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Analog Devices Inc. LTC7149EFE#PBF
- Part No.:
- LTC7149EFE#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 28-TSSOP (0.173", 4.40mm Width) Exposed Pad
- Datasheet:
-
LTC7149EFE#PBF.pdf
- Description:
- IC REG BUCK ADJ 4A 28TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:598
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Product details
Overview
LTC7149EFE#PBF from Analog Devices (formerly Linear Technology) is a 60V, 4A synchronous monolithic step-down regulator configured for inverting output applications. It delivers adjustable negative output voltages from 0 V to –28 V, features single-resistor output programming, peak current mode control, and supports Burst Mode® or forced continuous switching modes. It is used in telecom power supplies requiring high-efficiency negative rail generation.
For engineers reviewing the LTC7149EFE#PBF datasheet, LTC7149EFE#PBF pinout, LTC7149EFE#PBF application, or LTC7149EFE#PBF equivalent, key selection criteria include its –28 V output capability, 4 A inductor current rating, 28-lead TSSOP package with board-ground-referenced I/O, ±0.8% output voltage accuracy, and programmable 300 kHz–3 MHz switching frequency via external RT resistor.
Technical Context
The LTC7149EFE#PBF implements a peak current mode architecture with internal 110 mΩ top and 50 mΩ bottom N-channel MOSFETs, enabling fast transient response and inherent cycle-by-cycle current limiting. Its error amplifier uses ISET as a precision 50 µA reference input, allowing unity-gain output voltage programming via a single resistor to VOUT–.
Board-ground-referenced RUN, MODE/SYNC, and PGOOD pins simplify system-level interfacing without level-shifting circuitry. The device supports input voltage regulation via VINREG, overvoltage lockout at 64 V, and thermal shutdown, with quiescent current of 440 µA in Burst Mode and 15 µA in shutdown.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VIN Range | 3.4 V to 60 V - supports wide-input industrial and telecom supplies without pre-regulation. |
| VOUT Range | 0 V to –28 V - enables generation of high-current negative rails for op-amp biasing, RF stages, or data acquisition. |
| Output Current | Up to 4 A inductor current - sufficient for powering multiple downstream analog or mixed-signal ICs. |
| Switching Frequency | 300 kHz to 3 MHz (±50% sync range) - allows optimization of size vs. EMI; RT resistor sets exact value. |
| Output Accuracy | ±0.8% - ensures stable reference for precision analog circuits without post-regulation. |
| IQ (Burst Mode) | 440 µA - maintains high light-load efficiency in always-on subsystems like monitoring or standby logic. |
| Package | 28-Lead Plastic TSSOP - surface-mount, thermally enhanced, compatible with standard reflow profiles. |
Pinout & Package
Package: 28-Lead Plastic TSSOP (4 mm × 9.7 mm), exposed pad (Pin 29) connected to SVOUT– for thermal and electrical integrity. Requires soldering of exposed pad to PCB copper plane.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VOUT– (Pins 1–5) | Negative output return | Primary power return path; all output capacitors and load grounds connect here. |
| VIN (Pins 6, 7) | Input supply input | Accepts 3.4–60 V; powers internal regulators and switches; requires local ceramic bypassing. |
| RUN (Pin 8) | Enable control input | Logic-high (>1.2 V) initiates startup; resistor divider from VIN to GND sets precise UVLO threshold. |
| GND (Pin 9) | Board ground sense | Reference for internal bias and feedback; must be low-impedance connection to PCB ground plane. |
| MODE/SYNC (Pin 10) | Operating mode selector | GND = Burst Mode; floating = forced continuous; external clock = synchronization with ±50% capture range. |
| PGOOD (Pin 11) | Power-good open-drain output | Pulled low if VPGDFB < 0.555 V or > 0.645 V relative to VOUT–; includes 64-cycle blanking delay. |
| 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 | Programmable input undervoltage clamp; tie to INTVCC to disable. |
| RT (Pin 15) | Oscillator frequency set | Resistor to SVOUT– programs fSW from 300 kHz to 3 MHz; critical for EMI and inductor sizing. |
| VOUTSNS (Pin 16) | Error amp inverting input | Typically tied to GND; enables unity-gain servo of VOUT– to ISET voltage. |
| ISET (Pin 17) | 50 µA reference & error amp non-inverting input | Single resistor to VOUT– sets VOUT– = –50 µA × RSET; capacitor adds soft-start ramp. |
| ITH (Pin 18) | Error amp output & compensation node | Tie to INTVCC for internal compensation; external network enables OPTI-LOOP® optimization. |
| EXTVCC (Pin 19) | External LDO input | Enables lower-loss INTVCC regulation when >3.2 V above VOUT–; tie to GND for –3.3 V or lower outputs. |
| INTVCC (Pin 20) | Internal LDO output | 3.3 V (or 3.1 V with EXTVCC active) above VOUT–; requires ≥2.2 µF ceramic bypass to VOUT–. |
| BOOST (Pin 21) | Bootstrap supply for top FET gate driver | Requires 0.1 µF ceramic capacitor between BOOST and SW; critical for high-side switch operation. |
| SW (Pins 22–28) | Switch node | Connects to inductor; carries high di/dt square wave; requires tight layout and Kelvin routing. |
| SVOUT– (Pins 13, 29) | Exposed pad / negative output common | Must be soldered to PCB thermal plane; serves as primary thermal path and electrical return. |
Key Features
| Feature | Design Value |
|---|---|
| Inverting buck topology | Generates regulated negative output from positive input without external inverting charge pump or transformer. |
| Board-ground-referenced I/O | RUN, MODE/SYNC, and PGOOD operate referenced to system GND - eliminates need for isolated level shifters. |
| Single-resistor VOUT programming | VOUT– = –50 µA × RSET enables accurate, temperature-stable output setting with minimal BOM count. |
| Programmable soft-start | Capacitor from ISET to VOUT– controls ramp rate (tSS ≅ 2.3 × RSET × CSET), preventing inrush into pre-biased loads. |
| Integrated dual MOSFETs | 110 mΩ top + 50 mΩ bottom N-channel switches reduce conduction loss and simplify layout vs. discrete solutions. |
Applications
| Industrial Process Control | Telecom Line Card Power |
|---|---|
Use Scenario: Generating –15 V and –5 V rails for analog front-end instrumentation and sensor signal conditioning in PLC modules. IC Role / Device Role / Timing Role: Primary negative voltage regulator delivering up to 4 A with ±0.8% accuracy and low noise under dynamic load steps. Use Value: Eliminates need for discrete inverting converters or isolated DC/DC modules, reducing board area and component count while maintaining precision. | Use Scenario: Providing –12 V bias for RF transceivers and line interface ICs in 48 V-powered telecom equipment. IC Role / Device Role / Timing Role: High-efficiency inverting regulator operating from 36–60 V input, supporting burst-mode operation during low-traffic standby periods. Use Value: Achieves >92% efficiency at 12 VIN/–5 VOUT, minimizing heat dissipation in densely packed line cards. |
| Distributed Power Systems | Test & Measurement Equipment |
Use Scenario: Local generation of –24 V for op-amp rails and DAC reference buffers in modular power distribution architectures. IC Role / Device Role / Timing Role: Synchronous step-down regulator with programmable frequency (300 kHz–3 MHz) to avoid sensitive measurement bands. Use Value: Enables EMI-aware layout with external RT resistor tuning and low-output-ripple forced continuous mode when required. | Use Scenario: Supplying calibrated negative supplies for high-resolution ADC drivers and precision integrators in benchtop analyzers. IC Role / Device Role / Timing Role: Regulator with ±0.8% output accuracy and 440 µA quiescent current in Burst Mode for low-power idle states. Use Value: Maintains voltage stability across temperature and load, directly supporting 16-bit+ measurement accuracy without post-regulation. |
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 60 V input, 5 A output, integrated 75 mΩ/35 mΩ MOSFETs, supports 100 kHz–3 MHz fSW, ±0.5% accuracy. | Better suited for higher-current or tighter-accuracy requirements; larger die size and higher cost. | Select when >4 A output or sub-0.8% tolerance is required; same TSSOP footprint but different pinout. |
| TPS63710DRRR | 3.5–20 V input, –1.2 to –18 V output, 2 A max, fixed 1.2 MHz fSW, no RT programming, ±1.5% accuracy. | Limited input/output range and accuracy; lacks Burst Mode, SYNC, and VINREG features. | Consider only for cost-sensitive, low-complexity designs where 2 A and ±1.5% are acceptable. |
Compared with LTC7151SEFE#PBF, LTC7149EFE#PBF offers lower cost and adequate performance for 4 A/–28 V applications; versus TPS63710DRRR, it provides wider voltage range, higher accuracy, and greater configurability at the expense of design complexity.
Availability
LTC7149EFE#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 RoHS-compliant packaging.
Supply support for LTC7149EFE#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, Inc. (ADI) is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, serving industrial, automotive, communications, and healthcare markets.
The LTC7149 product line was developed by Linear Technology (acquired by ADI in 2017) specifically for high-efficiency, wide-input-range inverting buck regulators targeting telecom, test equipment, and precision analog power systems.
FAQ
What is the maximum negative output voltage supported by the LTC7149EFE#PBF?
The LTC7149EFE#PBF supports an output voltage range from 0 V to –28 V. This is achieved using its inverting buck topology and precision 50 µA ISET reference. Operation at –28 V requires appropriate input voltage headroom (VIN ≥ |VOUT–| + minimum dropout), proper inductor selection, and adherence to minimum on-time constraints per the datasheet. The device maintains ±0.8% output accuracy across this full range when properly compensated.
Can the LTC7149EFE#PBF be synchronized to an external clock, and what is the allowable frequency deviation?
Yes, the LTC7149EFE#PBF can be synchronized to an external clock via the MODE/SYNC pin. Its internal PLL has a ±50% synchronization capture range around the frequency set by the RT resistor. For example, if RT programs 1 MHz, the external clock must be between 500 kHz and 1.5 MHz for reliable lock. The device enters forced continuous mode during synchronization, disabling Burst Mode operation.
How does the LTC7149EFE#PBF achieve board-ground-referenced I/O functionality despite generating a negative output?
The LTC7149EFE#PBF integrates internal level-shift circuits that reference RUN, MODE/SYNC, and PGOOD pins to board GND rather than VOUT–. This is implemented using dedicated internal bias networks and isolation structures, eliminating the need for external level shifters. As a result, these pins accept standard 0–3.3 V or 0–5 V logic signals directly from microcontrollers or supervisors without additional components.
What is the purpose of the VINREG pin on the LTC7149EFE#PBF, and how is it typically configured?
The VINREG pin on the LTC7149EFE#PBF enables input voltage regulation to prevent excessive current draw when the input supply sags under heavy load. It senses VIN via a resistor divider and reduces peak inductor current when VINREG falls below 2 V above VOUT–. To disable this feature - the default for most applications - tie VINREG to INTVCC. When enabled, it helps maintain stable input bus voltage in high-impedance source environments like long cables or shared PSUs.
Does the LTC7149EFE#PBF support soft-start, and how is it implemented?
Yes, the LTC7149EFE#PBF supports programmable soft-start via the ISET pin. Connecting an external capacitor (CSET) from ISET to VOUT– creates an RC time constant that controls the ramp rate of the output voltage. The soft-start time from 0% to 90% of final VOUT– is tSS ≅ 2.3 × RSET × CSET. This prevents inrush current into bulk capacitance and avoids triggering upstream current limits or causing output overshoot during startup.
LTC7149EFE#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
LTC7149EFE#PBF FAQ
1.How can I place an order for LTC7149EFE#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC7149EFE#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 LTC7149EFE#PBF reliable?
The price and inventory of LTC7149EFE#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC7149EFE#PBF is usually 5 days.
3.What payment methods are accepted for LTC7149EFE#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC7149EFE#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC7149EFE#PBF?
LTC7149EFE#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC7149EFE#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 LTC7149EFE#PBF?
For technical support, including LTC7149EFE#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC7149EFE#PBF requirements.
6.How does Aetrix verify that LTC7149EFE#PBF is sourced from the original manufacturer or authorized distributors?
All LTC7149EFE#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 LTC7149EFE#PBF meets industry standards.
7.What is the process for return or replacement of LTC7149EFE#PBF?
All LTC7149EFE#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC7149EFE#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 LTC7149EFE#PBF part is unused and in its original packaging.
Return procedure for LTC7149EFE#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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