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Texas Instruments LM5574QMT/NOPB
- Part No.:
- LM5574QMT/NOPB
- Manufacturer:
- Texas Instruments
- Package:
- 16-TSSOP (0.173", 4.40mm Width)
- Datasheet:
-
LM5574QMT/NOPB.pdf
- Description:
- IC REG BUCK ADJ 500MA 16TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:416
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Product details
Overview
LM5574QMT/NOPB from Texas Instruments is a 75V-input, 0.5A synchronous step-down DC/DC regulator with integrated 750mΩ N-channel MOSFET, emulated current-mode control, and adjustable 50–500kHz switching frequency. It delivers stable output down to 1.225V with 1.5% feedback reference accuracy and supports industrial power bus applications requiring high-voltage input tolerance and robust fault protection.
For engineers reviewing the LM5574QMT/NOPB datasheet, LM5574QMT/NOPB pinout, LM5574QMT/NOPB application, or LM5574QMT/NOPB equivalent, key selection considerations include its 6–75V input range, cycle-by-cycle current limiting, thermal shutdown, SYNC pin for multi-device synchronization, and TSSOP-16 package compatibility with layout-sensitive high-voltage buck designs.
Technical Context
The LM5574QMT/NOPB implements emulated current-mode control using a reconstructed ramp signal-generated via internal voltage-controlled current source (IRAMP = (10µA × (VIN − VOUT)) + 50µA) and external RAMP capacitor-to avoid noise sensitivity and leading-edge spikes inherent in direct switch-current sensing. This architecture enables stable regulation at very low duty cycles typical of high VIN / low VOUT operation.
It integrates a dual-mode VCC regulator (direct connection below 9V, regulated ~7V above 9V), programmable soft-start via SS pin (10µA current source), and a dedicated IS pin for diode current sampling during off-time to enable accurate DC-level current reconstruction and fast overcurrent response. The SYNC pin supports both master-slave synchronization and external clock locking with 15ns minimum pulse width.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 6V to 75V - supports wide industrial and telecom bus voltages without pre-regulation |
| Output Current | 0.5A continuous - defined by integrated 750mΩ N-MOSFET RDS(on) and thermal design margin |
| Feedback Reference | 1.225V ±1.5% - sets minimum output voltage and determines resistor-divider accuracy requirements |
| Switching Frequency | 50kHz to 500kHz - adjusted via single RT-to-AGND resistor; impacts inductor size, efficiency, and EMI |
| Current Limit Threshold | 0.7A cycle-by-cycle - protects against overload and short-circuit while allowing transient headroom |
| Thermal Shutdown | 165°C with 25°C hysteresis - prevents permanent damage during sustained overload or poor heatsinking |
| Soft-Start Current | 10µA nominal - controls ramp rate of SS capacitor to limit inrush current and stabilize startup |
Pinout & Package
LM5574QMT/NOPB is housed in a 16-pin TSSOP (PW) package measuring 5mm × 6.4mm, optimized for thermal performance (RθJA = 95°C/W) and high-voltage PCB layout with exposed PGND pad.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VIN | Input supply voltage | Main high-voltage rail input (6–75V); connects to bulk capacitor and requires local high-frequency bypass |
| VCC | Bias regulator output | Internally regulated ~7V supply for control circuitry; must be decoupled with 0.1–1µF ceramic capacitor |
| SW | Switching node | Drain of internal N-MOSFET; connects to inductor and Schottky diode anode; high dv/dt node requiring tight layout |
| BST | Bootstrap capacitor input | Connects to SW via 0.022µF ceramic capacitor to sustain gate drive for high-side N-MOSFET during on-time |
| FB | Feedback input | Inverting input of error amplifier; referenced to 1.225V; sets output voltage via resistor divider from VOUT |
| COMP | Error amplifier output | Connects to FB via type-II compensation network to stabilize loop response and reject input/output disturbances |
| RT | Oscillator frequency set | Resistor-to-AGND sets switching frequency; value calculated per RT = (1/F) × 1.35×10⁻⁹ – 5.8×10⁻⁷ |
| RAMP | Emulated current ramp | External capacitor (50–2000pF) sets slope; reconstructs inductor current for noise-immune PWM control |
| SS | Soft-start control | 10µA current source charges external capacitor to ramp reference voltage and limit startup inrush |
| SD | Shutdown/UVLO input | Logic-level enable: <0.7V = shutdown, >1.225V = active; supports line undervoltage lockout via divider |
| SYNC | Oscillator sync I/O | Open-drain capable; allows multiple LM5574QMT/NOPB devices to synchronize or lock to external clock |
| IS | Diode current sense | Connects to Schottky diode anode; samples recirculating current for DC-level reconstruction and overcurrent detection |
| OUT | Regulated output | Direct connection to output capacitor; low-impedance path critical for load transient response |
| PGND | Power ground | Low-side return for MOSFET and IS sense resistor; separate from AGND to minimize noise coupling |
| AGND | Analog ground | Reference for FB, COMP, RT, RAMP, and SS; must be star-connected near IC to avoid control loop instability |
| PRE | Pre-charge assist | Open-drain output tied to SW to boost BST capacitor charge under light-load or pre-charged output conditions |
Key Features
| Feature | Design Value |
|---|---|
| Emulated current-mode control | Eliminates leading-edge spikes and measurement delay, enabling stable regulation at sub-10% duty cycles in high-VIN applications |
| Integrated 75V/750mΩ N-MOSFET | Reduces BOM count and layout complexity while maintaining 0.5A output capability without external switch |
| Adjustable soft-start (SS pin) | 10µA current source enables precise control of output voltage ramp rate to prevent inrush-induced system reset |
| Multi-device synchronization (SYNC) | Allows up to five LM5574QMT/NOPB regulators to share switching edge, reducing conducted EMI peaks and simplifying filtering |
| Dual-mode VCC regulator | Self-biases from VIN across full 6–75V range: direct connection ≤9V, regulated ~7V >9V-minimizes external bias supply needs |
| Comprehensive protection suite | Includes cycle-by-cycle current limit, thermal shutdown (165°C), remote shutdown (SD), and VCC UVLO (5.35V) |
Applications
| Industrial Power Supplies | Telecom Line Cards |
|---|---|
|
Use Scenario: Converting 48V or 72V telecom battery backup or PoE++ midspan voltage to 3.3V/5V for FPGA, MCU, or interface ICs. IC Role / Device Role / Timing Role: Primary buck regulator providing isolated, efficient, and fault-tolerant point-of-load conversion with no external MOSFET required. Use Value: Enables single-chip 48V→3.3V conversion with 85%+ efficiency at 0.5A, eliminating need for pre-regulator stages and reducing board area by >30%. |
Use Scenario: Powering analog front-end circuits (ADCs, amplifiers) in industrial PLC I/O modules operating from 24V or 48V field buses. IC Role / Device Role / Timing Role: High-reliability DC/DC converter delivering clean, regulated rails with built-in thermal and overcurrent protection for harsh environments. Use Value: Maintains regulation during brownouts (down to 6V VIN) and survives transients up to 75V, reducing need for TVS clamping on input. |
| Railway Signaling Systems | Test & Measurement Equipment |
|
Use Scenario: Generating stable 12V or 15V supplies from variable 72–110V DC traction power in onboard signaling controllers. IC Role / Device Role / Timing Role: Input-tolerant buck controller managing wide-range input while meeting EN 50155 surge immunity requirements. Use Value: Operates continuously across full 72–110V input range with only minor efficiency derating, avoiding costly discrete HV front-end solutions. |
Use Scenario: Providing programmable auxiliary rails (e.g., ±12V, 5V) in portable benchtop instruments powered from universal AC adapters or batteries. IC Role / Device Role / Timing Role: Flexible, low-noise power stage supporting rapid output reconfiguration via RT and feedback resistors. Use Value: Adjustable frequency (50–500kHz) allows optimization for low-noise (low-f) or compact size (high-f), matching instrument form factor constraints. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar buck regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM5576QMT/NOPB | Higher 1.5A output current, same 75V input, identical pinout and control architecture | Required where load exceeds 0.5A or higher thermal margin is needed; shares same PCB footprint | Select when output current demand exceeds 0.5A but 75V input and TSSOP-16 layout must be retained |
| LM5164QWRNTRQ1 | Automotive-grade 100V-input, 0.6A buck with integrated FET; uses constant-on-time control instead of emulated current mode | Designed for AEC-Q100 Grade 1; lacks SYNC and RAMP pins; different compensation behavior and transient response | Choose for automotive systems needing 100V rating and qualification, accepting trade-offs in control flexibility and EMI management |
Compared with LM5574QMT/NOPB, LM5576QMT/NOPB offers scalable current capacity in identical packaging, while LM5164QWRNTRQ1 provides automotive qualification and higher input rating at the cost of reduced synchronization and ramp-based loop tuning capabilities.
Availability
LM5574QMT/NOPB is available at Aetrix Electronics and suitable for industrial power supplies, telecom line cards, railway signaling systems, and test & measurement equipment requiring stable component supply, long-term lifecycle support, and automotive-qualified alternatives.
Supply support for LM5574QMT/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 decades of expertise in high-reliability power conversion ICs.
The LM5574QMT/NOPB belongs to TI's high-voltage buck regulator product line, designed specifically for industrial and telecom applications demanding wide-input operation, integrated FETs, and robust protection in compact TSSOP packages.
FAQ
What is the maximum input voltage rating for LM5574QMT/NOPB?
The absolute maximum input voltage (VIN to GND) for LM5574QMT/NOPB is 76V, with recommended operating range from 6V to 75V. Exceeding 76V-even transiently-risks permanent damage. Layout best practices include placing high-quality input capacitors close to VIN and PGND, and adding snubbers if line ringing exceeds this limit. LM5574QMT/NOPB incorporates internal UVLO and cycle-by-cycle current limiting to enhance survivability within its rated range.
Does LM5574QMT/NOPB require an external bootstrap capacitor, and what value is recommended?
Yes, LM5574QMT/NOPB requires an external ceramic capacitor between BST and SW pins to sustain gate drive for its internal N-MOSFET. Texas Instruments recommends a 0.022µF X7R or C0G capacitor placed with minimal trace length. This capacitor is charged through an internal diode during SW low-time; insufficient capacitance or poor placement causes gate drive collapse and erratic switching. LM5574QMT/NOPB also includes a PRE pin to assist BST charging under light-load conditions.
How does the RAMP pin function in LM5574QMT/NOPB, and what capacitor value should be used?
The RAMP pin in LM5574QMT/NOPB connects to an external capacitor (50–2000pF) that sets the slope of the emulated current ramp used for PWM comparison. Its value is calculated as CRAMP = L × 5 × 10⁻⁶, where L is the output inductor in henrys-e.g., 100µH → 500pF. This ramp replaces direct current sensing to eliminate noise susceptibility. LM5574QMT/NOPB's internal current source (IRAMP = (10µA × (VIN − VOUT)) + 50µA) ensures accurate scaling across input/output combinations.
Can LM5574QMT/NOPB synchronize with other switching regulators, and how is it implemented?
Yes, LM5574QMT/NOPB supports oscillator synchronization via its open-drain SYNC pin. Multiple LM5574QMT/NOPB devices can be synchronized by connecting their SYNC pins together-the highest-frequency device acts as master. Alternatively, an external clock (minimum 15ns pulse width, higher than free-running frequency) can drive SYNC directly. LM5574QMT/NOPB's SYNC sink impedance is 110Ω, and its source impedance is 11kΩ, enabling robust multi-device timing alignment without additional level-shifting circuitry.
What protection features are integrated into LM5574QMT/NOPB?
LM5574QMT/NOPB integrates cycle-by-cycle current limiting (0.7A threshold), thermal shutdown at 165°C with 25°C hysteresis, VCC undervoltage lockout (5.35V turn-on), remote shutdown via SD pin (<0.7V = off), and forced 500ns off-time for reliable diode current sampling. These protections operate independently and concurrently-e.g., thermal shutdown discharges the SS capacitor and halts switching until junction temperature falls below 140°C. No external components are required to activate these functions; LM5574QMT/NOPB executes them autonomously.
LM5574QMT/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):
- 75V
- Voltage - Output (Min/Fixed):
- 1.225V
- Voltage - Output (Max):
- 70V
- Current - Output:
- 500mA
- Frequency - Switching:
- 50kHz ~ 500kHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- Automotive
- Qualification:
- AEC-Q100
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-TSSOP
LM5574QMT/NOPB FAQ
1.How can I place an order for LM5574QMT/NOPB through Aetrix?
Please submit a Request for Quotation (RFQ) for LM5574QMT/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 LM5574QMT/NOPB reliable?
The price and inventory of LM5574QMT/NOPB are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM5574QMT/NOPB is usually 5 days.
3.What payment methods are accepted for LM5574QMT/NOPB?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM5574QMT/NOPB transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM5574QMT/NOPB?
LM5574QMT/NOPB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM5574QMT/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 LM5574QMT/NOPB?
For technical support, including LM5574QMT/NOPB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM5574QMT/NOPB requirements.
6.How does Aetrix verify that LM5574QMT/NOPB is sourced from the original manufacturer or authorized distributors?
All LM5574QMT/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 LM5574QMT/NOPB meets industry standards.
7.What is the process for return or replacement of LM5574QMT/NOPB?
All LM5574QMT/NOPB units undergo pre-shipment inspection (PSI). If there is an issue with LM5574QMT/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 LM5574QMT/NOPB part is unused and in its original packaging.
Return procedure for LM5574QMT/NOPB:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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