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Analog Devices Inc. LT1931IS5#TRPBF
- Part No.:
- LT1931IS5#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- SOT-23-5 Thin, TSOT-23-5
- Datasheet:
-
LT1931IS5#TRPBF.pdf
- Description:
- IC REG CUK ADJ 1A TSOT23-5
- Quantity:
- Payment:
- Shipping:
Inventory:3,972
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Product details
Overview
LT1931IS5#TRPBF 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. It delivers –5V at 350mA or –12V at 150mA from a 5V input within a 5-lead ThinSOT™ package, targeting compact negative bias generation in imaging and analog signal chains.
For engineers reviewing the LT1931IS5#TRPBF datasheet, LT1931IS5#TRPBF pinout, LT1931IS5#TRPBF application, or LT1931IS5#TRPBF equivalent, this device offers verified low-noise (1mVP-P ripple), wide 2.6V–16V input range, <1µA shutdown current, and dual-inductor topology for simultaneous input/output filtering - critical for MR head bias, CCD bias, and GaAs FET applications requiring stable local negative supplies.
Technical Context
The LT1931IS5#TRPBF employs constant-frequency current-mode control with a 1.2MHz oscillator, enabling precise regulation and fast transient response. Its dual inductor inverting topology inherently filters both input and output currents, supporting ultra-low output ripple when paired with ceramic capacitors.
It integrates a 36V-rated switch with 400mV VCE(SAT) at 1A and features a –1.255V feedback reference referenced to VOUT, allowing accurate output voltage setting via external resistor divider. The device operates across –40°C to +85°C and supports up to 34V VIN-to-VOUT differential.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Switching Frequency | 1.2MHz - enables use of sub-3mm-height inductors and low-ESR ceramic capacitors for space-constrained designs |
| Output Voltage Range | –5V @ 350mA or –12V @ 150mA from 5V input - supports common analog bias rails without external pass devices |
| Input Voltage Range | 2.6V to 16V - accommodates single-cell Li-ion, USB, and industrial 12V supply inputs |
| Feedback Reference | –1.255V - precision reference enables stable output regulation with ±1% tolerance over temperature |
| Shutdown Current | <1µA - ensures negligible battery drain in portable systems during standby |
| Switch VCE(SAT) | 400mV at 1A - minimizes conduction loss and thermal rise in high-current inverting topologies |
| Output Ripple | 1mVP-P - achieved with ceramic output caps; critical for noise-sensitive analog circuits like CCDs and MR heads |
Pinout & Package
LT1931IS5#TRPBF is housed in a 5-lead ThinSOT™ (TSOT-23) package, 1mm profile, JEDEC MO-193 compliant. Pin 1 (SW) connects to inductor/diode node; Pin 2 (GND) requires direct local ground plane tie; Pin 3 (NFB) sources bias current for feedback divider; Pin 4 (SHDN) enables/disables operation with logic-level control; Pin 5 (VIN) accepts input supply with local bypassing.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| SW (Pin 1) | Switch collector node | Connects to coupled/uncoupled inductor and Schottky diode cathode; high dI/dt node requiring minimal trace area |
| GND (Pin 2) | Power and signal ground reference | Must be tied directly to local ground plane to maintain stability and minimize EMI coupling |
| NFB (Pin 3) | Inverting error amplifier input | Sources 4–8µA bias current; connects to resistive divider tap to set output voltage with –1.255V reference |
| SHDN (Pin 4) | Enable/disable control input | Logic-high ≥2.4V enables operation; grounded or ≤0.5V places device in ultra-low-IQ shutdown mode |
| VIN (Pin 5) | Main power input | Accepts 2.6–16V; requires local 1–4.7µF ceramic decoupling capacitor placed adjacent to pin |
Key Features
| Feature | Design Value |
|---|---|
| Dual-inductor inverting topology | Simultaneously filters input and output current ripple - eliminates need for additional LC stages in noise-critical bias supplies |
| 1.2MHz fixed-frequency operation | Enables use of 2mm-height inductors (e.g., Sumida CLS62-100) and X5R ceramics - reduces solution footprint by >40% vs. lower-frequency alternatives |
| Integrated 1A, 36V switch | Supports up to –12V/150mA from 5V while maintaining thermal safety margin in 5-lead SOT; no external MOSFET required |
| –1.255V precision feedback reference | Allows accurate output setting with standard 1% resistors; maintains regulation within 1% during large load steps |
| Low 1mVP-P output ripple | Validated with ceramic output caps (e.g., Taiyo Yuden JMK325BJ226MM); essential for MR head bias and CCD analog front-ends |
Applications
| Disk Drive MR Head Bias | Digital Camera CCD Bias |
|---|---|
Use Scenario: Generating stable –5V rail for magnetoresistive (MR) read/write head preamplifiers in HDDs. IC Role / Device Role / Timing Role: Inverting DC/DC converter providing low-noise, regulated negative supply directly from 5V system rail. Use Value: 1mVP-P ripple ensures minimal head positioning error; 350mA output supports multi-head configurations without derating. |
Use Scenario: Supplying –5V to CCD image sensor analog signal chain in compact digital cameras. IC Role / Device Role / Timing Role: High-efficiency inverting regulator delivering clean bias voltage with fast transient response to pixel clock edges. Use Value: Dual-inductor topology suppresses switching noise coupling into sensitive analog pixel outputs; ThinSOT package fits tight camera module layouts. |
| LCD Panel Bias Supply | GaAs FET RF Amplifier Bias |
Use Scenario: Providing –12V bias for LCD source driver ICs in industrial displays. IC Role / Device Role / Timing Role: Inverting converter generating high-voltage negative rail from 5V or 12V input with minimal external components. Use Value: 150mA capability at –12V meets typical source driver quiescent current; 16V max input supports direct connection to display main supply. |
Use Scenario: Delivering low-noise –5V gate bias to GaAs FETs in RF front-end modules. IC Role / Device Role / Timing Role: Local negative supply generator placed near RF stage to minimize parasitic inductance and noise injection. Use Value: Low impedance output maintains <1% regulation during RF burst loading; 1.2MHz switching avoids interference with IF bands. |
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#TRPBF | 2.2MHz switching frequency, 75% max duty cycle, 300mA @ –5V (vs. 350mA), lower inductor size requirement | Better suited for ultra-compact designs where board area is constrained more than efficiency or output current | Select LT1931AIS5#TRPBF when using ≤4.7µH coupled inductors and prioritizing solution miniaturization over peak current capability |
| LT1611ES5#TRPBF | 1.4MHz, 150mA @ –5V, no integrated 1A switch - requires external transistor; higher quiescent current (12mA vs. 6mA) | Legacy option for lower-power bias rails where cost sensitivity outweighs size and efficiency demands | Choose LT1611ES5#TRPBF only if existing design uses it and upgrade path is limited; LT1931IS5#TRPBF provides 2.3× higher output current in same footprint |
Compared with LT1931AIS5#TRPBF, LT1931IS5#TRPBF delivers higher output current and lower EMI due to its 1.2MHz frequency, while LT1611ES5#TRPBF lacks integrated switching and cannot match the power density or noise performance of LT1931IS5#TRPBF in modern imaging or RF bias applications.
Availability
LT1931IS5#TRPBF is available at Aetrix Electronics and suitable for disk drive MR head bias, digital camera CCD bias, and LCD panel bias applications requiring stable component supply, extended temperature support (–40°C to +85°C), and long-term production continuity.
Supply support for LT1931IS5#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 continues to manufacture and support its high-performance power management portfolio with emphasis on precision, reliability, and application-specific integration.
The LT1931 series was designed specifically for high-current, low-noise inverting DC/DC conversion in space-constrained analog systems - targeting imaging sensors, RF bias, and precision instrumentation where traditional charge pumps fail to meet ripple or current requirements.
FAQ
What is the maximum input voltage rating for LT1931IS5#TRPBF?
The LT1931IS5#TRPBF has an absolute maximum input voltage rating of 16V. Operation above this level risks permanent damage to the internal 36V-rated switch and control circuitry. For reliable long-term use, the recommended operating range is 2.6V to 16V, with derating advised near the upper limit under high ambient temperature conditions. Always verify VIN-to-VOUT differential does not exceed 34V.
Can LT1931IS5#TRPBF generate –12V from a 5V input, and what is the maximum load current?
Yes, the LT1931IS5#TRPBF is specified to deliver –12V at up to 150mA from a 5V input, as confirmed in the datasheet's Typical Applications section (Figure 1931 TA02). This performance assumes proper layout, recommended components (e.g., Sumida CLS62-100 inductors, ON Semiconductor MBR0520 diode), and ceramic output capacitance. Efficiency drops at higher loads, so thermal design must accommodate ~75% efficiency at full 150mA.
What is the feedback reference voltage of LT1931IS5#TRPBF, and how is output voltage set?
The LT1931IS5#TRPBF uses a precision –1.255V feedback reference voltage at the NFB pin. Output voltage is set using a resistive divider between VOUT and GND, with the divider tap connected to NFB. For example, to achieve –5V output, R1 = 29.4kΩ and R2 = 10kΩ yields VOUT = –1.255V × (1 + R1/R2). The NFB pin sources 4–8µA bias current, so resistor values must balance accuracy and current-induced error.
Does LT1931IS5#TRPBF require external compensation components?
No, the LT1931IS5#TRPBF uses internal compensation and is stable with standard ceramic output capacitors. However, a phase-lead capacitor (e.g., 220pF) may be added across R1 in the feedback divider to improve transient response damping - as shown in Figure 1 and validated in Figures 1931 F03–F04. This optional network enhances phase margin without altering basic loop stability.
Is LT1931IS5#TRPBF pin-compatible with LT1611, and what are the key functional improvements?
Yes, LT1931IS5#TRPBF is pin-for-pin compatible with LT1611 per the datasheet's feature list. Key improvements include: integrated 1A switch (vs. external transistor in LT1611), 2.3× higher output current (350mA vs. 150mA at –5V), 1mVP-P output ripple (vs. ~10mV for LT1611), and lower quiescent current (6mA vs. 12mA). These enable direct drop-in upgrades in existing LT1611-based bias supplies.
LT1931IS5#TRPBF 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#TRPBF FAQ
1.How can I place an order for LT1931IS5#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT1931IS5#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 LT1931IS5#TRPBF reliable?
The price and inventory of LT1931IS5#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT1931IS5#TRPBF is usually 5 days.
3.What payment methods are accepted for LT1931IS5#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT1931IS5#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT1931IS5#TRPBF?
LT1931IS5#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT1931IS5#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 LT1931IS5#TRPBF?
For technical support, including LT1931IS5#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT1931IS5#TRPBF requirements.
6.How does Aetrix verify that LT1931IS5#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT1931IS5#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 LT1931IS5#TRPBF meets industry standards.
7.What is the process for return or replacement of LT1931IS5#TRPBF?
All LT1931IS5#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT1931IS5#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 LT1931IS5#TRPBF part is unused and in its original packaging.
Return procedure for LT1931IS5#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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