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Analog Devices Inc. LT1961IMS8E#TRPBF
- Part No.:
- LT1961IMS8E#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 8-TSSOP, 8-MSOP (0.118", 3.00mm Width) Exposed Pad
- Datasheet:
-
LT1961IMS8E#TRPBF.pdf
- Description:
- IC REG BST FLYBCK ADJ 1.5A 8MSOP
- Quantity:
- Payment:
- Shipping:
Inventory:4,642
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Product details
Overview
LT1961IMS8E#TRPBF from Analog Devices (formerly Linear Technology) is a 1.25MHz current-mode boost switching regulator with integrated 1.5A/0.2Ω NPN power switch in an exposed-pad MSOP-8 package. It operates from 3V to 25V input, delivers ±2% output voltage accuracy via 1.2V feedback reference, and supports synchronization from 1.5MHz to 2MHz - ideal for compact, high-efficiency battery-powered DC-DC conversion in portable computing and DSL modems.
For engineers reviewing the LT1961IMS8E#TRPBF datasheet, LT1961IMS8E#TRPBF pinout, LT1961IMS8E#TRPBF application, or LT1961IMS8E#TRPBF equivalent, key selection considerations include its constant-frequency current-mode control architecture, thermal derating behavior at high duty cycles, 6μA shutdown current, and compatibility with ceramic or tantalum output capacitors in space-constrained designs.
Technical Context
The LT1961IMS8E#TRPBF implements dual-loop current-mode control: an error amplifier sets the peak switch current threshold via the VC pin, while a cycle-by-cycle current sense comparator resets the internal RS flip-flop when switch current reaches that threshold. Its 1.25MHz fixed oscillator (1.5MHz min, 2MHz max when synchronized) enables small external magnetics and low-profile ceramic capacitors.
Thermal performance is managed through an exposed die pad thermally enhanced MSOP-8 package (θJA = 50°C/W with full copper plane), with built-in full-cycle switch current limiting and thermal shutdown. The 1.2V feedback reference and ±2% overall output tolerance are maintained across –40°C to 125°C junction temperature.
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 (1.5–2MHz sync range) - enables use of ≤10μH chip inductors and reduces EMI filter size. |
| Feedback Reference | 1.2V ±1.5% (1.176–1.224V) - sets precise output voltage with standard resistor dividers; low FB bias current (<0.4μA) minimizes divider error. |
| Input Voltage Range | 3V to 25V - supports single Li-ion (2.7–4.2V), multi-cell battery stacks, and 24V industrial rails. |
| Shutdown Current | 6μA max at VIN = 25V - extends battery life in standby mode without external load switches. |
| Switch On Resistance | 310mV typical at 1.5A - yields >87% efficiency at 5V→12V/0.5A, reducing thermal load in sealed enclosures. |
| Operating Junction Temp | –40°C to 125°C - qualified for automotive under-hood and industrial embedded applications requiring extended temperature reliability. |
Pinout & Package
LT1961IMS8E#TRPBF uses an 8-lead plastic MSOP package with exposed thermal pad (MS8E), optimized for thermal dissipation in high-current boost applications. The exposed pad must be soldered to a large PCB copper area for θJA = 50°C/W performance.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VIN | Input supply and internal bias rail | Accepts 3–25V; powers internal regulator and gate driver; requires local 1–4.7μF ceramic bypass near pin. |
| VSW | Collector of integrated NPN power switch | Carries high di/dt switching current; must connect directly to inductor and catch diode with minimal trace length. |
| GND (pins 3 & 4) | Power and signal ground reference | Shorted together and tied to exposed pad; forms return path for switch current and feedback reference - critical for load regulation. |
| FB | Inverting input of error amplifier | Senses output via resistor divider; 1.2V reference sets VOUT = 1.2V × (1 + R1/R2); <5kΩ impedance required for current-limit foldback. |
| VC | Error amplifier output / current limit control node | Used for loop compensation (RC network); also serves as current clamp point - 0.3V (light load) to 0.9V (full load). |
| SHDN | Logic-level enable/disable input | 1.35V threshold; pull high or float for operation; pull low for 6μA shutdown; supports UVLO with external resistor divider. |
| SYNC | External clock synchronization input | Accepts 1.5–2MHz logic-level signal (20–80% duty); disables internal oscillator when driven; tie to GND if unused. |
Key Features
| Feature | Design Value |
|---|---|
| Current-mode control | Enables fast transient response and stable loop compensation without complex type-II/III networks - simplifies design for variable loads. |
| Exposed thermal pad (MS8E) | Reduces thermal resistance by ~40% vs standard MSOP; enables 1.5A continuous operation with proper PCB copper area and vias. |
| Constant maximum switch current | Maintains 1.5A current limit regardless of duty cycle - eliminates output droop during high-VOUT/low-VIN conditions. |
| Synchronization capability | Allows EMI reduction via frequency dithering or alignment with system clocks - avoids beat frequencies in noise-sensitive applications. |
| Low shutdown quiescent current | 6μA max enables >1-year battery shelf life in always-on IoT sensors powered by coin cells or Li-SOCl₂ batteries. |
Applications
| DSL Modem Power Supply | Portable Computer Auxiliary Rail |
|---|---|
Use Scenario: Generating isolated 12V/0.5A from 5V motherboard rail to power ADSL line drivers and PHY ICs. IC Role / Device Role / Timing Role: Primary boost converter delivering regulated output with tight ripple control and fast load-step response. Use Value: Enables compact, fanless modem design using 6.8μH chip inductor and 2.2μF ceramic output capacitor - no electrolytics required. |
Use Scenario: Stepping up single-cell Li-ion (3.0–4.2V) to stable 5V for USB peripherals and display backlight drivers. IC Role / Device Role / Timing Role: High-efficiency DC-DC stage with programmable UVLO to prevent deep discharge below 3.0V. Use Value: Delivers 1.0A at 3.6V input with >89% efficiency, extending runtime while maintaining thermal safety in thin clamshell form factors. |
| Battery-Powered Test Equipment | Distributed Power for Industrial Sensors |
Use Scenario: Providing 15V bias for op-amp front-ends and ADC references in handheld multimeters and data loggers. IC Role / Device Role / Timing Role: Precision boost regulator with ±2% output tolerance and low 1.2V feedback reference for accurate voltage scaling. Use Value: Eliminates need for post-regulation LDOs - reduces BOM count and improves overall system efficiency by 8–12%. |
Use Scenario: Converting 24V field bus voltage to 12V for analog sensor signal conditioning and microcontroller I/O rails in factory automation nodes. IC Role / Device Role / Timing Role: Robust industrial-grade boost stage with –40°C to 125°C operation and thermal shutdown. Use Value: Sustains full 1.5A output at 85°C ambient using exposed-pad thermal management - avoids derating in enclosed DIN-rail enclosures. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar boost regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3401EDD#TRPBF | 3MHz synchronous boost, 1A max, 0.85–5V input, integrated MOSFETs; higher frequency but lower current rating. | Better suited for ultra-low-input-voltage (single alkaline) and high-efficiency sub-1A loads; lacks SYNC and thermal pad. | Select LTC3401EDD#TRPBF when input drops below 2.7V or when >95% efficiency at light loads is critical. |
| LT3467EMS8E#TRPBF | 1.3MHz boost, 1.3A switch, 2.7–16V input, 1.25V FB, no SYNC pin; similar MSOP-8 package but no exposed pad. | Lower thermal capability (θJA ≈ 75°C/W); limited to <1A continuous at 85°C ambient without forced air. | Choose LT3467EMS8E#TRPBF only for cost-sensitive, lower-power designs where thermal margin is sufficient. |
Compared with LTC3401EDD#TRPBF and LT3467EMS8E#TRPBF, the LT1961IMS8E#TRPBF offers superior thermal handling via its exposed pad, wider 3–25V input range, and 1.5A current capability - making it the preferred choice for industrial and high-reliability battery systems demanding sustained output current and robust thermal performance.
Availability
LT1961IMS8E#TRPBF is available at Aetrix Electronics and suitable for DSL modems, portable computers, battery-powered test equipment, and distributed industrial sensor power supplies requiring stable component supply, long-term lifecycle support, and guaranteed lead-free compliance.
Supply support for LT1961IMS8E#TRPBF 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 all Linear power products, including rigorous AEC-Q200-aligned qualification for select parts.
The LT1961IMS8E#TRPBF belongs to Linear's high-frequency current-mode boost regulator family, designed specifically for space-constrained, high-efficiency DC-DC conversion in portable and industrial applications where thermal management and precise output regulation are critical.
FAQ
What is the absolute maximum input voltage rating for the LT1961IMS8E#TRPBF?
The LT1961IMS8E#TRPBF has an absolute maximum input voltage rating of 25V on the VIN pin. Exceeding this voltage - even momentarily - risks permanent damage. The recommended operating range remains 3V to 25V, and internal undervoltage lockout activates below 2.47V to prevent erratic startup behavior. Always verify input transient suppression in 24V industrial environments.
Does the LT1961IMS8E#TRPBF require an external catch diode, and what type is recommended?
Yes, the LT1961IMS8E#TRPBF requires an external Schottky catch diode. The datasheet recommends the UPS120 (20V, 1A) or 1N5818 due to their low forward voltage (~0.5V at 1A) and fast recovery. Peak reverse voltage equals the output voltage, so diode VR must exceed VOUT; average forward current equals load current. Avoid standard PN diodes due to excessive switching losses.
How does the SYNC pin function on the LT1961IMS8E#TRPBF, and what happens if left unconnected?
The SYNC pin on the LT1961IMS8E#TRPBF accepts a logic-level square wave (1.5–2MHz, 20–80% duty) to override the internal oscillator. If left unconnected or floating, the device operates at its nominal 1.25MHz frequency. Do not leave SYNC open in noisy environments - tie directly to GND if unused to prevent spurious triggering and EMI coupling into the control loop.
Can the LT1961IMS8E#TRPBF be used in SEPIC or flyback topologies, or is it limited to boost only?
The LT1961IMS8E#TRPBF is designed and characterized exclusively for boost (step-up) topology. While application notes show modified SEPIC and flyback circuits using the LT1961IMS8E#TRPBF, these require careful validation of current sensing, slope compensation, and stability - and are not production-qualified. For SEPIC/flyback, Analog Devices recommends purpose-built controllers like the LT3751 or LTC3766 instead of repurposing the LT1961IMS8E#TRPBF.
What thermal design practices are essential to achieve full 1.5A output current with the LT1961IMS8E#TRPBF?
To sustain 1.5A output with the LT1961IMS8E#TRPBF, solder the exposed thermal pad to ≥2 cm² of 2-oz copper with ≥6 thermal vias (0.3mm diameter) to an internal ground plane. Keep high-current paths (VIN→VSW→inductor→diode→GND) short and wide. Derate output current above 85°C ambient - at 125°C junction, maximum continuous output drops to ~0.8A per thermal calculations in the datasheet.
LT1961IMS8E#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 8-TSSOP, 8-MSOP (0.118", 3.00mm Width) Exposed Pad
- Packaging:
- Tape & Reel (TR)
- 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#TRPBF FAQ
1.How can I place an order for LT1961IMS8E#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT1961IMS8E#TRPBF 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#TRPBF reliable?
The price and inventory of LT1961IMS8E#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT1961IMS8E#TRPBF is usually 5 days.
3.What payment methods are accepted for LT1961IMS8E#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT1961IMS8E#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT1961IMS8E#TRPBF?
LT1961IMS8E#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT1961IMS8E#TRPBF 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#TRPBF?
For technical support, including LT1961IMS8E#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT1961IMS8E#TRPBF requirements.
6.How does Aetrix verify that LT1961IMS8E#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT1961IMS8E#TRPBF 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#TRPBF meets industry standards.
7.What is the process for return or replacement of LT1961IMS8E#TRPBF?
All LT1961IMS8E#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT1961IMS8E#TRPBF, 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#TRPBF part is unused and in its original packaging.
Return procedure for LT1961IMS8E#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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