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Texas Instruments LM25576MHX
- Part No.:
- LM25576MHX
- Manufacturer:
- Texas Instruments
- Package:
- 20-PowerTSSOP (0.173", 4.40mm Width)
- Datasheet:
-
LM25576MHX.pdf
- Description:
- IC REG BUCK ADJ 3A 20HTSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:2,610
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Product details
Overview
LM25576MHX 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 range and supports industrial power bus regulation in space-constrained 6.5mm × 4.4mm HTSSOP-20EP package.
For engineers reviewing the LM25576MHX datasheet, LM25576MHX pinout, LM25576MHX application, or LM25576MHX equivalent, key selection considerations include its programmable 50kHz–1MHz switching frequency, cycle-by-cycle current limiting, thermal shutdown, remote shutdown capability, and SYNC pin for multi-device synchronization in high-reliability power systems.
Technical Context
The LM25576MHX 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 very low duty cycles. Its dual-mode VCC regulator delivers ~7V bias above 9V VIN while tracking VIN below that threshold, supporting wide-input operation without external LDO.
Functional modes include three-level SD pin control (shutdown/standby/active), oscillator synchronization via open-drain SYNC pin, and soft-start timing set by external capacitor on SS pin. Protection includes cycle-by-cycle current limit (4.2A threshold), thermal shutdown at 165°C with 25°C hysteresis, and BST UVLO at 3.8V.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 6V to 42V - supports direct connection to industrial 24V/36V/42V buses without pre-regulation |
| Output Current | 3A continuous - sufficient for powering FPGAs, DSPs, and industrial I/O modules |
| Feedback Reference | 1.225V ±1.5% - enables precise output voltage setting down to 1.225V with minimal external resistor tolerance impact |
| Switching Frequency | 50kHz to 1MHz - adjustable via single RT resistor to optimize size vs. efficiency trade-off |
| MOSFET RDS(on) | 170mΩ typical - reduces conduction loss and thermal stress in high-current buck stages |
| Thermal Resistance | RθJA = 40°C/W - enabled by exposed pad (EP) tied to PCB ground plane for enhanced heat dissipation |
| Protection Features | Cycle-by-cycle current limit, thermal shutdown (165°C), remote shutdown, BST UVLO - ensures robust operation under fault conditions |
Pinout & Package
LM25576MHX is housed in a thermally enhanced HTSSOP-20EP (PWP) package measuring 6.5mm × 4.4mm with an exposed die attach pad for improved thermal performance. The package requires soldering the EP to a large copper pour connected to PGND for optimal junction-to-board thermal resistance (RθJB = 6.9°C/W).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VIN | Power input | Main input supply (6V–42V); powers internal VCC regulator and buck switch |
| VCC | Bias supply output | ~7V regulated output for internal circuitry; accepts external 7.5V–14V auxiliary supply to reduce IC dissipation |
| SW | Switch node | Source of internal N-MOSFET; connects to external Schottky diode cathode and buck inductor |
| BST | Bootstrap supply | Connects to SW via 0.022µF ceramic capacitor to drive high-side gate during on-time |
| PGND | Power ground | Low-side return for buck switch and IS sense resistor; must be separate from AGND in layout |
| AGND | Analog ground | Reference for FB, COMP, RT, RAMP, SS; requires star grounding near IC for noise immunity |
| FB | Feedback input | Inverting input of error amplifier; regulates output when voltage = 1.225V |
| COMP | Error amp output | Connects to FB via type-II compensation network to stabilize loop response |
| RT | Frequency set | Resistor to AGND sets oscillator frequency (50kHz–1MHz); placement critical for noise immunity |
| SYNC | Oscillator sync | Open-drain input/output for synchronizing multiple LM25576MHX devices or external clock source |
| SS | Soft-start control | Capacitor to AGND sets startup ramp time; held low during thermal shutdown or standby |
| SD | Shutdown control | Three-state logic: <0.7V = shutdown, 0.7–1.225V = standby, >1.225V = active; internal 5µA pullup |
| IS | Diode current sense | Connects to Schottky diode anode to sample recirculating current for emulated ramp generation |
| RAMP | Emulated ramp | External capacitor to AGND sets slope; current source scales with (VIN–VOUT) for accurate current reconstruction |
| PRE | Bootstrap precharge | Open-drain assist for BST capacitor charging during light-load or precharged-output conditions |
| OUT | Output voltage | Direct connection to regulated output; low-impedance path required for stability |
| EP | Exposed pad | Thermal and electrical ground; must be soldered to PCB ground plane for thermal performance and EMI reduction |
Key Features
| Feature | Design Value |
|---|---|
| Emulated current mode control | Eliminates current-sense spike filtering delays and enables stable sub-10% duty cycle operation at high VIN/VOUT ratios |
| Programmable switching frequency | Single RT resistor adjusts frequency from 50kHz to 1MHz - allows optimization of inductor size, efficiency, and EMI profile |
| Multi-device synchronization | SYNC pin enables deterministic phase alignment of up to five LM25576MHX regulators without external clock generator |
| Integrated high-voltage start-up regulator | Dual-mode VCC supply tracks VIN ≤9V and regulates to 7V above - eliminates need for external bias rail in wide-input designs |
| Robust protection suite | Cycle-by-cycle current limit (4.2A), thermal shutdown (165°C), BST UVLO (3.8V), and remote shutdown ensure field reliability |
Applications
| Industrial Power Bus Converter | Telecom Remote Radio Unit (RRU) |
|---|---|
Use Scenario: Converting 48V telecom bus to 3.3V/5V for FPGA, ADC, and RF front-end ICs in outdoor base stations. IC Role / Device Role / Timing Role: Primary buck regulator delivering 3A continuous output with tight load transient response and EMI-controlled switching. Use Value: Emulated current mode enables stable 3.3V output from 48V input (6.9% duty cycle) without instability or minimum-on-time limitations. | Use Scenario: Powering analog front-end and digital control circuits in distributed antenna systems operating from 24V or 36V industrial rails. IC Role / Device Role / Timing Role: High-efficiency point-of-load regulator with programmable frequency to avoid sensitive RF bands and meet EN55022 Class B limits. Use Value: SYNC pin allows synchronized switching of multiple LM25576MHX units to collapse EMI peaks and simplify filtering. |
| Factory Automation I/O Module | Heavy-Duty Motor Control Auxiliary Supply |
Use Scenario: Generating isolated 5V and 12V rails for PLC digital I/O, CAN transceivers, and sensor interfaces in harsh factory environments. IC Role / Device Role / Timing Role: Main non-isolated DC/DC stage providing clean, regulated 5V at 3A with thermal margin for extended ambient temperatures. Use Value: Exposed pad and RθJB = 6.9°C/W enable reliable 3A operation at 85°C ambient without heatsink. | Use Scenario: Supplying gate drivers, MCU, and communication ICs in motor drives where input voltage may sag to 12V during stall conditions. IC Role / Device Role / Timing Role: Wide-input buck converter maintaining regulation from 12V–42V with fast line transient response. Use Value: 6V minimum input and 42V absolute max rating tolerate battery float charging, regenerative braking spikes, and long cable drops. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar buck regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM5164MHX | 42V input, 1A output, integrated high-side MOSFET only; no PGND/IS pins; uses constant-on-time control | Lower current capacity; less suitable for 3A loads; better for ultra-low IQ or fast transient apps | Select LM5164MHX only if output current ≤1A and constant-on-time topology is preferred for light-load efficiency |
| TPS54340DDAR | 42V input, 3.5A output, integrated 95mΩ MOSFET; fixed 340kHz frequency; no SYNC or RAMP pins | Lacks frequency synchronization and emulated ramp tuning; simpler layout but less flexible EMI control | Choose TPS54340DDAR when design prioritizes ease-of-use over multi-device sync or custom ramp compensation |
Compared with LM5164MHX and TPS54340DDAR, LM25576MHX uniquely combines 3A capability with emulated current mode, full-frequency programmability, and multi-device SYNC-making it the only option among the three capable of stable, low-duty-cycle, synchronized operation in high-VIN industrial power supplies.
Availability
LM25576MHX is available at Aetrix Electronics and suitable for industrial automation, telecom infrastructure, and factory I/O systems requiring stable component supply, long-term lifecycle support, and consistent parametric performance across production batches.
Supply support for LM25576MHX 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 LM25576MHX belongs to TI's high-voltage buck regulator product line, engineered specifically for robust, wide-input industrial and telecom power supplies where input transients, thermal constraints, and EMI compliance are critical design factors.
FAQ
What is the maximum output current supported by the LM25576MHX?
The LM25576MHX delivers 3A of continuous output current under recommended operating conditions (TJ ≤125°C, proper thermal layout). This rating assumes use of the exposed pad (EP) soldered to a minimum 1-inch² copper area on the PCB. At elevated ambient temperatures or with reduced copper area, derating is required per the RθJA = 40°C/W thermal metric. Peak current capability reaches 4.2A before cycle-by-cycle limiting activates.
How does the LM25576MHX achieve stable operation at very low duty cycles?
The LM25576MHX achieves stable low-duty-cycle operation through its emulated current mode architecture, which reconstructs the inductor current ramp without sensing the noisy switch-node current. This eliminates blanking delays and leading-edge spikes, enabling reliable PWM control even at sub-10% duty cycles-critical for high-VIN/low-VOUT applications like 48V-to-3.3V conversion. The RAMP pin allows fine-tuning of slope compensation for optimal stability.
Can the LM25576MHX synchronize with other switching regulators?
Yes, the LM25576MHX features a dedicated SYNC pin that supports both master and slave operation. Multiple LM25576MHX devices can be synchronized by connecting their SYNC pins together, with the highest-frequency device acting as master. It also accepts external clock signals (≥15ns pulse width, higher than free-running frequency) for system-level timing coordination-reducing beat frequencies and simplifying EMI filter design.
What is the purpose of the IS pin on the LM25576MHX?
The IS pin on the LM25576MHX connects to the anode of the external Schottky freewheeling diode to sample the recirculating diode current. This sampled current establishes the DC level of the emulated current ramp used in the PWM comparator. Unlike traditional current-mode controllers, this method avoids switch-node noise and propagation delay, enabling accurate current reconstruction and stable regulation across wide input/output voltage ranges.
Does the LM25576MHX require an external bootstrap capacitor?
Yes, the LM25576MHX requires a 0.022µF ceramic capacitor between the BST and SW pins to charge the internal high-side gate driver. This capacitor is replenished during the off-time via an internal diode from the VCC rail. The PRE pin provides optional precharge assistance during light-load or precharged-output conditions to maintain BST voltage stability. Proper BST capacitor placement-close to the IC with short traces-is essential for reliable high-side switching.
LM25576MHX 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:
- Obsolete
- 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:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 20-HTSSOP
LM25576MHX FAQ
1.How can I place an order for LM25576MHX through Aetrix?
Please submit a Request for Quotation (RFQ) for LM25576MHX 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 LM25576MHX reliable?
The price and inventory of LM25576MHX are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM25576MHX is usually 5 days.
3.What payment methods are accepted for LM25576MHX?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM25576MHX transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM25576MHX?
LM25576MHX orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM25576MHX 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 LM25576MHX?
For technical support, including LM25576MHX datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM25576MHX requirements.
6.How does Aetrix verify that LM25576MHX is sourced from the original manufacturer or authorized distributors?
All LM25576MHX 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 LM25576MHX meets industry standards.
7.What is the process for return or replacement of LM25576MHX?
All LM25576MHX units undergo pre-shipment inspection (PSI). If there is an issue with LM25576MHX, 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 LM25576MHX part is unused and in its original packaging.
Return procedure for LM25576MHX:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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