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Analog Devices Inc. LTC7149EUFD#PBF
- Part No.:
- LTC7149EUFD#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 28-WFQFN Exposed Pad
- Datasheet:
-
LTC7149EUFD#PBF.pdf
- Description:
- IC REG BUCK ADJ 4A 28QFN
- Quantity:
- Payment:
- Shipping:
Inventory:527
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Product details
Overview
LTC7149EUFD#PBF from Analog Devices is a 60V, 4A synchronous monolithic step-down regulator configured for inverting output applications, delivering –28V to 0V output with ±0.8% voltage accuracy, 92% efficiency at 12VIN/–5VOUT, and peak current mode control. It integrates 110mΩ top/50mΩ bottom N-channel MOSFETs and supports programmable switching frequency (300kHz–3MHz) via external RT resistor.
For engineers reviewing the LTC7149EUFD#PBF datasheet, LTC7149EUFD#PBF pinout, LTC7149EUFD#PBF application, or LTC7149EUFD#PBF equivalent, key selection considerations include its board-ground-referenced I/O pins (RUN, PGOOD, MODE/SYNC), single-resistor VOUT programming via ISET, Burst Mode® vs forced continuous mode trade-offs, and thermal management of the exposed SVOUT– pad in the 4mm × 5mm QFN package.
Technical Context
The LTC7149EUFD#PBF implements a peak current mode architecture with internal level-shifted I/O, enabling direct board GND referencing for RUN, PGOOD, and MODE/SYNC pins despite negative output operation. Its error amplifier uses ISET as a 50µA precision current source referenced to VOUT–, allowing unity-gain output voltage programming via RSET.
Switching frequency is set by an external resistor from RT to SVOUT–, with ±50% synchronization range for external clock locking. The device features dual LDOs (VIN- and EXTVCC-powered) for INTVCC regulation, programmable input voltage regulation via VINREG, and automatic BOOST capacitor refresh during high-duty-cycle operation.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 3.4V to 60V; supports wide-input industrial and telecom supplies without pre-regulation |
| Output Voltage Range | –28V to 0V; enables true negative rail generation from positive input |
| Max Output Current | 4A inductor current; sufficient for powering op-amps, ADCs, and analog front-ends requiring clean negative bias |
| Output Voltage Accuracy | ±0.8%; ensures stable reference for precision signal conditioning circuits |
| Quiescent Current | 440µA in Burst Mode; extends battery life in low-power portable instrumentation |
| Switching Frequency | 300kHz–3MHz via RT resistor; allows optimization of size (high-f) vs EMI (low-f) |
| Package | 28-Lead 4mm × 5mm QFN with exposed SVOUT– pad; requires soldering pad to PCB for thermal and electrical integrity |
Pinout & Package
Package: 28-Lead (4mm × 5mm) Plastic QFN with exposed thermal pad (Pin 29 = SVOUT–), rated for –40°C to 125°C junction temperature. Exposed pad must be soldered to PCB plane connected to SVOUT– for thermal performance and electrical return path.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VOUT– (Pins 1,2,26–28) | Negative output terminal | Primary power return node; all output capacitors and load grounds tie here |
| VIN (Pins 3,4) | Positive input supply | Accepts 3.4V–60V; powers internal regulators and top FET driver |
| RUN (Pin 5) | Enable control input | Logic-high threshold 1.2V; used with resistor divider for precise VIN undervoltage lockout |
| GND (Pin 6) | Board ground sense | Reference for internal level-shifted I/O; must connect to PCB ground plane |
| MODE/SYNC (Pin 7) | Operating mode select / clock sync | Tie to GND for Burst Mode; float for forced continuous; drive with external clock for synchronization |
| PGOOD (Pin 8) | Power-good open-drain output | Pulled low when VPGDFB < 0.555V or > 0.645V relative to VOUT–; 64-cycle blanking prevents transient glitches |
| ISET (Pin 14) | 50µA reference current source | Connect RSET to VOUT– to set VOUT– = –50µA × RSET; add CSET for soft-start |
| RT (Pin 12) | Oscillator frequency programming | Resistor to SVOUT– sets fSW = 1011/RT(Ω); determines minimum on-time compliance |
| SW (Pins 19–25) | Switch node | Connects to inductor; carries high di/dt; requires tight layout and Kelvin connection for stability |
| SVOUT– (Pins 10,29) | Exposed thermal pad / negative output return | Mandatory solder connection to PCB copper; serves as primary thermal path and low-impedance return |
Key Features
| Feature | Design Value |
|---|---|
| Board-ground-referenced I/O | RUN, PGOOD, MODE/SYNC operate with respect to PCB GND-not VOUT–-simplifying level-shifting and control logic integration |
| Single-resistor VOUT programming | ISET delivers precise 50µA current; VOUT– = –50µA × RSET enables accurate, temperature-stable negative rail setting |
| Burst Mode® operation | Reduces quiescent current to 440µA at light loads while maintaining regulated output, critical for standby power in test equipment |
| Programmable soft-start | External capacitor from ISET to VOUT– controls ramp rate (tSS ≈ 2.3 × RSET × CSET), preventing inrush into pre-biased loads |
| Integrated dual LDOs | Automatic switchover between VIN- and EXTVCC-powered INTVCC regulators minimizes power loss at high input voltages |
Applications
| Industrial Process Control | Telecom Line Card Power |
|---|---|
Use Scenario: Generating –15V and –5V rails for analog sensor signal conditioning and isolation amplifiers in PLC modules. IC Role / Device Role / Timing Role: Inverting buck regulator providing isolated negative bias with high PSRR and low noise. Use Value: Eliminates need for discrete charge pumps or transformers; ±0.8% accuracy ensures consistent ADC reference levels across temperature. | Use Scenario: Supplying –12V for line interface ICs (e.g., SLICs) in central office equipment with 48V backplane input. IC Role / Device Role / Timing Role: High-efficiency negative voltage converter operating directly from telecom DC bus. Use Value: 92% efficiency at 12VIN/–5VOUT reduces thermal load in dense line cards; 60V rating accommodates 48V transients. |
| Distributed Power Systems | Test & Measurement Equipment |
Use Scenario: Local generation of –24V for op-amp rails in modular instrumentation with distributed 24V/48V intermediate bus. IC Role / Device Role / Timing Role: Point-of-load inverting regulator with programmable frequency to avoid sensitive measurement bands. Use Value: 300kHz–3MHz RT-programmable switching enables EMI tuning; forced continuous mode ensures ultra-low output ripple during signal acquisition. | Use Scenario: Providing stable –5V and –12V for high-speed DACs, comparators, and RF mixers in portable oscilloscopes and spectrum analyzers. IC Role / Device Role / Timing Role: Low-noise, low-IQ negative supply with Burst Mode for battery-operated modes. Use Value: 440µA quiescent current in Burst Mode extends runtime; ±50% SYNC range allows lock to system clock for deterministic jitter reduction. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar inverting buck regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC7150S | Higher 60V/5A rating; integrated MOSFETs with lower RDS(ON) (75mΩ/35mΩ); supports parallel operation | Targeted at higher-current systems (>4A) and multi-phase designs; lacks ISET-based single-resistor programming | Select LTC7150S when output current exceeds 4A or paralleling is required; LTC7149EUFD#PBF remains optimal for cost-sensitive ≤4A designs with simple VOUT programming |
| TPS543B20 | 36V max input; 3A output; uses external compensation; no Burst Mode; different pinout and control scheme | Designed for non-inverting buck only; requires external inverting stage (e.g., transformer or charge pump) to generate negative rails | Choose TPS543B20 only if negative output is generated externally and higher switching frequency (up to 2.2MHz) is prioritized over integrated inversion capability |
Compared with LTC7150S and TPS543B20, the LTC7149EUFD#PBF uniquely combines true inverting topology, single-resistor VOUT programming, board-ground-referenced I/O, and Burst Mode efficiency in a compact QFN-making it the most direct solution for standalone negative rail generation up to 4A.
Availability
LTC7149EUFD#PBF is available at Aetrix Electronics and suitable for industrial process control, telecom line card power, and distributed power systems requiring stable component supply, long-term lifecycle support, and guaranteed traceability.
Supply support for LTC7149EUFD#PBF 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
Analog Devices (ADI) is a global leader in high-performance analog, mixed-signal, and digital signal processing technologies, serving industrial, automotive, communications, and healthcare markets.
The LTC7149EUFD#PBF belongs to ADI's Power by Linear™ family of high-voltage monolithic DC/DC regulators, designed specifically for robust, high-efficiency power conversion in space-constrained and thermally demanding environments.
FAQ
What is the maximum input voltage the LTC7149EUFD#PBF can handle?
The LTC7149EUFD#PBF has an absolute maximum input voltage rating of 64V, with a recommended operating range of 3.4V to 60V. This 60V upper limit ensures reliable operation in industrial and telecom applications where input transients may exceed standard 48V or 24V rails. Exceeding 60V risks triggering VIN overvoltage lockout (VOVLO = 64V), suspending switching until VIN falls below VOVLO – VOVLO(HYS) = 62V.
How is the output voltage programmed on the LTC7149EUFD#PBF?
The LTC7149EUFD#PBF uses a precision 50µA current source on the ISET pin to program output voltage: VOUT– = –50µA × RSET, where RSET connects from ISET to VOUT–. For example, a 100kΩ resistor sets VOUT– = –5V. This method provides ±0.8% accuracy over temperature and line/load conditions, eliminating trimming resistors and simplifying design versus traditional feedback dividers.
Does the LTC7149EUFD#PBF require external components for basic operation?
Yes-the LTC7149EUFD#PBF requires external components for core functionality: an inductor (e.g., 6.8µH), input/output capacitors (e.g., 22µF × 2 + 150µF), bootstrap capacitor (0.1µF between BOOST and SW), RT resistor for frequency setting, and RSET for output voltage. The typical application circuit in the datasheet shows all mandatory parts; omitting any compromises regulation, efficiency, or thermal performance.
What thermal considerations apply to the LTC7149EUFD#PBF QFN package?
The LTC7149EUFD#PBF's 28-lead QFN package features an exposed SVOUT– pad (Pin 29) that must be soldered to a PCB copper plane tied to VOUT–. This pad is essential for thermal dissipation (θJA = 43°C/W) and electrical return. Insufficient solder coverage or missing thermal vias degrades junction temperature rise, potentially triggering overtemperature protection above 125°C and reducing reliability in continuous 4A operation.
Can the LTC7149EUFD#PBF synchronize to an external clock?
Yes-the MODE/SYNC pin on the LTC7149EUFD#PBF accepts an external clock signal to synchronize switching frequency. The internal PLL supports a ±50% capture range around the RT-programmed frequency. For example, if RT sets 1MHz, the external clock must be between 500kHz and 1.5MHz. Synchronization forces forced continuous mode and eliminates beat frequencies in noise-sensitive applications like audio or RF systems.
LTC7149EUFD#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 28-WFQFN Exposed Pad
- Packaging:
- Tube
- Product Status:
- Active
- Function:
- Step-Down
- Output Configuration:
- Negative
- Topology:
- Buck
- Output Type:
- Adjustable
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 3.4V
- Voltage - Input (Max):
- 60V
- Voltage - Output (Min/Fixed):
- 0V
- Voltage - Output (Max):
- -28V
- Current - Output:
- 4A
- Frequency - Switching:
- 1MHz
- Synchronous Rectifier:
- Yes
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 28-QFN (4x5)
LTC7149EUFD#PBF FAQ
1.How can I place an order for LTC7149EUFD#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC7149EUFD#PBF 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 LTC7149EUFD#PBF reliable?
The price and inventory of LTC7149EUFD#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC7149EUFD#PBF is usually 5 days.
3.What payment methods are accepted for LTC7149EUFD#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC7149EUFD#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC7149EUFD#PBF?
LTC7149EUFD#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC7149EUFD#PBF 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 LTC7149EUFD#PBF?
For technical support, including LTC7149EUFD#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC7149EUFD#PBF requirements.
6.How does Aetrix verify that LTC7149EUFD#PBF is sourced from the original manufacturer or authorized distributors?
All LTC7149EUFD#PBF 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 LTC7149EUFD#PBF meets industry standards.
7.What is the process for return or replacement of LTC7149EUFD#PBF?
All LTC7149EUFD#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC7149EUFD#PBF, 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 LTC7149EUFD#PBF part is unused and in its original packaging.
Return procedure for LTC7149EUFD#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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