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Analog Devices Inc. LT1308BCF#TR
- Part No.:
- LT1308BCF#TR
- Manufacturer:
- Analog Devices Inc.
- Package:
- 14-TSSOP (0.173", 4.40mm Width)
- Datasheet:
-
LT1308BCF#TR.pdf
- Description:
- IC REG BST SEPIC ADJ 2A 14TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:1,332
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Product details
Overview
LT1308BCF#TR from Analog Devices (formerly Linear Technology) is a micropower, fixed-frequency 600kHz step-up DC/DC converter optimized for single-cell Li-ion and multi-cell NiCd/NiMH battery inputs. It delivers up to 1A at 5V from 1.1V–10V input, features 2.5mA quiescent current in continuous switching mode, 36V switch rating, and ±2% 200mV low-battery reference - used in digital cameras and handheld computers requiring stable high-efficiency boost conversion.
For engineers reviewing the LT1308BCF#TR datasheet, LT1308BCF#TR pinout, LT1308BCF#TR application, or LT1308BCF#TR equivalent, this page provides verified technical context, package mapping, real-world efficiency curves, confirmed alternative parts with functional differences, and layout-critical pin functions - all specific to the TSSOP-14 Commercial-grade variant.
Technical Context
The LT1308BCF#TR implements a current-mode PWM architecture with fixed 600kHz switching frequency and no Burst Mode operation - unlike the LT1308A, it maintains continuous switching even at light loads. Its error amplifier uses external VC-pin compensation (47kΩ + 100pF typical), and the internal 0.03Ω switch achieves 290mV VCE(SAT) at 2A and 25°C.
It integrates a precision low-battery detector with 200mV ±2% reference (over temperature), open-collector LBO output sinking 50μA, and independent SHDN pin operable from 1V–10V - eliminating need for VIN tie. The TSSOP-14 package features four GND pins (4–7), three SW pins (8–10), and dual VIN pins (11–12) for low-impedance power routing.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Switching Frequency | 600kHz fixed - enables compact magnetics and EMI filtering above audio band. |
| Input Voltage Range | 1.1V to 10V - supports single Li-ion (2.7–4.2V), 3×NiCd (3.6V), or 4×NiCd (4.8V) without external regulation. |
| Output Voltage Range | Up to 34V - achieved via external resistor divider on FB pin (1.22V reference). |
| Quiescent Current | 2.5mA during switching - ensures predictable light-load efficiency without Burst Mode ripple. |
| Switch VCE(SAT) | 290mV at 2A, 25°C - minimizes conduction loss in high-current boost stages. |
| Low-Battery Reference | 200mV ±2% over temperature - enables accurate battery monitoring with <±4mV absolute threshold error. |
| Shutdown Current | 1μA max - preserves battery life during system sleep states. |
Pinout & Package
LT1308BCF#TR is housed in a 14-lead plastic TSSOP package (0°C to 70°C operating range), with exposed pad thermal enhancement. Pin assignments are validated per Linear Technology's official pin configuration diagram and block diagram for the TSSOP variant.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VC (Pin 1) | Compensation node for error amplifier | Connects to series RC (e.g., 47kΩ + 100pF) to ground - sets loop stability; trace area must be minimized to reduce noise coupling. |
| FB (Pin 2) | Feedback input referenced to 1.22V | Resistive divider output connects here; determines regulated VOUT = 1.22V × (1 + R1/R2); sensitive node requiring short, shielded trace. |
| SHDN (Pin 3) | Enable/disable control | Active-high: ≥1V enables converter; 0V disables; floats to disable - no VIN tie required, simplifying power sequencing. |
| GND (Pins 4–7) | Power and signal ground | All four pins must be connected together at the package and tied to local ground plane - serves as primary heat sink in TSSOP. |
| SW (Pins 8–10) | Power switch output | Three paralleled pins carry high di/dt switching current; must be joined at package and routed with minimal loop area to suppress EMI. |
| VIN (Pins 11–12) | Main supply input | Dual pins reduce IR drop and improve transient response; requires local ceramic bypass capacitor placed ≤5mm away. |
| LBI (Pin 13) | Low-battery detector input | Accepts voltage from resistive divider across battery; operates within –100mV to 1V; bias current flows out (33nA typ). |
| LBO (Pin 14) | Low-battery open-collector output | Sinks 50μA when LBI < 200mV; requires external pull-up (e.g., 220kΩ); high-impedance when SHDN = 0V. |
Key Features
| Feature | Design Value |
|---|---|
| Continuous switching at light loads | Eliminates low-frequency output ripple inherent in Burst Mode - critical for noise-sensitive analog or RF circuits. |
| 36V-rated internal switch | Supports >30V outputs (e.g., LCD bias, white LED strings) without external FET - reduces BOM count and board space. |
| Independent 1V–10V SHDN pin | Enables flexible power sequencing with microcontroller GPIO or dedicated supervisor IC - no dependency on VIN rail. |
| Four-GND-pin thermal design | PCB copper connected to Pins 4–7 acts as integrated heatsink - achieves θJA = 80°C/W in TSSOP, enabling 1A continuous operation. |
| ±2% low-battery reference accuracy | Reduces false low-battery triggers in portable systems - allows tighter battery utilization without premature shutdown. |
Applications
| Digital Cameras | LCD Bias Supplies |
|---|---|
Use Scenario: Boosting single Li-ion cell (3.0–4.2V) to 5V for image sensor and processor rails while maintaining low-noise operation. IC Role / Device Role / Timing Role: Primary step-up regulator delivering up to 1A with continuous switching to avoid Burst Mode ripple corrupting image data. Use Value: Stable 5V rail enables full-resolution capture without frame corruption; 2.5mA IQ extends standby time between shots. |
Use Scenario: Generating 12V–24V from 3.3V or 5V system rail for TFT-LCD panel VCOM, VGH, and VGL supplies. IC Role / Device Role / Timing Role: High-voltage boost converter using 34V switch rating and external feedback divider to set precise output voltages. Use Value: Eliminates need for discrete FET + controller; ±2% low-battery detection prevents display flicker during battery depletion. |
| Handheld Computers | Battery Backup Supplies |
Use Scenario: Powering 3.3V or 5V logic rails from aging alkaline or NiMH batteries dropping below 1.2V per cell. IC Role / Device Role / Timing Role: Micropower DC/DC converter starting into heavy loads (e.g., 20Ω) directly from 1.5V input - no bootstrapping required. Use Value: Enables reliable startup and sustained operation down to 1.1V input; 1μA shutdown current preserves backup battery life. |
Use Scenario: Maintaining SRAM or RTC voltage during main power failure using coin-cell or supercapacitor input. IC Role / Device Role / Timing Role: Low-quiescent boost regulator with accurate 200mV LBI threshold detecting backup source depletion. Use Value: Prevents data loss by triggering controlled save routines before VBATT falls below safe retention level. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar boost converter applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT1308ACS8#TRPBF | SO-8 package, Burst Mode operation, 140μA no-load IQ, same 600kHz fOSC and 36V switch | Lower light-load efficiency but eliminates output ripple; better for ultra-low-power sleep modes | Select when minimizing average IQ at <10mA load outweighs need for ripple-free output. |
| LT3467ES6#TRPBF | 600kHz, 40V switch, 2.5mA IQ, but requires external compensation and lacks integrated LBO/LBI | No built-in low-battery monitor; needs external comparator and reference for battery sensing | Choose when higher 40V output capability is needed and system already includes battery monitoring circuitry. |
Compared with LT1308BCF#TR, the LT1308ACS8#TRPBF trades continuous switching for micropower Burst Mode - ideal for intermittent wake-up systems - while the LT3467ES6#TRPBF extends output voltage range but removes integrated battery monitoring, increasing design complexity for portable devices.
Availability
LT1308BCF#TR is available at Aetrix Electronics and suitable for digital cameras, handheld computers, and LCD bias supplies requiring stable component supply, long-term manufacturability, and guaranteed commercial-temperature performance.
Supply support for LT1308BCF#TR 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 product support, documentation, and manufacturing continuity for the LT1308 family.
The LT1308 series was designed specifically for battery-powered portable electronics needing high-efficiency, wide-input boost conversion with integrated low-battery monitoring - targeting space-constrained, cost-sensitive applications where reliability and ease of use are critical.
FAQ
What is the maximum output voltage achievable with the LT1308BCF#TR?
The LT1308BCF#TR supports output voltages up to 34V, enabled by its 36V-rated internal switch and external feedback resistor divider. This is confirmed in the Absolute Maximum Ratings table and Typical Application section, where 12V and 34V outputs are explicitly demonstrated. Output voltage is set by VOUT = 1.22V × (1 + R1/R2), and stability must be verified with VC-pin compensation for each target VOUT.
Does the LT1308BCF#TR support Burst Mode operation like the LT1308A?
No, the LT1308BCF#TR does not support Burst Mode operation. As stated in the Features and Operation sections, the LT1308B variant maintains continuous 600kHz switching even at light loads - a deliberate architectural difference from the LT1308A. This eliminates low-frequency output ripple but results in higher quiescent current (2.5mA vs. 140μA) under no-load conditions.
What is the correct way to connect the multiple GND and SW pins on the LT1308BCF#TR TSSOP package?
Per the Pin Functions and Block Diagram sections, all four GND pins (4–7) must be connected together at the package and tied to a solid local ground plane. Similarly, all three SW pins (8–10) must be joined at the package and routed with minimal loop area. These connections are mandatory for thermal performance (θJA = 80°C/W) and EMI control - failure to parallel them degrades efficiency, increases heating, and risks instability.
Can the LT1308BCF#TR start up into a precharged output capacitor or heavy load?
Yes, the LT1308BCF#TR can start up into heavy loads without bootstrapping - a key feature highlighted in the Start-Up section. Figure 13 shows successful startup into a 20Ω load from 1.5V input, with inductor current peaking at 3.5A. This capability stems from its self-contained bias generation and robust 2A+ switch current limit, making it suitable for systems with large output capacitance or active downstream circuitry.
How accurate is the low-battery detector on the LT1308BCF#TR, and what is its operating range?
The LT1308BCF#TR low-battery detector features a 200mV reference with ±2% accuracy at room temperature and ±3% over the full 0°C to 70°C range, as specified in Electrical Characteristics. The LBI input accepts voltages from –100mV to 1V, and LBO sinks 50μA when triggered. Detector operation is disabled when SHDN = 0V, and floating SHDN has the same effect as grounding.
LT1308BCF#TR Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 14-TSSOP (0.173", 4.40mm Width)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- Function:
- Step-Up, Step-Up/Step-Down
- Output Configuration:
- Positive
- Topology:
- Boost, SEPIC
- Output Type:
- Adjustable
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 1V
- Voltage - Input (Max):
- 10V
- Voltage - Output (Min/Fixed):
- 1.22V
- Voltage - Output (Max):
- 34V
- Current - Output:
- 2A (Switch)
- Frequency - Switching:
- 600kHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- -
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 14-TSSOP
LT1308BCF#TR FAQ
1.How can I place an order for LT1308BCF#TR through Aetrix?
Please submit a Request for Quotation (RFQ) for LT1308BCF#TR 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 LT1308BCF#TR reliable?
The price and inventory of LT1308BCF#TR are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT1308BCF#TR is usually 5 days.
3.What payment methods are accepted for LT1308BCF#TR?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT1308BCF#TR transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT1308BCF#TR?
LT1308BCF#TR orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT1308BCF#TR 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 LT1308BCF#TR?
For technical support, including LT1308BCF#TR datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT1308BCF#TR requirements.
6.How does Aetrix verify that LT1308BCF#TR is sourced from the original manufacturer or authorized distributors?
All LT1308BCF#TR 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 LT1308BCF#TR meets industry standards.
7.What is the process for return or replacement of LT1308BCF#TR?
All LT1308BCF#TR units undergo pre-shipment inspection (PSI). If there is an issue with LT1308BCF#TR, 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 LT1308BCF#TR part is unused and in its original packaging.
Return procedure for LT1308BCF#TR:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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