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Analog Devices Inc. LTC1550LCS8-4.1#PBF
- Part No.:
- LTC1550LCS8-4.1#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
LTC1550LCS8-4.1#PBF.pdf
- Description:
- IC REG CHARG PUMP -4.1V 20MA 8SO
- Quantity:
- Payment:
- Shipping:
Inventory:161
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Product details
Overview
LTC1550LCS8-4.1#PBF from Analog Devices (formerly Linear Technology) is a fixed-output, low-noise switched-capacitor voltage inverter with integrated linear post-regulator, delivering –4.1V at up to 20mA load current with <1mVP-P output ripple. It operates from a single 4.5V–5.25V supply, features active-low TTL-compatible shutdown (SHDN), and is optimized for GaAs FET bias generation in portable RF transmitters.
For engineers reviewing the LTC1550LCS8-4.1#PBF datasheet, LTC1550LCS8-4.1#PBF pinout, LTC1550LCS8-4.1#PBF application, or LTC1550LCS8-4.1#PBF equivalent, key selection criteria include guaranteed ±2.5% output regulation over line/load/temperature, 900kHz charge pump frequency enabling compact 0.1µF external capacitors, and MSOP-8 package compatibility with space-constrained portable designs.
Technical Context
The LTC1550LCS8-4.1#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 stabilization.
It requires only four external components: one 2.2µF input bypass capacitor, two 0.1µF charge pump capacitors (C1+, C1–), and a ≥10µF output filter capacitor (with parallel 0.1µF ceramic). The SHDN pin enables <1µA quiescent current in shutdown mode, while REG provides open-drain power-valid indication.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | Fixed –4.1V, guaranteed ±2.5% regulation across 4.5V–5.25V input, 0–10mA load, and –40°C to 85°C. |
| Output Ripple | <1mVP-P typical with 10µF + 0.1µF output capacitor; critical for low-noise GaAs FET gate bias stability. |
| Charge Pump Frequency | 900kHz internal oscillator - avoids IF bands (400–600kHz), enables use of standard 0.1µF ceramic flying capacitors. |
| Supply Current | 3.65mA typical at 5V input; drops to 0.2µA in shutdown - extends battery life in portable RF systems. |
| Input Voltage Range | 4.5V to 5.25V minimum required for –4.1V output at full 20mA load - ensures stable operation in Li-ion powered devices. |
| Shutdown Interface | TTL-compatible active-low SHDN pin - compatible with standard logic-level control without level-shifting circuitry. |
Pinout & Package
Package: 8-lead MSOP (MS8), 3.0mm × 3.0mm × 0.85mm body, exposed pad not electrically connected. Pin pitch: 0.65mm. RoHS-compliant, lead-free (Pb-free) 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 power sequencing. |
| 2 (CPOUT) | Negative charge pump output | Supplies input to linear regulator; requires 0.1µF storage capacitor tied directly to GND and VCC bypass node to minimize AC current path. |
| 3 (GND) | Analog/power ground reference | Single ground connection for all internal blocks; must tie directly to low-impedance PCB ground plane to minimize regulation error. |
| 4 (C1–) | Negative flying capacitor terminal | Connects to 0.1µF charge pump capacitor (C1); forms half of charge-transfer network with C1+ (Pin 7). |
| 5 (SHDN) | Active-low shutdown control | Drives internal charge pump and regulator into ultra-low-power state (<1µA IQ) when pulled low; high-impedance input with no internal pull-up. |
| 6 (VCC) | Positive input supply | Accepts 4.5V–5.25V; requires ≥2.2µF low-ESR ceramic bypass capacitor placed adjacent to pin to prevent supply droop during charge-pump switching. |
| 7 (C1+) | Positive flying capacitor terminal | Connects to same 0.1µF charge pump capacitor as C1– (Pin 4); alternately charges/discharges with CPOUT to generate negative voltage. |
| 8 (VOUT) | Regulated negative output | Delivers –4.1V; requires ≥10µF output capacitor (moderate ESR) plus parallel 0.1µF ceramic to suppress high-frequency spikes and ensure loop stability. |
Key Features
| Feature | Design Value |
|---|---|
| Integrated linear post-regulator | Reduces charge pump ripple to <1mVP-P without external LDO, eliminating need for additional filtering components. |
| 900kHz charge pump frequency | Enables use of small, low-cost 0.1µF ceramic flying capacitors and avoids interference with common RF IF bands. |
| Ultra-low shutdown current | 0.2µA typical quiescent current in shutdown - preserves battery capacity during standby in cellular handsets. |
| Guaranteed output regulation | ±2.5% over full temperature range (–40°C to 85°C), line (4.5V–5.25V), and load (0–10mA) - ensures consistent GaAs FET bias under real-world conditions. |
| Power-valid flag (REG) | Open-drain output confirms regulated –4.1V delivery - simplifies system-level power monitoring and sequencing without external comparators. |
Applications
| GaAs FET Transmitter Bias | Portable RF Power Amplifier Supply |
|---|---|
Use Scenario: Generating stable negative gate bias for GaAs pHEMT power amplifiers in 3G/4G cellular handsets and portable radios. IC Role / Device Role / Timing Role: Fixed –4.1V voltage inverter with linear post-regulation serving as precision DC bias source for amplifier gate control. Use Value: Low 1mVP-P ripple prevents AM-to-PM distortion and maintains amplifier linearity and efficiency across operating temperature. |
Use Scenario: Providing clean, regulated negative supply to RF front-end ICs requiring dual-rail operation in battery-powered IoT sensors and wearables. IC Role / Device Role / Timing Role: Compact switched-capacitor inverter delivering –4.1V from single Li-ion cell (3.6V nominal) with minimal external components. Use Value: 8-pin MSOP footprint and four external capacitors reduce PCB area by >40% versus discrete inverter + LDO solutions. |
| Battery-Powered Instrumentation | Low-Noise Analog Signal Chain Bias |
Use Scenario: Biasing op-amp inputs or sensor interfaces in handheld test equipment where battery life and signal integrity are critical. IC Role / Device Role / Timing Role: Low-quiescent-current (3.65mA) negative supply generator enabling extended runtime between charges. Use Value: Shutdown mode reduces supply current to 0.2µA - extends shelf life and standby time in field-deployed instruments. |
Use Scenario: Supplying clean negative rail to precision ADC drivers or instrumentation amplifiers in medical or audio applications. IC Role / Device Role / Timing Role: Ultra-low-noise inverter with ESR-tuned output capacitance delivering stable –4.1V reference for analog signal conditioning. Use Value: Spot noise below 1µV/√Hz at 10kHz and flat spectrum up to 1MHz preserve SNR in high-resolution data acquisition systems. |
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 |
|---|---|---|---|
| LTC1550LMS8-4.1#PBF | Identical electrical specs and pinout; differs only in package marking (MS8 vs S8) - same MSOP-8 footprint and thermal performance. | No functional difference; both support identical GaAs FET bias and portable RF applications. | Select LTC1550LCS8-4.1#PBF for standard SO-8-compatible assembly lines; choose LTC1550LMS8-4.1#PBF if MSOP-specific reel packaging or traceability is required. |
| LTC1551LCS8-4.1#PBF | Same output voltage, ripple, and regulation; differs only in active-high SHDN pin (vs active-low on LTC1550LCS8-4.1#PBF). | Requires inverted logic control signal; unsuitable for existing active-low shutdown architectures without level-shifting. | Choose LTC1551LCS8-4.1#PBF only when system MCU GPIO defaults high or when active-high enable simplifies power sequencing logic. |
Compared with LTC1550LCS8-4.1#PBF, LTC1550LMS8-4.1#PBF offers identical performance in the same MSOP-8 package but with alternate part marking, while LTC1551LCS8-4.1#PBF provides identical regulation and noise performance but mandates active-high control - making LTC1550LCS8-4.1#PBF the optimal choice for legacy active-low shutdown designs.
Availability
LTC1550LCS8-4.1#PBF is available at Aetrix Electronics and suitable for GaAs FET bias generation, portable RF power amplifier supplies, and battery-powered instrumentation requiring stable component supply, guaranteed long-term availability, and full RoHS compliance.
Supply support for LTC1550LCS8-4.1#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, datasheet documentation, and manufacturing continuity for all Linear-branded parts including the LTC series.
The LTC1550L/LTC1551L family was designed specifically for low-noise, space-constrained portable RF applications - emphasizing ultra-low output ripple, minimal external component count, and robust operation across industrial temperature ranges.
FAQ
What is the minimum input voltage required for LTC1550LCS8-4.1#PBF to deliver –4.1V at 20mA?
The LTC1550LCS8-4.1#PBF requires a minimum VCC of 4.5V to guarantee –4.1V output regulation at 20mA load, as specified in the Electrical Characteristics table. Below 4.5V, output voltage may drop out of regulation or current capability decreases - consult the "Maximum Output Current vs Supply Voltage" graph (Figure G04) for precise derating curves.
Can LTC1550LCS8-4.1#PBF be used with ceramic output capacitors only?
Yes, but with strict ESR requirements: LTC1550LCS8-4.1#PBF requires a moderate-ESR output capacitor (e.g., tantalum or polymer) ≥10µF for loop stability; adding a parallel 0.1µF ceramic capacitor is mandatory to suppress high-frequency spikes. Using only low-ESR ceramics risks oscillation due to missing phase-lead zero in the feedback loop.
Does LTC1550LCS8-4.1#PBF require external resistors for the –4.1V output?
No. LTC1550LCS8-4.1#PBF is a fixed-output variant with internal resistor divider; no external resistors are needed. External resistors are required only for adjustable versions (e.g., LTC1550LCS8#PBF) connected to the ADJ pin - which is not present on the 8-pin S8/MS8 packages of the fixed-output LTC1550LCS8-4.1#PBF.
How does the REG pin on LTC1550LCS8-4.1#PBF function in system power monitoring?
The REG pin on LTC1550LCS8-4.1#PBF is an open-drain output that pulls low when VOUT is within ±5% of –4.1V. It sinks up to 4mA and must be externally pulled up (to VCC or ≤6V) to generate a logic-high "power good" signal - enabling microcontroller-based fault detection and safe system startup sequencing.
Is LTC1550LCS8-4.1#PBF compatible with lead-free reflow soldering profiles?
Yes. LTC1550LCS8-4.1#PBF carries the #PBF suffix indicating Pb-free (lead-free) finish and is qualified for standard JEDEC J-STD-020D reflow profiles, including peak temperatures up to 260°C. The MSOP-8 package supports both SnPb and lead-free assembly processes without derating.
LTC1550LCS8-4.1#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 8-SOIC (0.154", 3.90mm 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-SO
LTC1550LCS8-4.1#PBF FAQ
1.How can I place an order for LTC1550LCS8-4.1#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC1550LCS8-4.1#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 LTC1550LCS8-4.1#PBF reliable?
The price and inventory of LTC1550LCS8-4.1#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC1550LCS8-4.1#PBF is usually 5 days.
3.What payment methods are accepted for LTC1550LCS8-4.1#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC1550LCS8-4.1#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC1550LCS8-4.1#PBF?
LTC1550LCS8-4.1#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC1550LCS8-4.1#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 LTC1550LCS8-4.1#PBF?
For technical support, including LTC1550LCS8-4.1#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC1550LCS8-4.1#PBF requirements.
6.How does Aetrix verify that LTC1550LCS8-4.1#PBF is sourced from the original manufacturer or authorized distributors?
All LTC1550LCS8-4.1#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 LTC1550LCS8-4.1#PBF meets industry standards.
7.What is the process for return or replacement of LTC1550LCS8-4.1#PBF?
All LTC1550LCS8-4.1#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC1550LCS8-4.1#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 LTC1550LCS8-4.1#PBF part is unused and in its original packaging.
Return procedure for LTC1550LCS8-4.1#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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