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Analog Devices Inc. LT1308ACF#PBF
- Part No.:
- LT1308ACF#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 14-TSSOP (0.173", 4.40mm Width)
- Datasheet:
-
LT1308ACF#PBF.pdf
- Description:
- IC REG BST SEPIC ADJ 2A 14TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:4,751
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Product details
Overview
LT1308ACF#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 1V–10V input, features automatic Burst Mode™ operation (140μA no-load quiescent current), 36V switch rating, and ±2% 200mV low-battery detector reference. It is used in digital cameras and handheld computers requiring high-efficiency light-load regulation.
For engineers reviewing the LT1308ACF#PBF datasheet, LT1308ACF#PBF pinout, LT1308ACF#PBF application, or LT1308ACF#PBF equivalent, key selection criteria include its 14-lead TSSOP package with four GND pins and three SW pins, Burst Mode™ efficiency at sub-1mA loads, VC-compensated error amplifier, and compatibility with SEPIC topologies for wide-input-range bias supplies.
Technical Context
The LT1308ACF#PBF implements a current-mode PWM architecture with a 600kHz oscillator and ramp compensation to prevent subharmonic oscillation above 50% duty cycle. Its Burst Mode™ operation-enabled by a hysteretic comparator on the VC pin-reduces switching activity at light loads while maintaining output regulation via low-frequency ripple.
It integrates a 36V-rated N-channel MOSFET switch with 300mV VCE(SAT) at 2A, a 1.22V feedback reference with ±0.02V accuracy, and an independent low-battery detector with 200mV ±2% internal reference and open-collector LBO output capable of sinking 50μA.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Switching Frequency | 600kHz fixed frequency enables compact magnetics and predictable EMI filtering. |
| Input Voltage Range | 1V to 10V supports direct operation from single Li-Ion (2.7–4.2V), two/three NiCd (1.2V/cell), or alkaline cells. |
| No-Load Quiescent Current | 140μA in Burst Mode™ ensures >1-year shelf life in battery-backed devices. |
| Switch Voltage Rating | 36V maximum allows stable 34V boost outputs and robustness against inductive kickback. |
| Feedback Reference Voltage | 1.22V ±0.02V enables precise output setting (e.g., 5V via 309k/100k divider) with minimal load regulation error. |
| Low-Battery Detector Accuracy | 200mV ±2% over temperature ensures reliable battery cutoff without premature shutdown. |
| Shutdown Current | ≤1μA guarantees zero standby drain when disabled-critical for emergency backup systems. |
Pinout & Package
LT1308ACF#PBF is housed in a 14-lead plastic TSSOP package (0°C to 70°C operating range) with thermal-enhanced ground plane connection. Four GND pins (4–7), three SW pins (8–10), and two VIN pins (11–12) must be internally shorted per layout guidelines to minimize impedance and thermal resistance.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VC (Pin 1) | Compensation node for error amplifier | External RC network (e.g., 47kΩ + 100pF) sets loop stability; sensitive to noise-minimize trace area. |
| FB (Pin 2) | Feedback input for output voltage regulation | 1.22V reference point; connects to resistor divider tap-trace routing affects regulation accuracy. |
| SHDN (Pin 3) | Enable/disable control input | Active-high logic: ≥1V enables; floating or grounded disables; no VIN tie required-simplifies system-level power sequencing. |
| GND (Pins 4–7) | Power and signal ground return | Four dedicated pins reduce ground impedance and serve as primary heat path-must connect to solid copper pour. |
| SW (Pins 8–10) | Switch node for inductor/diode connection | High-dI/dt node; all three pins carry full switch current-short externally to minimize parasitic inductance. |
| VIN (Pins 11–12) | Main power input supply | Dual pins reduce IR drop and improve transient response-requires local 47μF bypass capacitor placed ≤5mm away. |
| LBI (Pin 13) | Low-battery detector analog input | Accepts scaled battery voltage; operates only when SHDN is high; bias current flows out (33nA typical). |
| LBO (Pin 14) | Open-collector low-battery alert output | Sinks 50μA max; requires external pull-up (e.g., 220kΩ); asserts low when LBI < 200mV. |
Key Features
| Feature | Design Value |
|---|---|
| Burst Mode™ Operation | Reduces average input current to 140μA at no load while maintaining regulated output-enables multi-year battery life in always-on sensors. |
| 36V Switch Rating | Supports 34V output in boost mode and enables SEPIC configurations across wide input ranges (e.g., 3V–10V → 5V), eliminating need for higher-voltage alternatives. |
| Integrated Low-Battery Detector | 200mV ±2% reference with open-collector LBO output provides accurate, externally scalable battery monitoring without external comparators. |
| Multi-Pin Power Routing | Dual VIN and triple SW pins lower conduction losses and thermal stress-critical for 1A continuous output in space-constrained TSSOP footprint. |
| VC Pin Compensation | External RC network allows full loop stability tuning for diverse output capacitors (tantalum, ceramic, or hybrid), enabling optimal transient response across load steps. |
Applications
| Digital Cameras | GSM/CDMA Phones |
|---|---|
Use Scenario: Powering CCD/CMOS image sensor bias rails and flash LED drivers from single Li-Ion cell. IC Role / Device Role / Timing Role: Boost converter generating stable 5V/3.3V from 3.0–4.2V battery, with Burst Mode™ extending capture time between charges. Use Value: 90%+ efficiency at 10mA–500mA loads preserves battery capacity during preview and burst capture modes. | Use Scenario: Supplying RF power amplifier and baseband processor core voltage in dual-mode mobile handsets. IC Role / Device Role / Timing Role: High-current step-up regulator delivering 2.8V/3.3V from declining battery (3.6V → 2.8V), with low-battery detection triggering graceful shutdown. Use Value: ±2% LBI threshold prevents false low-battery alerts during RF transmit bursts, improving user experience. |
| LCD Bias Supplies | Battery Backup Supplies |
Use Scenario: Generating positive and negative bias voltages (e.g., +12V/–5V) for TFT-LCD panels in portable medical monitors. IC Role / Device Role / Timing Role: Primary boost stage in charge-pump-assisted topology; operates in SEPIC mode to maintain regulation as battery drops below output voltage. Use Value: 600kHz switching allows small 4.7μH inductors and 22μF ceramic caps-reducing board area by >40% vs. 100kHz solutions. | Use Scenario: Maintaining SRAM or real-time clock (RTC) power during main supply failure in industrial controllers. IC Role / Device Role / Timing Role: Micropower DC/DC converter activated only when main rail fails; shutdown current ≤1μA extends backup battery life to >5 years. Use Value: Automatic Burst Mode™ eliminates need for external enable logic-simplifies failover circuitry and reduces BOM count. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar boost converter applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT1308BCF#PBF | Continuous switching at light loads (2.5mA IQ), no Burst Mode™; identical pinout and package. | Preferred where low-output-ripple is mandatory (e.g., audio bias), but sacrifices light-load efficiency. | Select LT1308BCF#PBF only if system-level EMI testing shows Burst Mode™ ripple unacceptable-otherwise LT1308ACF#PBF delivers superior battery runtime. |
| MAX77818EWL+ | Single-inductor dual-output buck-boost with I2C interface; 2.5V–5.5V input; 1.8V–5.2V programmable outputs. | Replaces discrete boost + LDO in complex PMIC designs; adds dynamic voltage scaling and telemetry. | Choose MAX77818EWL+ only when multi-rail sequencing, telemetry, or adaptive output control is required-LT1308ACF#PBF remains optimal for cost-sensitive, fixed-output boost applications. |
Compared with LT1308BCF#PBF, LT1308ACF#PBF trades minor output ripple for >10× lower no-load current-extending battery life in infrequently active devices. Against MAX77818EWL+, it offers simpler design, lower BOM cost, and proven reliability in legacy portable equipment without firmware dependency.
Availability
LT1308ACF#PBF is available at Aetrix Electronics and suitable for digital cameras, GSM/CDMA phones, and LCD bias supplies requiring stable component supply with guaranteed long-term manufacturability and consistent parametric performance.
Supply support for LT1308ACF#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 product support, datasheet documentation, and application engineering resources for legacy Linear parts.
The LT1308A series was designed specifically for high-efficiency, single-cell portable electronics-emphasizing micropower operation, robust start-up into heavy loads, and integrated battery monitoring to simplify power architecture in space- and battery-limited devices.
FAQ
What is the maximum output voltage achievable with the LT1308ACF#PBF?
The LT1308ACF#PBF supports boost converter outputs up to 34V, enabled by its 36V-rated internal switch. This is confirmed in the Absolute Maximum Ratings table and Typical Application section of the official datasheet. Output voltage is set by the FB resistive divider, and stability must be verified with appropriate compensation (VC network) and output capacitor ESR for the chosen voltage and load.
Does the LT1308ACF#PBF support SEPIC topology?
Yes, the LT1308ACF#PBF supports SEPIC configuration, as explicitly shown in Figure 8 and detailed in the Applications Information section. Its ability to operate across input voltages both above and below the regulated output-combined with high switch voltage rating and robust start-up-makes it suitable for wide-input-range applications like 3V–10V to 5V conversion.
How does Burst Mode™ operation affect output voltage ripple in the LT1308ACF#PBF?
Burst Mode™ in the LT1308ACF#PBF introduces low-frequency output voltage ripple (typically 1–10kHz) during light loads, as the IC cycles between active switching and sleep states to conserve power. This ripple amplitude depends on output capacitance and load current, and is documented in Figure 3 waveforms. It is absent in continuous-mode variants like LT1308BCF#PBF.
What is the recommended PCB layout practice for the SW pins on the LT1308ACF#PBF?
The LT1308ACF#PBF's three SW pins (8–10) must be shorted together directly at the package using minimum-length, wide copper traces to reduce parasitic inductance. Layout Figure 7 confirms this, and the Pin Functions section emphasizes minimizing trace area at SW nodes to suppress EMI. Failure to interconnect all SW pins increases switching losses and may cause instability or excessive radiated emissions.
Can the LT1308ACF#PBF start up into a precharged output capacitor?
Yes, the LT1308ACF#PBF can start up into a precharged output capacitor, as demonstrated in Figure 13–15 waveforms showing successful start-up into 5Ω and 10Ω loads with output voltages reaching regulation within 500μs–1ms. Unlike bootstrapped converters, it derives bias from VIN-not VOUT-enabling reliable start-up even when the output is held high by external circuitry.
LT1308ACF#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 14-TSSOP (0.173", 4.40mm Width)
- Packaging:
- Tube
- 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:
- 0°C ~ 70°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 14-TSSOP
LT1308ACF#PBF FAQ
1.How can I place an order for LT1308ACF#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT1308ACF#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 LT1308ACF#PBF reliable?
The price and inventory of LT1308ACF#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT1308ACF#PBF is usually 5 days.
3.What payment methods are accepted for LT1308ACF#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT1308ACF#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT1308ACF#PBF?
LT1308ACF#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT1308ACF#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 LT1308ACF#PBF?
For technical support, including LT1308ACF#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT1308ACF#PBF requirements.
6.How does Aetrix verify that LT1308ACF#PBF is sourced from the original manufacturer or authorized distributors?
All LT1308ACF#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 LT1308ACF#PBF meets industry standards.
7.What is the process for return or replacement of LT1308ACF#PBF?
All LT1308ACF#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT1308ACF#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 LT1308ACF#PBF part is unused and in its original packaging.
Return procedure for LT1308ACF#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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