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Texas Instruments LM2655MTC-ADJ
- Part No.:
- LM2655MTC-ADJ
- Manufacturer:
- Texas Instruments
- Package:
- 16-TSSOP (0.173", 4.40mm Width)
- Datasheet:
-
LM2655MTC-ADJ.pdf
- Description:
- IC REG BUCK ADJ 2.5A 16TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:1,886
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Product details
Overview
LM2655MTC-ADJ from Texas Instruments (formerly National Semiconductor) is a 2.5A synchronous step-down DC-DC regulator with adjustable output voltage, internal 33mΩ high-side MOSFET, 300kHz fixed-frequency PWM control, and programmable soft-start. It operates in either synchronous or asynchronous mode and targets portable and space-constrained power rails requiring >90% efficiency and low quiescent current.
For engineers reviewing the LM2655MTC-ADJ datasheet, LM2655MTC-ADJ pinout, LM2655MTC-ADJ application, or LM2655MTC-ADJ equivalent, key selection criteria include its 4V–14V input range, 1.238V feedback reference, TSSOP-16 package thermal performance, and dual-mode operation flexibility for cost–efficiency trade-offs in battery-powered and peripheral power systems.
Technical Context
The LM2655MTC-ADJ implements constant-frequency current-mode PWM control using patented resistorless current sensing. Its architecture integrates all control, drive, and power functions for asynchronous operation while providing a dedicated low-side gate driver (LDR pin) to enable synchronous rectification with an external N-channel MOSFET.
It features dual-input voltage domains (PVIN for power path, AVIN for analog circuitry), programmable undervoltage/overvoltage protection thresholds (81%–114% of VOUT), and thermal shutdown at 165°C with 25°C hysteresis. The 30ns deadtime between high-side and low-side switching prevents shoot-through, requiring external MOSFETs with ≤1000pF input capacitance for reliable synchronous operation.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4V to 14V - supports wide industrial and adapter-fed inputs; PVIN can operate down to ~500mV above VOUT when AVIN is separately powered. |
| Output Current | 2.5A continuous - rated for sustained load delivery with thermal derating per θJA = 140°C/W in TSSOP-16. |
| Feedback Reference | 1.238V ±30mV - enables precise adjustable output from 1.24V to 13V using external resistor divider. |
| Switching Frequency | 300kHz ±15kHz - fixed frequency simplifies EMI filtering and allows predictable ripple current design. |
| High-Side RDS(ON) | 33mΩ typical - reduces conduction loss and improves efficiency at medium-to-high loads. |
| Shutdown Current | <12µA - ensures minimal battery drain in standby mode for portable applications. |
| Soft-Start Control | Programmable via capacitor on SD(SS) pin - limits inrush current and enables controlled power-up sequencing. |
Pinout & Package
LM2655MTC-ADJ is housed in a 16-pin Thin Shrink Small Outline Package (TSSOP-16), NS package code MTC16, with exposed thermal pad (not electrically connected). Pin pitch is 0.65mm; body dimensions are 5.0mm × 4.4mm × 1.2mm.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1–2, SW | Switched-node connection | Drain of internal high-side MOSFET; connects to inductor and external Schottky diode or low-side MOSFET source. |
| 3–5, 14–16, PVIN | Main power supply input | High-current input path for power stage; multiple pins reduce trace resistance and improve thermal dissipation. |
| 6, VCB | Bootstrap capacitor connection | Provides gate drive voltage for internal high-side N-MOSFET; requires 0.1µF ceramic capacitor to SW. |
| 7, AVIN | Analog supply input | Separate 4V–14V supply for control circuitry; enables extended input range when decoupled from PVIN. |
| 8, SD(SS) | Shutdown and soft-start control | Pulling below 0.25V disables regulator; capacitor to ground sets soft-start ramp time and enables sequencing. |
| 9, FB | Output voltage feedback | Senses regulated output via resistor divider; 1.238V reference defines VOUT = 1.238V × (1 + R1/R2). |
| 10, COMP | Compensation network node | Connects to error amplifier output; external RC network stabilizes loop response and ensures ≥45° phase margin. |
| 11, LDELAY | Undervoltage latch delay timing | 5µA current source charges external capacitor; 2V threshold enables latch after delay if VOUT remains <81% of nominal. |
| 12, LDR | Low-side gate driver output | Drives external N-MOSFET gate in synchronous mode; 500mA sink / 180mA source capability with 7ns fall/18ns rise time. |
| 13, GND | Power ground | Common return for PVIN, SW, and LDR paths; must be low-inductance plane for noise control and thermal management. |
Key Features
| Feature | Design Value |
|---|---|
| Resistorless current sensing | Eliminates external sense resistor, reducing BOM cost, board area, and I²R losses while improving noise immunity. |
| Dual-mode operation | Supports both synchronous (higher efficiency) and asynchronous (lower cost) topologies without changing IC or layout. |
| Programmable protection delays | LDELAY pin allows user-defined timeout before undervoltage latch activation, preventing nuisance shutdown during transient dips. |
| Separate AVIN/PVIN supplies | Enables operation with input voltages as low as ~500mV above VOUT by powering control circuitry independently. |
| Integrated thermal shutdown | 165°C junction limit with 25°C hysteresis ensures safe operation under overload or poor heatsinking conditions. |
Applications
| Hard Disk Drives | TFT Monitors |
|---|---|
Use Scenario: Powering 3.3V logic and motor drivers in 2.5″ and 3.5″ HDDs with tight thermal constraints and burst-load requirements. IC Role / Device Role / Timing Role: Primary 3.3V buck regulator delivering up to 2.5A with fast transient response and programmable soft-start for spin-up sequencing. Use Value: High efficiency (>90% at 1A) extends battery life in portable drives; synchronous mode minimizes heat buildup near sensitive magnetic components. |
Use Scenario: Generating stable 5V or 12V bias rails for LCD panel timing controllers and backlight drivers in compact TFT displays. IC Role / Device Role / Timing Role: Adjustable-output DC-DC converter supporting multiple panel configurations via resistor-divider programming. Use Value: 300kHz fixed frequency enables small external inductors; TSSOP-16 footprint fits narrow bezel PCBs without compromising thermal performance. |
| Internet Appliances | Battery-Powered Devices |
Use Scenario: Providing clean 3.3V or 5V rails for embedded networking modules (Wi-Fi, Ethernet PHY) in set-top boxes and VoIP adapters. IC Role / Device Role / Timing Role: Main system regulator with input undervoltage lockout (3.8V threshold) to prevent brownout during AC adapter fluctuations. Use Value: Low 12µA shutdown current preserves standby battery life; programmable soft-start avoids reset glitches during power recovery. |
Use Scenario: Supplying regulated voltage to microcontrollers and sensors in handheld test equipment, medical monitors, and portable instrumentation. IC Role / Device Role / Timing Role: High-efficiency synchronous buck converter operating from single-cell Li-ion (3.0–4.2V) or dual-cell alkaline inputs. Use Value: Ability to run with PVIN as low as ~500mV above VOUT (when AVIN is externally supplied) extends usable battery range and runtime. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar step-down regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| TPS54260DGQ | Wider 3.5–60V input range; integrated 0.57Ω high-side FET; no low-side driver; 2.5A rating at lower efficiency. | Preferred for high-input-voltage industrial systems; unsuitable for synchronous rectification or ultra-low-VIN operation. | Select when input exceeds 14V or when board space prohibits external MOSFET; avoid if synchronous efficiency or sub-4V PVIN operation is required. |
| LM2678SD-ADJ | Same 4–40V input; 5A rating; no low-side driver; requires external sense resistor; larger SO-8 package. | Better for higher-current, non-synchronous designs where thermal headroom is available and layout simplicity is prioritized. | Choose for cost-sensitive, high-current applications without need for synchronous efficiency or TSSOP footprint; verify thermal design for 5A loads. |
Compared with TPS54260DGQ and LM2678SD-ADJ, LM2655MTC-ADJ uniquely balances adjustable output, synchronous capability, and compact TSSOP-16 packaging-making it optimal for space-constrained, battery-aware designs needing flexible topology selection and precise voltage control.
Availability
LM2655MTC-ADJ is available at Aetrix Electronics and suitable for hard disk drives, TFT monitors, internet appliances, computer peripherals, and battery-powered devices requiring stable component supply, long-term lifecycle support, and consistent parametric performance across production batches.
Supply support for LM2655MTC-ADJ 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 acquired National Semiconductor in 2011 and maintains full technical and manufacturing continuity for legacy power management products including the LM2655 series.
The LM2655 product line was designed for high-density, high-efficiency point-of-load regulation in portable and peripheral electronics, emphasizing flexible topology selection, low-noise operation, and robust protection features.
FAQ
What is the minimum input voltage required for LM2655MTC-ADJ to regulate properly?
The LM2655MTC-ADJ requires PVIN to be at least ~500mV above the desired output voltage when AVIN is powered separately (e.g., from a low-dropout regulator). With combined PVIN/AVIN operation, the absolute minimum input is 3.8V due to undervoltage lockout. This dual-supply architecture allows LM2655MTC-ADJ to function in low-input scenarios where conventional buck regulators fail, such as single-cell Li-ion systems with tight discharge curves.
Can LM2655MTC-ADJ operate in synchronous mode without an external Schottky diode?
Yes - LM2655MTC-ADJ can operate synchronously using only an external N-channel MOSFET driven by the LDR pin. However, TI's datasheet recommends placing a Schottky diode in parallel with the low-side MOSFET to conduct during the 30ns deadtime, preventing body-diode conduction that would degrade efficiency by 1–2% and increase switching noise. Omitting the diode is possible but compromises peak efficiency and EMI performance, especially at high VIN or heavy loads.
How does the programmable soft-start function work on LM2655MTC-ADJ?
The LM2655MTC-ADJ implements soft-start via a current-source charging of an external capacitor on the SD(SS) pin: initial 2µA charge until 0.6V (shutdown threshold), then 10µA charge to 2V. This creates a controlled ramp of current limit and duty cycle, limiting inrush current and enabling power sequencing. The soft-start time is approximated by TSS = CSS × (0.6V/2µA + 1.4V/10µA). At 2V, undervoltage/overvoltage protections activate - so LM2655MTC-ADJ requires sufficient soft-start time to reach regulation before protection triggers.
What is the purpose of the LDELAY pin on LM2655MTC-ADJ, and how is it configured?
The LDELAY pin on LM2655MTC-ADJ hosts a 5µA current source that charges an external capacitor when output voltage falls below 81% of nominal. When capacitor voltage reaches 2V, undervoltage latch protection activates, holding the device in shutdown until reset via input cycling or SD pin toggle. Delay time is calculated as TDELAY(ms) = CDELAY(nF) × 400. Connecting LDELAY directly to GND disables this latch function entirely - a useful option in systems where brief dips should not cause latched failure.
Does LM2655MTC-ADJ require an external compensation network, and what are typical values?
Yes - LM2655MTC-ADJ requires external compensation on the COMP pin to stabilize the control loop. For most applications with COUT > 68µF, TI recommends Cc1 = 2.2nF and Rc = 15kΩ. If the output capacitor's ESR zero cannot be canceled by the natural pole, a second capacitor Cc2 may be added. Layout-critical: place compensation components close to COMP and FB pins, use short traces, and avoid routing near noisy nodes like SW or PVIN to maintain phase margin ≥45°.
LM2655MTC-ADJ Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- 16-TSSOP (0.173", 4.40mm Width)
- Packaging:
- Tube
- Product Status:
- Obsolete
- Function:
- Step-Down
- Output Configuration:
- Positive
- Topology:
- Buck
- Output Type:
- Adjustable
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 4V
- Voltage - Input (Max):
- 14V
- Voltage - Output (Min/Fixed):
- 1.238V
- Voltage - Output (Max):
- 13V
- Current - Output:
- 2.5A
- Frequency - Switching:
- 300kHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-TSSOP
LM2655MTC-ADJ FAQ
1.How can I place an order for LM2655MTC-ADJ through Aetrix?
Please submit a Request for Quotation (RFQ) for LM2655MTC-ADJ 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 LM2655MTC-ADJ reliable?
The price and inventory of LM2655MTC-ADJ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM2655MTC-ADJ is usually 5 days.
3.What payment methods are accepted for LM2655MTC-ADJ?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM2655MTC-ADJ transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM2655MTC-ADJ?
LM2655MTC-ADJ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM2655MTC-ADJ 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 LM2655MTC-ADJ?
For technical support, including LM2655MTC-ADJ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM2655MTC-ADJ requirements.
6.How does Aetrix verify that LM2655MTC-ADJ is sourced from the original manufacturer or authorized distributors?
All LM2655MTC-ADJ 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 LM2655MTC-ADJ meets industry standards.
7.What is the process for return or replacement of LM2655MTC-ADJ?
All LM2655MTC-ADJ units undergo pre-shipment inspection (PSI). If there is an issue with LM2655MTC-ADJ, 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 LM2655MTC-ADJ part is unused and in its original packaging.
Return procedure for LM2655MTC-ADJ:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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