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Analog Devices Inc. LTC1550LCMS8-4.1#PBF
- Part No.:
- LTC1550LCMS8-4.1#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 8-TSSOP, 8-MSOP (0.118", 3.00mm Width)
- Datasheet:
-
LTC1550LCMS8-4.1#PBF.pdf
- Description:
- IC REG CHARGE PUMP -4.1V 8MSOP
- Quantity:
- Payment:
- Shipping:
Inventory:171
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Product details
Overview
LTC1550LCMS8-4.1#PBF 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 output ripple, and 900kHz charge pump frequency. It operates from a single 4.5V–5.25V supply and features active-low TTL-compatible shutdown (SHDN), making it suitable for GaAs FET bias generation in portable RF transmitters.
For engineers reviewing the LTC1550LCMS8-4.1#PBF datasheet, LTC1550LCMS8-4.1#PBF pinout, LTC1550LCMS8-4.1#PBF application, or LTC1550LCMS8-4.1#PBF equivalent, key selection considerations include guaranteed ±2.5% output regulation over line/load/temperature, minimal external component count (four capacitors), MSOP-8 package compatibility, and verified performance in battery-powered RF biasing circuits.
Technical Context
The LTC1550LCMS8-4.1#PBF 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 architecture minimizes switching artifacts via fast transient response and ESR-dependent loop stability-requiring ≥4.7µF output capacitance with moderate ESR.
It employs dual 0.1µF ceramic flying capacitors (C1+, C1–) and a dedicated CPOUT storage node, with VOUT regulation maintained across 4.5V–5.25V input range and 0–10mA load. The SHDN pin enables <0.2µA quiescent current in shutdown, and REG provides open-drain power-valid indication when output is within ±5% of nominal.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | Fixed –4.1V, guaranteed –4.203V to –3.998V over full operating temperature and load range |
| Output Ripple | <1mVP-P typical at 5mA load with 10µF + 0.1µF output capacitor-critical for noise-sensitive RF bias rails |
| Supply Range | 4.5V to 5.25V minimum required for –4.1V output; below 4.5V, regulation not guaranteed |
| Max Output Current | 20mA at VCC ≥ 4.75V and VOUT = –4.1V-enables direct biasing of multiple GaAs FETs |
| Regulation Accuracy | ±2.5% over line, load, and temperature-ensures stable gate bias under varying battery and thermal conditions |
| Shutdown Current | 0.2µA typical-preserves battery life in standby mode of portable transceivers |
| Oscillator Frequency | 900kHz fixed-places switching energy outside 400–600kHz IF bands used in cellular radios |
Pinout & Package
Package: 8-lead MSOP (MS8), 3.0mm × 3.0mm × 0.85mm body, exposed pad optional, RoHS-compliant #PBF finish.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (REG) | Open-drain power-valid output | Pulls low when VOUT is within ±5% of –4.1V; requires external pull-up to VCC or higher (≤6V); enables system-level power sequencing |
| 2 (CPOUT) | Negative charge pump output | Stores inverted charge from flying capacitor; must connect 0.1µF capacitor directly to GND with star-ground routing to minimize ripple |
| 3 (GND) | Analog/power ground reference | Single ground pin for 8-lead MSOP; serves as return for VCC bypass, CPOUT, and VOUT capacitors-star grounding essential for low noise |
| 4 (C1–) | Flying capacitor negative terminal | Completes charge transfer path with C1+; connects to 0.1µF ceramic capacitor (C1) opposite C1+ |
| 5 (SHDN) | Active-low shutdown control | TTL-compatible input; drives device into <0.2µA shutdown when pulled low; no internal pull-up-requires external resistor |
| 6 (VCC) | Positive input supply | Accepts 4.5V–5.25V; requires ≥2.2µF low-ESR ceramic bypass capacitor placed adjacent to pin for stable operation |
| 7 (C1+) | Flying capacitor positive terminal | Connects to 0.1µF ceramic capacitor (C1) opposite C1–; forms core charge-transfer pair with C1– and internal switches |
| 8 (VOUT) | Regulated negative output | Delivers –4.1V; requires ≥10µF output capacitor (moderate ESR) plus 0.1µF ceramic in parallel to meet <1mVP-P ripple spec |
Key Features
| Feature | Design Value |
|---|---|
| Integrated linear post-regulator | Reduces charge pump ripple to <1mVP-P without external LDO-eliminates need for second-stage filtering |
| 900kHz fixed-frequency oscillator | Enables use of small 0.1µF ceramic flying capacitors and avoids interference with cellular IF bands (400–600kHz) |
| Low-quiescent-current shutdown | Drops supply current to 0.2µA, extending battery runtime in intermittent-transmit RF systems |
| Guaranteed ±2.5% regulation | Maintains precise GaAs FET gate bias across battery discharge (4.5V–5.25V), temperature (0°C–70°C), and load (0–10mA) |
| Minimal external components | Only four capacitors required: 2.2µF input bypass, two 0.1µF flying caps, and 10µF+0.1µF output filter-reduces BOM cost and PCB area |
Applications
| GaAs FET Transmitter Bias | Negative Supply for RF ICs |
|---|---|
|
Use Scenario: Providing gate bias voltage to GaAs power amplifier FETs in GSM/EDGE cellular handsets. IC Role / Device Role / Timing Role: Regulated –4.1V DC bias source with ultra-low ripple to set optimal FET conduction point and maximize PA efficiency. Use Value: Enables stable RF output power across battery voltage sag and temperature drift, meeting 3GPP ACLR and EVM specs. |
Use Scenario: Generating clean negative rail for analog front-end ICs (e.g., mixers, IF amplifiers) in portable SDR receivers. IC Role / Device Role / Timing Role: Low-noise inverting voltage source replacing discrete charge pump + LDO solutions. Use Value: Eliminates 900kHz switching harmonics from signal path, preserving SNR and dynamic range in sub-100MHz IF stages. |
| Battery-Powered Instrumentation | Portable Medical Sensors |
|
Use Scenario: Powering precision op-amps and ADC drivers in handheld multimeters or portable oscilloscopes. IC Role / Device Role / Timing Role: Compact, low-ripple negative supply enabling rail-to-rail input/output swing in single-supply systems. Use Value: Supports 16-bit+ measurement accuracy by minimizing offset drift induced by supply ripple on analog signal chains. |
Use Scenario: Supplying bias to photodiode transimpedance amplifiers in wearable pulse oximeters. IC Role / Device Role / Timing Role: Ultra-low-noise –4.1V source for low-current analog front-ends requiring high common-mode rejection. Use Value: Reduces baseline noise floor by >20dB versus unregulated charge pumps, improving SpO₂ detection sensitivity. |
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#PBF | Same electrical specs and pinout, but in 8-lead SO (S8) package (4.9mm × 3.9mm vs MSOP's 3.0mm × 3.0mm) | Preferred where board space allows larger footprint and reflow compatibility with legacy SO designs | Select for ease of manual soldering or compatibility with existing SO-based layouts; identical functionality otherwise |
| LTC1551LCMS8-4.1#PBF | Identical except SHDN pin is active-high instead of active-low; all other parameters match | Required when host MCU GPIO defaults high or lacks pull-down capability for shutdown control | Choose when system-level logic polarity mandates active-high enable; no change to bias performance or layout |
Compared with LTC1550LCMS8-4.1#PBF, the SO-package alternative offers mechanical robustness and soldering flexibility at the cost of 60% larger PCB area, while the LTC1551L variant preserves identical regulation and noise performance but shifts shutdown control logic-both require no schematic or layout revision beyond pin-level connection adjustments.
Availability
LTC1550LCMS8-4.1#PBF is available at Aetrix Electronics and suitable for GaAs FET biasing, portable RF power supplies, and battery-powered instrumentation requiring stable component supply, long-term lifecycle support, and guaranteed RoHS-compliant sourcing.
Supply support for LTC1550LCMS8-4.1#PBF 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, documentation, and manufacturing continuity for the LTC portfolio.
The LTC1550L series was designed specifically for low-noise, compact negative voltage generation in portable RF systems-emphasizing ripple suppression, minimal external components, and GaAs FET bias accuracy.
FAQ
What is the minimum input voltage required for LTC1550LCMS8-4.1#PBF to regulate at –4.1V?
The LTC1550LCMS8-4.1#PBF requires a minimum VCC of 4.5V to guarantee –4.1V output regulation across temperature and load. Below 4.5V, output voltage drops out of specification; at 4.75V–5.25V, it delivers full 20mA with ±2.5% accuracy. This constraint ensures sufficient headroom for the internal linear post-regulator stage.
Can LTC1550LCMS8-4.1#PBF be used with ceramic output capacitors only?
Yes, but only with careful ESR selection: LTC1550LCMS8-4.1#PBF requires ≥10µF total output capacitance with moderate ESR (e.g., 100–500mΩ) for loop stability. Using very low-ESR ceramics alone risks oscillation; the recommended solution is 10µF tantalum or aluminum polymer in parallel with 0.1µF X7R ceramic to suppress high-frequency spikes.
Does LTC1550LCMS8-4.1#PBF include power-good signaling?
Yes-the REG pin on LTC1550LCMS8-4.1#PBF is an open-drain output that pulls low when VOUT is within ±5% of –4.1V. It sinks up to 4mA at 5V supply and requires an external pull-up resistor (typically 10kΩ to VCC or another logic rail) to generate a logic-high power-valid signal for system monitoring.
How does the shutdown function behave on LTC1550LCMS8-4.1#PBF?
The SHDN pin on LTC1550LCMS8-4.1#PBF is active-low: pulling it to GND disables the charge pump and reduces quiescent current to 0.2µA typical. The pin has no internal pull-up, so a pull-up resistor (e.g., 100kΩ to VCC) is mandatory to ensure normal operation on power-up. In shutdown, VOUT collapses to 0V.
What external capacitors are mandatory for stable operation of LTC1550LCMS8-4.1#PBF?
Four capacitors are mandatory: (1) ≥2.2µF ceramic input bypass (CIN) at VCC–GND, (2) 0.1µF ceramic flying cap (C1) between C1+ and C1–, (3) 0.1µF ceramic storage cap (CCP) between CPOUT and GND, and (4) ≥10µF output filter (COUT) at VOUT–GND with 0.1µF ceramic in parallel. All must use star-ground routing at the GND pin.
LTC1550LCMS8-4.1#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 8-TSSOP, 8-MSOP (0.118", 3.00mm Width)
- Packaging:
- Tube
- 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-MSOP
LTC1550LCMS8-4.1#PBF FAQ
1.How can I place an order for LTC1550LCMS8-4.1#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC1550LCMS8-4.1#PBF 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 LTC1550LCMS8-4.1#PBF reliable?
The price and inventory of LTC1550LCMS8-4.1#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC1550LCMS8-4.1#PBF is usually 5 days.
3.What payment methods are accepted for LTC1550LCMS8-4.1#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC1550LCMS8-4.1#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC1550LCMS8-4.1#PBF?
LTC1550LCMS8-4.1#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC1550LCMS8-4.1#PBF 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 LTC1550LCMS8-4.1#PBF?
For technical support, including LTC1550LCMS8-4.1#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC1550LCMS8-4.1#PBF requirements.
6.How does Aetrix verify that LTC1550LCMS8-4.1#PBF is sourced from the original manufacturer or authorized distributors?
All LTC1550LCMS8-4.1#PBF 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 LTC1550LCMS8-4.1#PBF meets industry standards.
7.What is the process for return or replacement of LTC1550LCMS8-4.1#PBF?
All LTC1550LCMS8-4.1#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC1550LCMS8-4.1#PBF, 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 LTC1550LCMS8-4.1#PBF part is unused and in its original packaging.
Return procedure for LTC1550LCMS8-4.1#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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