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Analog Devices Inc. LT1961IMS8E#PBF
- Part No.:
- LT1961IMS8E#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 8-TSSOP, 8-MSOP (0.118", 3.00mm Width) Exposed Pad
- Datasheet:
-
LT1961IMS8E#PBF.pdf
- Description:
- IC REG BST FLYBCK ADJ 1.5A 8MSOP
- Quantity:
- Payment:
- Shipping:
Inventory:197
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Product details
Overview
LT1961IMS8E#PBF from Analog Devices (formerly Linear Technology) is a 1.25MHz, current-mode boost switching regulator with an integrated 1.5A/0.2Ω NPN power switch in an exposed-pad MSOP-8 package. It operates from 3V to 25V input, delivers up to 12V output at 0.5A in typical 5V-to-12V conversion, and features ±2% output voltage tolerance, 1.2V feedback reference, and 6μA shutdown current. It is used in portable computers and battery-powered systems requiring compact, high-frequency DC/DC conversion.
For engineers reviewing the LT1961IMS8E#PBF datasheet, LT1961IMS8E#PBF pinout, LT1961IMS8E#PBF application, or LT1961IMS8E#PBF equivalent, key selection criteria include its constant-frequency current-mode control architecture, thermally enhanced MSOP-8 package with exposed pad, 1.5A switch current limit across all duty cycles, synchronization capability from 1.5MHz to 2MHz, and integrated protection including cycle-by-cycle current limiting and thermal shutdown.
Technical Context
The LT1961IMS8E#PBF implements a fixed-frequency (1.25MHz typ), current-mode control architecture with dual feedback loops: an error amplifier sets the peak switch current threshold via the VC pin, while a current-sense amplifier monitors switch current on a cycle-by-cycle basis. Its internal 1.5A NPN switch exhibits 310mV typical on-voltage drop at 1.5A, enabling high efficiency over wide input ranges.
It integrates a 2.5V bias regulator for stable internal operation, slope compensation to prevent subharmonic oscillation above 50% duty cycle, and logic-compatible SYNC input for external frequency synchronization. The SHDN pin provides 1.35V threshold UVLO with 7μA hysteresis, supporting precise input voltage supervision without external components.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Switching Frequency | 1.25MHz typical; enables use of small chip inductors (e.g., 6.8μH) and ceramic capacitors, reducing board area and EMI filter complexity. |
| Max Switch Current | 1.5A guaranteed minimum; constant over full duty cycle range, ensuring predictable current-limit behavior during startup and overload. |
| Feedback Reference | 1.2V ±1.5% (±2% over temp); sets output voltage via external resistor divider, enabling precise regulation independent of input or load variation. |
| Input Voltage Range | 3V to 25V; supports single Li-ion (2.7–4.2V), multi-cell battery stacks, and industrial 24V rails without external pre-regulation. |
| Shutdown Current | 6μA max at VIN = 25V; minimizes battery drain in standby mode for portable equipment with long idle periods. |
| Thermal Resistance | θJA = 50°C/W with exposed pad soldered to large copper area; allows 0.62W dissipation at 125°C junction limit in typical 5V→12V/0.5A design. |
| Oscillator Sync Range | 1.5MHz to 2MHz; permits EMI reduction via spread-spectrum or noise-sensitive system clock alignment without changing layout. |
Pinout & Package
LT1961IMS8E#PBF is housed in an 8-lead plastic MSOP package (MS8E) with thermally enhanced exposed die pad. The pad must be soldered to a large PCB copper area for effective heat dissipation and electrical grounding.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VIN | Input supply and internal bias rail | Power source for IC core and switch driver; requires local 1μF–4.7μF ceramic bypass capacitor to minimize high-frequency ripple and ensure stable regulation. |
| VSW | Switch collector node | High-current, high-dV/dt node connected to inductor and catch diode; must be routed with minimal trace length to reduce radiated EMI and voltage spikes. |
| GND (pins 3 & 4) | Power and signal reference ground | Low-impedance return path for switch current and feedback loop; pins 3/4 and exposed pad must be shorted to common ground plane to avoid load regulation error. |
| FB | Feedback input | Senses output voltage via resistor divider; 1.2V reference enables accurate output setting; input bias current <0.4μA minimizes divider error. |
| VC | Error amplifier output / current limit control | Provides loop compensation node and sets peak switch current; voltage range 0.3V–0.9V corresponds to light-to-full load; used for frequency compensation and current clamping. |
| SHDN | Enable/disable control | Logic-level input with 1.35V threshold; floating or pulled high enables operation; internal 3μA pull-up ensures default ON state; supports UVLO implementation with external resistors. |
| SYNC | External oscillator synchronization | Accepts 1.5–2MHz logic-level square wave (20–80% duty); synchronizes internal oscillator to reduce beat frequencies and improve EMI performance in multi-rail systems. |
Key Features
| Feature | Design Value |
|---|---|
| Current-mode control | Enables fast transient response and inherent cycle-by-cycle current limiting without external sense resistor; simplifies stability compensation with single-pole RC network on VC pin. |
| Thermally enhanced MSOP-8 | Exposed die pad reduces θJA to 50°C/W when soldered to ≥1 cm² copper; enables 0.62W power dissipation in compact footprint-critical for space-constrained portable designs. |
| Constant 1.5A switch current limit | Maintains consistent overcurrent protection across all input/output combinations and duty cycles, eliminating derating tables and simplifying fault analysis. |
| 1.2V precision feedback reference | ±2% tolerance over –40°C to 125°C ensures stable output regulation under temperature extremes without trimming; low FB bias current (<0.4μA) preserves accuracy with high-value dividers. |
| Synchronization capability | Allows external clock alignment from 1.5MHz to 2MHz, enabling EMI reduction in noise-sensitive applications (e.g., audio, RF) and deterministic timing in synchronized power domains. |
Applications
| DSL Modems | Portable Computers |
|---|---|
Use Scenario: Powering 12V line drivers and analog front-end circuitry from a 5V or 3.3V system rail in compact DSL modem designs. IC Role / Device Role / Timing Role: Boost converter providing regulated 12V output with fast load-step response to handle burst-mode line signaling. Use Value: High 1.25MHz switching frequency allows use of 6.8μH chip inductor and 2.2μF ceramic output capacitor, minimizing solution size while maintaining >85% efficiency at 0.5A. |
Use Scenario: Generating 12V bias for LCD backlight inverters or USB charging circuits from a single-cell Li-ion battery (2.7–4.2V). IC Role / Device Role / Timing Role: Primary DC/DC step-up regulator delivering stable output despite wide input voltage swing and dynamic load changes. Use Value: 6μA shutdown current extends battery life during sleep modes; 1.5A switch supports peak backlight loads without external current boosting. |
| Battery-Powered Systems | Distributed Power |
Use Scenario: Providing isolated 15V rails for op-amp biasing and sensor excitation in handheld test equipment powered by AA/AAA cells. IC Role / Device Role / Timing Role: Compact, high-efficiency boost stage enabling multi-rail generation from a low-voltage primary source. Use Value: Wide 3V–25V input range accommodates both alkaline (0.9–1.5V/cell) and Li-ion sources; ±2% output tolerance ensures precision analog circuit operation. |
Use Scenario: Local 12V generation for remote I/O modules in industrial PLC backplanes fed from 24V distributed bus. IC Role / Device Role / Timing Role: Point-of-load regulator converting 24V bus to lower intermediate voltage with high reliability and thermal margin. Use Value: Exposed-pad MSOP-8 package achieves 50°C/W thermal resistance with standard PCB layout, enabling continuous 0.5A output at 70°C ambient without heatsink. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar boost regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3401EDD#PBF | 3MHz synchronous boost, 1A max, 0.85V–5V input, integrated MOSFETs; higher frequency but lower current rating and narrower input range. | Better suited for ultra-low-input (single-cell) applications below 3V; not suitable for 24V input or >1A loads. | Select LTC3401EDD#PBF only when input voltage is ≤5V and peak current ≤1A; LT1961IMS8E#PBF remains preferred for wider Vin and higher Isw. |
| LT1372IS8#PBF | 500kHz boost, 1.5A switch, 35V switch rating, SO-8 package; lower switching frequency, no SYNC, no exposed pad, higher θJA (~80°C/W). | Requires larger magnetics and capacitors; less suitable for space-constrained or thermally demanding layouts. | Choose LT1372IS8#PBF only if 1.25MHz EMI is problematic and board area/thermal budget allow larger passive components. |
Compared with LTC3401EDD#PBF and LT1372IS8#PBF, the LT1961IMS8E#PBF uniquely balances 1.25MHz operation, 1.5A current capability, 3V–25V input flexibility, and thermally optimized MSOP-8 packaging-making it optimal for mid-power portable and industrial boost applications where size, efficiency, and thermal performance are jointly critical.
Availability
LT1961IMS8E#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 RoHS-compliant sourcing.
Supply support for LT1961IMS8E#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 its legacy high-performance power management portfolio, emphasizing precision, efficiency, and ruggedness for industrial, automotive, and communications applications.
The LT1961IMS8E#PBF belongs to Linear's monolithic boost regulator family designed for compact, high-frequency DC/DC conversion in space- and thermal-constrained environments-targeting portable, telecom, and distributed power systems.
FAQ
What is the maximum output current achievable with the LT1961IMS8E#PBF in a 5V-to-12V boost configuration?
The LT1961IMS8E#PBF delivers up to 0.5A at 12V output from a 5V input in typical operation, as verified in the datasheet's TA01 schematic and efficiency curve. Maximum output current is thermally limited and subject to derating above 70°C ambient; at 25°C with proper PCB copper area, 0.5A is sustainable. Higher currents require careful thermal design and may trigger current foldback or thermal shutdown.
Does the LT1961IMS8E#PBF support synchronization to an external clock, and what is the valid frequency range?
Yes, the LT1961IMS8E#PBF supports external synchronization via its SYNC pin, accepting logic-level signals from 1.5MHz to 2MHz with 20–80% duty cycle. This feature allows EMI reduction and deterministic timing alignment in multi-rail systems. Operation outside this range may cause instability or loss of synchronization, as confirmed in the Electrical Characteristics table and Applications Information section.
How does the LT1961IMS8E#PBF implement undervoltage lockout (UVLO), and can the threshold be adjusted?
The LT1961IMS8E#PBF has a built-in 1.35V SHDN pin threshold that functions as a precise UVLO. An external resistor divider from VIN to GND, connected to SHDN, allows adjustable turn-on/turn-off thresholds-for example, 4.75V turn-on and 3.75V turn-off using R1 = 143kΩ and R2 = 50.4kΩ. Internal 3μA pull-up ensures default ON state when SHDN is floating.
What package type and thermal characteristics define the LT1961IMS8E#PBF?
The LT1961IMS8E#PBF uses an 8-lead plastic MSOP package (MS8E) with exposed die pad. With the pad soldered to ≥1 cm² copper area, its thermal resistance is θJA = 50°C/W. This enables reliable operation at 125°C junction temperature with 0.62W total dissipation in a 5V→12V/0.5A design, as calculated in the Thermal Calculations section of the datasheet.
Can the LT1961IMS8E#PBF operate from a single Li-ion cell, and what is the minimum input voltage?
Yes, the LT1961IMS8E#PBF operates from a single Li-ion cell (2.7V–4.2V). Its absolute minimum input voltage is 2.47V (typical), per the VIN Undervoltage Lockout specification. In practice, stable 5V output is achievable down to ~2.7V input with appropriate inductor and capacitor selection, as demonstrated in the "Single Li-Ion Cell to 5V" application (TA04).
LT1961IMS8E#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:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-MSOP-EP
LT1961IMS8E#PBF FAQ
1.How can I place an order for LT1961IMS8E#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT1961IMS8E#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 LT1961IMS8E#PBF reliable?
The price and inventory of LT1961IMS8E#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT1961IMS8E#PBF is usually 5 days.
3.What payment methods are accepted for LT1961IMS8E#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT1961IMS8E#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT1961IMS8E#PBF?
LT1961IMS8E#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT1961IMS8E#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 LT1961IMS8E#PBF?
For technical support, including LT1961IMS8E#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT1961IMS8E#PBF requirements.
6.How does Aetrix verify that LT1961IMS8E#PBF is sourced from the original manufacturer or authorized distributors?
All LT1961IMS8E#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 LT1961IMS8E#PBF meets industry standards.
7.What is the process for return or replacement of LT1961IMS8E#PBF?
All LT1961IMS8E#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT1961IMS8E#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 LT1961IMS8E#PBF part is unused and in its original packaging.
Return procedure for LT1961IMS8E#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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