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Analog Devices Inc. LTC1551LCS8#TRPBF
- Part No.:
- LTC1551LCS8#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
LTC1551LCS8#TRPBF.pdf
- Description:
- IC REG CHARGE PUMP ADJ 20MA 8SO
- Quantity:
- Payment:
- Shipping:
Inventory:2,935
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Product details
Overview
LTC1551LCS8#TRPBF from Analog Devices (formerly Linear Technology) is a switched-capacitor regulated negative voltage inverter with integrated linear post-regulator, delivering –4.1V output at up to 20mA load current with <1mVP-P ripple, operating from 4.5V–5.25V input supply, and featuring active-high TTL-compatible shutdown. It serves as a low-noise bias generator for GaAs FETs in portable RF transmitters.
For engineers reviewing the LTC1551LCS8#TRPBF datasheet, LTC1551LCS8#TRPBF pinout, LTC1551LCS8#TRPBF application, or LTC1551LCS8#TRPBF equivalent, key selection criteria include guaranteed ±2.5% output regulation over line/load/temperature, 900kHz charge pump frequency enabling compact 0.1µF external capacitors, shutdown current <1µA, and SO-8 package compatibility with space-constrained portable designs.
Technical Context
The LTC1551LCS8#TRPBF integrates a 900kHz inverting charge pump stage followed by a negative linear regulator using an N-channel MOSFET pass device and internal 1.225V reference. Its feedback loop is optimized for fast transient response to suppress switching artifacts from CPOUT, achieving sub-millivolt ripple under 10mA loads.
Unlike the LTC1550L variant, the LTC1551LCS8#TRPBF uses an active-high SHDN pin with internal 5µA pull-down, eliminating need for external pull-up. The SO-8 package places all functional pins-including REG open-drain power-valid indicator-within an 8-pin footprint requiring only four external capacitors for full operation.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | Fixed –4.1V, guaranteed –4.203V to –3.998V across 4.5V–5.25V input and 0–10mA load |
| Output Ripple | <1mVP-P with 10µF + 0.1µF output capacitor, enabling clean bias for sensitive RF FETs |
| Charge Pump Freq | 900kHz internal oscillator, placing noise outside 400–600kHz IF bands and allowing 0.1µF ceramic flying caps |
| Supply Current | 3.65mA typical at 5V (active), 0.2µA typical in shutdown-critical for battery runtime in portable systems |
| Output Regulation | ±2.5% over line, load, and temperature (0°C–70°C), ensuring stable GaAs gate bias across operating conditions |
| Shutdown Logic | Active-high SHDN with internal 5µA pull-down, simplifying control interface without external components |
| Max Output Current | 20mA at VCC ≥ 4.75V and VOUT = –4.1V, sufficient for multi-FET transmitter bias rails |
Pinout & Package
Package: 8-lead narrow SO (S8), 0.150-inch width, RoHS-compliant, surface-mountable.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (REG) | Open-drain power-valid indicator | Pulls low when VOUT is within ±5% of –4.1V; requires external pull-up to monitor regulation status |
| 2 (CPOUT) | Negative charge pump output | Connects to 0.1µF storage capacitor; ground return must tie directly to VCC bypass and GND pin to minimize AC path |
| 3 (GND) | Ground reference | Low-impedance analog/power ground connection; star-ground layout required for ripple performance |
| 4 (C1–) | Charge pump capacitor negative terminal | Completes flying capacitor (C1) path with C1+; forms charge transfer network with internal switches S1–S4 |
| 5 (SHDN) | Active-high shutdown control | Drives internal enable logic; internal 5µA pull-down defaults device to active state |
| 6 (VCC) | Positive input supply | Accepts 4.5V–5.25V; requires ≥2.2µF low-ESR ceramic bypass capacitor placed adjacent to pin |
| 7 (C1+) | Charge pump capacitor positive terminal | Completes flying capacitor (C1) path with C1–; internal clock alternately charges/discharges C1 |
| 8 (VOUT) | Regulated negative output | Delivers –4.1V; requires ≥10µF output capacitor (moderate ESR) plus 0.1µF ceramic for stability and ripple suppression |
Key Features
| Feature | Design Value |
|---|---|
| Integrated linear post-regulator | Reduces charge pump ripple to <1mVP-P without external LDO, eliminating need for second-stage filtering |
| 900kHz charge pump frequency | Enables use of standard 0.1µF ceramic capacitors instead of larger tantalum, reducing board area and cost |
| Active-high shutdown with pull-down | Eliminates external pull-up resistor, simplifying PCB layout and reducing BOM count for portable applications |
| Guaranteed ±2.5% regulation | Maintains precise GaAs FET gate bias across temperature and load variations, preventing gain drift or distortion |
| SO-8 package compatibility | Enables drop-in replacement in existing narrow-SO footprints while supporting high-density RF layouts |
Applications
| Portable RF Transmitter Bias | GaAs FET Power Amplifier Supply |
|---|---|
Use Scenario: Generating stable negative gate bias for GaAs FETs in cellular handsets and Bluetooth transmitters. IC Role / Device Role / Timing Role: Regulated –4.1V inverter providing precise DC bias voltage referenced to RF ground. Use Value: Sub-millivolt ripple ensures minimal AM-to-PM conversion and phase noise degradation in transmit paths. | Use Scenario: Supplying gate control voltage to discrete GaAs power amplifier stages in 2G/3G/4G front-end modules. IC Role / Device Role / Timing Role: Low-noise negative voltage source synchronized to RF envelope timing via fast turn-on (<5ms). Use Value: ±2.5% regulation maintains consistent FET transconductance across battery discharge, preserving PA efficiency. |
| Battery-Powered Instrumentation | Single-Supply Signal Conditioning |
Use Scenario: Creating isolated negative rail for op-amp biasing in handheld test equipment powered by single Li-ion cell. IC Role / Device Role / Timing Role: Compact inverter generating –4.1V from 4.5V–5.25V input, enabling true bipolar signal swing. Use Value: 0.2µA shutdown current extends battery life during measurement standby without compromising wake-up speed. | Use Scenario: Providing negative supply for precision ADC drivers and sensor signal conditioning circuits in IoT edge nodes. IC Role / Device Role / Timing Role: Low-noise auxiliary rail generator supporting rail-to-rail input op-amps in single-supply microcontroller systems. Use Value: 900kHz switching frequency avoids interference with 2.4GHz ISM band, preventing RF coupling into analog signal paths. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar negative voltage inverter applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC1550LCS8-4.1 | Active-low SHDN pin; no internal pull-up; requires external pull-up resistor | Same –4.1V output and SO-8 package, but incompatible control logic level | Select only if system design already implements active-low enable signaling |
| LTC1261LCS8 | Adjustable output (–1.2V to –5V); lower max output current (15mA); 100kHz charge pump | Higher ripple (>5mVP-P) and slower response; suitable for non-RF general-purpose bias | Choose when adjustable voltage or lower quiescent current (2.5mA) outweighs RF noise requirements |
Compared with LTC1551LCS8#TRPBF, LTC1550LCS8-4.1 demands additional pull-up circuitry and lacks the internal pull-down convenience, while LTC1261LCS8 trades RF-grade low-noise performance for flexibility and lower power-making LTC1551LCS8#TRPBF optimal for GaAs FET bias where ripple and frequency agility are critical.
Availability
LTC1551LCS8#TRPBF is available at Aetrix Electronics and suitable for portable RF transmitters, GaAs power amplifier biasing, and battery-powered instrumentation requiring stable component supply with guaranteed long-term availability.
Supply support for LTC1551LCS8#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 its high-performance analog IC portfolio, emphasizing precision, low-noise, and power-efficient solutions for demanding signal chain applications.
The LTC1551LCS8#TRPBF belongs to Linear's switched-capacitor voltage inverter product line, designed specifically for low-ripple, compact negative rail generation in portable RF and battery-operated systems where size and noise are critical constraints.
FAQ
What is the minimum input voltage required for LTC1551LCS8#TRPBF to deliver –4.1V at 10mA?
The LTC1551LCS8#TRPBF requires a minimum VCC of 4.75V to guarantee –4.1V output regulation at 10mA load, as specified in the Electrical Characteristics table. Below this voltage, output may deviate beyond ±2.5% tolerance or collapse entirely due to insufficient headroom for the linear post-regulator stage.
Can LTC1551LCS8#TRPBF be used with ceramic output capacitors only?
Yes, LTC1551LCS8#TRPBF supports ceramic output capacitors, but requires ≥10µF total capacitance with moderate ESR-achieved by paralleling a 10µF tantalum or polymer cap with a 0.1µF ceramic. Using only low-ESR ceramics risks regulator loop instability and oscillation per the Applications Information section.
Does LTC1551LCS8#TRPBF require external resistors for the –4.1V fixed output version?
No, LTC1551LCS8#TRPBF is a fixed-output device with internal resistor divider setting –4.1V; no external resistors are needed. External resistors are required only for adjustable versions (e.g., LTC1551LMS8) connecting ADJ to GND and VOUT.
How does the REG pin on LTC1551LCS8#TRPBF function in system monitoring?
The REG pin on LTC1551LCS8#TRPBF is an open-drain output that pulls low when VOUT is within ±5% of –4.1V. An external pull-up to any logic-compatible voltage (≤6V) allows microcontrollers to monitor power-good status without additional supervision ICs, enhancing system reliability.
What is the thermal performance of LTC1551LCS8#TRPBF in SO-8 package at 20mA load?
LTC1551LCS8#TRPBF in SO-8 has θJA = 135°C/W. At 20mA output and 5V input, power dissipation is ~100mW, resulting in ~13.5°C rise above ambient-well within the 0°C to 70°C commercial temperature range and compatible with standard PCB copper pour for thermal relief.
LTC1551LCS8#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):
- 5.5V
- Voltage - Output (Min/Fixed):
- -1.225V
- Voltage - Output (Max):
- -4.8V
- Current - Output:
- 20mA
- Frequency - Switching:
- 900kHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- 0°C ~ 70°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-SO
LTC1551LCS8#TRPBF FAQ
1.How can I place an order for LTC1551LCS8#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC1551LCS8#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 LTC1551LCS8#TRPBF reliable?
The price and inventory of LTC1551LCS8#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC1551LCS8#TRPBF is usually 5 days.
3.What payment methods are accepted for LTC1551LCS8#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC1551LCS8#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC1551LCS8#TRPBF?
LTC1551LCS8#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC1551LCS8#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 LTC1551LCS8#TRPBF?
For technical support, including LTC1551LCS8#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC1551LCS8#TRPBF requirements.
6.How does Aetrix verify that LTC1551LCS8#TRPBF is sourced from the original manufacturer or authorized distributors?
All LTC1551LCS8#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 LTC1551LCS8#TRPBF meets industry standards.
7.What is the process for return or replacement of LTC1551LCS8#TRPBF?
All LTC1551LCS8#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC1551LCS8#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 LTC1551LCS8#TRPBF part is unused and in its original packaging.
Return procedure for LTC1551LCS8#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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