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Analog Devices Inc. LT1308IS8#TRPBF
- Part No.:
- LT1308IS8#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
LT1308IS8#TRPBF.pdf
- Description:
- IC REG BOOST ADJ 2A 8SO
- Quantity:
- Payment:
- Shipping:
Inventory:3,851
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Product details
Overview
LT1308IS8#TRPBF from Analog Devices (formerly Linear Technology) is an industrial-grade micropower fixed-frequency boost DC/DC converter optimized for single-cell battery systems. It delivers 5V at 1A from a 1V–3.6V Li-Ion input, features 600kHz current-mode PWM switching, integrated 2A NPN switch with 300mV VCE(SAT), and automatic Burst Mode™ operation below ~200mA load. Used in GSM RF power stages and DECT phone pulsed loads.
For engineers reviewing the LT1308IS8#TRPBF datasheet, LT1308IS8#TRPBF pinout, LT1308IS8#TRPBF application, or LT1308IS8#TRPBF equivalent, key selection criteria include minimum 1.2V startup voltage (–40°C), 1.22V feedback reference accuracy, low-battery comparator with 200mV threshold, shutdown current ≤3µA, and SO-8 thermal performance (θJA = 80°C/W).
Technical Context
The LT1308IS8#TRPBF employs current-mode PWM control with a 600kHz oscillator and ramp generator, enabling fast transient response to pulsed loads like GSM transmit bursts (577µs) and DECT frames (416µs). Its error amplifier (100V/V gain at –40°C) drives a compensation network (VC pin) for stability across 1.2V–6V input and 3.3V/5V outputs.
It integrates a dedicated low-battery detector with 200mV internal reference, open-collector LBO output (≤0.25V @ 10µA sink), and LBI input bias current <30nA. Shutdown logic disables switching when SHDN is grounded, reducing quiescent current to ≤3µA while maintaining LBO high-impedance state.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 1.2V to 6V - supports single NiCd (1.2V) or Li-Ion (3.0–4.2V) cells without external regulation |
| Output Voltage Accuracy | 1.22V ±2.5% feedback reference - enables precise 3.3V (R1/R2 = 169k/100k) or 5V (301k/100k) regulation |
| Switching Frequency | 600kHz ±15% - allows use of compact 4.7µH inductors and ceramic output capacitors (e.g., 10µF + 100µF) |
| Peak Switch Current Limit | 2.0A min at 40% duty cycle - sustains 1A continuous output with margin for GSM pulse peaks |
| Quiescent Current | 100µA typical (no load) - extends battery life in standby; drops to ≤3µA in shutdown mode |
| Low-Battery Threshold | 200mV ±20mV - configurable via resistor divider on LBI to detect cell depletion before system reset |
| Thermal Performance | θJA = 80°C/W (SO-8 package) - requires minimal copper area for 1A operation at 85°C ambient |
Pinout & Package
LT1308IS8#TRPBF is housed in an 8-lead plastic SO (Small Outline) package, 0.150" narrow body, RoHS-compliant, with exposed pad not electrically connected. Pin 1 is LBO (low-battery output), pin 8 is GND; package meets JEDEC MS-012AC standard.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| LBO (Pin 1) | Open-collector low-battery flag output | Sinks ≤10µA when LBI < 200mV; requires external 1MΩ pullup to notify host processor of battery depletion |
| LBI (Pin 2) | Low-battery detector input | Compares external divider voltage against 200mV reference; bias current <30nA minimizes divider error |
| VIN (Pin 3) | Main power input | Accepts 1.2–6V; must be bypassed with ≤10mm trace to 10µF ceramic capacitor to prevent oscillation |
| SW (Pin 4) | Internal NPN switch collector | Drives external inductor/diode; 300mV VCE(SAT) at 2A ensures >85% efficiency at 1A load |
| VC (Pin 5) | Error amplifier compensation node | Connects RC network (e.g., 47kΩ + 22nF) to ground; controls loop stability for varying output capacitance |
| FB (Pin 6) | Feedback input | 1.22V reference point; resistive divider sets output voltage; trace area must be minimized to reduce noise coupling |
| SHDN (Pin 7) | Enable/disable control | Ground to shut down (≤3µA IQ); tie to VIN or higher to operate; floating causes erratic behavior |
| GND (Pin 8) | Power and signal ground | Must connect directly to solid ground plane enclosing all power components; critical for EMI suppression |
Key Features
| Feature | Design Value |
|---|---|
| Burst Mode™ operation | Automatically engages below ~200mA load to maintain >75% efficiency at 1mA, extending battery runtime in idle states |
| Guaranteed start-up at 1.2V | Operates from cold-start at –40°C with single NiCd or depleted Li-Ion, eliminating need for auxiliary wake-up circuitry |
| Integrated low-battery detector | Dedicated 200mV reference and comparator enable accurate end-of-discharge signaling without external ICs |
| Current-mode PWM architecture | Provides inherent cycle-by-cycle current limiting and stable operation with wide output capacitor ESR ranges |
| 600kHz fixed-frequency switching | Enables use of small, low-profile inductors (e.g., Coilcraft DO3316-472) and avoids AM radio band interference |
Applications
| GSM Mobile Transmitter Power | DECT Cordless Phone RF Stage |
|---|---|
|
Use Scenario: Powering GSM RF power amplifier during 577µs transmit bursts from a single Li-Ion cell (3.0–4.2V). IC Role / Device Role / Timing Role: Boost converter providing regulated 5V rail with fast transient response (<10µs recovery) and low output ripple. Use Value: Maintains 5V ±3% under 100mA→1A load step; 85% efficiency at 1A reduces thermal stress in compact handset PCBs. |
Use Scenario: Supplying 3.3V to DECT base station RF IC during 416µs transmit pulses from a single NiCd cell (1.2V). IC Role / Device Role / Timing Role: High-current boost regulator with Burst Mode™ to sustain peak 400mA pulses while minimizing average current draw. Use Value: Delivers 3.3V with <50mV droop using 100µF output capacitance; 100µA quiescent current extends talk time between charges. |
| Digital Camera CCD Bias Supply | Portable Medical Sensor Node |
|
Use Scenario: Generating multiple rails (5V, 3.3V, ±10V, +18V) from a 1.6–6V battery pack for CCD imaging and analog front-end. IC Role / Device Role / Timing Role: Primary boost controller in multi-output flyback-derived topology, driving transformer-coupled secondaries. Use Value: Fixed 600kHz frequency simplifies EMI filtering; low 100µA IQ preserves battery life during image capture standby intervals. |
Use Scenario: Providing stable 3.3V supply to ultra-low-power microcontroller and biosensor analog circuitry from coin-cell or Li-SOCl₂ battery. IC Role / Device Role / Timing Role: Micropower DC/DC converter enabling operation down to 1.2V input, with shutdown controlled by MCU GPIO. Use Value: ≤3µA shutdown current prevents battery drain during multi-week sleep cycles; 200mV LBI threshold enables precise end-of-life detection. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar boost converter applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3525EDC-5#TRMPBF | 5V fixed-output, 2MHz switching, 600mA max, 15µA IQ, 6-pin DFN | Lower current, higher frequency, no low-battery detector or Burst Mode™ | Preferred for space-constrained 5V-only designs where 600mA suffices and LBI/LBO signals are unnecessary |
| MAX1706ESA+ | Adjustable output, 1.2MHz, 1.2A switch, 22µA IQ, 8-pin SO | No integrated low-battery comparator; requires external voltage monitor for battery warning | Suitable when design flexibility (adjustable VOUT) outweighs need for built-in battery monitoring |
Compared with LT1308IS8#TRPBF, LTC3525EDC-5#TRMPBF offers smaller footprint and higher efficiency above 10mA but lacks battery monitoring; MAX1706ESA+ provides higher peak current and adjustable output yet requires external circuitry for low-battery indication-making LT1308IS8#TRPBF optimal for cost-sensitive, battery-aware portable RF applications.
Availability
LT1308IS8#TRPBF is available at Aetrix Electronics and suitable for GSM terminals, DECT phones, digital cameras, and portable medical sensors requiring stable component supply across industrial temperature range (–40°C to 85°C).
Supply support for LT1308IS8#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 its precision analog and power management portfolio. Linear pioneered high-performance DC/DC converters for battery-powered systems.
The LT1308IS8#TRPBF belongs to Linear's micropower boost converter family, designed specifically for single-cell handheld devices demanding high efficiency at light loads, robust start-up under voltage sag, and integrated battery health monitoring.
FAQ
What is the minimum input voltage required for LT1308IS8#TRPBF to start up and regulate at –40°C?
The LT1308IS8#TRPBF guarantees start-up at 1.2V input voltage over the full industrial temperature range (–40°C to 85°C), as specified in the Electrical Characteristics table for Industrial Grade devices. This ensures reliable operation from a partially discharged NiCd cell or low-voltage Li-Ion source in cold environments. Below 1.2V, regulation cannot be assured per datasheet limits.
Does LT1308IS8#TRPBF support adjustable output voltage, and how is it set?
Yes, LT1308IS8#TRPBF supports adjustable output voltage via a resistive divider connected to the FB (Pin 6) pin. The internal 1.22V reference determines VOUT = 1.22V × (1 + R1/R2), where R2 connects from FB to GND and R1 from VOUT to FB. For example, 3.3V uses R1 = 169kΩ and R2 = 100kΩ; 5V uses R1 = 301kΩ and R2 = 100kΩ. Layout must minimize trace area at FB to avoid noise injection.
How does the low-battery detector in LT1308IS8#TRPBF function, and what external components are needed?
The LT1308IS8#TRPBF low-battery detector compares voltage on LBI (Pin 2) against an internal 200mV reference. When LBI falls below 180–220mV, LBO (Pin 1) pulls low (≤0.25V @ 10µA). An external resistor divider from VIN to GND sets the trip point; e.g., 200kΩ from VIN to LBI and 10kΩ from LBI to GND triggers at ~2.2V for a Li-Ion cell. A 1MΩ pullup on LBO is recommended to interface with microcontroller GPIO.
What layout practices are critical for stable operation of LT1308IS8#TRPBF at 1A load?
Stable 1A operation of LT1308IS8#TRPBF requires: (1) placing the 10µF ceramic input capacitor within 5mm of VIN and GND pins; (2) routing SW and GND traces as short, wide loops to minimize inductance; (3) connecting GND pin directly to a solid ground plane covering all power components; and (4) minimizing trace area at FB and VC pins to prevent noise coupling. Long input traces (>10mm) cause regulation failure or oscillation per Layout Hints section.
Is LT1308IS8#TRPBF pin-compatible with other members of the LT130x family, such as LT1307 or LT1302?
No, LT1308IS8#TRPBF is not pin-compatible with LT1307 or LT1302. LT1308IS8#TRPBF uses an 8-pin SO package with LBO/LBI pins for battery monitoring, while LT1307 (MSOP-8) and LT1302 (SO-8) have different pinouts: LT1307 places SHDN on Pin 1 and lacks LBI/LBO, and LT1302 assigns SW to Pin 1 and has no low-battery functionality. Substitution requires PCB redesign and firmware updates for battery monitoring logic.
LT1308IS8#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 8-SOIC (0.154", 3.90mm 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):
- 1V
- Voltage - Input (Max):
- 10V
- Voltage - Output (Min/Fixed):
- 1.22V
- Voltage - Output (Max):
- 30V (Switch)
- 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
LT1308IS8#TRPBF FAQ
1.How can I place an order for LT1308IS8#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT1308IS8#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 LT1308IS8#TRPBF reliable?
The price and inventory of LT1308IS8#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT1308IS8#TRPBF is usually 5 days.
3.What payment methods are accepted for LT1308IS8#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT1308IS8#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT1308IS8#TRPBF?
LT1308IS8#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT1308IS8#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 LT1308IS8#TRPBF?
For technical support, including LT1308IS8#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT1308IS8#TRPBF requirements.
6.How does Aetrix verify that LT1308IS8#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT1308IS8#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 LT1308IS8#TRPBF meets industry standards.
7.What is the process for return or replacement of LT1308IS8#TRPBF?
All LT1308IS8#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT1308IS8#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 LT1308IS8#TRPBF part is unused and in its original packaging.
Return procedure for LT1308IS8#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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