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Analog Devices Inc. LT1961EMS8E#PBF
- Part No.:
- LT1961EMS8E#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 8-TSSOP, 8-MSOP (0.118", 3.00mm Width) Exposed Pad
- Datasheet:
-
LT1961EMS8E#PBF.pdf
- Description:
- IC REG BST FLYBCK ADJ 1.5A 8MSOP
- Quantity:
- Payment:
- Shipping:
Inventory:4,259
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Product details
Overview
LT1961EMS8E#PBF from Analog Devices (formerly Linear Technology) is a 1.25MHz current-mode boost switching regulator with integrated 1.5A/0.2Ω NPN power switch, 1.2V feedback reference, ±2% output voltage tolerance, and thermally enhanced 8-lead MSOP package with exposed pad. It operates from 3V to 25V input and delivers regulated output in DSL modems, portable computers, and battery-powered systems.
For engineers reviewing the LT1961EMS8E#PBF datasheet, LT1961EMS8E#PBF pinout, LT1961EMS8E#PBF application, or LT1961EMS8E#PBF equivalent, key selection criteria include constant-frequency current-mode control, 1.25MHz fixed oscillator (synchronizable to 1.5–2MHz), thermal shutdown, cycle-by-cycle current limiting, and compatibility with ceramic/tantalum output capacitors.
Technical Context
The LT1961EMS8E#PBF implements a fixed-frequency, peak-current-mode control architecture with an internal 1.25MHz oscillator, error amplifier (gm = 850 μMho), slope-compensated current comparator, and RS flip-flop driving the on-die NPN switch. Its dual-loop structure enables fast transient response and stable operation across wide duty cycles.
It integrates a low-dropout internal bias regulator supporting inputs from Li-ion batteries (≥2.6V UVLO) to 24V industrial rails, maintains 1mA quiescent supply current at no load, and reduces shutdown current to 6μA. The VC pin serves as both error amplifier output and current-limit threshold input, enabling loop compensation and current clamping.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Switch Current Limit | 1.5A typical, constant across all duty cycles - ensures predictable overcurrent protection without foldback distortion. |
| Oscillator Frequency | 1.25MHz typical, synchronizable 1.5–2MHz - enables compact magnetics and reduced EMI filtering requirements. |
| Feedback Reference | 1.2V ±1.5% (±2% total tolerance) - sets output voltage via external resistor divider with minimal drift over temperature. |
| Input Voltage Range | 3V to 25V - supports single-cell Li-ion (2.7V start-up) through 24V industrial supplies with internal UVLO at 2.6V. |
| Switch On Resistance | 310mV typical at 1.5A - corresponds to ~0.2Ω RDS(on) equivalent, enabling >85% efficiency at mid-load in 5V→12V conversion. |
| Shutdown Current | 6μA max at VSHDN = 0V - preserves battery life in always-on portable systems during standby. |
| Thermal Protection | Internal thermal shutdown with exposed-pad MSOP (θJA ≈ 50°C/W with full ground plane) - prevents latch-up under sustained overload. |
Pinout & Package
LT1961EMS8E#PBF uses an 8-lead plastic MSOP package (MS8E) with thermally enhanced exposed die pad soldered to PCB ground plane for optimal heat dissipation (θJA = 50°C/W with large copper area).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1: VIN | Power input supply | Bypass capacitor must be placed adjacent to minimize high-frequency input ripple and ensure stable bias regulation. |
| 2: SW | Switch collector node | High di/dt node - requires shortest possible trace to inductor/catch diode to limit radiated EMI and voltage spikes. |
| 3,4: GND | Power and signal ground reference | Must be shorted together and connected to exposed pad; forms return path for switch current and feedback reference. |
| 5: SHDN | Logic-level shutdown control | 1.35V threshold enables precise undervoltage lockout; floating or pulled high enables operation. |
| 6: VC | Error amplifier output / current limit threshold | Used for frequency compensation (RC network); also sets peak switch current when clamped externally. |
| 7: FB | Feedback input | Senses divided output voltage; 1.2V reference enables accurate output setting with <5kΩ divider impedance. |
| 8: SYNC | External clock synchronization input | Logic-compatible (20–80% duty cycle); extends oscillator range from 1.5MHz to 2MHz for EMI reduction or timing alignment. |
Key Features
| Feature | Design Value |
|---|---|
| Current-mode control | Enables inherent cycle-by-cycle current limiting and stable operation up to 90% duty cycle without subharmonic oscillation. |
| Thermally enhanced MSOP | Exposed pad reduces junction-to-board thermal resistance by >40% vs standard MSOP, enabling 1.5A continuous operation at 70°C ambient. |
| Integrated 1.5A NPN switch | Eliminates external transistor and drive circuitry; 0.2Ω effective on-resistance minimizes conduction loss in high-current boost stages. |
| Synchronization capability | Allows EMI-sensitive designs to align switching frequency with system clocks or avoid critical bands without changing component values. |
| Low 6μA shutdown current | Extends battery runtime in sleep-mode applications such as handheld medical devices and IoT sensors. |
Applications
| DSL Modems | Portable Computers |
|---|---|
Use Scenario: Generating stable 12V rail from 5V motherboard supply to power line drivers and analog front-end circuits. IC Role / Device Role / Timing Role: Primary DC/DC boost converter providing regulated high-voltage bias for ADSL line interface ICs. Use Value: High 1.25MHz switching frequency allows use of 6.8μH chip inductors and 2.2μF ceramic output capacitors, reducing board area by >35% vs 500kHz alternatives. |
Use Scenario: Stepping up single-cell Li-ion (3.0–4.2V) to 5V USB peripheral bus voltage in ultrabooks and 2-in-1 tablets. IC Role / Device Role / Timing Role: System power management IC delivering 0.75–1.0A at 5V with automatic UVLO below 2.6V to prevent deep battery discharge. Use Value: 6μA shutdown current and 1mA quiescent operation extend battery life during suspend-to-RAM states without requiring auxiliary LDOs. |
| Battery-Powered Systems | Distributed Power |
Use Scenario: Powering 12V CCD image sensors and analog signal chains in portable diagnostic equipment powered by rechargeable NiMH packs. IC Role / Device Role / Timing Role: High-efficiency boost regulator operating from 3V–25V input range to accommodate varying battery chemistries and charge states. Use Value: Constant 1.5A switch current limit ensures consistent performance across input voltage range, eliminating need for dynamic current scaling firmware. |
Use Scenario: Local 12V generation from 24V backplane in industrial I/O modules where centralized DC/DC is impractical. IC Role / Device Role / Timing Role: Point-of-load (POL) boost converter with thermal shutdown and robust ESD-rated pins for harsh factory-floor environments. Use Value: Exposed-pad MS8E package and 125°C junction rating support operation in sealed enclosures with limited airflow, maintaining reliability at 70°C ambient. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar boost regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3401 | 3MHz synchronous boost, 1A max, 0.85V–5V input, 97% peak efficiency | Better suited for ultra-low-input (single alkaline or LiFePO4) and space-constrained applications; lacks SYNC and thermal shutdown. | Select LTC3401 when input voltage falls below 3V or when >95% efficiency at light loads is required; not drop-in due to different pinout and control scheme. |
| LT1946A | 1.2MHz/2.7MHz dual-frequency boost, 1.5A, 2.6V–16V input, integrated soft-start | Offers programmable frequency and built-in soft-start; lower max input voltage (16V vs 25V) and no SYNC pin. | Choose LT1946A when soft-start is mandatory or when operating exclusively below 16V input; pin-compatible but requires FB divider recalibration. |
Compared with LT1961EMS8E#PBF, LTC3401 provides higher efficiency at sub-1V inputs but sacrifices input voltage range and thermal safety features, while LT1946A adds soft-start convenience at the cost of maximum input headroom and synchronization flexibility.
Availability
LT1961EMS8E#PBF is available at Aetrix Electronics and suitable for DSL modems, portable computers, and battery-powered systems requiring stable component supply, long-term lifecycle support, and guaranteed lead-free compliance.
Supply support for LT1961EMS8E#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 acquired Linear Technology in 2017 and maintains full technical and manufacturing continuity for the LT product family, including rigorous AEC-Q200-aligned qualification for industrial-grade variants.
The LT1961 belongs to Linear's high-frequency monolithic boost regulator product line, designed specifically for space-constrained, high-efficiency DC/DC conversion in portable and distributed power systems where thermal performance and EMI control are critical.
FAQ
What is the absolute maximum input voltage rating for the LT1961EMS8E#PBF?
The LT1961EMS8E#PBF has an absolute maximum input voltage rating of 25V on the VIN pin. Exceeding this voltage risks permanent damage. The device operates continuously from 3V to 25V, with undervoltage lockout engaging below 2.6V to protect battery-fed systems. Always observe derating guidelines in thermal calculations when operating near maximum ratings.
Can the LT1961EMS8E#PBF synchronize to an external clock, and what are the valid frequency and duty cycle ranges?
Yes, the LT1961EMS8E#PBF supports external synchronization via the SYNC pin. It accepts logic-level signals with 20%–80% duty cycle across a frequency range of 1.5MHz to 2MHz. The internal oscillator is pulled from its nominal 1.25MHz to match the external signal; operation below 1.5MHz is not supported. Synchronization improves EMI profile and enables timing alignment in multi-rail systems.
What is the purpose of the VC pin on the LT1961EMS8E#PBF, and how is it used in design?
The VC pin on the LT1961EMS8E#PBF is the output of the internal error amplifier and serves as the threshold input for the peak current comparator. It is used for loop compensation (via series RC network), current limiting override, and stability tuning. At light loads, VC sits near 0.3V; at full load, it rises to ~0.9V. Proper VC compensation is essential to suppress switching ripple and maintain phase margin above 45°.
Does the LT1961EMS8E#PBF require an external catch diode, and what specifications are recommended?
Yes, the LT1961EMS8E#PBF requires an external Schottky catch diode. Recommended parts include UPS120 (20V, 1A) or 1N5818 (30V, 1A), with forward voltage ≤0.5V at 1A and reverse voltage ≥output voltage. The diode conducts only during switch-off time; average current equals output current. Fast recovery and low Qrr minimize switching losses and EMI.
How does the LT1961EMS8E#PBF handle thermal overload, and what layout practices improve thermal performance?
The LT1961EMS8E#PBF includes internal thermal shutdown that disables the switch when junction temperature exceeds ~125°C. To maximize thermal performance, the exposed pad must be soldered to a large PCB copper area (≥100 mm²) with ≥4 thermal vias to inner ground planes. Minimizing trace length between GND pins 3/4 and the exposed pad, and separating high-current paths from sensitive VC/FB nodes, further reduces thermal resistance and improves reliability.
LT1961EMS8E#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 8-TSSOP, 8-MSOP (0.118", 3.00mm Width) Exposed Pad
- Packaging:
- Tube
- Product Status:
- Active
- Function:
- Step-Up, Step-Up/Step-Down
- Output Configuration:
- Positive
- Topology:
- Boost, Flyback, SEPIC
- Output Type:
- Adjustable
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 3V
- Voltage - Input (Max):
- 25V
- Voltage - Output (Min/Fixed):
- 1.2V
- Voltage - Output (Max):
- 35V (Switch)
- Current - Output:
- 1.5A (Switch)
- Frequency - Switching:
- 1.25MHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- 0°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-MSOP-EP
LT1961EMS8E#PBF FAQ
1.How can I place an order for LT1961EMS8E#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT1961EMS8E#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 LT1961EMS8E#PBF reliable?
The price and inventory of LT1961EMS8E#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT1961EMS8E#PBF is usually 5 days.
3.What payment methods are accepted for LT1961EMS8E#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT1961EMS8E#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT1961EMS8E#PBF?
LT1961EMS8E#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT1961EMS8E#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 LT1961EMS8E#PBF?
For technical support, including LT1961EMS8E#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT1961EMS8E#PBF requirements.
6.How does Aetrix verify that LT1961EMS8E#PBF is sourced from the original manufacturer or authorized distributors?
All LT1961EMS8E#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 LT1961EMS8E#PBF meets industry standards.
7.What is the process for return or replacement of LT1961EMS8E#PBF?
All LT1961EMS8E#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT1961EMS8E#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 LT1961EMS8E#PBF part is unused and in its original packaging.
Return procedure for LT1961EMS8E#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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