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Analog Devices Inc. LT1946EMS8E#TRPBF
- Part No.:
- LT1946EMS8E#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 8-TSSOP, 8-MSOP (0.118", 3.00mm Width) Exposed Pad
- Datasheet:
-
LT1946EMS8E#TRPBF.pdf
- Description:
- IC REG BOOST ADJ 1.5A 8MSOP
- Quantity:
- Payment:
- Shipping:
Inventory:1,000
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Product details
Overview
LT1946EMS8E#TRPBF from Analog Devices (formerly Linear Technology) is a fixed-frequency, current-mode step-up DC/DC converter with an integrated 1.5A, 36V NPN switch. It delivers 8V at 430mA from a 3.3V input, features 1.2MHz switching, internal/external loop compensation, and soft-start control via external capacitor. It is designed for TFT-LCD bias supplies requiring compact, high-efficiency boost conversion.
For engineers reviewing the LT1946EMS8E#TRPBF datasheet, LT1946EMS8E#TRPBF pinout, LT1946EMS8E#TRPBF application, or LT1946EMS8E#TRPBF equivalent, key selection criteria include its 1.2MHz operation enabling small inductors/ceramics, 1.25V feedback reference, 8-lead MSOP-E package with exposed ground pad, and soft-start current of 4µA - all critical for low-profile portable power designs.
Technical Context
The LT1946EMS8E#TRPBF employs constant-frequency current-mode control with a 1.2MHz oscillator and frequency foldback (to 400kHz) when FB < 0.5V, improving start-up stability. Its error amplifier (transconductance = 40 µmhos, gain = 300 V/V) drives the VC pin to regulate peak switch current against a 1.25V reference.
Switching is managed by an internal NPN transistor with 340mV typical VCE(SAT) at 1A and 2.1A current limit (guaranteed by design). Soft-start is implemented by sourcing 4µA from the SS pin to charge an external capacitor, directly limiting VC ramp rate and thus peak switch current during startup.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Switching Frequency | 1.2 MHz (typical); enables use of ≤5.6mm × 5.2mm inductors and low-value ceramic capacitors for ultra-low profile layouts. |
| Internal Switch | 1.5A, 36V NPN; supports output voltages up to 34V and handles 430mA at 8V from 3.3V input with minimal conduction loss. |
| Feedback Reference | 1.250 V (±2% over temp); sets output voltage via R1/R2 divider (VOUT = 1.25 × (1 + R1/R2)) with 120nA max bias current. |
| Soft-Start Current | 4 µA (typical); charges external SS capacitor to 1.5V, controlling input current ramp rate and preventing inrush during startup. |
| Quiescent Current | 5 mA (typical, active); 1 µA (max, shutdown); enables efficient operation in battery-powered GPS receivers and DSL modems. |
| Operating Input Range | 2.45 V to 16 V; supports single-cell Li-ion (3.3V), dual-cell alkaline (3V), and industrial 12V rails without pre-regulation. |
| Package | 8-Lead MSOP-E with exposed ground pad (Pin 9); provides low θJA = 125°C/W (4-layer board) and mechanical robustness for high-density PCBs. |
Pinout & Package
LT1946EMS8E#TRPBF uses the 8-lead plastic MSOP-E package with an exposed ground pad (Pin 9), which must be soldered to the PCB for thermal and electrical performance. The package measures 3.00 mm × 3.00 mm × 1.10 mm (max height) and supports reflow-compatible lead-free assembly.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VC (Pin 1) | Error amplifier output | Drives compensation network; short to COMP for internal compensation or connect RC/CC externally for optimized transient response. |
| FB (Pin 2) | Feedback input | Connects to resistor divider tap; 1.25V reference sets output voltage; trace area must be minimized to reduce noise coupling. |
| SHDN (Pin 3) | Shutdown control | Logic-high ≥2.4V enables operation; grounded disables switch and reduces quiescent current to ≤1µA; must not float. |
| GND (Pin 4) | Power ground | Primary return path for switch current and IC bias; tie directly to local ground plane with multiple vias. |
| SW (Pin 5) | Switch collector | High-di/dt node connecting to inductor and diode; minimize trace area and length to suppress EMI and voltage spikes. |
| VIN (Pin 6) | Input supply | Accepts 2.45–16V; requires local 2.2µF ceramic bypass capacitor placed adjacent to pin. |
| COMP (Pin 7) | Internal compensation | Provides access to internal 120kΩ/90pF network; tie to VC for internal compensation or leave open if using external network. |
| SS (Pin 8) | Soft-start control | Sources 4µA to external capacitor; voltage ramp on SS limits VC rise rate and controls inrush current during startup. |
| Exposed Pad (Pin 9) | Thermal & electrical ground | Must be soldered to PCB ground plane; improves thermal dissipation (θJC = 10°C/W) and reduces EMI. |
Key Features
| Feature | Design Value |
|---|---|
| 1.2MHz fixed-frequency operation | Enables use of 4.7µH–10µH low-profile ferrite inductors (e.g., TDK RLF5018T-4R7M1R4) and 2.2µF–20µF X5R/X7R ceramics, reducing solution height to <1.2mm. |
| Integrated 1.5A, 36V NPN switch | Delivers 8V/430mA from 3.3V input with 340mV VCE(SAT) at 1A, eliminating external MOSFET and gate driver in space-constrained TFT-LCD bias supplies. |
| Programmable soft-start | 4µA current source into SS pin allows precise control of startup slew rate via external capacitor (10nF–200nF), preventing input rail collapse and output overshoot. |
| Flexible compensation architecture | Supports both internal (VC–COMP short) and external (RC/CC from COMP to GND) loop compensation, enabling stable regulation with low-ESR ceramic outputs. |
| Frequency foldback during start-up | Reduces switching frequency to 400kHz when FB < 0.5V, lowering minimum duty cycle and improving controllability of peak switch current during output voltage ramp. |
Applications
| TFT-LCD Panel Bias Supply | GPS Receiver Local Power |
|---|---|
|
Use Scenario: Generating AVDD (+8V), VON (+23V), and VOFF (–8V) for large-format TFT-LCD panels in automotive infotainment systems. IC Role / Device Role / Timing Role: Primary boost controller providing regulated positive and negative bias rails from a 3.3V system rail. Use Value: Achieves 85% efficiency at 375mA AVDD load (VIN = 3.3V) while maintaining <1.2mm solution height via 1.2MHz operation and MSOP-E package. |
Use Scenario: Powering RF front-end and baseband ICs in handheld GPS modules where input is a single Li-ion cell (3.0–4.2V). IC Role / Device Role / Timing Role: Step-up regulator generating stable 3.3V or 5V rail for sensitive GNSS receivers requiring low-noise, fast-transient response. Use Value: Delivers 430mA at 8V with 1.25V reference accuracy (±2%) and soft-start control, ensuring clean power-up without disrupting satellite signal acquisition. |
| DSL Modem Line Driver Supply | Industrial Local Power Supply |
|
Use Scenario: Providing isolated ±12V rails for line driver amplifiers in ADSL/VDSL customer premises equipment. IC Role / Device Role / Timing Role: High-voltage boost stage feeding charge-pump or transformer-isolated secondary stages. Use Value: Supports output voltages up to 34V with 36V switch rating and 86% max duty cycle, enabling direct generation of 12V+ rails without cascaded conversion. |
Use Scenario: Generating auxiliary 12V or 15V rails from 5V or 3.3V backplane supplies in programmable logic controllers and sensor nodes. IC Role / Device Role / Timing Role: Compact, self-contained DC/DC converter replacing discrete boost circuits in space-limited industrial modules. Use Value: Integrates 1.5A switch, error amp, oscillator, and soft-start in an 8-lead MSOP-E package, reducing BOM count by ≥4 components versus discrete solutions. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar boost converter applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT1946AEMS8E#TRPBF | 2.7MHz switching frequency, same 8-lead MSOP-E package, identical pinout; higher frequency enables smaller inductors but increases switching losses above 300mA. | Better suited for ultra-compact designs needing <2.2µH inductors; less optimal for high-current (>350mA), high-efficiency TFT-LCD bias where 1.2MHz offers superior efficiency. | Select LT1946AEMS8E#TRPBF only when board area is more critical than full-load efficiency; verify thermal performance at 430mA due to higher fSW. |
| LT1930AIMS5#TRMPBF | 5-lead ThinSOT package, 1.2MHz, 1A switch, no soft-start or frequency foldback; lacks VC/COMP/SS pins and requires external compensation. | Targeted at cost-sensitive, lower-current (≤300mA) applications like sensors or wearables; unsuitable for demanding TFT-LCD or GPS start-up sequences. | Choose LT1930AIMS5#TRMPBF only for simple, low-power boost needs where soft-start, flexible compensation, and 1.5A capability are unnecessary. |
Compared with LT1946EMS8E#TRPBF, the LT1946A variant trades efficiency for size reduction via higher frequency, while the LT1930 offers lower integration and current capability in a smaller footprint - making LT1946EMS8E#TRPBF the optimal balance of performance, feature set, and thermal management for mid-power portable boost applications.
Availability
LT1946EMS8E#TRPBF is available at Aetrix Electronics and suitable for TFT-LCD bias supplies, GPS receiver power rails, and DSL modem line drivers requiring stable component supply, long-term lifecycle support, and RoHS-compliant lead-free packaging.
Supply support for LT1946EMS8E#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 its precision analog and power management portfolio. Linear pioneered high-performance DC/DC converters for portable and industrial applications.
The LT1946EMS8E#TRPBF belongs to Linear's high-frequency boost converter product line, engineered specifically for space-constrained, high-efficiency applications such as TFT-LCD panel biasing and portable RF subsystems.
FAQ
What is the maximum output voltage achievable with the LT1946EMS8E#TRPBF?
The LT1946EMS8E#TRPBF supports output voltages up to 34V, as confirmed by its 36V-rated internal NPN switch and absolute maximum SW pin rating of 36V. This capability is demonstrated in typical applications delivering 23V (VON) and 12V outputs, with proper selection of external diode (e.g., Microsemi UPS140 for >20V differential) and output capacitor voltage rating.
Does the LT1946EMS8E#TRPBF require external compensation components?
The LT1946EMS8E#TRPBF supports both internal and external compensation. Internal compensation is enabled by shorting VC to COMP; external compensation uses a resistor-capacitor network from COMP to GND (e.g., 49.9kΩ + 470pF). The choice depends on transient response requirements - external networks allow optimization for specific output capacitor ESR and load dynamics.
How does the soft-start function operate on the LT1946EMS8E#TRPBF?
The LT1946EMS8E#TRPBF sources a precise 4µA current from the SS pin to charge an external capacitor. When the SS voltage reaches 1.5V, soft-start completes and full regulation begins. This linear ramp on SS directly limits the VC pin voltage rise rate, thereby controlling peak switch current and preventing input inrush - critical for battery-powered GPS receivers.
What is the purpose of the exposed pad (Pin 9) on the LT1946EMS8E#TRPBF?
The exposed pad (Pin 9) on the LT1946EMS8E#TRPBF is electrically and thermally connected to ground. It must be soldered to the PCB ground plane to achieve specified thermal performance (θJA = 125°C/W on 4-layer board) and reduce EMI. Leaving it unconnected degrades efficiency, increases junction temperature, and risks reliability failure under sustained 430mA loads.
Can the LT1946EMS8E#TRPBF be used in SEPIC topology?
Yes, the LT1946EMS8E#TRPBF can be configured in SEPIC topology, as noted in its application notes. Its current-mode control, 1.5A switch, and wide input range (2.45V–16V) support buck-boost operation. However, external components (two inductors, additional capacitor) and compensation must be carefully selected - the datasheet recommends inductor current ratings ≥1.5A and low-DCR ferrite cores for optimal efficiency.
LT1946EMS8E#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
- Output Configuration:
- Positive
- Topology:
- Boost
- Output Type:
- Adjustable
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 2.45V
- Voltage - Input (Max):
- 16V
- Voltage - Output (Min/Fixed):
- 2.45V
- Voltage - Output (Max):
- 34V
- Current - Output:
- 1.5A (Switch)
- Frequency - Switching:
- 1.2MHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- 0°C ~ 70°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-MSOP-EP
LT1946EMS8E#TRPBF FAQ
1.How can I place an order for LT1946EMS8E#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT1946EMS8E#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 LT1946EMS8E#TRPBF reliable?
The price and inventory of LT1946EMS8E#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT1946EMS8E#TRPBF is usually 5 days.
3.What payment methods are accepted for LT1946EMS8E#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT1946EMS8E#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT1946EMS8E#TRPBF?
LT1946EMS8E#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT1946EMS8E#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 LT1946EMS8E#TRPBF?
For technical support, including LT1946EMS8E#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT1946EMS8E#TRPBF requirements.
6.How does Aetrix verify that LT1946EMS8E#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT1946EMS8E#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 LT1946EMS8E#TRPBF meets industry standards.
7.What is the process for return or replacement of LT1946EMS8E#TRPBF?
All LT1946EMS8E#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT1946EMS8E#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 LT1946EMS8E#TRPBF part is unused and in its original packaging.
Return procedure for LT1946EMS8E#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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