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Analog Devices Inc. LT1305CS8#TRPBF
- Part No.:
- LT1305CS8#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
LT1305CS8#TRPBF.pdf
- Description:
- IC REG BOOST 5V 2.5A 8SO
- Quantity:
- Payment:
- Shipping:
Inventory:1,054
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Product details
Overview
LT1305CS8#TRPBF from Analog Devices (formerly Linear Technology) is a micropower step-up DC/DC converter with integrated low-battery detector, designed for 2-cell/3-cell alkaline or NiMH battery-powered systems. It delivers 5V at 400mA from as low as 1.8V input, features 120µA quiescent current, 1.24V feedback reference, and open-collector LBO output that asserts low at 2.2V input-enabling portable instrumentation and EL panel drivers.
For engineers reviewing the LT1305CS8#TRPBF datasheet, LT1305CS8#TRPBF pinout, LT1305CS8#TRPBF application, or LT1305CS8#TRPBF equivalent, key selection criteria include input voltage range (1.8–10V), Burst Mode™ operation for ultra-low IQ, internal 2A switch with 280mV typical VCE(SAT), and SO-8 package compatibility with surface-mount inductor designs.
Technical Context
The LT1305CS8#TRPBF uses Burst Mode™ operation to maintain high efficiency across light loads: it disables switching until output voltage droops below regulation threshold, then delivers controlled energy bursts via a 2A internal NPN switch. Its oscillator runs at 120–185kHz with ±0.2%/°C TC and supports up to 95% duty cycle for low-input operation.
It integrates two independent comparators: one for feedback regulation (1.24V ±10mV reference, 6mV hysteresis) and another for low-battery detection (LBI trip at 1.24V ±30mV, disabled during shutdown). The LBO output is open-collector, sinking 100µA, and shares no internal hysteresis-external resistor networks must be added if hysteresis is required.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 1.8V to 10V - supports 2-cell (2.4V nominal) and 3-cell (4.5V nominal) alkaline/NiMH batteries with headroom for full discharge down to 1.8V. |
| Output Voltage | 5V regulated - set by external resistor divider on FB pin; accuracy defined by 1.24V ±10mV internal reference. |
| Max Output Current | 400mA at 5V - achievable from ≥2.5V input; limited by peak switch current (2.35A typ) and thermal dissipation (500mW max). |
| Quiescent Current | 120µA typ - enables multi-year battery life in standby; drops to 7µA in shutdown mode. |
| Low-Battery Threshold | 2.2V input - LBO pin goes low when VIN falls below this level, determined by LBI comparator with 1.24V reference and external resistive divider. |
| Switch Saturation Voltage | 280mV typ at 1A - minimizes conduction loss in boost path; enables use of low-cost Schottky diodes like MBRS130LT3. |
| Oscillator Frequency | 155kHz typ - balances EMI, inductor size, and efficiency; varies ±15% over temperature and supply. |
Pinout & Package
LT1305CS8#TRPBF is housed in an 8-lead plastic SOIC (SO-8) package with standard 0.150" body width and 1.27mm pitch. Pin 1 (PGND) and Pin 8 (PGND) are both power ground terminals, requiring direct connection to the inductor return path and input capacitor negative terminal within 0.2" for optimal EMI and thermal performance.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Pin 1 (PGND) | Power Ground | High-current return path for switch and input capacitor; must be tied directly to Pin 8 and bypassed locally to minimize noise coupling into signal ground. |
| Pin 2 (LBO) | Low-Battery Output | Open-collector output; sinks 100µA when LBI < 1.24V; high-impedance during shutdown - requires external pull-up for logic-level interface. |
| Pin 3 (SHDN) | Shutdown Control | Active-low enable: <0.5V = normal operation; >1.8V = shutdown (IQ ≤7µA); bias current <3µA at 2V. |
| Pin 4 (FB) | Feedback Input | Connects to resistor divider from VOUT; regulates output by comparing divided voltage to 1.24V internal reference. |
| Pin 5 (LBI) | Low-Battery Input | Input to dedicated comparator; voltage divider from VIN sets trip point (e.g., 100kΩ + 309kΩ → 2.2V trip); bias current <20nA. |
| Pin 6 (VIN) | Main Supply Input | Accepts 1.8–10V; requires ≥220µF low-ESR capacitor placed within 0.2" of pin and tied directly to PGND. |
| Pin 7 (SW) | Switch Node | Drives external inductor and Schottky diode; carries high dI/dt - layout must be short, wide, and isolated from sensitive nodes. |
| Pin 8 (PGND) | Power Ground | Second PGND terminal; electrically identical to Pin 1 - both must be connected to same low-impedance copper pour under device. |
Key Features
| Feature | Design Value |
|---|---|
| Burst Mode™ Operation | Enables 120µA quiescent current at light loads while maintaining tight output regulation - critical for battery runtime in intermittent-use instruments. |
| Integrated 2A Low-VCE(SAT) Switch | Reduces conduction loss and heat rise: 280mV typical saturation voltage at 1A allows efficient 5V/400mA conversion from 2V input without external MOSFET. |
| Dual Independent Comparators | Separate FB and LBI comparators allow simultaneous precision regulation and battery monitoring - no shared reference or timing interference. |
| SO-8 Package with Dual PGND Pins | Minimizes PCB area vs. DIP or TSSOP; dual PGND pins reduce ground loop inductance and improve thermal dissipation for 500mW max power handling. |
| Wide Input Range & Low Start-Up Voltage | Operates from 1.8V - supports full discharge of 2-cell alkaline (down to ~1.0V/cell) and enables single-stage boost where competing ICs require pre-regulation. |
Applications
| Portable Instrumentation | EL Panel Drivers |
|---|---|
|
Use Scenario: Handheld multimeters, gas detectors, and portable data loggers powered by two AA alkaline cells. IC Role / Device Role / Timing Role: Primary 5V power source enabling microcontroller, ADC, and display operation across full battery discharge curve (3.2V → 1.8V). Use Value: 120µA quiescent current extends battery life beyond 5 years in sleep mode; low 2.2V LBO threshold triggers graceful shutdown before system brownout. |
Use Scenario: Backlighting for membrane switches, medical device displays, and industrial control panels using electroluminescent (EL) wire or panels. IC Role / Device Role / Timing Role: Boost converter supplying 5V rail to EL driver IC (e.g., LT1182), with LBO signaling end-of-life battery condition to disable backlight. Use Value: High peak current capability (2.35A) supports fast EL turn-on transients; SO-8 footprint simplifies integration alongside compact EL transformers. |
| Low-Power Data Acquisition | Wireless Sensor Nodes |
|
Use Scenario: Battery-operated environmental sensors (temperature/humidity/CO₂) transmitting readings via UART or SPI to host MCU. IC Role / Device Role / Timing Role: Regulated 5V supply for analog front-end (op-amps, references) and communication interface; FB pin used for precise sensor biasing. Use Value: 1.24V ±10mV reference enables accurate ratiometric measurements; low-noise Burst Mode™ avoids interference with sensitive analog signals. |
Use Scenario: Zigbee/Z-Wave modules in smart home devices powered by coin cells or small alkaline packs. IC Role / Device Role / Timing Role: Efficient 5V generation for RF transceiver and microcontroller during brief transmit bursts; SHDN pin synchronized with MCU sleep cycles. Use Value: 7µA shutdown current eliminates leakage path; 155kHz switching frequency avoids ISM band interference; SO-8 allows dense RF layout. |
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 |
|---|---|---|---|
| LT1303CS8#PBF | Lower output current (200mA), same 120µA IQ and SO-8 package; lacks low-battery detector and uses different feedback architecture (no internal reference). | Suitable only for lighter loads; requires external reference for feedback; cannot replace LT1305CS8#TRPBF in LBO-dependent systems. | Select when cost or board space is constrained and battery monitoring is handled externally. |
| MAX756CPA+ | Fixed 5V output (no FB pin), 300mA max, 100µA IQ, 8-pin PDIP/SO; no LBO function; higher VSW rating (28V). | Used in legacy designs where fixed output suffices and through-hole assembly is acceptable; incompatible with adjustable or LBO-based architectures. | Choose only for drop-in replacement in existing MAX756-based layouts - not recommended for new designs requiring flexibility or battery monitoring. |
Compared with LT1303CS8#PBF and MAX756CPA+, the LT1305CS8#TRPBF uniquely combines 400mA output, integrated LBO, and programmable feedback in SO-8 - making it the only option among the three capable of supporting both high-current EL driving and autonomous low-battery shutdown in space-constrained portable systems.
Availability
LT1305CS8#TRPBF is available at Aetrix Electronics and suitable for portable instrumentation, EL panel drivers, low-power data acquisition, wireless sensor nodes, and handheld medical devices requiring stable component supply across extended production lifecycles.
Supply support for LT1305CS8#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 portfolio of high-performance analog ICs, including precision DC/DC converters, amplifiers, and power management solutions for industrial, automotive, and medical applications.
The LT1305CS8#TRPBF belongs to Linear's micropower DC/DC converter family, engineered specifically for battery-powered systems demanding ultra-low quiescent current, reliable low-voltage start-up, and integrated system monitoring functions like low-battery detection.
FAQ
What is the minimum input voltage required for LT1305CS8#TRPBF to start switching?
The LT1305CS8#TRPBF begins regulation at 1.8V input, with guaranteed operation down to 1.55V per datasheet specifications. Below 1.8V, startup may occur but output regulation and LBO functionality are not assured. For reliable 2-cell alkaline operation, design should ensure VIN stays ≥1.8V during peak load to avoid dropout - the LT1305CS8#TRPBF will continue switching until VIN falls below ~1.5V, though VOUT will sag.
Can LT1305CS8#TRPBF drive a 5V/400mA load continuously from a 2V input?
Yes - the LT1305CS8#TRPBF is rated for 400mA output at 5V from inputs ≥2.5V. At 2V input, continuous 400mA is thermally limited due to increased duty cycle and switch conduction loss; sustained operation requires careful thermal design (e.g., 2oz copper, thermal vias) and ambient ≤40°C. The LT1305CS8#TRPBF datasheet confirms 400mA is achievable with proper layout and cooling.
How is the low-battery detection threshold set for LT1305CS8#TRPBF?
The LT1305CS8#TRPBF uses an internal 1.24V reference for its LBI comparator. The threshold is set externally via a resistor divider from VIN to GND, with LBI connected to the divider midpoint. For a 2.2V trip point, a 100kΩ (top) + 309kΩ (bottom) divider yields 2.2V at LBI when VIN = 2.2V. The LT1305CS8#TRPBF LBO output goes low when this condition is met - no calibration or trimming is needed.
Does LT1305CS8#TRPBF require an external Schottky diode, and what are the key selection criteria?
Yes - the LT1305CS8#TRPBF requires an external Schottky diode (e.g., MBRS130LT3) in the boost path. Key criteria: 2A average current rating, ≤0.4V forward voltage at 400mA, fast recovery (<50ns), and low capacitance to minimize switching losses. General-purpose diodes like 1N4001 must be avoided - their slow recovery causes excessive power loss and potential oscillation in the LT1305CS8#TRPBF circuit.
Is LT1305CS8#TRPBF pin-compatible with other members of the LT130x family?
No - the LT1305CS8#TRPBF has a unique pinout optimized for dual PGND and separate LBI/LBO functions. LT1303CS8#PBF places SHDN on Pin 2 and omits LBI/LBO entirely; LT1302 uses different feedback and shutdown arrangements. Board redesign is required to substitute any LT130x variant - the LT1305CS8#TRPBF pin mapping is not interchangeable with earlier family members.
LT1305CS8#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:
- Fixed
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 1.8V
- Voltage - Input (Max):
- 10V
- Voltage - Output (Min/Fixed):
- 5V
- Voltage - Output (Max):
- -
- Current - Output:
- 2.5A (Switch)
- Frequency - Switching:
- 155kHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- 0°C ~ 70°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-SO
LT1305CS8#TRPBF FAQ
1.How can I place an order for LT1305CS8#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT1305CS8#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 LT1305CS8#TRPBF reliable?
The price and inventory of LT1305CS8#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT1305CS8#TRPBF is usually 5 days.
3.What payment methods are accepted for LT1305CS8#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT1305CS8#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT1305CS8#TRPBF?
LT1305CS8#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT1305CS8#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 LT1305CS8#TRPBF?
For technical support, including LT1305CS8#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT1305CS8#TRPBF requirements.
6.How does Aetrix verify that LT1305CS8#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT1305CS8#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 LT1305CS8#TRPBF meets industry standards.
7.What is the process for return or replacement of LT1305CS8#TRPBF?
All LT1305CS8#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT1305CS8#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 LT1305CS8#TRPBF part is unused and in its original packaging.
Return procedure for LT1305CS8#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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