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Analog Devices Inc. LT1614CS8#TRPBF
- Part No.:
- LT1614CS8#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
LT1614CS8#TRPBF.pdf
- Description:
- IC REG CUK ADJ 750MA 8SO
- Quantity:
- Payment:
- Shipping:
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Product details
Overview
LT1614CS8#TRPBF 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 voltages as low as 1V. It integrates an NPN power switch with 295mV VCE(SAT) at 500mA, operates at 600kHz, delivers up to 200mA at –5V from 5V input, and features a 200mV low-battery detector for portable bias applications like LCD or GaAs FET biasing.
For engineers reviewing the LT1614CS8#TRPBF datasheet, LT1614CS8#TRPBF pinout, LT1614CS8#TRPBF application, or LT1614CS8#TRPBF equivalent, this page provides verified technical context, exact pin functions, real-world efficiency curves, confirmed alternative parts with documented differences, and layout-critical design meaning for Cuk- and boost-derived inverting topologies.
Technical Context
The LT1614CS8#TRPBF implements a current-mode PWM architecture with a –1.24V internal reference and 600kHz oscillator, enabling stable regulation of negative outputs without external compensation complexity. Its error amplifier (100V/V gain, 16µmhos transconductance) drives a ramp-comparator-controlled flip-flop to regulate switch conduction on a cycle-by-cycle basis.
It supports two validated topologies: single-inductor charge-pump–boost (lower component count) and coupled/uncoupled Cuk (lower ripple, <5mVP–P with ceramic output caps). The integrated low-battery detector uses a 200mV reference and open-collector LBO output, disabled during shutdown.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Topology | Inverting DC/DC converter - directly regulates negative output voltage using internal NPN switch and external inductor/diode network. |
| Switching Frequency | 600kHz fixed - enables use of small 22µH inductors and ceramic capacitors; avoids audible noise and simplifies EMI filtering. |
| Input Voltage Range | 1V to 6V - supports single-cell Li-ion, NiMH, or 3.3V/5V rails; minimum 1V enables operation under deep discharge. |
| Output Capability | –24V at light load; –5V @ 200mA from 5V input - verified in Figure 1 and TA03–TA07 schematics with efficiency >70% across 10–200mA. |
| Quiescent Current | 1mA (active), 10µA (shutdown) - critical for battery life in always-on bias circuits such as MR head or LCD drivers. |
| Feedback Reference | –1.24V at NFB pin - sets output via resistor divider (e.g., 69.8k/24.9k for –5V); temperature drift ±0.5mV over –40°C to 85°C. |
| Low-Battery Threshold | 200mV at LBI pin - triggers LBO open-collector flag when supply drops below programmable threshold; gain = 1000V/V into 1MΩ load. |
Pinout & Package
LT1614CS8#TRPBF is housed in an 8-lead plastic SO package (SO-8, narrow 0.150", JEDEC MS-012AA), with θJA = 160°C/W and RoHS-compliant lead finish. Pin 1 is NFB, pin 8 is LBO; pin numbering follows standard SO-8 counterclockwise from notch.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| NFB (Pin 1) | Negative feedback input | Connects to resistor divider tap; –1.24V reference sets regulated output voltage; bias current flows out (–4.5µA typ). |
| VC (Pin 2) | Error amplifier compensation | External RC network (e.g., 100kΩ + 1nF) sets loop stability; trace area must be minimized to reduce noise coupling. |
| SHDN (Pin 3) | Shutdown control | Ground to disable (IQ < 10µA); tie to VIN or higher to enable; floating causes erratic behavior per Figure 13. |
| GND (Pin 4) | Power ground | Primary return path for switch, diode, and feedback currents; must connect directly to local ground plane per layout Fig. 12. |
| SW (Pin 5) | Internal NPN collector | High-dV/dt node; requires minimal trace area and direct routing to inductor/diode to suppress EMI spikes. |
| VIN (Pin 6) | Input supply | Accepts 1V–6V; requires 1µF ceramic bypass capacitor placed adjacent to pin per datasheet layout rules. |
| LBI (Pin 7) | Low-battery detector input | 200mV reference input; voltage range 0–700mV; bias current flows out (10–30nA); float if unused. |
| LBO (Pin 8) | Low-battery detector output | Open-collector NPN; sinks 10µA max; requires 1MΩ pull-up; high-Z when SHDN = low. |
Key Features
| Feature | Design Value |
|---|---|
| Fixed 600kHz switching | Enables consistent EMI profile and predictable filter design; eliminates subharmonic oscillation via ramp injection. |
| 0.1Ω effective output impedance | Delivers tight load regulation (<1% deviation from 10mA to 200mA) without external op-amp compensation. |
| 295mV VCE(SAT) at 500mA | Minimizes conduction loss in NPN switch; enables >70% efficiency at –5V/200mA from 5V input (Fig. TA01, TA04). |
| Integrated low-battery detector | 200mV reference with 1000V/V gain allows precise battery monitoring without external comparators or references. |
| Ceramic-capacitor compatible | Validated with X5R/X7R ceramics (e.g., TAIYO YUDEN EMK316BJ105MF); eliminates bulky tantalum, reduces size/cost, lowers ESR ripple. |
Applications
| MR Head Bias | LCD Bias |
|---|---|
|
Use Scenario: Providing stable negative bias voltage to magnetoresistive read heads in HDD preamplifiers. IC Role / Device Role / Timing Role: Inverting regulator generating –3.1V @ 200mA from 3.3V supply (Fig. TA03), with <5mVP–P ripple using ceramic caps. Use Value: Enables high-sensitivity signal detection by eliminating noise-induced offset drift; 1mA quiescent current extends battery runtime in portable storage. |
Use Scenario: Generating gate drive voltage for active-matrix LCD source drivers requiring –5V to –15V rails. IC Role / Device Role / Timing Role: Fixed-frequency inverter delivering –5V @ 200mA or –15V @ 80mA (Fig. TA01, TA05) with <1% line/load regulation. Use Value: Replaces discrete charge pumps; achieves 75% efficiency at full load while meeting stringent EMI limits for display modules. |
| GaAs FET Bias | Positive-to-Negative Conversion |
|
Use Scenario: Supplying gate bias for GaAs FET RF amplifiers in portable transceivers operating from single-cell batteries. IC Role / Device Role / Timing Role: Low-noise inverter producing –5V from 3V–5V input with 600kHz switching synchronized to avoid IF interference. Use Value: Maintains FET transconductance stability via <200mV output ripple; shutdown current <10µA preserves standby battery life. |
Use Scenario: Converting standard 5V logic supply to isolated –5V rail for analog front-end circuitry in data acquisition systems. IC Role / Device Role / Timing Role: Cuk-topology inverter (Fig. F04) delivering –5V @ 200mA with <5mVP–P ripple using coupled inductors and ceramic caps. Use Value: Eliminates need for isolated DC/DC modules; achieves 120dB PSRR at 600kHz via current-mode control and proper layout. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar inverting switching regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT1611CS5#TRPBF | 5-lead SOT-23, 1.4MHz switching, –5V @ 150mA, no LBO/LBI pins | Lacks low-battery detection; smaller footprint but lower output current and no shutdown flag | Choose for space-constrained designs where battery monitoring is handled externally and 150mA suffices. |
| LT1931ES5#TRPBF | 5-lead SOT-23, 1.2MHz, –5V @ 350mA, 1mVP–P ripple, no LBI/LBO | Higher frequency, higher current, lower ripple; no integrated battery monitor or shutdown control | Prefer for high-current, ultra-low-noise bias rails where system-level battery management exists. |
Compared with LT1614CS8#TRPBF, LT1611CS5#TRPBF trades battery monitoring and SO-8 thermal performance for compactness, while LT1931ES5#TRPBF offers higher output capability and lower ripple at the cost of feature integration-making LT1614CS8#TRPBF optimal for self-contained, battery-aware bias generation.
Availability
LT1614CS8#TRPBF 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-lifecycle support, and guaranteed commercial-grade (0°C to 70°C) performance.
Supply support for LT1614CS8#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-efficiency, low-voltage DC/DC conversion for portable electronics.
The LT1614CS8#TRPBF belongs to Linear's micropower inverting regulator family, designed specifically for compact, battery-sensitive bias applications including LCD, MR head, and RF FET circuits where input can drop to 1V.
FAQ
What is the minimum input voltage required for LT1614CS8#TRPBF to regulate –5V output?
The LT1614CS8#TRPBF guarantees operation down to 1V input across the commercial temperature range (0°C to 70°C), with typical minimum of 0.92V. At –5V/200mA output, it sustains regulation from 1V to 6V input per Electrical Characteristics table; efficiency drops below 60% below 2V input but remains functional.
Can LT1614CS8#TRPBF be used with ceramic output capacitors only?
Yes - the LT1614CS8#TRPBF is fully validated with ceramic output capacitors, including X5R/X7R dielectrics (e.g., TAIYO YUDEN EMK316BJ105MF). Figure 10 and TA07 show <5mVP–P ripple using 22µF ceramic caps and a 1nF phase-lead capacitor across R1, eliminating need for tantalum.
What is the purpose of the LBI and LBO pins on LT1614CS8#TRPBF?
The LBI (Pin 7) accepts a voltage divider from VIN to ground, comparing it against an internal 200mV reference; when voltage falls below threshold, LBO (Pin 8) pulls low (open-collector) to signal low battery. This function is disabled during shutdown (SHDN = GND), and LBO requires a 1MΩ pull-up per datasheet Figure 14.
Does LT1614CS8#TRPBF support both boost-derived and Cuk-derived inverting topologies?
Yes - the LT1614CS8#TRPBF supports two distinct topologies: Figure 3 shows the simpler boost+capacitive level-shift (one inductor, two diodes), while Figure 4 shows the Cuk topology (two inductors or one coupled inductor) which delivers lower output ripple (<5mVP–P) and better transient response due to continuous output inductor current.
What is the maximum output current achievable with LT1614CS8#TRPBF at –15V?
At –15V output, the LT1614CS8#TRPBF delivers up to 80mA while maintaining >65% efficiency (Figure TA06), limited by switch current limit (0.75–1.2A) and thermal constraints of the SO-8 package. Higher loads require derating or forced airflow; –5V operation supports 200mA continuously per Figure TA01.
LT1614CS8#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, 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#TRPBF FAQ
1.How can I place an order for LT1614CS8#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT1614CS8#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 LT1614CS8#TRPBF reliable?
The price and inventory of LT1614CS8#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT1614CS8#TRPBF is usually 5 days.
3.What payment methods are accepted for LT1614CS8#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT1614CS8#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT1614CS8#TRPBF?
LT1614CS8#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT1614CS8#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 LT1614CS8#TRPBF?
For technical support, including LT1614CS8#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT1614CS8#TRPBF requirements.
6.How does Aetrix verify that LT1614CS8#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT1614CS8#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 LT1614CS8#TRPBF meets industry standards.
7.What is the process for return or replacement of LT1614CS8#TRPBF?
All LT1614CS8#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT1614CS8#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 LT1614CS8#TRPBF part is unused and in its original packaging.
Return procedure for LT1614CS8#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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