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Analog Devices Inc. LT1308AIS8#PBF
- Part No.:
- LT1308AIS8#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
LT1308AIS8#PBF.pdf
- Description:
- IC REG BOOST SEPIC ADJ 2A 8SO
- Quantity:
- Payment:
- Shipping:
Inventory:5,036
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Product details
Overview
LT1308AIS8#PBF from Analog Devices (formerly Linear Technology) is a micropower, fixed-frequency 600kHz boost 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 140μA no-load quiescent current, 1.22V ±2% feedback reference, and integrated low-battery detector with 200mV ±2% threshold. It enables high-efficiency power conversion in space-constrained portable electronics.
For engineers reviewing the LT1308AIS8#PBF datasheet, LT1308AIS8#PBF pinout, LT1308AIS8#PBF application, or LT1308AIS8#PBF equivalent, key selection criteria include burst-mode efficiency at light loads, 36V switch rating for high-VOUT designs, SO-8 thermal performance (θJA = 190°C/W), and compatibility with ceramic or tantalum output capacitors in compact boost/SEPIC topologies.
Technical Context
The LT1308AIS8#PBF implements current-mode PWM control with automatic Burst Mode™ operation below ~400mA load, reducing average input current while maintaining regulation. Its internal 600kHz oscillator drives a 300mV VCESAT N-channel MOSFET switch rated to 36V, enabling output voltages up to 34V in boost mode or wide-input-range regulation in SEPIC configurations.
It integrates a precision 200mV low-battery detector (±2% over temperature) with open-collector LBO output, a VC compensation pin supporting external RC networks for loop stability, and shutdown logic requiring only ≥1V on SHDN-no VIN tie required. The device starts into heavy loads without bootstrapping, supporting robust 3.5A peak inductor current during cold-start.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Switching Frequency | 600kHz fixed - enables compact magnetics and reduces EMI filtering burden vs lower-frequency converters. |
| No-Load Quiescent Current | 140μA - sustains >100-hour standby in battery-powered devices without significant drain. |
| Feedback Reference Voltage | 1.22V ±2% - sets precise output voltage via resistor divider; supports stable 3.3V, 5V, or 12V outputs. |
| Switch Voltage Rating | 36V - allows boost outputs up to 34V or SEPIC operation across wide VIN/VOUT ranges. |
| Low-Battery Threshold | 200mV ±2% - provides accurate cell-voltage monitoring for Li-ion (2.7V cutoff) or NiCd (0.9V/cell) systems. |
| Shutdown Current | ≤1μA - ensures near-zero battery leakage during system sleep or storage. |
| Operating Input Range | 1.1V to 10V - supports single Li-ion (2.7–4.2V), two/three alkaline (1.8–4.5V), or four NiCd (4.0–5.6V) inputs. |
Pinout & Package
LT1308AIS8#PBF is housed in an 8-lead plastic SO package (S8), with θJA = 190°C/W and operating temperature range of –40°C to +85°C. Pin 4 serves as the sole ground connection; thermal performance relies on direct PCB copper connection to this pin.
| Pin | Circuit Role | Design Meaning |
|---|---|---|
| 1 (VC) | Compensation Node | Output of error amplifier; connects to external RC network (e.g., 47kΩ + 100pF) for loop stability and transient response tuning. |
| 2 (FB) | Feedback Input | Senses output voltage via resistive divider; 1.22V reference enables precise VOUT programming (e.g., 5V = 1.22V × (1 + R1/R2)). |
| 3 (SHDN) | Enable Control | Active-high logic input; ≥1V enables operation (no VIN tie needed); grounded disables switching and reduces IQ to ≤1μA. |
| 4 (GND) | Power Ground | Primary return path for switch current and IC bias; must connect directly to local ground plane with minimal trace inductance. |
| 5 (SW) | Power Switch Node | Drives external inductor/diode; handles peak currents >3A; requires minimized copper area to suppress EMI. |
| 6 (VIN) | Input Supply | Accepts 1.1V–10V input; requires local 47μF bypass capacitor placed <5mm from pin to prevent regulation instability. |
| 7 (LBI) | Low-Battery Input | High-impedance input referenced to 200mV; monitors battery voltage via external resistor divider; floats if unused. |
| 8 (LBO) | Low-Battery Output | Open-collector output sinking 50μA; pulls low when LBI < 200mV; requires external pull-up (e.g., 220kΩ) to host logic rail. |
Key Features
| Feature | Design Value |
|---|---|
| Burst Mode™ Operation | Reduces average input current at light loads while maintaining output regulation-critical for >100-hour battery life in pagers or GPS receivers. |
| 36V Switch Rating | Enables 34V boost outputs or SEPIC topologies spanning input voltages above/below output-ideal for LCD bias or industrial sensor supplies. |
| 200mV ±2% Low-Battery Detector | Provides accurate, temperature-stable cell monitoring without external references-eliminates need for discrete comparator circuits. |
| Start-Up into Heavy Loads | Delivers full 3.5A peak inductor current during cold start-avoids brownout in high-capacitance systems like digital cameras or handheld computers. |
| VC Compensation Pin | Allows full loop stability optimization with ceramic or low-ESR tantalum output capacitors-enables smaller, cheaper, and more reliable BOMs. |
Applications
| GSM/CDMA Handsets | Digital Cameras |
|---|---|
Use Scenario: Powering RF power amplifiers and baseband processors from a single Li-ion cell (3.0–4.2V). IC Role / Device Role / Timing Role: Step-up converter generating stable 5V rail for PA bias and 3.3V for logic, with Burst Mode extending talk time. Use Value: 140μA quiescent current and 600kHz switching minimize battery drain and filter size-enabling slim form factors. | Use Scenario: Supplying high-current flash LED drivers and CCD/CMOS image sensors requiring 5V/1A bursts. IC Role / Device Role / Timing Role: High-peak-current boost regulator delivering regulated 5V from 3.6V nominal battery, starting instantly under full load. Use Value: 3.5A start-up capability and 300mV VCESAT switch ensure fast flash charging without voltage droop or delay. |
| LCD Bias Supplies | Battery Backup Systems |
Use Scenario: Generating +12V and –5V rails for TFT-LCD panel gate/source drivers in portable medical displays. IC Role / Device Role / Timing Role: Primary boost controller in positive-output stage; paired with inverting charge pump for negative rail. Use Value: 36V switch rating and 600kHz frequency support compact 10μH inductors and low-ESR ceramic caps-reducing board area by >30%. | Use Scenario: Maintaining real-time clock (RTC) and SRAM backup during main power failure in industrial controllers. IC Role / Device Role / Timing Role: Micropower DC/DC converter stepping up depleted primary cell (e.g., 0.9V NiCd) to 3.3V for critical memory retention. Use Value: 1.1V minimum input and 200mV low-battery detection enable operation down to end-of-life cell voltage-extending system uptime. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar boost converter applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3530EDD#TRMPBF | Higher 2MHz switching frequency; 1.8V min input; integrated soft-start; no LBO/LBI pins. | Lacks low-battery monitoring; better suited for ultra-compact, high-frequency designs where footprint is critical. | Select when board space is constrained and battery monitoring is handled externally. |
| TPS61040DRVR | 5V fixed output option; 28V switch rating; 2.7V min input; no Burst Mode; 50μA IQ in shutdown. | Lower max output voltage and no integrated low-battery detector; simpler for fixed 5V applications without monitoring needs. | Select for cost-sensitive, fixed-output consumer devices where extended battery monitoring is unnecessary. |
Compared with LTC3530EDD#TRMPBF and TPS61040DRVR, the LT1308AIS8#PBF uniquely combines micropower Burst Mode operation, 36V switch capability, and integrated ±2% low-battery detection in an industry-standard SO-8 package-making it optimal for battery-critical portable systems requiring both efficiency and system-level health monitoring.
Availability
LT1308AIS8#PBF is available at Aetrix Electronics and suitable for GSM handsets, digital cameras, LCD bias supplies, and battery backup systems requiring stable component supply across industrial temperature ranges (–40°C to +85°C).
Supply support for LT1308AIS8#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 its legacy of high-performance analog and power management ICs for demanding applications.
The LT1308A product line was designed specifically for micropower, high-current boost conversion in portable battery-powered equipment-emphasizing light-load efficiency, robust start-up, and integrated system monitoring functions.
FAQ
What is the minimum input voltage required for LT1308AIS8#PBF to start and regulate?
The LT1308AIS8#PBF guarantees operation down to 1.1V input, with typical start-up observed at 0.92V. At 1.5V input, it delivers 5V/1A in the reference circuit-making it suitable for deeply discharged Li-ion cells or multi-cell alkaline/NiCd stacks. Below 1.1V, regulation may be lost, but the device remains functional until shutdown threshold is crossed.
Does LT1308AIS8#PBF support ceramic output capacitors, and how is stability ensured?
Yes, LT1308AIS8#PBF fully supports ceramic output capacitors via its dedicated VC compensation pin. Unlike older converters relying on capacitor ESR for loop stability, the LT1308AIS8#PBF uses an external RC network (e.g., 47kΩ + 100pF) from VC to GND to set dominant pole and phase margin-enabling stable operation with zero-ESR ceramics commonly used in space-constrained designs.
How does the low-battery detector in LT1308AIS8#PBF differ from the original LT1308?
The LT1308AIS8#PBF improves low-battery detection accuracy to ±2% over temperature (vs ±5% for LT1308) using a trimmed 200mV internal reference. Its LBO output sinks 50μA (vs 20μA), enabling direct interface with microcontroller GPIOs without external buffers. The LBI input also features tighter bias current specs (27–80nA), reducing divider error in precision battery monitoring.
Can LT1308AIS8#PBF be used in SEPIC topology, and what design considerations apply?
Yes, LT1308AIS8#PBF is explicitly validated for SEPIC operation-as shown in Figure 8 of its datasheet-supporting input voltages both above and below the regulated output (e.g., 3–10V in to 5V out). Key requirements include dual coupled inductors (e.g., Coiltronics CTX10-2), careful grounding of shared GND nodes, and use of low-ESR output capacitors (e.g., AVX TPSD227M006) to maintain ripple below 60mVP-P at 800mA load.
What thermal derating applies to LT1308AIS8#PBF in the SO-8 package at 85°C ambient?
In the SO-8 package (θJA = 190°C/W), LT1308AIS8#PBF reaches junction temperatures exceeding 125°C at full 1A load and 85°C ambient-requiring derating. For continuous 1A operation at 85°C, maximum allowable power dissipation is limited to ~210mW (ΔT = 40°C), achievable via reduced duty cycle, enhanced PCB copper area under Pin 4, or forced airflow. Derated output current should not exceed 700mA under these conditions.
LT1308AIS8#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 8-SOIC (0.154", 3.90mm 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):
- 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:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-SO
LT1308AIS8#PBF FAQ
1.How can I place an order for LT1308AIS8#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT1308AIS8#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 LT1308AIS8#PBF reliable?
The price and inventory of LT1308AIS8#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT1308AIS8#PBF is usually 5 days.
3.What payment methods are accepted for LT1308AIS8#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT1308AIS8#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT1308AIS8#PBF?
LT1308AIS8#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT1308AIS8#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 LT1308AIS8#PBF?
For technical support, including LT1308AIS8#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT1308AIS8#PBF requirements.
6.How does Aetrix verify that LT1308AIS8#PBF is sourced from the original manufacturer or authorized distributors?
All LT1308AIS8#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 LT1308AIS8#PBF meets industry standards.
7.What is the process for return or replacement of LT1308AIS8#PBF?
All LT1308AIS8#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT1308AIS8#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 LT1308AIS8#PBF part is unused and in its original packaging.
Return procedure for LT1308AIS8#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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