pin on the LM25574QMT/NOPB?
The PRE pin on the LM25574QMT/NOPB is an open-drain pre-charge assist output that pulses for 250 ns just before each SW on-time. It connects to the SW node to help charge the BST capacitor under light-load conditions or when the output is pre-biased, ensuring reliable gate drive for the internal high-side MOSFET.
Does the LM25574QMT/NOPB require special layout considerations for the RAMP pin?
Yes-the RAMP pin on the LM25574QMT/NOPB must connect to AGND via a capacitor placed directly adjacent to the IC with minimal trace length. Recommended values range from 50 pF to 2000 pF depending on inductor value and operating frequency. Poor RAMP layout causes instability, subharmonic oscillation, or erratic current limiting behavior.
LM25574QMT/NOPB Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- SIMPLE SWITCHER®
- Package/Case:
- 16-TSSOP (0.173", 4.40mm Width)
- Packaging:
- Tube
- Product Status:
- Active
- Function:
- Step-Down
- Output Configuration:
- Positive
- Topology:
- Buck
- Output Type:
- Adjustable
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 6V
- Voltage - Input (Max):
- 42V
- Voltage - Output (Min/Fixed):
- 1.225V
- Voltage - Output (Max):
- 40V
- Current - Output:
- 500mA
- Frequency - Switching:
- 50kHz ~ 1MHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- Automotive
- Qualification:
- AEC-Q100
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-TSSOP
LM25574QMT/NOPB FAQ
1.How can I place an order for LM25574QMT/NOPB through Aetrix?
Please submit a Request for Quotation (RFQ) for LM25574QMT/NOPB 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 LM25574QMT/NOPB reliable?
The price and inventory of LM25574QMT/NOPB are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM25574QMT/NOPB is usually 5 days.
3.What payment methods are accepted for LM25574QMT/NOPB?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM25574QMT/NOPB transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM25574QMT/NOPB?
LM25574QMT/NOPB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM25574QMT/NOPB 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 LM25574QMT/NOPB?
For technical support, including LM25574QMT/NOPB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM25574QMT/NOPB requirements.
6.How does Aetrix verify that LM25574QMT/NOPB is sourced from the original manufacturer or authorized distributors?
All LM25574QMT/NOPB 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 LM25574QMT/NOPB meets industry standards.
7.What is the process for return or replacement of LM25574QMT/NOPB?
All LM25574QMT/NOPB units undergo pre-shipment inspection (PSI). If there is an issue with LM25574QMT/NOPB, 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 LM25574QMT/NOPB part is unused and in its original packaging.
Return procedure for LM25574QMT/NOPB:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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