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Analog Devices Inc. LT1961EMS8E#TRPBF
- Part No.:
- LT1961EMS8E#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 8-TSSOP, 8-MSOP (0.118", 3.00mm Width) Exposed Pad
- Datasheet:
-
LT1961EMS8E#TRPBF.pdf
- Description:
- IC REG BST FLYBCK ADJ 1.5A 8MSOP
- Quantity:
- Payment:
- Shipping:
Inventory:4,647
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Product details
Overview
LT1961EMS8E#TRPBF 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 regulated output via 1.2V feedback reference, maintains ±2% output voltage tolerance, and supports external 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 LT1961EMS8E#TRPBF datasheet, LT1961EMS8E#TRPBF pinout, LT1961EMS8E#TRPBF application, or LT1961EMS8E#TRPBF equivalent, key selection criteria include verified 1.5A switch current limit across all duty cycles, thermally enhanced MSOP-8 package with exposed pad, constant-frequency current-mode control for fast transient response, and confirmed 6μA shutdown quiescent current - all critical for space-constrained, thermally sensitive boost designs.
Technical Context
The LT1961EMS8E#TRPBF implements fixed-frequency (1.25MHz typ.) current-mode control using an internal oscillator, cycle-by-cycle peak current sensing, and an error amplifier whose output (VC pin) sets the switch current trip threshold. Its dual-loop architecture - combining voltage regulation via FB-to-VC transconductance (850μMho) and real-time current limiting - ensures stable operation up to 80% duty cycle while preventing subharmonic oscillation through built-in slope compensation.
It integrates a 0.27Ω hot-switch on-die NPN transistor, a 2.5V bias regulator for consistent internal operation across 3V–25V input, and logic-compatible SYNC input enabling precise frequency alignment between 1.5MHz and 2MHz. The SHDN pin provides 1.35V threshold UVLO with 7μA hysteresis, and the exposed thermal pad enables θJA ≈ 50°C/W with proper PCB copper area.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Switching Frequency | 1.25MHz typical; enables use of small chip inductors (e.g., 2.2–6.8μH) and ceramic output capacitors ≤10μF. |
| Max Switch Current | 1.5A guaranteed minimum; constant over full duty cycle range - eliminates current foldback at high VOUT/VIN ratios. |
| Feedback Reference | 1.20V ±1.5% (1.176–1.224V); sets output voltage via external resistor divider - enables precise 5V, 12V, or 15V generation. |
| Input Voltage Range | 3V to 25V; supports single Li-ion (2.7–4.2V), multi-cell batteries, and 24V industrial rails without external pre-regulation. |
| Shutdown Current | 6μA max at VSHDN = 0V; reduces system standby power - critical for battery runtime in portable equipment. |
| Thermal Package | MSOP-8 with exposed thermal pad; requires soldered copper plane for θJA ≤ 50°C/W - essential for 0.6W+ dissipation at full load. |
| Oscillator Sync Range | 1.5MHz to 2MHz; accepts logic-level square wave (20–80% duty) on SYNC pin - enables EMI reduction via spread-spectrum or multi-rail synchronization. |
Pinout & Package
LT1961EMS8E#TRPBF is housed in an 8-lead plastic MSOP package (MS8E) with exposed thermal pad, rated for –40°C to +125°C junction temperature. The exposed pad must be soldered to a large PCB copper area for thermal performance and electrical grounding.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 - VIN | Power input supply | Bypass capacitor must be placed adjacent to this pin; powers internal bias regulator and switch driver - determines minimum startup voltage (2.6V UVLO). |
| 2 - SW | Switch collector node | High-current, high-dV/dt node; connects directly to inductor and catch diode - trace length must be minimized to reduce EMI and voltage spikes. |
| 3,4 - GND | Power and signal ground | Both pins plus exposed pad must be shorted to common ground plane; forms return path for switch current and reference for FB/VC - critical for load regulation and loop stability. |
| 5 - SHDN | Logic-controlled enable/disable | 1.35V threshold; pull low to enter 6μA shutdown - usable as accurate UVLO with external resistor divider (e.g., 4.75V turn-on / 3.75V turn-off). |
| 6 - VC | Error amplifier output / current limit control | Connects to RC compensation network; voltage (0.3–0.9V) sets peak switch current - also used for loop override or current clamping. |
| 7 - FB | Feedback input | Senses divided output voltage; 1.2V reference sets VOUT = 1.2V × (1 + R1/R2); input bias < –0.4μA minimizes divider error. |
| 8 - SYNC | External oscillator synchronization | Accepts 1.5–2MHz logic-level input; synchronizes internal oscillator - eliminates beat frequencies in multi-regulator systems. |
Key Features
| Feature | Design Value |
|---|---|
| Integrated 1.5A/0.2Ω NPN switch | Eliminates external MOSFET and gate driver - reduces BOM count and layout complexity in space-constrained boost designs. |
| Current-mode control with slope compensation | Enables stable operation >50% duty cycle without external compensation - simplifies design for high step-up ratios (e.g., 3.3V → 12V). |
| 1.2V ±1.5% feedback reference | Supports tight output regulation (±2% total) across line/load/temperature - suitable for powering precision analog or digital loads. |
| 6μA shutdown quiescent current | Extends battery life in always-on portable systems - verified at VIN = 25V and VSW = 25V. |
| Exposed thermal pad (MSOP-8) | Enables 50°C/W thermal resistance with proper PCB copper - allows continuous 0.5A output at 12V from 5V input without derating. |
Applications
| DSL Modem Power Supply | Portable Computer Auxiliary Rail |
|---|---|
Use Scenario: Generating stable 12V rail from 5V motherboard supply to power ADSL line drivers and PHY ICs. IC Role / Device Role / Timing Role: Primary non-isolated boost converter delivering up to 0.5A with low noise and fast load transient response. Use Value: Enables compact, fanless modem design using 6.8μH inductor and ceramic capacitors - meets ETSI Class B conducted emissions limits. |
Use Scenario: Providing 5V or 15V auxiliary voltage from single-cell Li-ion (2.7–4.2V) for USB peripherals or display backlight drivers. IC Role / Device Role / Timing Role: High-efficiency, thermally robust boost regulator operating across full battery discharge curve. Use Value: Delivers >90% efficiency at 0.75A (3.6V→5V) with no thermal derating - extends runtime and avoids thermal throttling in thin-profile laptops. |
| Battery-Powered Test Equipment | Distributed Industrial Sensor Node |
Use Scenario: Powering 3.3V or 5V microcontroller and analog front-end from two AA alkaline cells (1.8–3.2V). IC Role / Device Role / Timing Role: Input-UVLO-enabled boost converter with programmable shutdown threshold for battery end-of-life detection. Use Value: Uses SHDN pin hysteresis (7μA) to implement clean 2.47V turn-on / 2.33V turn-off - prevents brownout resets during battery sag. |
Use Scenario: Generating isolated 5V or 12V local supply from 24V field bus for wireless sensor modules with RS-485 or LoRa transceivers. IC Role / Device Role / Timing Role: Robust, wide-input boost stage preceding isolated DC-DC or LDO - handles 24V transients and ripple. Use Value: Operates reliably from 3V–25V input with 35V switch rating - withstands automotive-style load dump surges without external protection. |
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, 0.85V min start-up, 97% peak efficiency - but no SYNC input or exposed thermal pad. | Better suited for ultra-low-voltage single-cell (0.85–5V) applications; lacks 25V input capability and thermal headroom for >0.5A continuous loads. | Select LTC3401EDD#TRPBF only when input voltage dips below 3V and efficiency >95% at light loads is mandatory. |
| LT1946AEMS8E#TRPBF | 1.2MHz/2.7MHz dual-frequency boost, 1.5A switch, same MSOP-8 package, but higher 16V max input and integrated soft-start. | Optimized for lower-input systems (2.6–16V); cannot replace LT1961EMS8E#TRPBF in 24V industrial or DSL modem applications requiring 25V input rating. | Choose LT1946AEMS8E#TRPBF for consumer portable gear with <16V rails where soft-start and dual-frequency flexibility outweigh 25V input need. |
Compared with LTC3401EDD#TRPBF and LT1946AEMS8E#TRPBF, LT1961EMS8E#TRPBF uniquely balances 25V input tolerance, 1.25MHz fixed-frequency operation, exposed-pad thermal management, and SYNC capability - making it the only option among the three qualified for 24V-field-bus-powered industrial boost converters requiring EMI-controlled switching.
Availability
LT1961EMS8E#TRPBF is available at Aetrix Electronics and suitable for DSL modems, portable computers, and battery-powered test equipment requiring stable component supply, long-term industrial lifecycle support, and RoHS-compliant lead-free packaging.
Supply support for LT1961EMS8E#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 the LT® series of high-performance power management ICs.
The LT1961EMS8E#TRPBF belongs to Linear's monolithic boost regulator product line, engineered for high-frequency, high-efficiency DC-DC conversion in space- and thermally constrained applications - especially where wide input voltage range and precise current limiting are required.
FAQ
What is the absolute maximum input voltage rating for the LT1961EMS8E#TRPBF?
The LT1961EMS8E#TRPBF has an absolute maximum input voltage rating of 25V on the VIN pin, as specified in the Absolute Maximum Ratings table. Exceeding this voltage risks permanent damage. The device operates continuously from 3V to 25V, and its internal undervoltage lockout activates at 2.6V minimum - ensuring reliable startup across battery discharge curves. This 25V rating makes LT1961EMS8E#TRPBF suitable for 24V industrial bus and DSL line-powered applications.
Does the LT1961EMS8E#TRPBF support synchronization to an external clock, and what is the valid frequency range?
Yes, the LT1961EMS8E#TRPBF supports external synchronization via its SYNC pin, which accepts logic-level signals with 20–80% duty cycle. The valid synchronization frequency range is 1.5MHz to 2MHz - matching the worst-case upper limit of its internal oscillator. This allows EMI reduction in multi-rail systems and eliminates beat frequencies. The SYNC pin has 20kΩ input resistance and requires no external pull-up; unused SYNC must be grounded to prevent noise coupling.
What thermal design considerations apply to the LT1961EMS8E#TRPBF's exposed pad?
The LT1961EMS8E#TRPBF's exposed thermal pad must be soldered to a large PCB copper area to achieve θJA ≈ 50°C/W. Per the datasheet, this pad is electrically connected to GND and serves as the primary heat conduction path. Designers must use the recommended solder pad layout (0.42mm × 3.00mm), include ≥4 thermal vias filled with solder under the pad, and connect those vias to an internal ground plane. Failure to properly thermally anchor the pad results in junction temperature rise exceeding 125°C at moderate loads.
Can the LT1961EMS8E#TRPBF be used in SEPIC or flyback topologies, or is it limited to boost only?
The LT1961EMS8E#TRPBF is specifically designed and characterized for boost (step-up) topology, but application notes TA03 and TA04 confirm functional use in SEPIC and isolated flyback configurations. In SEPIC, it drives coupled inductors with bidirectional current; in flyback, it controls primary-side switching with opto-coupled feedback. These require careful compensation and layout - the IC's current-mode control and 1.5A switch make them viable, but LT1961EMS8E#TRPBF is not officially rated or tested for these topologies beyond the provided reference designs.
What is the guaranteed minimum switch current limit for the LT1961EMS8E#TRPBF across temperature and duty cycle?
The LT1961EMS8E#TRPBF guarantees a minimum switch current limit of 1.5A across the full operating junction temperature range (–40°C to +125°C) and at all duty cycles - a key differentiator versus competitors with current foldback. This is confirmed in the Electrical Characteristics table under "Maximum Switch Current Limit" with ● marking full-temp-range specification. At 125°C, the limit remains ≥1.5A, enabling predictable power delivery in thermally demanding environments without output current collapse.
LT1961EMS8E#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:
- 0°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-MSOP-EP
LT1961EMS8E#TRPBF FAQ
1.How can I place an order for LT1961EMS8E#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT1961EMS8E#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 LT1961EMS8E#TRPBF reliable?
The price and inventory of LT1961EMS8E#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT1961EMS8E#TRPBF is usually 5 days.
3.What payment methods are accepted for LT1961EMS8E#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT1961EMS8E#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT1961EMS8E#TRPBF?
LT1961EMS8E#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT1961EMS8E#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 LT1961EMS8E#TRPBF?
For technical support, including LT1961EMS8E#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT1961EMS8E#TRPBF requirements.
6.How does Aetrix verify that LT1961EMS8E#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT1961EMS8E#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 LT1961EMS8E#TRPBF meets industry standards.
7.What is the process for return or replacement of LT1961EMS8E#TRPBF?
All LT1961EMS8E#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT1961EMS8E#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 LT1961EMS8E#TRPBF part is unused and in its original packaging.
Return procedure for LT1961EMS8E#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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