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Analog Devices Inc. LT1949EMS8#PBF
- Part No.:
- LT1949EMS8#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 8-TSSOP, 8-MSOP (0.118", 3.00mm Width)
- Datasheet:
-
LT1949EMS8#PBF.pdf
- Description:
- IC REG BST SEPIC ADJ 1A 8MSOP
- Quantity:
- Payment:
- Shipping:
Inventory:737
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Product details
Overview
LT1949EMS8#PBF from Analog Devices (formerly Linear Technology) is a fixed-frequency, current-mode step-up DC/DC converter with an integrated 1A NPN switch (0.5Ω typical RCE(SAT)), designed for bias voltage generation in LCD panels and portable systems. It operates from 1.5V to 12V input, delivers up to 10V at 175mA from 3.3V input, and features 600kHz switching, 1.24V feedback reference, and active low-battery detection during shutdown.
For engineers reviewing the LT1949EMS8#PBF datasheet, LT1949EMS8#PBF pinout, LT1949EMS8#PBF application, or LT1949EMS8#PBF equivalent, key selection considerations include its 1A internal switch rating, 30V switch voltage capability, external compensation flexibility via VC pin, low 25µA shutdown quiescent current, and compatibility with ceramic output capacitors.
Technical Context
The LT1949EMS8#PBF implements current-mode control with a 600kHz oscillator and integrated ramp generator to suppress subharmonic oscillation above 50% duty cycle. Its error amplifier drives the VC pin to regulate output via an external RC network, enabling stable loop compensation with low-ESR ceramic capacitors.
It integrates a dedicated low-battery detector with 200mV ±5% internal reference, LBI input, and open-collector LBO output that remains functional in shutdown mode. The SHDN pin supports logic-level enable/disable with 1.4V high threshold and 0.4V low threshold.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Switch Type | Integrated 1A NPN transistor with 0.5Ω typical RCE(SAT), rated for 30V VSW max - enables boost topologies up to 28V output using single inductor. |
| Switching Frequency | Fixed 600kHz (500–750kHz range) - ensures predictable EMI profile and allows compact LC filter design with small inductors/ceramics. |
| Feedback Reference | 1.24V ±20mV over temperature - sets output voltage via resistor divider (VOUT = 1.24V × (1 + R1/R2)), enabling precise regulation across load/line variations. |
| Input Voltage Range | 1.5V to 12V - supports single-cell Li-ion (2.7–4.2V), 3.3V logic rails, and multi-cell battery inputs without external regulators. |
| Shutdown Quiescent Current | 25µA typical - preserves battery life in standby while maintaining low-battery monitoring functionality. |
| Low-Battery Threshold | 200mV ±10mV reference at LBI pin - allows configurable trip point for system brownout detection independent of main regulator operation. |
| Package | 8-lead MSOP (MS8) - 3mm × 3mm footprint with exposed pad option, optimized for thermal performance in space-constrained portable designs. |
Pinout & Package
LT1949EMS8#PBF is housed in an 8-lead plastic MSOP (MS8) package with exposed thermal pad, measuring 3.0mm × 3.0mm × 0.86mm, rated for –40°C to +85°C operating temperature and θJA = 120°C/W.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VC (Pin 1) | Compensation node for error amplifier | Connect external RC network (e.g., 68kΩ/330pF) to ground; directly controls loop stability and transient response with ceramic output caps. |
| FB (Pin 2) | Feedback input | Monitors output via resistor divider; 1.24V reference sets regulation point; low 12nA bias current minimizes divider error. |
| SHDN (Pin 3) | Logic-level shutdown enable | Pull ≤0.4V to disable switching (25µA IQ remains); tie ≥1.4V or float to enable; no external pull-up required. |
| GND (Pin 4) | Power and signal ground | Primary return path for switch current and analog circuitry; must connect directly to local ground plane with minimal impedance. |
| SW (Pin 5) | Switch collector node | Drives external inductor/diode; high dI/dt requires short, wide trace routing to minimize EMI and voltage spikes. |
| VIN (Pin 6) | Main power input | Accepts 1.5–12V; requires local 22µF ceramic bypass capacitor placed within 5mm to suppress supply ripple and ensure startup reliability. |
| LBI (Pin 7) | Low-battery detector input | High-impedance input referenced to 200mV; accepts 0–700mV; bias current flows out (5–60nA), enabling resistor-divider-based battery monitoring. |
| LBO (Pin 8) | Low-battery open-collector output | Sinks up to 10µA; requires external 1MΩ pull-up to host rail; asserts low when LBI < 200mV - remains active in shutdown. |
Key Features
| Feature | Design Value |
|---|---|
| Internal 1A NPN switch with 410mV VCE(SAT) at 800mA | Reduces conduction loss and heat rise in compact boost converters; eliminates need for external MOSFET and gate driver. |
| Active low-battery detector during shutdown | Enables continuous battery health monitoring without waking main regulator - critical for long-term portable device autonomy. |
| External compensation via VC pin | Permits optimization of phase margin and transient response for diverse output capacitor types (e.g., X5R, X7R, NP0) and values. |
| 600kHz fixed-frequency PWM operation | Ensures consistent EMI signature and simplifies filtering; avoids frequency jitter issues seen in hysteretic or variable-frequency controllers. |
| 1.24V precision feedback reference | Supports tight output tolerance (±1.6%) across temperature and line/load conditions - essential for stable LCD VPOS/VNEG rails. |
Applications
| Large-Screen LCD Bias Supply | GPS Receiver Power Management |
|---|---|
|
Use Scenario: Generating +10V and –8V bias rails for TFT-LCD source/gate drivers in handheld displays. IC Role / Device Role / Timing Role: Primary step-up controller for positive VPOS; paired with inverting charge pump or second LT1949 for negative rail. Use Value: Delivers 175mA at 10V from 3.3V input with <50mV load regulation, enabling sharp contrast and fast pixel response without audible coil whine. |
Use Scenario: Providing regulated 5V supply to GPS baseband IC and RF front-end from single Li-ion cell (3.0–4.2V). IC Role / Device Role / Timing Role: High-efficiency boost converter with low-noise 600kHz switching, minimizing interference with 1.575GHz GPS band. Use Value: Achieves >82% efficiency at 250mA load across input range, reducing thermal load in sealed GPS modules while maintaining RF sensitivity. |
| Battery-Backed Diagnostic Instrumentation | Portable Medical Sensor Interface |
|
Use Scenario: Maintaining real-time clock and SRAM backup during main power failure in portable ECG monitors. IC Role / Device Role / Timing Role: Always-on bias generator powered from coin cell or supercapacitor; leverages LBO to trigger firmware save before brownout. Use Value: 25µA shutdown IQ and active LBI/LBO allow >1-year coin-cell lifetime while providing deterministic low-voltage warning at 2.8V system threshold. |
Use Scenario: Powering low-noise analog front-end (AFE) and ADC in handheld pulse oximeters operating from AAA alkaline cells. IC Role / Device Role / Timing Role: Step-up regulator delivering clean 3.3V from declining 1.0–1.5V per cell; VC pin tuned for low-output-ripple under dynamic LED drive loads. Use Value: 410mV VCE(SAT) and ceramic-compatible compensation reduce output noise to <2mVPP, preserving AFE SNR during SpO2 acquisition. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar boost converter applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT1317BEMS8#PBF | Same 8-lead MSOP package and pinout; lower 600mA switch current; 1.5V min VIN; 500kHz nominal frequency. | Targeted at lower-power 3.3V/200mA outputs; lacks LBI/LBO pins and low-battery monitoring. | Select LT1317BEMS8#PBF only if output current ≤150mA and battery monitoring is handled externally. |
| LTC3400EDD#TRPBF | 2A switch, 1.5MHz switching, integrated soft-start; different pinout (10-lead DFN); no LBI/LBO; higher IQ (25µA vs 4.5mA op). | Optimized for ultra-compact, high-efficiency 5V USB-powered devices; requires PCB redesign due to non-pin-compatible layout. | Choose LTC3400EDD#TRPBF when board space is constrained and 2A peak current or faster transient response is required. |
Compared with LT1317BEMS8#PBF, the LT1949EMS8#PBF provides higher output current and integrated battery monitoring; versus LTC3400EDD#TRPBF, it offers pin compatibility with legacy Linear designs and simpler compensation but trades off switching frequency and peak current capability.
Availability
LT1949EMS8#PBF is available at Aetrix Electronics and suitable for large-screen LCD bias supplies, GPS receiver power management, and battery-backed diagnostic instrumentation requiring stable component supply, long-lifecycle support, and guaranteed parametric compliance.
Supply support for LT1949EMS8#PBF 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 legacy Linear power products including the LT1949 series.
The LT1949EMS8#PBF belongs to Linear's high-efficiency, micropower DC/DC converter product line, engineered specifically for portable and battery-operated systems demanding reliable voltage boosting with integrated protection and monitoring features.
FAQ
What is the minimum input voltage required for LT1949EMS8#PBF to start switching?
The LT1949EMS8#PBF can initiate switching with as little as 1.5V on VIN, verified across temperature and process corners. This enables operation directly from partially discharged single-cell Li-ion or NiMH batteries. Startup behavior is guaranteed down to 1.7V per Electrical Characteristics table, and the device sustains regulation down to 1.5V under light loads. Below 1.5V, the internal bandgap and oscillator may not function reliably.
Does LT1949EMS8#PBF support ceramic output capacitors, and what compensation is recommended?
Yes, the LT1949EMS8#PBF is explicitly designed for ceramic output capacitors. The datasheet specifies a 68kΩ resistor and 330pF capacitor in series from VC (Pin 1) to ground as the standard compensation network for ceramic COUT. This configuration stabilizes the current-mode loop and ensures adequate phase margin with low-ESR ceramics like X5R or X7R MLCCs, eliminating the need for high-ESR tantalum or aluminum electrolytics.
How does the low-battery detector in LT1949EMS8#PBF operate during shutdown mode?
The low-battery detector in the LT1949EMS8#PBF remains fully operational during shutdown: the 200mV internal reference, LBI comparator, and open-collector LBO output continue functioning with only 25µA total supply current. When SHDN is pulled low, the main switch disables, but LBO will sink current if the voltage at LBI falls below 200mV - allowing host microcontrollers to monitor battery state without waking the main power rail.
What is the maximum achievable output voltage using LT1949EMS8#PBF, and what limits it?
The LT1949EMS8#PBF supports output voltages up to 28V, limited by its 30V absolute maximum SW pin voltage rating. This is achieved using a single inductor in boost topology with appropriate external diode (e.g., MBRM120LT3) and output capacitor rated ≥35V. Output accuracy degrades above 15V due to FB pin bias current error and resistor divider tolerance; for 28V designs, use 1% metal-film resistors and verify regulation under worst-case load and temperature.
Is LT1949EMS8#PBF pin-compatible with other Linear boost converters, and which ones?
Yes, the LT1949EMS8#PBF is pin-for-pin compatible with the LT1317B series (e.g., LT1317BEMS8#PBF) in the 8-lead MSOP package, sharing identical pin assignments for VIN, SW, FB, GND, SHDN, VC, LBI, and LBO. However, LT1317B lacks LBI/LBO functionality and has a lower 600mA switch rating. No compatibility exists with SO-8 variants (LT1949ES8) due to differing pin 1–4 mapping.
LT1949EMS8#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 8-TSSOP, 8-MSOP (0.118", 3.00mm Width)
- Packaging:
- Tube
- 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):
- 1.7V
- Voltage - Input (Max):
- 12V
- Voltage - Output (Min/Fixed):
- 1.7V
- Voltage - Output (Max):
- 28V
- Current - Output:
- 1A (Switch)
- Frequency - Switching:
- 600kHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- 0°C ~ 70°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-MSOP
LT1949EMS8#PBF FAQ
1.How can I place an order for LT1949EMS8#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT1949EMS8#PBF 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 LT1949EMS8#PBF reliable?
The price and inventory of LT1949EMS8#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT1949EMS8#PBF is usually 5 days.
3.What payment methods are accepted for LT1949EMS8#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT1949EMS8#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT1949EMS8#PBF?
LT1949EMS8#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT1949EMS8#PBF 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 LT1949EMS8#PBF?
For technical support, including LT1949EMS8#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT1949EMS8#PBF requirements.
6.How does Aetrix verify that LT1949EMS8#PBF is sourced from the original manufacturer or authorized distributors?
All LT1949EMS8#PBF 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 LT1949EMS8#PBF meets industry standards.
7.What is the process for return or replacement of LT1949EMS8#PBF?
All LT1949EMS8#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT1949EMS8#PBF, 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 LT1949EMS8#PBF part is unused and in its original packaging.
Return procedure for LT1949EMS8#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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