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Analog Devices Inc. LTC1550LCS8-4.1#TRPBF
- Part No.:
- LTC1550LCS8-4.1#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
LTC1550LCS8-4.1#TRPBF.pdf
- Description:
- IC REG CHARG PUMP -4.1V 20MA 8SO
- Quantity:
- Payment:
- Shipping:
Inventory:3,022
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Product details
Overview
LTC1550LCS8-4.1#TRPBF from Analog Devices (formerly Linear Technology) is a low-noise, switched-capacitor regulated negative voltage inverter with integrated linear post-regulator, delivering a fixed –4.1V output at up to 20mA load current, <1mVP-P ripple, and 900kHz charge pump frequency. It operates from a single 4.5V–5.25V supply and features active-low TTL-compatible shutdown, making it suitable for GaAs FET bias generation in portable RF transmitters.
For engineers reviewing the LTC1550LCS8-4.1#TRPBF datasheet, LTC1550LCS8-4.1#TRPBF pinout, LTC1550LCS8-4.1#TRPBF application, or LTC1550LCS8-4.1#TRPBF equivalent, key selection criteria include guaranteed ±2.5% output regulation over line/load/temperature, minimal external component count (four capacitors), MSOP-8 package compatibility, and shutdown quiescent current <1µA.
Technical Context
The LTC1550LCS8-4.1#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, enabling stable regulation under dynamic loads.
It requires no external resistors for fixed –4.1V operation and uses only four external capacitors: one 2.2µF input bypass (CIN), two 0.1µF charge pump capacitors (C1, CCP), and one ≥10µF output filter (COUT) with parallel 0.1µF ceramic to achieve <1mVP-P ripple. Grounding follows star topology at GND pin to minimize noise coupling.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | Fixed –4.1V, guaranteed –4.203V to –3.998V across 4.5V–5.25V VCC and 0–10mA load. |
| Output Ripple | <1mVP-P typical with 10µF COUT + 0.1µF ceramic; critical for low-noise GaAs FET bias stability. |
| Charge Pump Frequency | 900kHz internal oscillator; avoids IF bands (400–600kHz) and enables use of small 0.1µF ceramic capacitors. |
| Supply Current | 3.65mA typical at 5V VCC; drops to 0.2µA in shutdown-enables battery-powered system power management. |
| Output Regulation Accuracy | ±2.5% over line, load, and temperature (0°C to 70°C); ensures consistent GaAs gate bias under varying conditions. |
| Input Voltage Range | 4.5V to 5.25V minimum for –4.1V output; prevents damage when |VCC − VOUT| exceeds 10.5V. |
| Shutdown Interface | TTL-compatible active-low SHDN pin; no internal pull-up-requires external resistor to default to normal operation. |
Pinout & Package
Package: 8-lead MSOP (MS8), 3.0mm × 3.0mm × 0.85mm body, 0.65mm pitch, exposed pad not electrically connected.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (REG) | Power-Valid Open-Drain Output | Pulls low when VOUT is within ±5% of –4.1V; requires external pull-up to VCC or higher (≤6V); used for system power-good signaling. |
| 2 (CPOUT) | Negative Charge Pump Output | Intermediate node supplying linear regulator input; requires 0.1µF capacitor to GND with direct ground tie to VCC bypass and GND pin. |
| 3 (GND) | Analog/Power Ground Reference | Single low-impedance ground connection point for all bypass caps and output capacitor return; star-ground layout mandatory. |
| 4 (C1–) | Charge Pump Flying Capacitor Negative Terminal | Connects to negative side of 0.1µF flying capacitor (C1); forms charge transfer path with C1+ during clock phases. |
| 5 (SHDN) | Active-Low Shutdown Control | Drives internal charge pump and regulator into sleep mode when pulled low; draws ≤1µA leakage in normal operation. |
| 6 (VCC) | Positive Input Supply | Accepts 4.5–5.25V; must be bypassed with ≥2.2µF ceramic cap directly to GND; ESR impacts ripple performance. |
| 7 (C1+) | Charge Pump Flying Capacitor Positive Terminal | Connects to positive side of 0.1µF flying capacitor (C1); alternately charged/discharged at 900kHz to generate negative voltage. |
| 8 (VOUT) | Regulated Negative Output | Delivers –4.1V; requires ≥10µF output capacitor (moderate ESR) + 0.1µF ceramic in parallel for stability and <1mVP-P ripple. |
Key Features
| Feature | Design Value |
|---|---|
| Integrated Linear Post-Regulator | Eliminates need for external LDO; provides fast transient response and <1mVP-P ripple without LC filtering. |
| Fixed –4.1V Output | No external resistors required-reduces BOM count and PCB area vs adjustable versions; optimized for GaAs FET gate bias. |
| 900kHz Switching Frequency | Enables use of standard 0.1µF ceramic flying capacitors; shifts noise spectrum away from sensitive RF IF bands. |
| Ultra-Low Shutdown Current | 0.2µA typical-extends battery life in portable RF systems during transmit idle periods. |
| Minimal External Components | Only four capacitors needed: CIN (2.2µF), C1 (0.1µF), CCP (0.1µF), COUT (10µF + 0.1µF); simplifies layout and reduces cost. |
Applications
| GaAs FET Transmitter Bias | Negative Supply for RF ICs |
|---|---|
Use Scenario: Generating stable gate bias voltage for GaAs power amplifier FETs in cellular handsets and portable radios. IC Role / Device Role / Timing Role: Regulated –4.1V DC bias source with ultra-low ripple to set FET operating point and maximize PAE. Use Value: Enables consistent RF output power and efficiency across battery discharge and temperature variation due to ±2.5% regulation and <1mVP-P noise. | Use Scenario: Providing clean negative supply rail for RF front-end ICs requiring dual-rail operation (e.g., mixers, LNAs). IC Role / Device Role / Timing Role: Low-noise inverting charge pump with linear post-regulation serving as dedicated negative VEE source. Use Value: Eliminates need for discrete inductor-based converters; 900kHz switching avoids interference with 400–600kHz IF bands in receiver chains. |
| Battery-Powered Portable Equipment | Single-Supply Signal Conditioning |
Use Scenario: Powering analog subsystems (e.g., op-amp rails, ADC references) in handheld test instruments or medical sensors. IC Role / Device Role / Timing Role: Efficient negative voltage generator from single Li-ion cell (3.0–4.2V) or regulated 5V rail, with shutdown control for duty-cycled operation. Use Value: 0.2µA shutdown current extends runtime; 4.5V min VCC requirement ensures compatibility with buck-boost regulated 5V supplies. | Use Scenario: Enabling true bipolar signal swing in single-supply data acquisition circuits (e.g., sensor front-ends, audio codecs). IC Role / Device Role / Timing Role: Compact, low-noise negative rail generator allowing rail-to-rail input/output operation without split supplies. Use Value: 10µF COUT + 0.1µF ceramic ensures <1mVP-P ripple-critical for high-resolution (<16-bit) ADC reference stability and SNR preservation. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar negative voltage inverter applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC1550LCMS8-4.1#TRPBF | Identical electrical specs and pinout; differs only in tape-and-reel packaging (TRPBF vs TRMPBF) and part marking (LTFQ vs LTGR). | No functional difference; both rated for 0°C to 70°C commercial temp range and MSOP-8 package. | Select LTC1550LCS8-4.1#TRPBF for standard reel delivery; LTC1550LCMS8-4.1#TRPBF if alternate reel format required. |
| LTC1551LCS8-4.1#TRPBF | Same –4.1V output, ripple, and regulation, but features active-high SHDN (vs active-low on LTC1550LCS8-4.1#TRPBF). | Requires inverted logic level on shutdown control line; otherwise identical in bias generation and noise performance. | Choose LTC1551LCS8-4.1#TRPBF only when system MCU GPIO drives high to disable-no hardware redesign needed beyond SHDN polarity. |
Compared with LTC1550LCMS8-4.1#TRPBF, LTC1550LCS8-4.1#TRPBF offers identical performance in same MSOP-8 package but with standard reel packaging; versus LTC1551LCS8-4.1#TRPBF, it provides active-low shutdown control-simplifying interface with microcontrollers lacking open-drain high-drive capability.
Availability
LTC1550LCS8-4.1#TRPBF is available at Aetrix Electronics and suitable for GaAs FET bias generation, portable RF transmitter power, and single-supply analog signal conditioning requiring stable component supply and guaranteed long-term availability.
Supply support for LTC1550LCS8-4.1#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 product support, datasheets, and application engineering for legacy Linear parts including the LTC series.
The LTC1550L/LTC1551L family was designed specifically for low-noise, compact negative voltage generation in portable RF systems-emphasizing GaAs FET bias, minimal external components, and sub-1mV ripple performance.
FAQ
What is the minimum input voltage required for stable –4.1V output from the LTC1550LCS8-4.1#TRPBF?
The LTC1550LCS8-4.1#TRPBF requires a minimum VCC of 4.5V to guarantee –4.1V output regulation across 0–10mA load and temperature (0°C to 70°C). Below 4.5V, output voltage may drop out of specification; the Electrical Characteristics table confirms guaranteed operation starts at 4.5V for the –4.1V variant. Always verify against the "Minimum Required VCC vs VOUT and IOUT" graph in the datasheet.
Can the LTC1550LCS8-4.1#TRPBF be used with a 3.3V input supply?
No-the LTC1550LCS8-4.1#TRPBF is not rated for 3.3V operation. Its specified input range for –4.1V output is 4.5V to 5.25V. Attempting to operate below 4.5V risks failure to regulate, increased ripple, or thermal stress. For lower input voltages, consider the LTC1550LCS8-2 (–2V) or LTC1550LCS8-2.5 (–2.5V) variants, which support down to 2.7V and 3.05V respectively.
What is the purpose of the REG pin on the LTC1550LCS8-4.1#TRPBF, and how should it be connected?
The REG pin on the LTC1550LCS8-4.1#TRPBF is an open-drain power-valid indicator that pulls low when VOUT is within ±5% of –4.1V. It must be externally pulled up to VCC (or up to 6V) with a resistor (typically 10kΩ–100kΩ); without pull-up, REG remains floating and cannot signal valid output. This pin enables system-level power sequencing and fault detection in RF transmitter modules.
Why does the LTC1550LCS8-4.1#TRPBF require two separate output capacitors (10µF + 0.1µF)?
The LTC1550LCS8-4.1#TRPBF requires ≥10µF moderate-ESR capacitor for loop stability and ≥0.1µF low-ESR ceramic capacitor in parallel to suppress high-frequency spikes from the 900kHz charge pump. The larger capacitor handles bulk energy storage and low-frequency ripple, while the ceramic shunts sharp switching artifacts-achieving <1mVP-P ripple. Using only one capacitor fails to meet either stability or noise requirements.
Is the LTC1550LCS8-4.1#TRPBF pin-compatible with the LTC1551LCS8-4.1#TRPBF?
Yes-the LTC1550LCS8-4.1#TRPBF and LTC1551LCS8-4.1#TRPBF share identical MSOP-8 pinout, package dimensions, and electrical specifications except for shutdown polarity: LTC1550LCS8-4.1#TRPBF has active-low SHDN, while LTC1551LCS8-4.1#TRPBF has active-high SHDN. No PCB changes are needed, but firmware or logic-level interface must invert the shutdown signal when substituting.
LTC1550LCS8-4.1#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):
- 5.5V
- Voltage - Output (Min/Fixed):
- -4.1V
- Voltage - Output (Max):
- -
- 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
LTC1550LCS8-4.1#TRPBF FAQ
1.How can I place an order for LTC1550LCS8-4.1#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC1550LCS8-4.1#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 LTC1550LCS8-4.1#TRPBF reliable?
The price and inventory of LTC1550LCS8-4.1#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC1550LCS8-4.1#TRPBF is usually 5 days.
3.What payment methods are accepted for LTC1550LCS8-4.1#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC1550LCS8-4.1#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC1550LCS8-4.1#TRPBF?
LTC1550LCS8-4.1#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC1550LCS8-4.1#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 LTC1550LCS8-4.1#TRPBF?
For technical support, including LTC1550LCS8-4.1#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC1550LCS8-4.1#TRPBF requirements.
6.How does Aetrix verify that LTC1550LCS8-4.1#TRPBF is sourced from the original manufacturer or authorized distributors?
All LTC1550LCS8-4.1#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 LTC1550LCS8-4.1#TRPBF meets industry standards.
7.What is the process for return or replacement of LTC1550LCS8-4.1#TRPBF?
All LTC1550LCS8-4.1#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC1550LCS8-4.1#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 LTC1550LCS8-4.1#TRPBF part is unused and in its original packaging.
Return procedure for LTC1550LCS8-4.1#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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