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Analog Devices Inc. LTC1261LIS8#TRPBF
- Part No.:
- LTC1261LIS8#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
LTC1261LIS8#TRPBF.pdf
- Description:
- IC REG CHARGE PUMP ADJ 20MA 8SO
- Quantity:
- Payment:
- Shipping:
Inventory:4,207
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Product details
Overview
LTC1261LIS8#TRPBF from Analog Devices (formerly Linear Technology) is an industrial-grade switched-capacitor regulated voltage inverter IC that generates a stable negative output from a single positive supply. It operates from 2.7V to 5.25V, delivers up to 20mA at ±4.5% regulation, and features an open-drain REG flag indicating output-in-regulation status - used in GaAs FET biasing, portable instrumentation, and dual-rail analog signal conditioning.
For engineers reviewing the LTC1261LIS8#TRPBF datasheet, LTC1261LIS8#TRPBF pinout, LTC1261LIS8#TRPBF application, or LTC1261LIS8#TRPBF equivalent, key selection criteria include its adjustable/fixed-output capability, 650kHz internal oscillator, shutdown quiescent current of 5µA, SO-8 industrial temperature range (–40°C to +85°C), and compatibility with ceramic flying/output capacitors.
Technical Context
The LTC1261LIS8#TRPBF implements a charge-pump inverter architecture with internal 650kHz oscillator and feedback-controlled duty-cycle modulation. Regulation is achieved by comparing a resistor-divided output voltage (at ADJ pin) against a 1.23V internal reference referenced to VOUT-not ground-enabling precise negative-voltage control without external op-amps.
Its REG pin uses a secondary comparator (1.17V threshold) to assert low when output magnitude is within 5% of setpoint; SHDN enables full shutdown with 5µA supply current. The device supports both adjustable (via external R-divider) and fixed-output variants (e.g., –4V/–4.5V), with identical SO-8 packaging and industrial-grade thermal specs (θJA = 135°C/W).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage Range | Adjustable: –1.23V to –5V; fixed options also available - enables flexible bias generation across analog rails. |
| Supply Voltage Range | 2.7V to 5.25V - compatible with Li-ion, 3.3V, and 5V systems without external LDO pre-regulation. |
| Output Regulation Accuracy | ±4.5% over load (0–20mA) and supply (2.7–5.25V) - ensures stable bias for precision amplifiers and RF front-ends. |
| Quiescent Current | 650µA typical operating / 5µA shutdown - extends battery life in portable instrumentation and sensor nodes. |
| Oscillator Frequency | 650kHz fixed internal clock - enables compact 0.1µF flying capacitor and reduces EMI vs lower-frequency pumps. |
| REG Output Function | Open-drain flag asserting low when |VOUT| is within 5% of target - provides system-level power-valid signaling without additional logic. |
| Operating Temperature | –40°C to +85°C (industrial grade) - validated for automotive cabin, industrial PLC, and outdoor IoT deployments. |
Pinout & Package
Package: 8-Lead Plastic SO (Narrow, 0.150-inch width), RoHS-compliant, lead-free finish (Pb-free). Thermal resistance θJA = 135°C/W; maximum junction temperature = 150°C.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VCC (Pin 1) | Positive supply input | Accepts 2.7–5.25V; requires ≥1µF local ceramic bypass to minimize supply noise coupling into charge pump. |
| C1+ (Pin 2) | Flying capacitor top node | Connects to 0.1µF ceramic flying capacitor (C1); high dv/dt node - keep trace short and low-inductance. |
| C1– (Pin 3) | Flying capacitor bottom node | Completes C1 connection; forms charge-transfer path during clock phase reversal - critical for efficiency. |
| GND (Pin 4) | Analog and power ground reference | Low-impedance return for flying capacitor discharge and output ripple current - tie to solid ground plane. |
| ADJ (Pin 5) | Feedback adjust/compensation | For adjustable versions: sets output via resistor divider to VOUT; for fixed versions: internal divider connection point - optional 100pF to GND reduces ripple. |
| OUT (Pin 6) | Negative regulated output | Delivers up to 20mA; requires ≥3.3µF low-ESR ceramic output capacitor - ESR >2Ω causes regulation error due to spike-induced comparator false trip. |
| REG (Pin 7) | Regulation status flag | Open-drain N-channel output; sinks ≥5mA at 5V VCC - must be externally pulled up to monitor power-good condition. |
| SHDN (Pin 8) | Shutdown control | Active-low enable; internal 5µA pull-down allows floating = operational mode - simplifies PCB layout in always-on applications. |
Key Features
| Feature | Design Value |
|---|---|
| Three-capacitor operation | Only 0.1µF flying + input/output bypass caps required - eliminates inductors and simplifies BOM for space-constrained designs. |
| Internal 650kHz oscillator | No external timing components needed - ensures consistent switching frequency across temperature and supply variations. |
| Reference-referred-to-VOUT topology | 1.23V bandgap reference referenced to OUT (not GND) - enables accurate regulation of negative voltages without level-shifting circuitry. |
| REG output with 5% tolerance window | Provides deterministic power-valid indication - avoids false asserts during startup or transient load events. |
| Industrial temperature qualification | Guaranteed performance from –40°C to +85°C - suitable for deployment in uncontrolled environments without derating. |
Applications
| GaAs FET Bias Generator | Negative Supply for Dual-Rail Op-Amps |
|---|---|
Use Scenario: Generating –4V bias for GaAs power amplifier stages in portable radios and satellite transceivers. IC Role / Device Role / Timing Role: Regulated negative voltage source enabling optimal gate bias point for P-channel GaAs FETs under varying battery voltage. Use Value: Maintains constant –4V output across 2.7–5.25V input range, ensuring stable amplifier gain and linearity without manual trimming or external regulators. | Use Scenario: Providing clean –2.5V rail for rail-to-rail input/output op-amps in data acquisition systems. IC Role / Device Role / Timing Role: Charge-pump inverter delivering low-noise negative supply synchronized to internal 650kHz clock - no external clock required. Use Value: Eliminates need for transformer-based or inductor-based negative supplies, reducing size, cost, and EMI in compact sensor interface modules. |
| Battery-Powered Instrumentation | Single-Supply Signal Conditioning |
Use Scenario: Powering precision ADC drivers and reference buffers in handheld multimeters and portable oscilloscopes. IC Role / Device Role / Timing Role: Low-quiescent-current (5µA shutdown) inverter supplying regulated negative rail during sleep mode and fast wake-up (<1.5ms turn-on time). Use Value: Extends battery life while maintaining fast response to measurement triggers - critical for energy-efficient test equipment. | Use Scenario: Enabling bipolar signal swing in single-supply microcontroller-based analog front-ends (e.g., audio codec interfaces). IC Role / Device Role / Timing Role: Adjustable-output inverter generating –1.23V to –5V from MCU's 3.3V rail - supports programmable gain stage biasing. Use Value: Allows dynamic adjustment of signal offset without hardware changes, improving design flexibility and reducing variant SKUs. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar switched-capacitor voltage inverter applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| MAX680ESA+ | Fixed –5V output only; 100kHz oscillator; requires 2 flying caps; ±1.5% regulation; SO-8 package | Lacks adjustable output and REG flag; higher output ripple due to lower frequency | Choose when fixed –5V suffices and lowest BOM count is priority over regulation accuracy or status signaling. |
| TPS60403DBVR | Adjustable –1.5V to –5.5V; 1MHz oscillator; 2.7–5.5V input; ±3% regulation; SOT-23-6 package | Smaller footprint but lower output current (60mA max); no REG pin; different pinout and layout | Prefer for ultra-compact designs where 60mA load and absence of power-valid signaling are acceptable. |
Compared with MAX680ESA+ and TPS60403DBVR, the LTC1261LIS8#TRPBF uniquely combines adjustable/fixed output flexibility, integrated REG flag for system monitoring, industrial temperature rating, and proven low-ripple performance with standard SO-8 layout - making it optimal for reliability-critical analog biasing.
Availability
LTC1261LIS8#TRPBF is available at Aetrix Electronics and suitable for GaAs FET bias generators, portable instrumentation power supplies, and dual-rail analog signal conditioning requiring stable component supply across extended temperature ranges.
Supply support for LTC1261LIS8#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 technical and manufacturing continuity for legacy Linear products including the LTC1261L series.
The LTC1261L product line was designed specifically for compact, low-noise negative voltage generation in battery-powered and space-constrained analog systems - emphasizing minimal external components, robust regulation, and industrial-grade reliability.
FAQ
What is the minimum input voltage required for LTC1261LIS8#TRPBF to regulate at –4V output?
The LTC1261LIS8#TRPBF requires a minimum supply voltage of 4.35V to guarantee ±4.5% regulation at –4V output across 0–20mA load and –40°C to +85°C. Below 4.35V, regulation may degrade - confirmed in Electrical Characteristics Table (Note 5). For reliable –4V operation, maintain VCC ≥4.35V.
Can LTC1261LIS8#TRPBF generate –1.23V output, and what resistor values are needed?
Yes, LTC1261LIS8#TRPBF supports adjustable output down to –1.23V using an external resistor divider from OUT to ADJ. To set VOUT = –1.23V, connect R1 between OUT and ADJ, R2 between ADJ and GND, with R1 = 0Ω and R2 open - effectively grounding ADJ. For other values, use R1/R2 ratio per VOUT = –1.23V × (1 + R1/R2).
Does LTC1261LIS8#TRPBF require an external compensation capacitor on the ADJ pin?
An external 100pF capacitor from ADJ to GND is optional but recommended to reduce output ripple, especially under heavy loads or with high-ESR output capacitors. The LTC1261LIS8#TRPBF datasheet confirms this improves regulation loop bandwidth and prevents "hunting" behavior - verified in Figure 2 and Applications Information section.
What is the maximum continuous output current for LTC1261LIS8#TRPBF at –4V and 5V input?
The LTC1261LIS8#TRPBF delivers up to 20mA continuous output current at –4V with 5V input while maintaining ±4.5% regulation - specified in both Electrical Characteristics (IOUT column) and Typical Performance Characteristics (Figure G02). Output current drops linearly below 4.35V input per Minimum Required VCC vs VOUT curve (Figure G01).
How does the REG pin on LTC1261LIS8#TRPBF behave during startup and load transients?
The REG pin on LTC1261LIS8#TRPBF remains high-impedance (open-drain off) until output reaches within 5% of target - then pulls low. During startup, it asserts low after ~250–1500µs (depending on load), and during load transients, it releases only if |VOUT| deviates >5% - confirmed by Turn-On Time spec and REG functional description in Pin Functions section.
LTC1261LIS8#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-Down
- Output Configuration:
- Negative
- Topology:
- Charge Pump
- Output Type:
- Adjustable
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 2.7V
- Voltage - Input (Max):
- 5.25V
- Voltage - Output (Min/Fixed):
- -1.23V
- Voltage - Output (Max):
- -5V
- Current - Output:
- 20mA
- Frequency - Switching:
- 650kHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-SO
LTC1261LIS8#TRPBF FAQ
1.How can I place an order for LTC1261LIS8#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC1261LIS8#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 LTC1261LIS8#TRPBF reliable?
The price and inventory of LTC1261LIS8#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC1261LIS8#TRPBF is usually 5 days.
3.What payment methods are accepted for LTC1261LIS8#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC1261LIS8#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC1261LIS8#TRPBF?
LTC1261LIS8#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC1261LIS8#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 LTC1261LIS8#TRPBF?
For technical support, including LTC1261LIS8#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC1261LIS8#TRPBF requirements.
6.How does Aetrix verify that LTC1261LIS8#TRPBF is sourced from the original manufacturer or authorized distributors?
All LTC1261LIS8#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 LTC1261LIS8#TRPBF meets industry standards.
7.What is the process for return or replacement of LTC1261LIS8#TRPBF?
All LTC1261LIS8#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC1261LIS8#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 LTC1261LIS8#TRPBF part is unused and in its original packaging.
Return procedure for LTC1261LIS8#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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