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Analog Devices Inc. LT1931IS5#TRMPBF
- Part No.:
- LT1931IS5#TRMPBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- SOT-23-5 Thin, TSOT-23-5
- Datasheet:
-
LT1931IS5#TRMPBF.pdf
- Description:
- IC REG CUK ADJ 1A TSOT23-5
- Quantity:
- Payment:
- Shipping:
Inventory:2,102
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Product details
Overview
LT1931IS5#TRMPBF from Analog Devices (formerly Linear Technology) is a high-power, fixed-frequency inverting DC/DC converter IC with integrated 1A switch, operating at 1.2MHz to generate –5V at 350mA or –12V at 150mA from a 5V input. It features ultra-low 1mVP-P output ripple, 400mV VCE(SAT) at 1A, and operates across 2.6V–16V input range in a low-profile 5-lead ThinSOT package.
For engineers reviewing the LT1931IS5#TRMPBF datasheet, LT1931IS5#TRMPBF pinout, LT1931IS5#TRMPBF application, or LT1931IS5#TRMPBF equivalent, key selection considerations include its dual-inductor inverting topology, –1.255V feedback reference, shutdown current <1µA, and compatibility with ceramic output capacitors for noise-sensitive bias supplies in imaging and RF systems.
Technical Context
The LT1931IS5#TRMPBF employs constant-frequency current-mode control with an internal 1.2MHz oscillator and integrated 1A NPN switch rated to 36V. Its dual-inductor inverting topology filters both input and output currents, enabling stable regulation within 1% during large load transients while achieving <1mVP-P ripple with X5R ceramic capacitors.
It uses a precision –1.255V feedback reference with ±20mV tolerance, supports wide VIN–VOUT differential up to 34V, and incorporates cycle-by-cycle current limiting (1.2A typ.) and thermal shutdown. The NFB pin sources bias current, requiring external resistive divider configuration per output voltage.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Switching Frequency | 1.2MHz - enables use of compact ≤2mm-height inductors and low-ESR ceramic capacitors |
| Output Polarity & Topology | Inverting dual-inductor - provides low-noise negative rail with simultaneous input/output current filtering |
| Max Output Current | 350mA at –5V from 5V input - sufficient for MR head bias, CCD, and GaAs FET applications |
| Feedback Reference | –1.255V (±20mV) - sets precise output voltage via external resistor divider on NFB pin |
| Quiescent Current | 6mA typ. - supports efficient operation in always-on bias supply circuits |
| Shutdown Current | <1µA - enables ultra-low power state for system-level power gating |
| Switch VCE(SAT) | 400mV at 1A - minimizes conduction loss and improves efficiency at high load |
| Input Voltage Range | 2.6V to 16V - accommodates single-cell Li-ion, USB, and industrial 5V/12V rails |
Pinout & Package
The LT1931IS5#TRMPBF is housed in a 5-lead ThinSOT (TSOT-23) package, 2.9mm × 1.6mm × 1.0mm max height, with exposed pad not connected internally.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| SW (Pin 1) | Switch collector node | Connects to coupled/uncoupled inductor(s) and Schottky diode anode; high dI/dt node requiring minimal trace area |
| GND (Pin 2) | Power and signal ground | Must tie directly to local ground plane; serves as return for switch, feedback amplifier, and shutdown circuitry |
| NFB (Pin 3) | Inverting feedback input | Sources 8µA bias current; connects to resistor divider tap; reference is –1.255V relative to GND |
| SHDN (Pin 4) | Enable/disable control | Logic-high ≥2.4V enables operation; logic-low ≤0.5V disables with <1µA quiescent draw |
| VIN (Pin 5) | Input power supply | Accepts 2.6V–16V; requires local 1µF ceramic bypass capacitor placed adjacent to pin |
Key Features
| Feature | Design Value |
|---|---|
| Ultra-low output ripple | 1mVP-P with ceramic output caps - eliminates need for post-regulation LDO in noise-critical analog bias rails |
| Integrated 1A switch | 36V-rated NPN transistor with 400mV VCE(SAT) - enables high-current negative outputs without external MOSFET or driver |
| Dual-inductor inverting topology | Simultaneous input/output current filtering - reduces EMI and improves transient response vs. single-inductor charge pumps |
| Fixed 1.2MHz frequency | Stable switching independent of load or input - avoids audible noise and simplifies EMI filter design |
| Wide input range | 2.6V–16V operation - supports direct connection to Li-ion, USB, and industrial 5V/12V supplies without pre-regulation |
| Low shutdown current | <1µA - enables true zero-power standby in battery-powered imaging or portable instrumentation |
Applications
| Disk Drive MR Head Bias | Digital Camera CCD Bias |
|---|---|
Use Scenario: Generating stable –5V rail for magnetoresistive read heads in HDD preamplifier ICs. IC Role / Device Role / Timing Role: Primary inverting DC/DC converter delivering regulated negative bias with sub-mV ripple. Use Value: Enables high-SNR signal recovery by eliminating switching noise coupling into sensitive analog front-end paths. |
Use Scenario: Supplying –12V bias to CCD image sensors in DSLR and industrial cameras. IC Role / Device Role / Timing Role: High-efficiency inverting regulator powering sensor substrate and gate drivers. Use Value: Supports full-frame readout with low dark current via clean, low-impedance negative rail under dynamic load steps. |
| LCD Panel Bias | GaAs FET Bias |
Use Scenario: Providing –5V to –15V gate bias for active-matrix LCD source drivers and TFT gate lines. IC Role / Device Role / Timing Role: Compact inverting converter integrated into display timing controller PCB. Use Value: Achieves fast load transient response (<1% deviation) during frame updates, preventing ghosting or flicker. |
Use Scenario: Delivering low-noise –5V bias to GaAs FET amplifiers in RF front-ends and microwave receivers. IC Role / Device Role / Timing Role: Local negative supply generator co-located with RF ICs on compact modules. Use Value: Maintains amplifier linearity and noise figure by suppressing ripple-induced AM-to-PM distortion. |
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 |
|---|---|---|---|
| LT1931AIS5#TRMPBF | 2.2MHz switching frequency, 75% max duty cycle, 300mA @ –5V, lower inductor size requirement | Better suited for space-constrained designs using ≤4.7µH chip inductors; trades ~3–5% efficiency for smaller footprint | Select when board area and BOM cost outweigh peak efficiency; verify duty cycle ≤75% for target VIN/VOUT ratio. |
| LT1611ES5#TRPBF | 1.4MHz, 150mA @ –5V, no integrated 1A switch - requires external transistor; higher quiescent current (8mA) | Lower output capability; suitable only for light-load bias (e.g., op-amp rails), not MR head or CCD loads | Choose only if legacy LT1611 footprint reuse is mandatory and load ≤150mA; not a functional upgrade path. |
Compared with LT1931AIS5#TRMPBF, the LT1931IS5#TRMPBF delivers higher output current and efficiency at the cost of larger magnetics; versus LT1611ES5#TRPBF, it offers 2.3× more current, integrated switch, and lower quiescent draw - making it the only viable drop-in replacement for demanding analog bias applications.
Availability
LT1931IS5#TRMPBF is available at Aetrix Electronics and suitable for disk drive MR head bias, digital camera CCD bias, LCD panel bias, GaAs FET bias, and local low-noise negative supply applications requiring stable component supply across industrial temperature ranges.
Supply support for LT1931IS5#TRMPBF 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 power management ICs, known for precision, reliability, and robust design-in support.
The LT1931 series was designed specifically for high-current, low-noise inverting DC/DC conversion in space-constrained analog subsystems - targeting imaging, RF, and precision instrumentation bias rails where ripple, size, and integration are critical.
FAQ
What is the operating temperature range for the LT1931IS5#TRMPBF?
The LT1931IS5#TRMPBF is specified for –40°C to +85°C ambient operation and is guaranteed over this full industrial temperature range. Its internal thermal shutdown activates above 125°C junction temperature, and the device maintains output regulation and current-limit accuracy across the entire range without derating.
How does the LT1931IS5#TRMPBF achieve 1mVP-P output ripple?
The LT1931IS5#TRMPBF achieves 1mVP-P output ripple through its dual-inductor inverting topology that inherently filters both input and output currents, combined with fixed 1.2MHz switching that allows effective use of low-ESR X5R ceramic capacitors. When paired with recommended 4.7µF–22µF ceramic output caps, the LC filtering suppresses high-frequency switching artifacts without requiring additional LDO post-regulation.
Can the LT1931IS5#TRMPBF generate –12V from a 5V input?
Yes, the LT1931IS5#TRMPBF can deliver –12V at 150mA from a 5V input, as confirmed in the datasheet's typical performance characteristics. This requires proper selection of feedback resistors (e.g., R1 = 84.5kΩ, R2 = 10kΩ) and appropriate magnetics (e.g., two 10µH coupled inductors), and remains within the device's 34V VIN–VOUT differential limit and 84% maximum duty cycle.
What is the purpose of the NFB pin on the LT1931IS5#TRMPBF?
The NFB pin on the LT1931IS5#TRMPBF is the inverting input of the internal error amplifier, referenced to a precise –1.255V internal voltage. It sources 8µA bias current and must be connected to the tap of an external resistor divider between VOUT and GND. The divider ratio determines output voltage: VOUT = –1.255V × (1 + R1/R2), enabling accurate programmable negative rail generation.
Is the LT1931IS5#TRMPBF pin-compatible with the LT1611?
Yes, the LT1931IS5#TRMPBF is explicitly stated as pin-for-pin compatible with the LT1611 in the datasheet. Both use the same 5-lead ThinSOT package and identical pinout (SW, GND, NFB, SHDN, VIN), allowing direct replacement in existing LT1611 layouts - though the LT1931IS5#TRMPBF delivers 2.3× higher output current and integrates a 1A switch not present in the LT1611.
LT1931IS5#TRMPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- SOT-23-5 Thin, TSOT-23-5
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Function:
- Step-Up/Step-Down
- Output Configuration:
- Negative
- Topology:
- Cuk
- Output Type:
- Adjustable
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 2.45V
- Voltage - Input (Max):
- 16V
- Voltage - Output (Min/Fixed):
- -1.255V
- Voltage - Output (Max):
- -34V
- Current - Output:
- 1A (Switch)
- Frequency - Switching:
- 1.2MHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- TSOT-23-5
LT1931IS5#TRMPBF FAQ
1.How can I place an order for LT1931IS5#TRMPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT1931IS5#TRMPBF 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 LT1931IS5#TRMPBF reliable?
The price and inventory of LT1931IS5#TRMPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT1931IS5#TRMPBF is usually 5 days.
3.What payment methods are accepted for LT1931IS5#TRMPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT1931IS5#TRMPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT1931IS5#TRMPBF?
LT1931IS5#TRMPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT1931IS5#TRMPBF 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 LT1931IS5#TRMPBF?
For technical support, including LT1931IS5#TRMPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT1931IS5#TRMPBF requirements.
6.How does Aetrix verify that LT1931IS5#TRMPBF is sourced from the original manufacturer or authorized distributors?
All LT1931IS5#TRMPBF 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 LT1931IS5#TRMPBF meets industry standards.
7.What is the process for return or replacement of LT1931IS5#TRMPBF?
All LT1931IS5#TRMPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT1931IS5#TRMPBF, 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 LT1931IS5#TRMPBF part is unused and in its original packaging.
Return procedure for LT1931IS5#TRMPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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