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Analog Devices Inc. LTC7149IFE#PBF
- Part No.:
- LTC7149IFE#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 28-TSSOP (0.173", 4.40mm Width) Exposed Pad
- Datasheet:
-
LTC7149IFE#PBF.pdf
- Description:
- IC REG BUCK ADJ 4A 28TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:164
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Product details
Overview
LTC7149IFE#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 LTC7149IFE#PBF datasheet, LTC7149IFE#PBF pinout, LTC7149IFE#PBF application, or LTC7149IFE#PBF equivalent, key selection considerations include its board-ground-referenced I/O pins (RUN, PGOOD, MODE/SYNC), single-resistor VOUT programming, Burst Mode® vs forced continuous mode trade-offs, and thermal performance in the 28-lead TSSOP package with exposed SVOUT– pad.
Technical Context
The LTC7149IFE#PBF employs peak current mode architecture with inherent cycle-to-cycle current limiting and fast transient response. Its error amplifier compares VOUTSNS (typically tied to GND) against ISET's 50µA bias current to regulate output voltage via RSET: VOUT– = –50µA × RSET.
Internal level-shift circuits enable RUN, PGOOD, and MODE/SYNC pins to operate referenced to board GND rather than SVOUT–. The MODE/SYNC pin selects between Burst Mode® (high light-load efficiency) and forced continuous mode (low output ripple) or enables external clock synchronization within ±50% of the RT-programmed frequency.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 3.4V to 60V - supports wide-input industrial and telecom supplies without external pre-regulation |
| Output Voltage Range | –28V to 0V - enables negative rail generation for op-amps, data converters, and RF biasing |
| Max Output Current | 4A inductor current - delivers sufficient power for distributed negative supply domains |
| Switching Frequency | 300kHz to 3MHz (RT-programmable) - allows optimization of size, efficiency, and EMI filtering |
| Output Accuracy | ±0.8% - ensures stable reference-level negative voltages for precision analog circuitry |
| IQ (Burst Mode) | 440µA - minimizes standby power in battery-backed or energy-sensitive systems |
| Shutdown IQ | 15µA - enables ultra-low-power system sleep states |
| Package | 28-Lead Plastic TSSOP - surface-mount compatible with standard PCB assembly and thermal relief via exposed SVOUT– pad |
Pinout & Package
Package: 28-Lead Plastic TSSOP (4mm × 5mm footprint), with exposed thermal pad (Pin 29) electrically connected to SVOUT– and requiring soldering to PCB copper for thermal and electrical integrity.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VOUT– (Pins 1–5) | Negative output terminal | Primary power return path; all output capacitors and load grounds connect here |
| VIN (Pins 6, 7) | Input supply input | Accepts 3.4V–60V; powers internal regulators and high-side switch driver |
| RUN (Pin 8) | Enable control input | Logic-high (>1.2V) initiates startup; resistor divider from VIN to GND sets precise undervoltage lockout |
| GND (Pin 9) | Board ground sense | Reference for RUN, MODE/SYNC, PGOOD; must connect directly to low-impedance PCB ground plane |
| MODE/SYNC (Pin 10) | Operating mode select / sync input | Tied to GND → Burst Mode®; floating → forced continuous mode; driven by external clock → synchronized operation |
| PGOOD (Pin 11) | Power-good open-drain output | Pulled low if VPGDFB < 0.555V or > 0.645V relative to VOUT–; blanked for ~64 switching cycles during transients |
| PGDFB (Pin 12) | Power-good feedback node | Connect resistor divider from GND to VOUT– to set PGOOD trip thresholds |
| VINREG (Pin 14) | Input voltage regulation sense | Programs input undervoltage threshold; tie to INTVCC to disable |
| RT (Pin 15) | Oscillator frequency programming | Resistor to SVOUT– sets fSW; 100kΩ yields ~1MHz; sync range ±50% of programmed frequency |
| VOUTSNS (Pin 16) | Error amplifier inverting input | Typically tied to GND; forms unity-gain buffer with ISET for output voltage setting |
| ISET (Pin 17) | 50µA bias current source / EA non-inverting input | Connect RSET to VOUT– to program VOUT– = –50µA × RSET; add CSET for soft-start |
| ITH (Pin 18) | Error amplifier output / compensation node | Tie to INTVCC for internal compensation; external network enables OPTI-LOOP® optimization |
| EXTVCC (Pin 19) | External LDO input | When >3.2V above VOUT– and VIN >5V above VOUT–, powers INTVCC LDO to reduce thermal stress |
| INTVCC (Pin 20) | Internal LDO output | 3.3V (or 3.1V with EXTVCC active) above VOUT–; bypass with ≥2.2µF ceramic capacitor to VOUT– |
| BOOST (Pin 21) | High-side gate driver bootstrap supply | Requires 0.1µF capacitor to SW; refreshes during bottom-FET conduction |
| SW (Pins 22–28) | Switch node | Connects to inductor; carries high di/dt square wave; requires tight layout and Kelvin connection |
| SVOUT– (Pins 13, 29) | Exposed thermal pad / power return | Must be soldered to large PCB copper area; serves as primary thermal path and low-impedance VOUT– return |
Key Features
| Feature | Design Value |
|---|---|
| Board-ground-referenced I/O | RUN, PGOOD, MODE/SYNC pins referenced to board GND - eliminates level-shifting circuitry in system design |
| Single-resistor VOUT programming | VOUT– = –50µA × RSET - simplifies BOM and layout versus multi-resistor feedback networks |
| Programmable soft-start | Capacitor from ISET to VOUT– sets tSS ≈ 2.3 × RSET × CSET - prevents inrush current into pre-biased loads |
| Accurate frequency sync range | ±50% capture window around RT-set frequency - enables robust synchronization to system clocks without tight tolerance oscillators |
| Integrated MOSFETs | 110mΩ high-side + 50mΩ low-side N-channel switches - reduces external component count and layout complexity |
| Overtemperature protection | Thermal shutdown activates above 125°C junction - protects device during overload or poor heatsinking |
Applications
| Industrial Process Control | Telecom Line Card Power |
|---|---|
Use Scenario: Generating isolated –12V and –5V rails for analog front-end instrumentation and sensor signal conditioning in PLC modules. IC Role / Device Role / Timing Role: Inverting buck regulator providing stable negative bias for precision op-amps and ADC drivers. Use Value: ±0.8% output accuracy and 440µA quiescent current maintain measurement integrity while minimizing standby power in always-on systems. | Use Scenario: Supplying –48V-derived auxiliary rails (e.g., –12V, –5V) on telecom line cards where space and thermal density are constrained. IC Role / Device Role / Timing Role: High-efficiency inverting DC/DC converter replacing discrete solutions in compact card-edge designs. Use Value: Integrated 110mΩ/50mΩ MOSFETs and 28-lead TSSOP package reduce board area by >40% versus discrete alternatives while sustaining 92% efficiency at full load. |
| Distributed Power Systems | RF Transceiver Biasing |
Use Scenario: Local negative voltage generation at point-of-load in server backplanes or base station subracks with 12V or 24V intermediate bus. IC Role / Device Role / Timing Role: Point-of-load inverting regulator delivering up to 4A at –15V for FPGA I/O banks and memory interfaces. Use Value: Peak current mode control and programmable 300kHz–3MHz switching enable optimal trade-off between transient response and EMI filter size in dense layouts. | Use Scenario: Providing clean, adjustable negative bias (e.g., –3.3V to –10V) for GaAs FETs and mixer stages in cellular infrastructure transceivers. IC Role / Device Role / Timing Role: Low-noise inverting power supply with Burst Mode® operation for standby sensitivity and forced continuous mode for transmit-linearity. Use Value: Board-ground-referenced PGOOD and RUN simplify system-level sequencing and fault reporting without additional level shifters. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar inverting buck regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC7151SEFE#PBF | Higher 80V input rating, 5A output, integrated compensation; no ISET-based VOUT programming | Supports wider input range and higher current; requires resistor divider feedback instead of single-R programming | Select when >60V input or >4A output is required; accept added feedback complexity for enhanced ruggedness |
| TPS63710DRRR | 3.5V–20V input, –5V to –20V output, 1.5A max; uses external op-amp for VOUT programming | Lower voltage/current capability; lacks board-ground-referenced I/O and Burst Mode® | Select for cost-sensitive, lower-power applications where GND-referenced control is not needed and thermal constraints are relaxed |
Compared with LTC7151SEFE#PBF and TPS63710DRRR, the LTC7149IFE#PBF uniquely combines 60V input, 4A output, single-resistor VOUT programming, and board-ground-referenced I/O in a thermally optimized TSSOP package-making it optimal for industrial and telecom systems requiring simplicity, precision, and layout efficiency.
Availability
LTC7149IFE#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 traceable sourcing.
Supply support for LTC7149IFE#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 semiconductors, serving industrial, automotive, communications, and healthcare markets.
The LTC7149IFE#PBF belongs to ADI's Power by Linear™ family of high-efficiency DC/DC regulators, designed specifically for demanding negative-rail generation in space-constrained, thermally sensitive applications such as telecom infrastructure and precision instrumentation.
FAQ
What is the function of the ISET pin on the LTC7149IFE#PBF?
The ISET pin on the LTC7149IFE#PBF provides a precise 50µA bias current that, when connected to VOUT– via an external resistor RSET, programs the output voltage as VOUT– = –50µA × RSET. It also serves as the non-inverting input to the error amplifier and accepts an external capacitor for programmable soft-start. This pin must never be left floating and is critical to both regulation accuracy and startup behavior of the LTC7149IFE#PBF.
How does the MODE/SYNC pin affect operation of the LTC7149IFE#PBF?
The MODE/SYNC pin on the LTC7149IFE#PBF determines operating mode: tied to GND enables Burst Mode® for highest light-load efficiency; left floating selects forced continuous mode for lowest output ripple; driven by an external clock synchronizes switching within ±50% of the RT-programmed frequency. All configurations retain the same regulated output voltage and current capability, but trade off ripple, efficiency, and EMI characteristics - a key flexibility point in the LTC7149IFE#PBF's system integration.
What thermal considerations apply to the LTC7149IFE#PBF in the TSSOP package?
The LTC7149IFE#PBF in the 28-lead TSSOP package has θJA = 30°C/W and requires soldering of the exposed SVOUT– pad (Pin 29) to a large PCB copper area for effective heat dissipation. Unlike the QFN variant, the TSSOP version relies more heavily on board-level copper for thermal management. For 4A continuous operation at high ambient temperatures, thermal vias under the pad and inner-layer copper pours are strongly recommended to maintain junction temperature below 125°C in the LTC7149IFE#PBF.
Can the LTC7149IFE#PBF start up into a pre-biased output?
Yes, the LTC7149IFE#PBF supports pre-biased start-up: when enabled, it remains in Burst Mode® with power switches off until the ISET pin voltage ramps up to match VOUTSNS, then begins controlled switching to ramp VOUT– downward. This prevents reverse current flow and output overshoot. The soft-start time is determined by the ISET-to-VOUT– capacitor value and is fully programmable - a robust feature for hot-swap and redundant power systems using the LTC7149IFE#PBF.
What is the purpose of the VINREG pin on the LTC7149IFE#PBF?
The VINREG pin on the LTC7149IFE#PBF enables input voltage regulation: when VIN drops below a user-programmed threshold (set by a resistor divider from VIN to VOUT–), the LTC7149IFE#PBF reduces peak inductor current to limit input current draw and prevent excessive input droop. If unused, VINREG should be tied to INTVCC to disable this loop. This feature is especially valuable in high-impedance input sources like long cables or unregulated adapters feeding the LTC7149IFE#PBF.
LTC7149IFE#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 28-TSSOP (0.173", 4.40mm Width) 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-TSSOP-EP
LTC7149IFE#PBF FAQ
1.How can I place an order for LTC7149IFE#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC7149IFE#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 LTC7149IFE#PBF reliable?
The price and inventory of LTC7149IFE#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC7149IFE#PBF is usually 5 days.
3.What payment methods are accepted for LTC7149IFE#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC7149IFE#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC7149IFE#PBF?
LTC7149IFE#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC7149IFE#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 LTC7149IFE#PBF?
For technical support, including LTC7149IFE#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC7149IFE#PBF requirements.
6.How does Aetrix verify that LTC7149IFE#PBF is sourced from the original manufacturer or authorized distributors?
All LTC7149IFE#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 LTC7149IFE#PBF meets industry standards.
7.What is the process for return or replacement of LTC7149IFE#PBF?
All LTC7149IFE#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC7149IFE#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 LTC7149IFE#PBF part is unused and in its original packaging.
Return procedure for LTC7149IFE#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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