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Analog Devices Inc. LT1614CS8#PBF
- Part No.:
- LT1614CS8#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
LT1614CS8#PBF.pdf
- Description:
- IC REG CUK ADJ 750MA 8SO
- Quantity:
- Payment:
- Shipping:
Inventory:247
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Product details
Overview
LT1614CS8#PBF from Analog Devices (formerly Linear Technology) is a fixed-frequency, current-mode inverting switching regulator IC that generates negative output voltages down to –24V from input as low as 1V. It integrates an NPN power switch with 295mV VCE(SAT) at 500mA, operates at 600kHz, and features a 200mV low-battery detector reference. It is used in LCD bias, GaAs FET bias, and positive-to-negative conversion circuits requiring compact, low-noise DC/DC solutions.
For engineers reviewing the LT1614CS8#PBF datasheet, LT1614CS8#PBF pinout, LT1614CS8#PBF application, or LT1614CS8#PBF equivalent, key selection criteria include its –1.24V feedback reference, 1mA quiescent current, 600kHz switching frequency, shutdown current <10µA, and compatibility with ceramic output capacitors for low-ripple designs.
Technical Context
The LT1614CS8#PBF employs a current-mode PWM architecture with a fixed 600kHz oscillator and internal ramp compensation to avoid subharmonic oscillation above 50% duty cycle. Its error amplifier has 100V/V gain and 16µmhos transconductance, referenced to –1.24V at the NFB pin.
It supports two inverting topologies: charge-pump–enhanced boost (single inductor) and Cuk-derived dual-inductor configuration. The latter enables <5mVP–P output ripple when paired with low-ESR ceramic capacitors and proper layout-especially grounding D1's cathode directly to the IC's GND pin.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Topology | Inverting DC/DC converter with integrated NPN switch - enables direct generation of regulated negative rail from positive input. |
| Switching Frequency | 600kHz (typical), fixed - ensures predictable EMI profile and allows use of small 22µH inductors and ceramic capacitors. |
| Input Voltage Range | 1V to 6V - supports single-cell Li-ion, NiMH, or 3.3V/5V system rails without pre-regulation. |
| Output Voltage Range | Up to –24V - set via external resistor divider on NFB pin; feedback reference is –1.24V (±30mV). |
| Quiescent Current | 1mA (typical) - enables high light-load efficiency in battery-powered systems such as portable instrumentation. |
| Shutdown Current | <10µA - preserves battery life during standby; SHDN pin must be pulled to GND to activate shutdown. |
| VCE(SAT) @ 500mA | 295mV (25°C) - minimizes conduction loss and thermal rise in the internal switch under full load. |
| Low-Battery Threshold | 200mV (±10mV) - precise LBI comparator reference enables accurate battery voltage monitoring without external components. |
Pinout & Package
LT1614CS8#PBF is housed in an 8-lead plastic SO package (SO-8, narrow 0.150", JEDEC MS-012AA), with θJA = 160°C/W. Pin 1 is NFB; pin 4 is GND; pin 5 is SW; pin 6 is VIN; pin 7 is LBI; pin 8 is LBO. All pins are electrically and thermally optimized for high-frequency switching layouts.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| NFB (Pin 1) | Negative feedback input | Connects to resistive divider tap; references –1.24V; sets output voltage with ±0.3% accuracy over temperature. |
| VC (Pin 2) | Error amplifier compensation node | External RC network (e.g., 100kΩ + 1nF) provides loop stability; trace area must be minimized to reduce noise coupling. |
| SHDN (Pin 3) | Enable/disable control | Drive to GND disables regulator and reduces IQ to <10µA; floating causes erratic operation - must not be left unconnected. |
| GND (Pin 4) | Power and signal ground reference | Primary return path for switch current and feedback; must connect directly to local ground plane with low-inductance routing. |
| SW (Pin 5) | Internal NPN switch collector | High di/dt node; requires minimal trace area and tight coupling to GND to suppress EMI; connects to inductor and Schottky diode anode. |
| VIN (Pin 6) | Input supply | Accepts 1V–6V; requires 1µF ceramic bypass capacitor placed adjacent to pin with short, low-impedance GND path. |
| LBI (Pin 7) | Low-battery detector input | Compares external voltage against 200mV internal reference; input bias current ≤50nA (85°C); float if unused. |
| LBO (Pin 8) | Open-collector low-battery output | Sinks up to 10µA; requires external 1MΩ pull-up; high-impedance when SHDN = GND; signals battery depletion to host controller. |
Key Features
| Feature | Design Value |
|---|---|
| Fixed 600kHz switching | Enables consistent EMI filtering and predictable transient response; eliminates need for frequency tuning in layout. |
| Integrated NPN switch with 295mV VCE(SAT) | Reduces conduction loss and thermal stress at 500mA load, supporting >75% efficiency at 200mA output. |
| –1.24V precision feedback reference | Allows accurate output regulation across temperature (±30mV) without trimming; simplifies resistor selection for target VOUT. |
| 200mV low-battery detector | Provides system-level battery monitoring with no external reference or comparator; LBO output interfaces directly with µC GPIO. |
| Ceramic-capacitor compatible design | Eliminates reliance on bulky tantalum capacitors; enables compact, high-reliability designs with <5mVP–P ripple using X5R/X7R MLCCs. |
| Current-mode PWM control | Delivers inherent cycle-by-cycle overcurrent protection and stable operation across wide input/output ratios and load steps. |
Applications
| MR Head Bias | LCD Bias |
|---|---|
Use Scenario: Providing stable negative bias voltage to magnetoresistive (MR) read heads in hard disk drive preamplifiers. IC Role / Device Role / Timing Role: Inverting regulator generating –5V at 200mA from 5V supply; delivers low-noise, tightly regulated rail critical for analog front-end sensitivity. Use Value: Enables >75% efficiency and <40mVP–P ripple with tantalum output caps, or <5mVP–P with ceramics - preserving SNR in high-density storage systems. |
Use Scenario: Supplying negative gate bias for active-matrix LCD column drivers in portable medical displays. IC Role / Device Role / Timing Role: Compact inverting DC/DC converter delivering –15V at 80mA from 5V input; operates down to 1V input during brownout conditions. Use Value: Supports fast load-step response (<100µs settling) and maintains regulation during battery voltage sag - ensuring consistent contrast and grayscale fidelity. |
| GaAs FET Bias | Positive-to-Negative Conversion |
Use Scenario: Generating negative gate voltage for GaAs FETs in RF front-end modules of handheld test equipment. IC Role / Device Role / Timing Role: Low-quiescent-current (1mA) inverter producing –3.1V at 200mA from 3.3V supply; includes low-battery detection for field-deployable units. Use Value: Delivers <10µA shutdown current and 200mV LBI threshold - extends battery runtime while enabling automatic power-down before deep discharge. |
Use Scenario: Converting 5V system rail to –5V auxiliary supply for op-amp dual-rail operation in industrial sensor signal conditioning. IC Role / Device Role / Timing Role: Fixed-frequency inverting regulator with Cuk topology support; achieves <5mVP–P ripple using coupled inductors and ceramic caps. Use Value: Eliminates need for external linear regulators or discrete charge pumps - reducing BOM count, board area, and thermal overhead in space-constrained enclosures. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar inverting DC/DC converter applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT1611IS5#TRMPBF | 5-lead SOT-23, 1.4MHz switching, –5V/150mA max; no LBI/LBO; lower IQ (85µA) | Targeted at ultra-compact, low-power applications where battery monitoring is handled externally | Select when board space is critical and low-battery detection is implemented elsewhere. |
| LT1931ES5#TRMPBF | 5-lead SOT-23, 1.2MHz, –5V/350mA, 1mVP–P ripple spec; no LBI/LBO; higher peak current capability | Optimized for low-noise analog supplies where ripple performance outweighs feature count | Select when sub-millivolt ripple is mandatory and system-level battery monitoring exists. |
Compared with LT1614CS8#PBF, LT1611IS5#TRMPBF offers smaller footprint and higher frequency but omits integrated battery monitoring, while LT1931ES5#TRMPBF delivers superior ripple performance at higher output current but lacks the 200mV LBI reference and shutdown-controlled LBO output.
Availability
LT1614CS8#PBF is available at Aetrix Electronics and suitable for MR head bias, LCD bias, GaAs FET bias, and positive-to-negative conversion applications requiring stable component supply, long-term lifecycle support, and guaranteed commercial-grade temperature performance (0°C to 70°C).
Supply support for LT1614CS8#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, Inc. (acquired Linear Technology in 2017) is a global leader in high-performance analog, mixed-signal, and power management semiconductors, serving industrial, automotive, communications, and healthcare markets.
The LT1614CS8#PBF belongs to Linear Technology's legacy micropower inverting regulator product line, designed specifically for space- and efficiency-constrained applications needing clean, regulated negative rails from low-input-voltage sources.
FAQ
What is the minimum input voltage required for LT1614CS8#PBF to operate?
The LT1614CS8#PBF operates with a minimum input voltage of 1V (typical), with specification guaranteed down to 0.92V at 25°C. At –40°C, the minimum valid input rises to 1.1V, while at 85°C it drops to 0.8V. This ultra-low VIN capability makes LT1614CS8#PBF suitable for single-cell battery systems including NiMH and LiFePO₄, where headroom is limited. Input below 1V may cause regulation failure or shutdown.
Does LT1614CS8#PBF support both single-inductor and dual-inductor inverting topologies?
Yes, LT1614CS8#PBF supports both configurations: a charge-pump–augmented boost topology (single inductor, higher ripple) and the Cuk-derived dual-inductor topology (lower ripple, higher efficiency). The datasheet provides complete schematics, component values, and layout guidance for both. Dual-inductor implementation with coupled windings (e.g., Coiltronics CTX10-1) further reduces size and improves ripple suppression in LT1614CS8#PBF designs.
What is the function of the LBI and LBO pins on LT1614CS8#PBF?
The LBI (Low-Battery Input) pin on LT1614CS8#PBF accepts an external voltage divider to compare against an internal 200mV reference; the LBO (Low-Battery Output) pin is an open-collector output that pulls low when LBI voltage falls below threshold. Both functions are disabled when SHDN is grounded. This integrated detector eliminates external comparators in battery-powered systems - for example, enabling host µC to initiate graceful shutdown when LT1614CS8#PBF detects cell voltage decay.
Can LT1614CS8#PBF use ceramic capacitors for both input and output filtering?
Yes, LT1614CS8#PBF is fully compatible with ceramic capacitors on both input and output. The datasheet explicitly recommends X5R/X7R dielectric types for the 1µF "flying" capacitor (C2) and validates 22µF–33µF ceramic output capacitors (e.g., Taiyo Yuden EMK316BJ105MF) achieving <5mVP–P ripple. Input bypass requires ≥1µF ceramic placed adjacent to VIN pin. Ceramic use eliminates ESR-related losses and improves reliability versus tantalum alternatives in LT1614CS8#PBF applications.
What is the maximum output current capability of LT1614CS8#PBF?
The LT1614CS8#PBF internal NPN switch is rated for 500mA continuous collector current with 295mV VCE(SAT) at 25°C. Practical output current depends on topology, inductor saturation rating, thermal management, and output voltage. For example, the datasheet demonstrates –5V/200mA and –15V/80mA operation. With proper heatsinking and low-DCR inductors, LT1614CS8#PBF reliably delivers up to 200mA at –5V or 80mA at –15V while maintaining regulation and thermal safety.
LT1614CS8#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:
- Negative
- Topology:
- Cuk
- Output Type:
- Adjustable
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 1V
- Voltage - Input (Max):
- 6V
- Voltage - Output (Min/Fixed):
- -1.24V
- Voltage - Output (Max):
- -24V
- Current - Output:
- 750mA (Switch)
- Frequency - Switching:
- 600kHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- 0°C ~ 70°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-SO
LT1614CS8#PBF FAQ
1.How can I place an order for LT1614CS8#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT1614CS8#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 LT1614CS8#PBF reliable?
The price and inventory of LT1614CS8#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT1614CS8#PBF is usually 5 days.
3.What payment methods are accepted for LT1614CS8#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT1614CS8#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT1614CS8#PBF?
LT1614CS8#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT1614CS8#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 LT1614CS8#PBF?
For technical support, including LT1614CS8#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT1614CS8#PBF requirements.
6.How does Aetrix verify that LT1614CS8#PBF is sourced from the original manufacturer or authorized distributors?
All LT1614CS8#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 LT1614CS8#PBF meets industry standards.
7.What is the process for return or replacement of LT1614CS8#PBF?
All LT1614CS8#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT1614CS8#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 LT1614CS8#PBF part is unused and in its original packaging.
Return procedure for LT1614CS8#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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