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Analog Devices Inc. LTC1261LIMS8-4#TRPBF
- Part No.:
- LTC1261LIMS8-4#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 8-TSSOP, 8-MSOP (0.118", 3.00mm Width)
- Datasheet:
-
LTC1261LIMS8-4#TRPBF.pdf
- Description:
- IC REG CHARG PUMP -4V 20MA 8MSOP
- Quantity:
- Payment:
- Shipping:
Inventory:3,990
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Product details
Overview
LTC1261LIMS8-4#TRPBF from Analog Devices (formerly Linear Technology) is a fixed-output switched-capacitor voltage inverter IC that generates a regulated –4V output from a single 4.35V to 5.25V positive supply. It delivers up to 20mA output current with ±4.5% regulation accuracy, features an open-drain REG flag indicating regulation status, and operates with only three external capacitors. It is used in GaAs FET bias generation and battery-powered negative rail applications.
For engineers reviewing the LTC1261LIMS8-4#TRPBF datasheet, LTC1261LIMS8-4#TRPBF pinout, LTC1261LIMS8-4#TRPBF application, or LTC1261LIMS8-4#TRPBF equivalent, key selection criteria include guaranteed –4V output regulation across industrial temperature (–40°C to +85°C), shutdown quiescent current of 5µA, MSOP-8 package compatibility, and REG pin behavior confirming output validity under load.
Technical Context
The LTC1261LIMS8-4#TRPBF implements a 650kHz internal oscillator-driven charge pump topology to invert and regulate input voltage. Its feedback loop compares a divided replica of VOUT at the ADJ/COMP pin against an internal 1.23V reference, enabling cycle-by-cycle duty-cycle control to maintain regulation.
Regulation is enforced via a comparator (COMP1) referenced to VOUT, while a second comparator (COMP2, 1.17V threshold) drives the open-drain REG output when output magnitude is within 5% of the setpoint. The device uses internal resistor division for fixed –4V output, eliminating external setting resistors.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | Fixed –4.0V ±4.5% over 4.35V–5.25V input and 0–20mA load - ensures stable bias for GaAs FETs without trimming. |
| Supply Range | 4.35V to 5.25V - compatible with standard 5V logic rails and tolerant of typical 5% tolerance supplies. |
| Output Current | Up to 20mA - sufficient for biasing multiple RF power transistors or low-power analog circuitry. |
| Quiescent Current | 650µA typical operating / 5µA shutdown - enables long battery life in portable instrumentation. |
| Oscillator Frequency | 650kHz typical - enables compact 0.1µF flying capacitor and low-output-ripple design with 3.3µF output cap. |
| REG Output Logic | Open-drain, sinks ≥5mA at 5V VCC - requires external pull-up; asserts low when |VOUT| ≥ 95% of setpoint (i.e., ≤ –3.8V). |
| Operating Temp | –40°C to +85°C - qualified for industrial environments including automotive infotainment and industrial sensors. |
Pinout & Package
Package: 8-pin MSOP (MS8), 3.0mm × 3.0mm × 0.86mm body, exposed pad not electrically connected, RoHS-compliant lead-free finish.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VCC (Pin 1) | Positive supply input | Must be bypassed with ≥1µF ceramic capacitor near pin; powers internal oscillator and charge pump switches. |
| C1+ (Pin 2) | Flying capacitor top connection | Connects to positive terminal of 0.1µF flying capacitor; forms charge-transfer path during pump phase. |
| C1– (Pin 3) | Flying capacitor bottom connection | Connects to negative terminal of 0.1µF flying capacitor; referenced to ground during charging, to OUT during transfer. |
| GND (Pin 4) | Analog ground reference | Low-impedance return for VCC bypass, flying cap, and output cap; critical for regulation stability. |
| ADJ/COMP (Pin 5) | Feedback/compensation node | Internally tied to fixed resistor divider for –4V output; optional 100pF to ground reduces output ripple. |
| OUT (Pin 6) | Negative regulated output | Delivers –4V; must be bypassed with ≥3.3µF low-ESR capacitor; ESR < 1Ω recommended to avoid regulation error. |
| REG (Pin 7) | Regulation status indicator | Open-drain N-channel output; pulls low when |VOUT| ≥ 95% of target - used for power-valid signaling. |
| SHDN (Pin 8) | Shutdown enable | Pulled low internally; drive high to enter 5µA shutdown - disables charge pump and collapses OUT to 0V. |
Key Features
| Feature | Design Value |
|---|---|
| Fixed –4V output with no external resistors | Eliminates component count and layout sensitivity; factory-trimmed for ±4.5% accuracy over temperature and load. |
| Integrated 650kHz oscillator | Removes need for external clock source; enables use of small 0.1µF ceramic flying capacitor and fast transient response. |
| REG pin with 5% regulation window | Provides system-level power-good signal without external comparators - simplifies monitoring of negative rail integrity. |
| Industrial temperature range (–40°C to +85°C) | Guaranteed performance in harsh environments such as factory automation controllers and outdoor telecom equipment. |
| Three-capacitor operation (0.1µF flying + input/output bypass) | Reduces BOM cost and PCB area vs inductor-based inverters; supports compact, low-noise designs in space-constrained layouts. |
Applications
| GaAs FET Bias Generator | Negative Supply for Single-Supply Op Amps |
|---|---|
Use Scenario: Generating precise –4V gate bias for GaAs power amplifier stages in 5G front-end modules. IC Role / Device Role / Timing Role: Regulated voltage inverter providing stable negative rail independent of input rail variation or load transients. Use Value: Enables consistent FET pinch-off voltage and linearity; REG pin confirms bias validity before RF transmission begins. | Use Scenario: Creating dual-rail supply for rail-to-rail op amps in portable data acquisition systems powered by single-cell Li-ion. IC Role / Device Role / Timing Role: Negative rail generator with low quiescent current and fast startup (<1.5ms) to support wake-on-event architectures. Use Value: Extends battery runtime via 5µA shutdown mode; 650kHz switching allows small 0.1µF flying cap and minimal EMI filtering. |
| Battery-Powered Instrumentation | Industrial Sensor Signal Conditioning |
Use Scenario: Providing isolated –4V reference for precision ADC drivers in handheld multimeters and thermal imagers. IC Role / Device Role / Timing Role: Low-noise, regulated inverter with <7mV typical output ripple (3.3µF output cap, 15mA load). Use Value: Minimizes measurement offset drift; MSOP-8 footprint fits tight board spaces without requiring inductors or transformers. | Use Scenario: Powering analog front-ends in 4–20mA loop-powered sensors operating in factory-floor environments. IC Role / Device Role / Timing Role: Industrial-grade negative rail generator with guaranteed –40°C to +85°C operation and robust ESD-tolerant pins. Use Value: Ensures reliable sensor calibration across ambient extremes; REG output interfaces directly with PLC status monitoring inputs. |
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; 100kHz oscillator; requires four external caps; ±1.5% initial accuracy but no REG pin. | Higher output voltage magnitude; slower switching limits capacitor size reduction; lacks regulation status flag. | Select when –5V is required and REG signaling is unnecessary; verify 100kHz ripple compatibility with downstream analog circuits. |
| TPS60403DBVR | Fixed –4V output; 1MHz oscillator; 20mA max; includes integrated soft-start; no REG pin; 2.7–5.5V input range. | Wider input range enables single-supply flexibility; higher frequency allows smaller caps; missing regulation confirmation function. | Prefer when input voltage may dip below 4.35V; omit if system-level power-valid signaling is mandatory for safety-critical sequencing. |
Compared with MAX680ESA+ and TPS60403DBVR, the LTC1261LIMS8-4#TRPBF uniquely combines industrial temperature rating, built-in REG flag for system validation, and optimized 650kHz operation for low-ripple, low-component-count –4V generation - making it ideal for GaAs bias and instrumentation where regulation certainty is essential.
Availability
LTC1261LIMS8-4#TRPBF is available at Aetrix Electronics and suitable for GaAs FET bias generators, battery-powered instrumentation, and industrial sensor signal conditioning requiring stable component supply across extended temperature ranges.
Supply support for LTC1261LIMS8-4#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 LTC1261LIMS8-4#TRPBF belongs to Linear's precision switched-capacitor DC/DC converter family, designed specifically for low-noise, low-component-count negative rail generation in RF, portable, and industrial analog systems.
FAQ
What is the minimum input voltage required for stable –4V output from the LTC1261LIMS8-4#TRPBF?
The LTC1261LIMS8-4#TRPBF requires a minimum supply voltage of 4.35V to guarantee ±4.5% output regulation across its full 0–20mA load range and –40°C to +85°C temperature range. Operation below 4.35V is possible but not specified - output accuracy degrades outside datasheet conditions. Always maintain VCC ≥ 4.35V for compliant performance.
Can the LTC1261LIMS8-4#TRPBF be used with a 3.3V input supply?
No - the LTC1261LIMS8-4#TRPBF is not rated for 3.3V operation. Its absolute minimum VCC is 4.35V, and electrical characteristics (including regulation accuracy and output current) are only guaranteed between 4.35V and 5.25V. For 3.3V-compatible inverters, consider the adjustable LTC1261L variant or alternative parts like TPS60400.
How does the REG pin on the LTC1261LIMS8-4#TRPBF behave during startup and fault conditions?
The REG pin on the LTC1261LIMS8-4#TRPBF is an open-drain output that remains high-impedance until VOUT reaches within 5% of –4V (i.e., ≤ –3.8V). It then pulls low and stays low as long as regulation is maintained. During startup, REG asserts low after ~250µs (typical); during overcurrent or undervoltage, it floats high - providing unambiguous power-valid signaling for system sequencers.
What external capacitors are mandatory for basic operation of the LTC1261LIMS8-4#TRPBF?
Three capacitors are mandatory: a 0.1µF ceramic flying capacitor between C1+ and C1–; a ≥1µF ceramic input bypass capacitor from VCC to GND; and a ≥3.3µF ceramic output capacitor from OUT to GND. An optional 100pF capacitor from ADJ/COMP to GND reduces output ripple. All capacitors must be placed close to respective pins per layout guidelines.
Is the LTC1261LIMS8-4#TRPBF pin-compatible with other variants in the LTC1261L family?
Yes - all LTC1261L variants (adjustable, –4V, –4.5V) share identical 8-pin MSOP and SO packages and pinout. The LTC1261LIMS8-4#TRPBF uses the same MS8 footprint and pin functions as LTC1261LIMS8#TRPBF and LTC1261LIMS8-4.5#TRPBF, enabling drop-in replacement where output voltage and temp grade match system requirements.
LTC1261LIMS8-4#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 8-TSSOP, 8-MSOP (0.118", 3.00mm Width)
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Function:
- Step-Up/Step-Down
- Output Configuration:
- Negative
- Topology:
- Charge Pump
- Output Type:
- Fixed
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 4.5V
- Voltage - Input (Max):
- 5.25V
- Voltage - Output (Min/Fixed):
- -4V
- Voltage - Output (Max):
- -
- 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-MSOP
LTC1261LIMS8-4#TRPBF FAQ
1.How can I place an order for LTC1261LIMS8-4#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC1261LIMS8-4#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 LTC1261LIMS8-4#TRPBF reliable?
The price and inventory of LTC1261LIMS8-4#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC1261LIMS8-4#TRPBF is usually 5 days.
3.What payment methods are accepted for LTC1261LIMS8-4#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC1261LIMS8-4#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC1261LIMS8-4#TRPBF?
LTC1261LIMS8-4#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC1261LIMS8-4#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 LTC1261LIMS8-4#TRPBF?
For technical support, including LTC1261LIMS8-4#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC1261LIMS8-4#TRPBF requirements.
6.How does Aetrix verify that LTC1261LIMS8-4#TRPBF is sourced from the original manufacturer or authorized distributors?
All LTC1261LIMS8-4#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 LTC1261LIMS8-4#TRPBF meets industry standards.
7.What is the process for return or replacement of LTC1261LIMS8-4#TRPBF?
All LTC1261LIMS8-4#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC1261LIMS8-4#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 LTC1261LIMS8-4#TRPBF part is unused and in its original packaging.
Return procedure for LTC1261LIMS8-4#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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