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Analog Devices Inc. LT1946AEMS8E#TRPBF
- Part No.:
- LT1946AEMS8E#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 8-TSSOP, 8-MSOP (0.118", 3.00mm Width) Exposed Pad
- Datasheet:
-
LT1946AEMS8E#TRPBF.pdf
- Description:
- IC REG BST SEPIC ADJ 1.5A 8MSOP
- Quantity:
- Payment:
- Shipping:
Inventory:1,603
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Product details
Overview
LT1946AEMS8E#TRPBF from Analog Devices (formerly Linear Technology) is a fixed-frequency, current-mode step-up DC/DC converter IC with an integrated 1.5A/36V NPN switch, 2.7MHz switching frequency, and adjustable output up to 35V. It delivers 12V at 430mA from a 5V input and is engineered for compact TFT-LCD bias supplies requiring low-profile power solutions.
For engineers reviewing the LT1946AEMS8E#TRPBF datasheet, LT1946AEMS8E#TRPBF pinout, LT1946AEMS8E#TRPBF application, or LT1946AEMS8E#TRPBF equivalent, key selection criteria include its 2.7MHz operation enabling sub-1.1mm height designs, internal/external loop compensation flexibility, soft-start control via external capacitor, 1.25V feedback reference, and thermally enhanced 8-lead MSOP package with exposed ground pad.
Technical Context
The LT1946AEMS8E#TRPBF employs constant-frequency current-mode control with a 2.7MHz oscillator and built-in frequency foldback (reducing to 0.85MHz when FB < 0.5V) to improve 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.
Switch control integrates an SR latch, ramp generator, and PWM comparator; current limit (1.5A typical, 2.1A guaranteed) is independent of duty cycle and protects both internal switch and external components. 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.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Switch Rating | 1.5A continuous, 36V max - supports high-current boost stages without external switch |
| Switching Frequency | 2.7MHz typical - enables use of ≤2.2µH inductors and low-ESR ceramic capacitors for ultra-low profile layouts |
| Feedback Voltage | 1.25V ±2% - sets precise output voltage via resistive divider (VOUT = 1.25 × (1 + R1/R2)) |
| Quiescent Current | 5mA typical (active), 1µA max (shutdown) - balances light-load efficiency and fast wake-up response |
| Output Range | VIN to 35V - accommodates wide output requirements including TFT AVDD/VON/VOFF rails |
| Max Duty Cycle | 80% - ensures stable regulation even at high step-up ratios (e.g., 3.3V → 24V) |
| VCESAT (Switch) | 340mV max at 1A - minimizes conduction loss and thermal stress in high-current boost paths |
Pinout & Package
Package: 8-lead MSOP (MS8E) with exposed thermal pad (pin 4 and pad both grounded). Total height ≤1.1mm. Pin pitch = 0.65mm. Exposed pad must be soldered to PCB ground plane using multiple vias for thermal and electrical integrity.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VC (1) | Error amplifier output | Connects to external RC compensation network or shorted to COMP for internal compensation; controls loop dynamics and transient response |
| FB (2) | Feedback input | Senses output voltage divider; 1.25V reference sets regulation point; trace area must be minimized to reduce noise coupling |
| SHDN (3) | Shutdown control | Active-high logic: ≥2.4V enables, ≤0.5V disables; 32µA max bias current allows direct MCU GPIO drive |
| GND (4) | Power and signal ground | Primary ground return; exposed pad is electrically and thermally part of this node - mandatory connection for thermal performance |
| SW (5) | Switch collector | High-slew-rate node driving external inductor/diode; requires minimal trace area and tight layout to suppress EMI |
| VIN (6) | Input supply | 2.45V–16V operating range; requires local 2.2µF ceramic bypass placed adjacent to pin |
| COMP (7) | Internal compensation | Internally connects 120kΩ resistor and 90pF capacitor; tie to VC for internal compensation or leave open if using external network |
| SS (8) | Soft-start control | 4µA current source charges external capacitor; rise time on SS pin directly limits VC ramp and inrush current during startup |
Key Features
| Feature | Design Value |
|---|---|
| 2.7MHz fixed-frequency operation | Enables <1.1mm solution height using 2.2µH inductors and 2.2µF ceramic caps - critical for space-constrained TFT-LCD modules |
| Integrated 1.5A/36V NPN switch | Eliminates external transistor and associated gate-drive complexity while maintaining low VCESAT (340mV max) for high efficiency |
| Flexible compensation (internal or external) | Supports optimized transient response with low-ESR ceramic outputs - internal option reduces BOM count; external RC allows tuning for varied loads |
| Adjustable soft-start via external capacitor | Prevents input inrush and output overshoot by controlling VC ramp rate - capacitor value (e.g., 100nF) sets startup time (~375ms) |
| Frequency foldback during start-up | Reduces switching frequency to 0.85MHz when FB < 0.5V - lowers minimum duty cycle and improves controllability of peak switch current at light loads |
Applications
| AVDD Bias for TFT-LCD Panels | GPS Receiver Local Supply |
|---|---|
Use Scenario: Powering the analog positive supply rail (typically 8–12V, 300–500mA) of active-matrix LCD panels in portable instrumentation and medical displays. IC Role / Device Role / Timing Role: Primary step-up regulator generating stable, low-noise AVDD from a 3.3V or 5V system rail; operates in continuous conduction mode with 2.7MHz switching. Use Value: Enables <1.1mm board height due to 2.2µH inductor and ceramic capacitor compatibility - essential for slim handheld form factors. | Use Scenario: Generating clean 3.3V or 5V local supply for GPS baseband ICs and RF front-ends in automotive telematics and asset trackers. IC Role / Device Role / Timing Role: Standalone boost converter powering sensitive GNSS receivers; uses internal compensation and soft-start to minimize startup transients affecting RF lock time. Use Value: Low quiescent current (5mA) and shutdown leakage (<1µA) extend battery life; 2.7MHz operation avoids interference with GPS L1 band (1.575GHz). |
| DSL Modem Line Card Supply | Industrial Sensor Signal Chain Bias |
Use Scenario: Providing isolated ±12V or +24V bias for line driver amplifiers and data converters in DSL access multiplexers and central office equipment. IC Role / Device Role / Timing Role: Core boost controller in SEPIC or flyback-derived triple-output configurations (e.g., AVDD/VOFF/VON); leverages frequency foldback for reliable cold-start under varying line conditions. Use Value: Adjustable output (up to 35V) and 80% max duty cycle support wide input/output differentials required in telecom power architectures. | Use Scenario: Generating precision ±5V, ±10V, or +15V rails for op-amps, ADC drivers, and reference buffers in industrial process monitoring systems. IC Role / Device Role / Timing Role: Compact, thermally robust DC/DC stage mounted near signal-chain ICs; exposed-pad MSOP package dissipates heat directly into ground plane. Use Value: Tight feedback tolerance (±2%) and low output ripple (<20mVpp with ceramic caps) preserve signal integrity and SNR in high-resolution measurement systems. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar step-up DC/DC converter applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT1946EMS8#TRPBF | 1.2MHz switching frequency, same 1.5A/36V switch, identical pinout and compensation architecture | Lower frequency requires larger inductors/caps; better EMI profile but incompatible with <1.1mm height targets | Select when board area > height is the constraint and lower EMI is prioritized over profile |
| LTC3531EDD#TRPBF | 2.25MHz sync rectified boost, 1.25A switch, integrated Schottky, 2.5V–5.5V input range only | Requires external diode removed; higher efficiency at light loads; narrower VIN range limits use with 12V inputs | Select for battery-powered apps with 3.3V/5V sources where integrated diode simplifies layout and improves efficiency |
Compared with LT1946AEMS8E#TRPBF, LT1946EMS8#TRPBF trades 2.7MHz speed for lower EMI and relaxed magnetics, while LTC3531EDD#TRPBF offers synchronous rectification and integrated diode at the cost of input voltage range - making LT1946AEMS8E#TRPBF uniquely suited for ultra-low-profile, wide-input, high-current TFT bias applications.
Availability
LT1946AEMS8E#TRPBF is available at Aetrix Electronics and suitable for TFT-LCD bias supplies, GPS receiver local power, and DSL modem line card designs requiring stable component supply, long-term production continuity, and RoHS-compliant packaging.
Supply support for LT1946AEMS8E#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 design support.
The LT1946AEMS8E#TRPBF belongs to Linear's high-frequency boost converter product line, designed specifically for space-constrained applications demanding high power density, such as portable display power, telecom bias, and sensor interface supplies.
FAQ
What is the maximum output voltage achievable with the LT1946AEMS8E#TRPBF?
The LT1946AEMS8E#TRPBF supports an adjustable output voltage range from VIN up to 35V, set by the external resistive divider on the FB pin using the formula VOUT = 1.25V × (1 + R1/R2). This capability enables generation of standard TFT-LCD rails like 12V, 20V, or 24V from common 3.3V or 5V inputs. The 36V switch rating provides sufficient margin for transient spikes and layout parasitics.
Can the LT1946AEMS8E#TRPBF operate with a 3.3V input to generate 12V output?
Yes, the LT1946AEMS8E#TRPBF supports a minimum operating voltage of 2.45V and can reliably generate 12V from a 3.3V input. At this ratio, the required duty cycle remains within the device's 80% maximum limit. Efficiency remains above 75% at 300mA load per typical performance curves, and frequency foldback ensures stable start-up under low-VIN conditions.
How does the soft-start function work on the LT1946AEMS8E#TRPBF?
The LT1946AEMS8E#TRPBF implements soft-start by sourcing a precise 4µA current from the SS pin to charge an external capacitor. As the capacitor voltage rises to 1.5V, the VC pin voltage ramps proportionally, limiting peak switch current during startup. A 100nF capacitor yields ~375ms startup time. Leaving SS open disables soft-start; floating the pin is not allowed - it must be tied to GND or a capacitor.
Is external compensation required for stable operation of the LT1946AEMS8E#TRPBF?
No, external compensation is optional. The LT1946AEMS8E#TRPBF provides internal compensation via a 120kΩ resistor and 90pF capacitor accessible at the COMP pin. Shorting COMP to VC enables this network. External RC (e.g., 27.4kΩ + 270pF) is recommended for optimized transient response with low-ESR ceramic outputs, especially in high-dynamic-load applications like LCD panel gating.
What thermal considerations apply to the LT1946AEMS8E#TRPBF in continuous operation?
The LT1946AEMS8E#TRPBF has θJA = 40°C/W and θJC = 10°C/W. To maintain junction temperature ≤125°C at full 1.5A load, the exposed pad must be soldered to a solid ground plane with ≥4 thermal vias (0.3mm diameter) within 2mm of the pad. Without proper thermal relief, power dissipation >0.8W may cause thermal shutdown. Derating is advised above 70°C ambient.
LT1946AEMS8E#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, SEPIC
- 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):
- 35V
- Current - Output:
- 1.5A (Switch)
- Frequency - Switching:
- 2.7MHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- 0°C ~ 70°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-MSOP-EP
LT1946AEMS8E#TRPBF FAQ
1.How can I place an order for LT1946AEMS8E#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT1946AEMS8E#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 LT1946AEMS8E#TRPBF reliable?
The price and inventory of LT1946AEMS8E#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT1946AEMS8E#TRPBF is usually 5 days.
3.What payment methods are accepted for LT1946AEMS8E#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT1946AEMS8E#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT1946AEMS8E#TRPBF?
LT1946AEMS8E#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT1946AEMS8E#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 LT1946AEMS8E#TRPBF?
For technical support, including LT1946AEMS8E#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT1946AEMS8E#TRPBF requirements.
6.How does Aetrix verify that LT1946AEMS8E#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT1946AEMS8E#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 LT1946AEMS8E#TRPBF meets industry standards.
7.What is the process for return or replacement of LT1946AEMS8E#TRPBF?
All LT1946AEMS8E#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT1946AEMS8E#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 LT1946AEMS8E#TRPBF part is unused and in its original packaging.
Return procedure for LT1946AEMS8E#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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