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Texas Instruments LM25576QMHX/NOPB
- Part No.:
- LM25576QMHX/NOPB
- Manufacturer:
- Texas Instruments
- Package:
- 20-PowerTSSOP (0.173", 4.40mm Width)
- Datasheet:
-
LM25576QMHX/NOPB.pdf
- Description:
- IC REG BUCK ADJ 3A 20HTSSOP
- Quantity:
- Payment:
- Shipping:
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Product details
Overview
LM25576QMHX/NOPB from Texas Instruments is a 42V, 3A synchronous step-down DC/DC switching regulator with integrated 170mΩ N-channel MOSFET, adjustable 1.225V output, 1.5% feedback reference accuracy, and emulated current-mode control architecture. It operates across 6V–42V input for industrial power bus and telecom applications requiring robust high-voltage conversion.
For engineers reviewing the LM25576QMHX/NOPB datasheet, LM25576QMHX/NOPB pinout, LM25576QMHX/NOPB application, or LM25576QMHX/NOPB equivalent, key selection criteria include input voltage range (6–42V), output current capability (3A continuous), thermal performance in HTSSOP-20EP, soft-start programmability, and oscillator synchronization support for multi-rail EMI reduction.
Technical Context
The LM25576QMHX/NOPB implements emulated current-mode control using a reconstructed ramp signal derived from VIN–VOUT and diode current sampling-eliminating leading-edge spikes and enabling stable operation at low duty cycles. Its dual-mode VCC regulator delivers 7V bias up to 42V input while limiting internal dissipation.
Functional modes include three-level shutdown (shutdown/standby/active) via SD pin, cycle-by-cycle current limiting with 4.2A threshold, thermal shutdown at 165°C, and forced off-time (500ns) that constrains maximum duty cycle per switching frequency. The SYNC pin supports master-slave synchronization of multiple LM25576QMHX/NOPB units or external clock locking.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 6V to 42V - supports wide industrial and telecom bus voltages without pre-regulation |
| Output Current | 3A continuous - sufficient for FPGA core rails, PLC I/O modules, and motor drive logic supplies |
| Feedback Reference | 1.225V ±1.5% - enables precise low-VOUT regulation down to 1.225V with minimal external divider error |
| Switch RDS(on) | 170mΩ typical - reduces conduction loss and thermal stress in high-current buck stages |
| Switching Frequency | 50kHz to 1MHz - adjustable via RT resistor for trade-off between inductor size and efficiency |
| Thermal Resistance | RθJA = 40°C/W - requires exposed pad soldered to PCB ground plane for full 3A operation at 125°C junction |
| Protection Features | Cycle-by-cycle current limit, thermal shutdown (165°C), remote shutdown, and UVLO on VCC and SD pins - ensures fault resilience in unattended systems |
Pinout & Package
LM25576QMHX/NOPB uses the HTSSOP-20EP (PWP) package: 6.5mm × 4.4mm body with 0.65mm pitch and exposed thermal pad (EP) connected to PGND for enhanced heat dissipation.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VIN (pins 3,4) | Main power input | Accepts 6–42V; powers internal bias regulator and high-side switch; must be bypassed with low-ESR capacitor near pins |
| SW (pins 17,18) | Switch node | Connects to inductor and Schottky diode anode; carries high di/dt; layout critical for EMI control |
| PGND (pins 13,14) | Power ground return | Low-impedance return path for switch and IS sense resistor; separate from AGND to avoid noise coupling |
| AGND (pin 10) | Analog reference ground | Reference for FB, COMP, RAMP, and error amplifier; must be star-connected to minimize offset errors |
| FB (pin 7) | Feedback input | Connects to resistor divider from VOUT; regulates output by comparing to 1.225V internal reference |
| COMP (pin 6) | Error amplifier output | Interface for type-II compensation network between COMP and FB to stabilize loop response |
| RT (pin 8) | Oscillator set | Single resistor to AGND sets switching frequency from 50kHz to 1MHz; placement critical for noise immunity |
| SYNC (pin 5) | Frequency sync I/O | Open-drain capable; allows daisy-chaining multiple LM25576QMHX/NOPB units or external clock locking |
| SD (pin 2) | Shutdown control | Three-state logic: <0.7V = shutdown, 0.7–1.225V = standby, >1.225V = active; internal 5µA pull-up if floating |
| IS (pins 15,16) | Diode current sense | Connects to Schottky diode anode; enables sample-and-hold DC level for emulated current ramp generation |
| BST (pin 20) | Bootstrap supply | Connects via 0.022µF ceramic to SW; charges internal high-side gate driver during off-time |
| PRE (pin 19) | Precharge assist | Open-drain output tied to SW; aids BST capacitor charging under light-load or precharged-output conditions |
| SS (pin 11) | Soft-start control | External capacitor sets ramp time for output voltage rise; held low during thermal shutdown or UVLO |
| RAMP (pin 9) | Emulated ramp source | External capacitor to AGND sets slope; current source scales with (VIN–VOUT) for accurate duty-cycle tracking |
| VCC (pin 1) | Bias supply output | 7V regulated output (up to 25mA); tracks VIN below 9V; can accept external 7.5–14V supply to reduce IC dissipation |
| OUT (pin 12) | Regulated output | Direct connection to output capacitor; not a power terminal but voltage sense reference point |
| EP | Exposed thermal pad | Must be soldered to solid copper pour tied to PGND; primary thermal path for 3A operation |
Key Features
| Feature | Design Value |
|---|---|
| Emulated current-mode control | Eliminates current-sense spike filtering delays and enables stable sub-10% duty-cycle operation at 42V→3.3V |
| Integrated 42V/170mΩ MOSFET | Reduces BOM count and layout area vs. controller + external FET; optimized for 3A continuous at ≤125°C ambient |
| Adjustable soft start | External SS capacitor sets monotonic output ramp time-prevents inrush current in cascaded power systems |
| Frequency synchronization | SINGLE-pin SYNC interface enables deterministic interleaving of multiple LM25576QMHX/NOPB regulators to lower input ripple |
| Dual-mode VCC regulator | Tracks VIN below 9V, regulates to 7V above-enables direct 42V input without external bias supply or LDO |
| Diode current sensing (IS pin) | Enables accurate DC current reconstruction without shunt resistor losses or high-side sensing complexity |
Applications
| Industrial PLC Power Supply | Telecom Remote Radio Unit |
|---|---|
Use Scenario: Provides isolated 5V/3.3V rails for CPU, FPGA, and I/O modules in DIN-rail mounted programmable logic controllers operating from 24V/48V DC bus. IC Role / Device Role / Timing Role: Primary buck regulator delivering 3A continuous output with line transient immunity and thermal fault protection. Use Value: Eliminates need for external high-voltage MOSFET and gate driver; HTSSOP-20EP package enables compact 2-layer PCB layout with minimal heatsinking. | Use Scenario: Generates 12V intermediate rail from -48V telecom battery backup system for RF power amplifiers and digital baseband processing. IC Role / Device Role / Timing Role: High-input-voltage buck converter supporting wide input range (6–42V) with synchronized switching to meet stringent EMI limits. Use Value: SYNC pin allows phase alignment with other converters in multi-rail system, reducing peak input current and conducted emissions. |
| Factory Automation Sensor Hub | Electric Vehicle Onboard Charger Control |
Use Scenario: Powers microcontroller, CAN transceiver, and analog front-end in distributed sensor nodes deployed in harsh factory environments with 24V nominal supply. IC Role / Device Role / Timing Role: Robust DC/DC regulator with undervoltage lockout, thermal shutdown, and 1.5% reference accuracy for precision analog sensing. Use Value: SD pin enables coordinated power sequencing with host MCU; 1.225V reference supports accurate ADC reference voltage generation. | Use Scenario: Supplies auxiliary 15V rail for gate drivers and microcontrollers in bidirectional OBC systems where main DC link varies from 200–450V. IC Role / Device Role / Timing Role: Pre-regulator stepping down from isolated 42V auxiliary supply to stable 15V with fast load transient response. Use Value: Emulated current-mode architecture delivers tight load regulation (<±1%) during rapid PWM gate drive current pulses. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar buck regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM5164QWRNTRQ1 | 42V input, 1A output, integrated FET, 100kHz–2.2MHz adjustable frequency, AEC-Q100 qualified | Lower output current; automotive-grade qualification; higher max frequency | Select when automotive qualification or >1MHz switching is required; not suitable for 3A loads |
| TPS54340DDAR | 42V input, 3.5A output, integrated FET, 100kHz–2.5MHz frequency, no SYNC pin, different pinout | No synchronization capability; higher current rating; lacks IS pin for diode current sensing | Select when SYNC is unnecessary and higher peak current margin is needed; requires PCB redesign due to pinout mismatch |
Compared with LM5164QWRNTRQ1 and TPS54340DDAR, the LM25576QMHX/NOPB uniquely combines 3A output, SYNC capability, and diode-current-based emulated current sensing-making it optimal for industrial multi-rail systems requiring EMI control and precise current monitoring without external sense resistors.
Availability
LM25576QMHX/NOPB is available at Aetrix Electronics and suitable for industrial automation, telecom infrastructure, and electric vehicle auxiliary power systems requiring stable component supply and long-term manufacturability.
Supply support for LM25576QMHX/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 specializing in analog, embedded processing, and power management technologies with over 50 years of innovation in high-reliability power conversion.
The LM25576QMHX/NOPB belongs to TI's high-voltage buck regulator product line, engineered for industrial and telecom applications demanding wide input range, integrated FETs, and robust fault protection without external complexity.
FAQ
What is the absolute maximum input voltage rating for LM25576QMHX/NOPB?
The absolute maximum input voltage (VIN to GND) for LM25576QMHX/NOPB is 45V. Operation beyond this rating risks permanent damage. The recommended operating range remains 6V to 42V. Transient voltage spikes on the VIN line-such as those caused by inductive kickback or poor PCB layout-must be clamped externally to stay within the 45V limit. TI specifies this rating in Section 5.1 of the SNVS470I datasheet, and the device includes internal UVLO but no overvoltage protection circuitry.
Does LM25576QMHX/NOPB require an external Schottky diode, and why?
Yes, LM25576QMHX/NOPB requires an external Schottky diode connected between SW and OUT. Although it integrates a high-side N-channel MOSFET, it does not integrate a synchronous rectifier; the diode provides the freewheeling path during the switch off-time. The IS pin connects to the diode anode to enable diode-current-based current sensing for the emulated ramp generator. TI recommends devices like CSHD6-60C in the typical application schematic, selected for low forward voltage and fast recovery to minimize conduction loss and improve efficiency.
How is the switching frequency set on LM25576QMHX/NOPB, and what tolerance should be expected?
The switching frequency of LM25576QMHX/NOPB is set by a single resistor (RT) connected between the RT pin and AGND. Frequency ranges from 50kHz to 1MHz per the equation RT = (1/F − 580 ns)/135 ps. At 200kHz, RT ≈ 32.4kΩ; at 500kHz, RT ≈ 11kΩ. Typical frequency tolerance is ±10% over temperature and process variation, as confirmed in Section 5.5 Electrical Characteristics (e.g., "Frequency1" min/typ/max values). Layout best practice requires placing RT close to the IC with short traces to AGND.
Can LM25576QMHX/NOPB operate with an output voltage lower than 1.225V?
No, LM25576QMHX/NOPB cannot regulate below 1.225V because its internal feedback reference is fixed at 1.225V ±1.5%. The output voltage is set by the resistor divider on the FB pin: VOUT = 1.225V × (1 + R1/R2). To achieve lower outputs, an external reference or post-regulation (e.g., LDO) is required. This limitation is inherent to the bandgap reference design and is explicitly stated in the "Adjustable output voltage as low as 1.225V" feature and Section 5.5 Electrical Characteristics (Feedback Voltage parameter).
What thermal derating guidance applies to LM25576QMHX/NOPB at 3A output?
At 3A continuous output, LM25576QMHX/NOPB requires the exposed pad (EP) to be soldered to a minimum 250mm² copper pour tied to PGND to maintain junction temperature ≤125°C. With RθJA = 40°C/W, 3A operation at 24V input yields ~2.5W dissipation; ambient must be ≤90°C with proper airflow or heatsinking. Thermal shutdown activates at 165°C with 25°C hysteresis. TI's layout guidelines (Section 7.4) mandate thermal vias under EP and separation of PGND/AGND planes to prevent thermal runaway.
LM25576QMHX/NOPB Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- SIMPLE SWITCHER®
- Package/Case:
- 20-PowerTSSOP (0.173", 4.40mm Width)
- Packaging:
- Tape & Reel (TR)
- 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:
- 3A
- 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:
- 20-HTSSOP
LM25576QMHX/NOPB FAQ
1.How can I place an order for LM25576QMHX/NOPB through Aetrix?
Please submit a Request for Quotation (RFQ) for LM25576QMHX/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 LM25576QMHX/NOPB reliable?
The price and inventory of LM25576QMHX/NOPB are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM25576QMHX/NOPB is usually 5 days.
3.What payment methods are accepted for LM25576QMHX/NOPB?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM25576QMHX/NOPB transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM25576QMHX/NOPB?
LM25576QMHX/NOPB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM25576QMHX/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 LM25576QMHX/NOPB?
For technical support, including LM25576QMHX/NOPB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM25576QMHX/NOPB requirements.
6.How does Aetrix verify that LM25576QMHX/NOPB is sourced from the original manufacturer or authorized distributors?
All LM25576QMHX/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 LM25576QMHX/NOPB meets industry standards.
7.What is the process for return or replacement of LM25576QMHX/NOPB?
All LM25576QMHX/NOPB units undergo pre-shipment inspection (PSI). If there is an issue with LM25576QMHX/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 LM25576QMHX/NOPB part is unused and in its original packaging.
Return procedure for LM25576QMHX/NOPB:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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