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Analog Devices Inc. LTC1261LCS8-4#TRPBF
- Part No.:
- LTC1261LCS8-4#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
LTC1261LCS8-4#TRPBF.pdf
- Description:
- IC REG CHARGE PUMP -4V 20MA 8SO
- Quantity:
- Payment:
- Shipping:
Inventory:2,829
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Product details
Overview
LTC1261LCS8-4#TRPBF from Analog Devices (acquired 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 systems requiring compact negative rail synthesis.
For engineers reviewing the LTC1261LCS8-4#TRPBF datasheet, LTC1261LCS8-4#TRPBF pinout, LTC1261LCS8-4#TRPBF application, or LTC1261LCS8-4#TRPBF equivalent, key selection criteria include guaranteed –4V output regulation across temperature, shutdown quiescent current of 5µA, REG pin logic compatibility with 3.3V/5V systems, and SO-8 package suitability for space-constrained PCB layouts.
Technical Context
The LTC1261LCS8-4#TRPBF implements a 650kHz internal oscillator-driven inverting charge pump topology. Its regulation loop compares a divided replica of the output voltage at the ADJ (COMP) pin against a 1.23V internal reference, dynamically adjusting duty cycle to maintain output within ±4.5% tolerance. The REG pin uses a separate 1.17V comparator threshold to signal when output magnitude is within 5% of the setpoint.
It employs a two-phase switching sequence: during phase one, the flying capacitor (C1) charges between VCC and GND; during phase two, C1+ is grounded and C1– transfers charge to the output capacitor. This architecture eliminates inductors and enables high-efficiency DC/DC inversion with minimal external components.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | Fixed –4.0V, guaranteed ±4.5% regulation over 4.35V–5.25V input and 0–20mA load. |
| Supply Voltage Range | 4.35V to 5.25V - minimum VCC required for full specification compliance; operation below 4.35V not guaranteed. |
| Output Current | Up to 20mA continuous - sufficient for GaAs FET gate biasing and low-power analog circuitry. |
| Quiescent Current | 650µA typical operating current; drops to 5µA in shutdown - enables ultra-low-power standby modes. |
| Oscillator Frequency | 650kHz typical - enables use of small ceramic capacitors and minimizes output ripple with proper filtering. |
| REG Pin Function | Open-drain output sinking ≥5mA at 5V VCC - provides system-level power-valid signaling without external level-shifting. |
| Operating Temperature | 0°C to 70°C - commercial-grade rating suitable for consumer and industrial embedded applications. |
Pinout & Package
Package: 8-Lead Plastic SO (Small Outline, Narrow 0.150-inch body), RoHS-compliant, lead-free finish.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VCC (Pin 1) | Positive supply input | Accepts 4.35V–5.25V; requires ≥1µF local bypass capacitor to sustain charge pump peak currents. |
| C1+ (Pin 2) | Flying capacitor positive terminal | Connects to + side of 0.1µF flying capacitor; forms half of charge-transfer path. |
| C1– (Pin 3) | Flying capacitor negative terminal | Connects to – side of 0.1µF flying capacitor; switches between ground and OUT during pumping cycle. |
| GND (Pin 4) | Analog ground reference | Low-impedance return for all internal circuits; critical for regulation accuracy and noise immunity. |
| ADJ/COMP (Pin 5) | Feedback compensation node | Internally connected to fixed resistor divider for –4V output; optional 100pF to ground reduces output ripple. |
| OUT (Pin 6) | Negative regulated output | Delivers –4V; requires ≥3.3µF output capacitor with low ESR to minimize droop and ripple. |
| REG (Pin 7) | Regulation status indicator | Open-drain N-channel output pulls low when |VOUT| is within 5% of –4V; requires external pull-up. |
| SHDN (Pin 8) | Shutdown control input | Logic-low enables operation; floating defaults to active via internal 5µA pull-down; high disables charge pump. |
Key Features
| Feature | Design Value |
|---|---|
| Fixed –4V output with no external resistors | Eliminates feedback network design effort and component count; ensures consistent output across production lots. |
| Integrated 650kHz oscillator | Removes need for external timing components; enables predictable ripple frequency for filter design and EMI mitigation. |
| REG pin with 5% regulation window | Provides unambiguous system-level power-good signal without additional monitoring circuitry or firmware polling. |
| Three-capacitor solution | Reduces BOM cost and board area vs inductor-based inverters; supports high-density portable designs. |
| 5µA shutdown current | Extends battery life in always-on devices by enabling deep sleep states without compromising wake-up latency. |
Applications
| GaAs FET Bias Generator | Negative Supply Generator |
|---|---|
Use Scenario: Providing precise –4V gate bias to GaAs power amplifier transistors in RF front-end modules. IC Role / Device Role / Timing Role: Regulated negative voltage source generating stable bias independent of main supply fluctuations. Use Value: Enables optimal transistor linearity and efficiency by maintaining exact –4V gate voltage under varying load and temperature conditions. | Use Scenario: Generating isolated negative rails for op-amp dual-supply operation in data acquisition systems. IC Role / Device Role / Timing Role: Compact DC/DC inverter replacing discrete charge-pump or transformer-based solutions. Use Value: Reduces PCB footprint by >60% versus inductor-based alternatives while delivering ±4.5% regulation without trimming. |
| Battery-Powered Systems | Single-Supply Signal Conditioning |
Use Scenario: Powering analog sensors and interface ICs requiring negative reference in portable medical or IoT devices. IC Role / Device Role / Timing Role: Low-quiescent-current inverter enabling long battery runtime with reliable negative rail availability. Use Value: Achieves 5µA shutdown current and 650µA operating current - extends coin-cell life beyond 12 months in intermittent-use applications. | Use Scenario: Supporting bipolar signal swing in single-supply instrumentation amplifiers and ADC drivers. IC Role / Device Role / Timing Role: Local negative rail generator ensuring full-scale analog input range without external power supplies. Use Value: Eliminates need for dual-output wall adapters or split-rail DC/DC converters, simplifying system power architecture. |
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; 800kHz oscillator; requires four external capacitors; ±1.5% initial accuracy but no REG pin. | Lacks regulation status flag; tighter initial accuracy but wider drift over temperature and load. | Select when absolute output precision outweighs need for power-valid signaling and lower component count. |
| ICL7660SIPAZ | Adjustable output (–1.5V to –VCC); no internal regulation; 10kHz oscillator; higher quiescent current (1.2mA). | No regulation or REG functionality; suited for non-critical bias where simplicity trumps accuracy. | Select only for cost-sensitive, non-regulated applications where ±10% output variation is acceptable. |
Compared with MAX680ESA+ and ICL7660SIPAZ, the LTC1261LCS8-4#TRPBF uniquely combines fixed –4V regulation, integrated REG flag, three-capacitor operation, and 5µA shutdown - making it optimal for battery-powered RF bias and precision analog systems requiring verified rail integrity.
Availability
LTC1261LCS8-4#TRPBF is available at Aetrix Electronics and suitable for GaAs FET bias generators, portable medical sensor interfaces, and single-supply signal conditioning circuits requiring stable component supply and long-term lifecycle support.
Supply support for LTC1261LCS8-4#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, Inc. (ADI) is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, formed through the acquisition of Linear Technology in 2017.
The LTC1261L series was developed by Linear Technology specifically for compact, low-noise, regulated negative voltage generation in space-constrained and battery-sensitive applications - emphasizing minimal external components and robust regulation under dynamic load.
FAQ
What is the minimum input voltage required for LTC1261LCS8-4#TRPBF to maintain specified –4V output regulation?
The LTC1261LCS8-4#TRPBF requires a minimum supply voltage of 4.35V to guarantee ±4.5% output regulation across temperature and load. Operation below this voltage is possible but not characterized per datasheet specifications - output may deviate beyond tolerance, especially at full 20mA load or elevated temperatures.
Can LTC1261LCS8-4#TRPBF be used with a 3.3V input supply?
No, LTC1261LCS8-4#TRPBF cannot maintain its –4V output regulation with a 3.3V input. Its specified supply range begins at 4.35V; using 3.3V will result in insufficient headroom for the charge pump to generate –4V, causing output collapse or severe regulation error. For lower-input applications, consider the adjustable LTC1261LCS8 or alternative regulators.
What is the purpose of the 100pF capacitor recommended on the ADJ/COMP pin of LTC1261LCS8-4#TRPBF?
The 100pF capacitor from ADJ/COMP (Pin 5) to GND on LTC1261LCS8-4#TRPBF compensates the regulation loop bandwidth to suppress high-frequency hunting behavior. It stabilizes feedback response to rapid output transients, reducing output voltage ripple - particularly critical when driving capacitive loads or under fast load steps - without degrading regulation accuracy.
How does the REG pin on LTC1261LCS8-4#TRPBF function, and what pull-up voltage is supported?
The REG pin on LTC1261LCS8-4#TRPBF is an open-drain output that pulls low when |VOUT| is within 5% of –4V (i.e., –3.8V ≤ VOUT ≤ –4.2V). It sinks ≥5mA at 5V VCC and tolerates external pull-up voltages up to 6V above ground - enabling direct interfacing with 3.3V, 5V, or mixed-voltage logic systems without level shifters.
Is LTC1261LCS8-4#TRPBF pin-compatible with other variants like LTC1261LCS8-4.5#TRPBF?
Yes, LTC1261LCS8-4#TRPBF is pin-compatible with LTC1261LCS8-4.5#TRPBF and all other SO-8 variants in the LTC1261L family. They share identical pinout, package dimensions, and electrical interface - only the internal feedback network differs to set –4V vs –4.5V output. No PCB layout change is needed when substituting between these fixed-output versions.
LTC1261LCS8-4#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:
- 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:
- 0°C ~ 70°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-SO
LTC1261LCS8-4#TRPBF FAQ
1.How can I place an order for LTC1261LCS8-4#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC1261LCS8-4#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 LTC1261LCS8-4#TRPBF reliable?
The price and inventory of LTC1261LCS8-4#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC1261LCS8-4#TRPBF is usually 5 days.
3.What payment methods are accepted for LTC1261LCS8-4#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC1261LCS8-4#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC1261LCS8-4#TRPBF?
LTC1261LCS8-4#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC1261LCS8-4#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 LTC1261LCS8-4#TRPBF?
For technical support, including LTC1261LCS8-4#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC1261LCS8-4#TRPBF requirements.
6.How does Aetrix verify that LTC1261LCS8-4#TRPBF is sourced from the original manufacturer or authorized distributors?
All LTC1261LCS8-4#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 LTC1261LCS8-4#TRPBF meets industry standards.
7.What is the process for return or replacement of LTC1261LCS8-4#TRPBF?
All LTC1261LCS8-4#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC1261LCS8-4#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 LTC1261LCS8-4#TRPBF part is unused and in its original packaging.
Return procedure for LTC1261LCS8-4#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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