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Texas Instruments LM2651MTC-ADJ
- Part No.:
- LM2651MTC-ADJ
- Manufacturer:
- Texas Instruments
- Package:
- 16-TSSOP (0.173", 4.40mm Width)
- Datasheet:
-
LM2651MTC-ADJ.pdf
- Description:
- IC REG BUCK ADJ 1.5A 16TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:4,140
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Product details
Overview
LM2651MTC-ADJ from Texas Instruments is a 1.5-A synchronous step-down DC-DC switching regulator in a 16-pin TSSOP package, featuring adjustable output voltage (set via external resistor divider), 300-kHz fixed-frequency current-mode PWM control, and automatic hysteretic mode transition at light loads to sustain >80% efficiency down to 15 mA. It integrates high- and low-side MOSFETs with 75-mΩ RDS(on), patented internal current sensing, and operates from 4-V to 14-V input for battery-powered portable electronics.
For engineers reviewing the LM2651MTC-ADJ datasheet, LM2651MTC-ADJ pinout, LM2651MTC-ADJ application, or LM2651MTC-ADJ equivalent, key selection criteria include its 1.5-A continuous output capability, ADJ feedback reference of 1.238 V, 7-µA shutdown current, integrated soft-start, and thermal shutdown at 165°C - all critical for compact, high-efficiency power management in space-constrained embedded systems.
Technical Context
The LM2651MTC-ADJ employs constant-frequency (300 kHz) current-mode PWM control under moderate-to-heavy loads and automatically transitions to low-power hysteretic mode below ~100 mA to maintain high efficiency across a 100:1 load range. Its patented internal current sensing eliminates the need for an external sense resistor, reducing BOM cost and noise susceptibility.
It integrates both high-side and low-side N-channel MOSFETs with 75-mΩ typical RDS(on), uses bootstrap gate drive (VCB pin), and features input undervoltage lockout (3.8–3.95 V rising threshold), cycle-by-cycle current limiting (2 A typ), and thermal shutdown with 25°C hysteresis - enabling robust operation in variable-input, thermally constrained environments.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output current | 1.5 A continuous - supports mid-power microcontroller cores, FPGAs, and interface ICs without external current boosting. |
| Input voltage range | 4 V to 14 V - compatible with 5-V, 9-V, and 12-V rails, including multi-cell Li-ion and lead-acid battery inputs. |
| Feedback reference voltage | 1.238 V (typ) - enables precise adjustable output from ~1.25 V to >12 V using standard resistor dividers. |
| Switching frequency | 300 kHz (±15%) - allows use of small, low-profile inductors (e.g., 4.7–10 µH) and ceramic output capacitors. |
| Efficiency peak | Up to 97% - achieved via synchronous rectification and low RDS(on), minimizing conduction losses at full load. |
| Shutdown current | 7 µA (typ) - extends battery life in standby by disabling switching and bias circuits while retaining fast wake-up. |
| Thermal shutdown | 165°C with 25°C hysteresis - protects against sustained overload or poor PCB thermal design without latch-up. |
Pinout & Package
LM2651MTC-ADJ is housed in a 16-pin TSSOP (PW) package measuring 5.00 mm × 4.40 mm, with exposed thermal pad (not electrically connected). The package supports standard reflow profiles and provides adequate thermal dissipation (RθJA = 97.3°C/W) when mounted on 2-oz copper with thermal vias.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1, 2 - SW | Switched-node output | Connection to source of internal high-side MOSFET and drain of low-side MOSFET; carries high di/dt square wave - requires tight layout to PGND. |
| 3–5 - VIN | Main power input | Primary DC input supply (4–14 V); must be decoupled locally with low-ESR capacitor to suppress transients. |
| 6 - VCB | Bootstrap capacitor node | Connects to 0.1-µF ceramic capacitor between SW and VCB to generate gate drive voltage for high-side MOSFET. |
| 7 - SD(SS) | Shutdown/soft-start control | Pulling below 0.3 V disables regulator; capacitor to GND sets soft-start ramp - prevents inrush current during power-up. |
| 9 - FB | Feedback input | Monitors output voltage via resistor divider; internal 1.238-V reference enables precise ADJ output regulation. |
| 10 - COMP | Error amplifier compensation | Connects external RC network to stabilize loop response; supports Type II compensation for wide load/transient performance. |
| 11 - NC | No connection | Internally unconnected pin - must remain floating; no routing or soldering required. |
| 12, 13 - AGND | Analog ground | Low-noise reference for error amplifier and feedback circuitry; should be separated from PGND and joined at single point. |
| 14–16 - PGND | Power ground | High-current return path for MOSFETs and input/output capacitors; requires wide copper pour and multiple vias to minimize impedance. |
Key Features
| Feature | Design Value |
|---|---|
| Integrated synchronous MOSFETs | Eliminates external diode and reduces conduction loss - enables >95% efficiency at 1-A load with minimal external components. |
| Patented internal current sensing | Replaces external sense resistor - saves board space, lowers cost, and improves noise immunity in current-mode control loop. |
| Automatic PWM-to-hysteretic mode transition | Maintains >80% efficiency at 15-mA load - extends runtime in battery-powered standby modes without manual mode selection. |
| Adjustable soft-start | Capacitor-programmable startup ramp - limits inrush current and prevents input rail collapse during cold start or sequencing. |
| Input UVLO with hysteresis | 3.8 V turn-on / 3.59 V turn-off - prevents erratic operation during brownout and ensures clean restart after low-voltage events. |
| Thermal and overcurrent protection | Non-latching thermal shutdown (165°C) + cycle-by-cycle current limit (2 A) - enables safe operation under fault conditions without external circuitry. |
Applications
| Personal Digital Assistants (PDAs) | Computer Peripherals |
|---|---|
|
Use Scenario: Powering ARM-based application processors and DDR memory in handheld PDAs with dual-cell Li-ion (7.2–8.4 V) input. IC Role / Device Role / Timing Role: Primary buck regulator delivering 3.3 V or 1.8 V at up to 1.5 A with tight load transient response. Use Value: Sustains >90% efficiency across 10-mA to 1.5-A load range, extending battery life in both active and sleep states without manual mode switching. |
Use Scenario: Generating 5-V rail for USB hubs, card readers, and external storage enclosures powered from 12-V wall adapters. IC Role / Device Role / Timing Role: High-efficiency 12-V-to-5-V conversion with integrated MOSFETs and UVLO to prevent malfunction during adapter plug/unplug events. Use Value: Delivers stable 5-V output with <0.3% load regulation and 7-µA shutdown current - ideal for always-on peripheral standby functionality. |
| Battery-Powered Devices | Handheld Scanners |
|
Use Scenario: Supplying 2.5-V logic and 1.2-V core voltage to microcontrollers and sensors in portable medical monitors and IoT edge nodes. IC Role / Device Role / Timing Role: Adjustable-output buck converter configured via precision resistors to meet exact system voltage requirements. Use Value: 1.238-V feedback reference enables ±1% output accuracy; soft-start prevents sensor initialization errors during power-up. |
Use Scenario: Powering CMOS image sensors, laser drivers, and decode ASICs in barcode scanners operating from single-cell Li-ion (3.0–4.2 V) with boost-buck architecture. IC Role / Device Role / Timing Role: Secondary buck stage regulating 3.3-V I/O and 1.8-V core from intermediate 5-V rail generated by upstream boost converter. Use Value: 300-kHz switching frequency allows compact 4.7-µH inductor and 22-µF ceramic output cap - critical for ultra-thin scanner form factors. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar synchronous buck regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| TPS5430DDAR | 3-A output, 500-kHz switching, wider 5.5–36-V input range; requires external bootstrap diode and compensation. | Better suited for industrial 24-V input systems; lacks integrated soft-start and sleep-mode optimization for battery life. | Choose when higher current or wider input range is needed, but accept added external components and reduced light-load efficiency. |
| MP2315GJ-Z | 2-A output, 500-kHz, 4.5–28-V input; includes integrated soft-start and light-load PFM mode, but no programmable UVLO. | Offers faster transient response and smaller solution size; lower quiescent current (22 µA) but no thermal hysteresis spec. | Prefer for cost-sensitive consumer designs where 2-A headroom and 500-kHz frequency outweigh need for TI's validated thermal protection. |
Compared with LM2651MTC-ADJ, TPS5430DDAR delivers higher current and input voltage range at the expense of external component count and light-load efficiency, while MP2315GJ-Z offers higher integration and smaller footprint but less detailed thermal fault recovery behavior and no adjustable UVLO threshold.
Availability
LM2651MTC-ADJ is available at Aetrix Electronics and suitable for personal digital assistants, computer peripherals, battery-powered devices, and handheld scanners requiring stable component supply, long-term lifecycle support, and consistent parametric performance across production batches.
Supply support for LM2651MTC-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 is a global semiconductor company headquartered in Dallas, Texas, specializing in analog, embedded processing, and power management ICs for industrial, automotive, and consumer applications.
The LM2651 series was designed as a high-efficiency, integrated synchronous buck regulator family targeting portable and battery-operated equipment where small solution size, low quiescent current, and wide load-range efficiency are critical.
FAQ
What is the minimum output voltage achievable with LM2651MTC-ADJ?
The LM2651MTC-ADJ has a feedback reference voltage of 1.238 V (typ), so the minimum practical output voltage is approximately 1.25 V when using standard 1% resistors and accounting for tolerance and temperature drift. Lower outputs require precision trimming or external reference buffering, which is not supported by the LM2651MTC-ADJ's internal architecture.
Does LM2651MTC-ADJ require an external Schottky diode?
Yes - TI recommends adding an external Schottky diode (e.g., 2-A, 30-V rated) between SW and PGND to prevent conduction through the low-side MOSFET's intrinsic body diode during dead time. This improves efficiency by 1–2% and reduces noise, especially at higher input voltages and loads, as confirmed in the LM2651MTC-ADJ datasheet Section 8.2.2.8.
What is the purpose of the VCB pin on LM2651MTC-ADJ?
VCB is the bootstrap capacitor terminal for the high-side MOSFET gate driver. A 0.1-µF ceramic capacitor must be connected between VCB and SW to generate the ~6.7-V gate drive voltage required to fully enhance the internal high-side N-channel MOSFET. Without proper VCB decoupling, the high-side switch fails to turn on, causing regulator failure.
Can LM2651MTC-ADJ operate with a 3.3-V input supply?
No - LM2651MTC-ADJ has a minimum recommended input voltage of 4 V per the datasheet's Recommended Operating Conditions (Section 6.3). At 3.3 V, the internal UVLO circuit prevents startup, and the bootstrap circuit cannot generate sufficient gate drive voltage. Operation below 4 V risks unstable regulation or complete disablement.
How does the soft-start function work on LM2651MTC-ADJ?
The LM2651MTC-ADJ implements soft-start via the SD(SS) pin: a capacitor from SD(SS) to AGND is charged by an internal current source (2 µA then 10 µA), ramping the pin voltage from 0 to ~2 V. Output voltage rises only after SD(SS) exceeds 1.3 V, and duty cycle increases gradually - preventing inrush current and ensuring controlled power-up of downstream circuitry.
LM2651MTC-ADJ Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- 16-TSSOP (0.173", 4.40mm Width)
- Packaging:
- Bulk
- 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:
- 1.5A
- Frequency - Switching:
- 300kHz
- Synchronous Rectifier:
- Yes
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-TSSOP
LM2651MTC-ADJ FAQ
1.How can I place an order for LM2651MTC-ADJ through Aetrix?
Please submit a Request for Quotation (RFQ) for LM2651MTC-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 LM2651MTC-ADJ reliable?
The price and inventory of LM2651MTC-ADJ are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM2651MTC-ADJ is usually 5 days.
3.What payment methods are accepted for LM2651MTC-ADJ?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM2651MTC-ADJ transactions.
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4.How is shipping managed for LM2651MTC-ADJ?
LM2651MTC-ADJ orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM2651MTC-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 LM2651MTC-ADJ?
For technical support, including LM2651MTC-ADJ datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM2651MTC-ADJ requirements.
6.How does Aetrix verify that LM2651MTC-ADJ is sourced from the original manufacturer or authorized distributors?
All LM2651MTC-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 LM2651MTC-ADJ meets industry standards.
7.What is the process for return or replacement of LM2651MTC-ADJ?
All LM2651MTC-ADJ units undergo pre-shipment inspection (PSI). If there is an issue with LM2651MTC-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 LM2651MTC-ADJ part is unused and in its original packaging.
Return procedure for LM2651MTC-ADJ:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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