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Analog Devices Inc. LT1946EMS8#TRPBF
- Part No.:
- LT1946EMS8#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 8-TSSOP, 8-MSOP (0.118", 3.00mm Width)
- Datasheet:
-
LT1946EMS8#TRPBF.pdf
- Description:
- IC REG BOOST ADJ 1.5A 8MSOP
- Quantity:
- Payment:
- Shipping:
Inventory:2,470
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Product details
Overview
LT1946EMS8#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 programmable soft-start via external capacitor. It is engineered for TFT-LCD bias supplies requiring compact, high-efficiency boost conversion.
For engineers reviewing the LT1946EMS8#TRPBF datasheet, LT1946EMS8#TRPBF pinout, LT1946EMS8#TRPBF application, or LT1946EMS8#TRPBF equivalent, key selection considerations include its 1.25V feedback reference, 1.2MHz constant-frequency operation, 8-lead MSOP package, soft-start control via SS pin, and compatibility with low-ESR ceramic output capacitors in space-constrained portable power designs.
Technical Context
The LT1946EMS8#TRPBF employs a constant-frequency current-mode control architecture with a 1.2MHz oscillator and frequency foldback (to 400kHz) when FB < 0.5V, improving startup stability. Its error amplifier (transconductance = 40 µmhos, gain = 300 V/V) drives the VC pin to regulate peak switch current, while the internal 120kΩ resistor and 90pF capacitor on the COMP pin enable simplified internal compensation.
Switch current limiting is fixed at 1.5A (typ), independent of duty cycle, with VCE(SAT) = 240 mV (typ) at 1A. Soft-start is implemented by sourcing 4µA from the SS pin to charge an external capacitor, directly controlling VC ramp rate and thus limiting inrush current during startup.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Switching Frequency | 1.2 MHz (typ); enables use of small 4.7–10 µH inductors and low-value ceramic capacitors for ultra-low-profile layouts. |
| Internal Switch Rating | 1.5A continuous, 36V breakdown; supports output voltages up to 34V with robust overcurrent protection. |
| Feedback Reference Voltage | 1.250 V (±20 mV over temp); sets output voltage via external R1/R2 divider: VOUT = 1.25(1 + R1/R2). |
| Soft-Start Control | 4 µA constant current source on SS pin; start-up slew rate determined by external capacitor value (e.g., 100 nF → ~375 ms to 1.5 V). |
| Quiescent Current | 5 mA (typ) active, 1 µA (max) shutdown; minimizes battery drain in always-on or low-power standby modes. |
| Operating Input Range | 2.45 V to 16 V; supports single-cell Li-ion (3.0–4.2 V), 3.3 V logic rails, and multi-cell alkaline/NiMH inputs. |
| Output Voltage Range | Up to 34 V; configurable via feedback resistors - demonstrated at 8 V (430 mA), 12 V (275 mA), and 23 V (5 mA) in reference designs. |
Pinout & Package
LT1946EMS8#TRPBF is housed in an 8-lead plastic MSOP (MS8) package, 3.0 mm × 3.0 mm × 1.1 mm, with standard lead pitch of 0.65 mm and exposed pad not present (distinct from MS8E variant). The package is RoHS-compliant and lead-free (#PBF suffix).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VC (Pin 1) | Error amplifier output | Drives compensation network; connects to external RC or shorted to COMP for internal compensation. |
| FB (Pin 2) | Feedback input | Senses output via resistive divider; 1.25 V reference sets regulation point; trace area must be minimized to reduce noise coupling. |
| SHDN (Pin 3) | Enable/disable control | Active-high logic: ≥2.4 V enables, ≤0.5 V shuts down; must not be left floating; draws ≤32 µA when enabled. |
| GND (Pin 4) | Analog/digital ground | Primary return path; requires low-inductance connection to local ground plane with multiple vias. |
| SW (Pin 5) | Switch collector node | Connects to inductor and Schottky diode anode; high dI/dt node - minimize trace area to reduce EMI. |
| VIN (Pin 6) | Input supply | Accepts 2.45–16 V; requires local 2.2–4.7 µF ceramic bypass capacitor placed adjacent to pin. |
| COMP (Pin 7) | Internal compensation access | Provides internal 120 kΩ/90 pF network; tie to VC for internal compensation or leave open for external RC network. |
| SS (Pin 8) | Soft-start timing | Sources 4 µA to external capacitor; voltage ramp on SS controls VC ramp and limits inrush current during startup. |
Key Features
| Feature | Design Value |
|---|---|
| Integrated 1.5A, 36V NPN switch | Eliminates external transistor and drive circuitry; reduces BOM count and layout complexity in boost topologies. |
| 1.2MHz fixed-frequency operation | Enables sub-2 mm profile solutions using 4.7 µH ferrite inductors (e.g., TDK RLF5018T-4R7M1R4) and 10–20 µF ceramic outputs. |
| Programmable soft-start via SS pin | Prevents input voltage droop and output overshoot during power-up; avoids stress on input source and downstream loads. |
| Flexible compensation (internal or external) | Internal network (120 kΩ/90 pF) simplifies design; external RC allows optimization for transient response with low-ESR ceramics. |
| Frequency foldback at light load | Reduces switching frequency to 400 kHz when FB < 0.5 V, improving light-load efficiency and enabling controlled startup under weak input sources. |
Applications
| TFT-LCD Panel Bias Supply | GPS Receiver Local Power Rail |
|---|---|
|
Use Scenario: Generating +8 V, –8 V, and +23 V bias rails for active-matrix LCD displays in handheld navigation devices. IC Role / Device Role / Timing Role: Primary boost controller delivering regulated AVDD (8 V/375 mA) and VON (23 V/5 mA) from 3.3 V system rail. Use Value: Achieves full-rail efficiency >85% at 375 mA and maintains stable output during rapid load transients typical of display gate driver switching. |
Use Scenario: Providing isolated 3.3 V-to-5 V local supply for GPS baseband ICs and RF front-end components. IC Role / Device Role / Timing Role: Compact, low-noise boost stage powering sensitive analog sections where EMI and ripple must be tightly controlled. Use Value: Delivers 5 V at 200 mA with <20 mVPP ripple using X5R ceramic caps and optimized layout per Figure 6 - critical for GNSS signal integrity. |
| DSL Modem Line Driver Supply | Portable Medical Sensor Local Boost |
|
Use Scenario: Generating 12 V at 275 mA for DSL line driver amplifiers operating from 3.3 V or 5 V system bus. IC Role / Device Role / Timing Role: High-current, fast-transient boost regulator supporting burst-mode line signaling with minimal dropout. Use Value: Maintains regulation under 100 mA → 275 mA load steps with <5% output deviation and <200 µs recovery - verified in TA02 reference design. |
Use Scenario: Powering 5 V analog front-end (AFE) and ADC stages in battery-operated patient monitors and wearable biosensors. IC Role / Device Role / Timing Role: Low-quiescent, shutdown-capable boost converter enabling long battery life and instant wake-up capability. Use Value: Draws only 1 µA in shutdown and starts cleanly via SS pin - avoids sensor initialization faults caused by uncontrolled voltage ramp. |
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 | 2.7 MHz switching, MS8E package with exposed thermal pad, higher quiescent current (6.5 mA typ), same 1.5A switch. | Better suited for ultra-compact designs needing enhanced thermal performance; requires PCB land pattern with soldered exposed pad. | Select LT1946AEMS8E#TRPBF only if board space is constrained below 1.2 mm height and thermal dissipation exceeds 0.5 W. |
| LT1930AIMS5#TRPBF | 5-lead ThinSOT, 1.2 MHz, 1 A switch, no soft-start or frequency foldback, lower IQ (40 µA), no COMP/VC pins. | Targeted at cost-sensitive, low-current (<300 mA) applications where simplicity and minimal footprint outweigh advanced control features. | Choose LT1930AIMS5#TRPBF for fixed 12 V/300 mA outputs where soft-start and precise transient response are non-critical. |
Compared with LT1946EMS8#TRPBF, the LT1946AEMS8E#TRPBF trades higher switching frequency and thermal headroom for increased complexity and layout constraints, while the LT1930AIMS5#TRPBF sacrifices control flexibility and current capability for extreme miniaturization and lower static power - making LT1946EMS8#TRPBF optimal for mid-power, feature-rich boost applications.
Availability
LT1946EMS8#TRPBF is available at Aetrix Electronics and suitable for TFT-LCD bias supplies, GPS receiver power rails, DSL modem line drivers, portable medical sensors, and industrial HMI displays requiring stable component supply, long-term lifecycle support, and consistent parametric performance across temperature.
Supply support for LT1946EMS8#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. Linear was founded to deliver high-performance analog ICs with exceptional reliability and precision.
The LT1946EMS8#TRPBF belongs to Linear's high-efficiency DC/DC converter product line, designed specifically for portable and space-constrained systems requiring regulated high-voltage bias from low-input rails - especially in display, communications, and sensing applications.
FAQ
What is the maximum output voltage achievable with the LT1946EMS8#TRPBF?
The LT1946EMS8#TRPBF supports output voltages up to 34 V, as confirmed by Absolute Maximum Ratings and Typical Performance Characteristics. This is achieved using an external resistive feedback divider (e.g., R1 = 28.7 kΩ, R2 = 5.23 kΩ yields 23 V), with proper selection of Schottky diode (e.g., Microsemi UPS140 for >20 V differential) and output capacitor voltage rating.
Does the LT1946EMS8#TRPBF require external compensation components?
The LT1946EMS8#TRPBF supports both internal and external compensation. Internal compensation is enabled by shorting the VC pin to the COMP pin, leveraging the built-in 120 kΩ resistor and 90 pF capacitor. External compensation uses a series RC network from COMP to GND (e.g., 49.9 kΩ and 470 pF), allowing optimization for specific output capacitor ESR and transient response requirements.
Can the LT1946EMS8#TRPBF operate from a 2.5 V input?
No - the LT1946EMS8#TRPBF has a minimum operating input voltage of 2.45 V (typ), but guaranteed operation begins at 2.6 V per Electrical Characteristics table. At 2.5 V, startup may fail or regulation may be unstable, especially under load. For true 2.5 V operation, consider the LT1944-1 or LT1945, which specify 1.2 V minimum input.
What is the purpose of the SS pin on the LT1946EMS8#TRPBF?
The SS (Soft-Start) pin on the LT1946EMS8#TRPBF sources a precise 4 µA current to charge an external capacitor, controlling the ramp rate of the VC pin voltage. This linearly limits peak switch current during startup, preventing input current surges, output overshoot, and stress on input capacitors and the switch itself - critical for battery-powered and low-impedance source applications.
Is the LT1946EMS8#TRPBF pin-compatible with the LT1946AEMS8E#TRPBF?
No - the LT1946EMS8#TRPBF uses an 8-lead MSOP (MS8) package without an exposed pad, while the LT1946AEMS8E#TRPBF uses an 8-lead MSOP with exposed pad (MS8E, Pin 9 = GND). Their pinouts differ: MS8E adds thermal pad connectivity and reassigns mechanical dimensions; PCB layout and thermal design are not interchangeable.
LT1946EMS8#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 8-TSSOP, 8-MSOP (0.118", 3.00mm Width)
- 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
LT1946EMS8#TRPBF FAQ
1.How can I place an order for LT1946EMS8#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT1946EMS8#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 LT1946EMS8#TRPBF reliable?
The price and inventory of LT1946EMS8#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT1946EMS8#TRPBF is usually 5 days.
3.What payment methods are accepted for LT1946EMS8#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT1946EMS8#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT1946EMS8#TRPBF?
LT1946EMS8#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT1946EMS8#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 LT1946EMS8#TRPBF?
For technical support, including LT1946EMS8#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT1946EMS8#TRPBF requirements.
6.How does Aetrix verify that LT1946EMS8#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT1946EMS8#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 LT1946EMS8#TRPBF meets industry standards.
7.What is the process for return or replacement of LT1946EMS8#TRPBF?
All LT1946EMS8#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT1946EMS8#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 LT1946EMS8#TRPBF part is unused and in its original packaging.
Return procedure for LT1946EMS8#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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