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Analog Devices Inc. LT1611CS5#TRPBF
- Part No.:
- LT1611CS5#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- SC-74A, SOT-753
- Datasheet:
-
LT1611CS5#TRPBF.pdf
- Description:
- IC REG CUK ADJ 550MA SOT23-5
- Quantity:
- Payment:
- Shipping:
Inventory:6,412
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Product details
Overview
LT1611CS5#TRPBF from Analog Devices (formerly Linear Technology) is a current-mode, fixed-frequency inverting DC/DC switching regulator in a 5-lead SOT-23 package. It generates –5V at 150mA from a 5V input, operates down to 1.1V input, switches at 1.4MHz, delivers 0.14Ω effective output impedance, and achieves <1µA shutdown current. It replaces charge-pump solutions in low-noise bias generation for analog sensors and imaging circuits.
For engineers reviewing the LT1611CS5#TRPBF datasheet, LT1611CS5#TRPBF pinout, LT1611CS5#TRPBF application, or LT1611CS5#TRPBF equivalent, key selection criteria include its dual-inductor inverting topology, –1.23V internal reference, 36V switch rating, 1mVP–P output ripple capability with ceramic output capacitors, and compatibility with compact 2mm-height magnetics.
Technical Context
The LT1611CS5#TRPBF implements a current-mode PWM architecture with internal slope compensation and a fixed 1.4MHz oscillator. Its dual-inductor Cuk-derived topology filters both input and output sides, enabling ultra-low noise operation without low-frequency beat components typical of charge pumps.
It features an internal –1.23V reference tied to the NFB pin, cycle-by-cycle switch current regulation, and automatic pulse-skipping at light loads. The 300mV VCE(SAT) at 300mA and 36V maximum SW voltage support wide VIN-to-VOUT differential operation up to 33V.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Topology | Inverting Cuk converter - enables simultaneous input/output filtering and <1mVP–P ripple with proper layout and ceramic output caps |
| Switching Frequency | 1.4MHz (TYP) - allows use of 2mm-height inductors and sub-100nF ceramic timing/output capacitors |
| Output Voltage Accuracy | ±2.4% over temp - based on –1.23V ±2.5mV feedback reference, enabling stable negative rail regulation |
| Max Output Current | 150mA at –5V from 5V input - limited by 800mA switch current limit and thermal design in SOT-23 |
| Quiescent Current | 3mA no-load, 0.5µA in shutdown - supports battery-powered systems requiring long standby life |
| Input Voltage Range | 1.1V to 10V - enables single-cell Li-ion, 3.3V, and 5V system rail operation |
| Switch Rating | 36V max SW voltage - permits up to 33V VIN-to-VOUT differential, e.g., 36V input → –5V output |
Pinout & Package
LT1611CS5#TRPBF is housed in a 5-lead plastic SOT-23 (SC-74A) package, 2.8–3.0mm × 1.9mm × 1.1–1.3mm, with gull-wing leads and 0.95mm lead pitch. Thermal resistance θJA = 256°C/W.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| SW (Pin 1) | Internal NPN switch collector | Carries high di/dt switching current; requires minimal trace area and direct connection to inductor L1A to reduce EMI |
| GND (Pin 2) | Power and signal ground reference | Must tie directly to local ground plane; serves as return for switch, feedback, and shutdown paths |
| NFB (Pin 3) | Negative feedback input | Accepts –1.23V reference voltage; connects to resistor divider tap for output voltage setting (e.g., R1=29.4kΩ, R2=10kΩ for –5V) |
| SHDN (Pin 4) | Active-low enable control | Drives device into <1µA shutdown when pulled ≤0.3V; requires ≥1V to enable; bias current <50µA at 3V |
| VIN (Pin 5) | Input supply connection | Supplies internal circuitry and switch base drive; must be locally bypassed with ≥1µF ceramic capacitor |
Key Features
| Feature | Design Value |
|---|---|
| Fixed 1.4MHz switching frequency | Enables consistent EMI profile and use of miniature 22µH coupled inductors (e.g., Sumida CLS62-220) under 2mm height |
| Dual-inductor inverting topology | Provides inherent input and output filtering - eliminates need for external LC filters in noise-sensitive applications like CCD bias |
| Internally compensated current-mode control | Removes need for external compensation network; supports stable operation with ceramic output capacitors down to 22µF |
| Low-noise 1mVP–P output ripple | Achievable with ceramic C3 (e.g., Taiyo Yuden JMK325BJ226MM) and proper layout - critical for MR head and GaAs FET bias rails |
| 36V switch voltage rating | Supports high-differential applications such as 12V input → –5V output (300mA) or 4-cell → –10V conversion |
Applications
| MR Head Bias | Digital Camera CCD Bias |
|---|---|
Use Scenario: Providing stable, ultra-low-noise negative bias voltage for magnetoresistive (MR) read heads in hard disk drives. IC Role / Device Role / Timing Role: Inverting DC/DC regulator generating –5V rail with <1mVP–P ripple to minimize head positioning error and signal distortion. Use Value: Enables higher areal density storage by reducing magnetic read-head noise floor through clean, regulated negative supply. | Use Scenario: Supplying precise negative bias to CCD image sensor vertical/horizontal shift registers. IC Role / Device Role / Timing Role: Fixed-frequency inverting regulator delivering –5V at 100mA from 3V supply, synchronized to pixel clock timing. Use Value: Eliminates charge-pump-induced low-frequency noise that corrupts analog image data during integration periods. |
| LCD Bias Generation | GaAs FET Bias |
Use Scenario: Generating negative gate bias (e.g., –10V) for active-matrix LCD source driver ICs in portable displays. IC Role / Device Role / Timing Role: Dual-inductor inverting converter operating from 4-cell alkaline (6.5V) to deliver –10V/60mA with >70% efficiency. Use Value: Replaces discrete transformer-based solutions with <0.25 in² PCB footprint while maintaining display contrast stability across temperature. | Use Scenario: Supplying low-noise –5V gate bias to GaAs FETs in RF front-end modules for satellite communications receivers. IC Role / Device Role / Timing Role: High-PSRR inverting regulator with 0.14Ω effective output impedance, rejecting switching noise from adjacent digital sections. Use Value: Maintains FET transconductance stability and minimizes phase noise in L-band downconverters via ripple-free bias rail. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar inverting DC/DC regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT1614EMS8#PBF | MSOP-8 package; includes low-battery detector; 200mA output capability; same 1.4MHz frequency and –1.23V reference | Targeted at space-constrained industrial sensors requiring supply monitoring; larger footprint but higher current | Select LT1614EMS8#PBF when battery voltage supervision is required and MSOP-8 layout is acceptable |
| LT3467EDD#TRPBF | 3mm × 3mm DFN-10; 1.2MHz switching; integrated Schottky; 250mA output; requires external feedback resistors | Better suited for high-current portable audio codecs where board area is less constrained than height | Choose LT3467EDD#TRPBF when higher output current and integrated diode simplify BOM, and DFN thermal performance is needed |
Compared with LT1611CS5#TRPBF, LT1614EMS8#PBF adds system-level monitoring at the cost of larger package and higher quiescent current, while LT3467EDD#TRPBF trades SOT-23 compactness for higher current and integrated power stage - neither is pin-compatible, but both address overlapping negative rail generation needs with distinct trade-offs in size, integration, and feature set.
Availability
LT1611CS5#TRPBF is available at Aetrix Electronics and suitable for MR head bias, CCD imaging, LCD panel drivers, and GaAs FET bias applications requiring stable component supply, low-noise negative voltage generation, and SOT-23 footprint constraints.
Supply support for LT1611CS5#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 full product support, documentation, and manufacturing continuity for legacy Linear parts including the LT1611 family.
The LT1611CS5#TRPBF belongs to Linear's precision inverting DC/DC converter product line, designed specifically for compact, low-noise negative rail generation in portable imaging, data storage, and RF bias applications where charge pumps fall short in regulation and ripple performance.
FAQ
What is the minimum input voltage required for LT1611CS5#TRPBF to regulate –5V output?
The LT1611CS5#TRPBF requires a minimum input voltage of 1.1V to operate, but to sustain –5V output regulation at 150mA, the input must be ≥5V ±10%. At lower inputs (e.g., 3V), output current drops to 100mA for –5V. The 1.1V spec reflects start-up capability under light load, not full-load regulation.
Can LT1611CS5#TRPBF generate –10V output, and what design changes are needed?
Yes, LT1611CS5#TRPBF can generate –10V output using the dual-inductor topology. To achieve –10V/60mA from a 4-cell (6.5V) input, adjust the feedback divider (e.g., R1 = 68.1kΩ, R2 = 10kΩ) and use 15µH inductors (e.g., Sumida CL562-150). Input capacitor must be rated for ≥10V, and diode should handle peak reverse voltage ≥16V.
What is the purpose of the CPL capacitor in LT1611CS5#TRPBF applications?
The CPL capacitor (e.g., 1200pF) connects in parallel with R1 to add phase lead compensation. In LT1611CS5#TRPBF designs, it improves transient response - reducing load-step settling time from 150µs to 40µs - and enhances phase margin when using low-ESR ceramic output capacitors, preventing instability without increasing output ripple.
Does LT1611CS5#TRPBF require external compensation components?
No, LT1611CS5#TRPBF is internally compensated and requires no external compensation network. Its current-mode architecture with built-in ramp generator and RC/CC network ensures stability with standard output capacitor values (22µF tantalum or ceramic). Only optional CPL is used for transient optimization - not for basic loop stability.
How does LT1611CS5#TRPBF achieve 1mVP–P output ripple when datasheet shows 20mVP–P in Figure 10?
The 20mVP–P ripple in Figure 10 results from using a 22µF tantalum capacitor (ESR ≈ 1Ω). LT1611CS5#TRPBF achieves 1mVP–P by substituting a low-ESR ceramic capacitor (e.g., Taiyo Yuden JMK325BJ226MM, ESR ≈ 2mΩ) and implementing the recommended layout - especially the cut ground copper at D1's cathode - as shown in Figures 11–12.
LT1611CS5#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- SC-74A, SOT-753
- 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):
- 0.9V
- Voltage - Input (Max):
- 10V
- Voltage - Output (Min/Fixed):
- -0.9V
- Voltage - Output (Max):
- -10V (Switch)
- Current - Output:
- 550mA (Switch)
- Frequency - Switching:
- 1.4MHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- 0°C ~ 70°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- SOT-23-5
LT1611CS5#TRPBF FAQ
1.How can I place an order for LT1611CS5#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT1611CS5#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 LT1611CS5#TRPBF reliable?
The price and inventory of LT1611CS5#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT1611CS5#TRPBF is usually 5 days.
3.What payment methods are accepted for LT1611CS5#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT1611CS5#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT1611CS5#TRPBF?
LT1611CS5#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT1611CS5#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 LT1611CS5#TRPBF?
For technical support, including LT1611CS5#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT1611CS5#TRPBF requirements.
6.How does Aetrix verify that LT1611CS5#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT1611CS5#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 LT1611CS5#TRPBF meets industry standards.
7.What is the process for return or replacement of LT1611CS5#TRPBF?
All LT1611CS5#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT1611CS5#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 LT1611CS5#TRPBF part is unused and in its original packaging.
Return procedure for LT1611CS5#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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