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Analog Devices Inc. LTC1550LCMS8-4.1#TRPBF
- Part No.:
- LTC1550LCMS8-4.1#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 8-TSSOP, 8-MSOP (0.118", 3.00mm Width)
- Datasheet:
-
LTC1550LCMS8-4.1#TRPBF.pdf
- Description:
- IC REG CHARGE PUMP -4.1V 8MSOP
- Quantity:
- Payment:
- Shipping:
Inventory:2,890
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Product details
Overview
LTC1550LCMS8-4.1#TRPBF 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 output current with ±2.5% regulation over line, load, and temperature. It operates from a single 4.5V–5.25V supply, features 900kHz charge pump frequency, <1mVP-P output ripple, and TTL-compatible active-low shutdown (SHDN). It is optimized for GaAs FET bias generation in portable RF transmitters.
For engineers reviewing the LTC1550LCMS8-4.1#TRPBF datasheet, LTC1550LCMS8-4.1#TRPBF pinout, LTC1550LCMS8-4.1#TRPBF application, or LTC1550LCMS8-4.1#TRPBF equivalent, key selection criteria include guaranteed –4.1V output regulation under 20mA load, 0.2µA shutdown current, MSOP-8 package compatibility, and minimal external component count (four capacitors only).
Technical Context
The LTC1550LCMS8-4.1#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 despite high-frequency charge pumping.
It requires no inductors and uses only two 0.1µF ceramic flying capacitors (C1+, C1–), one 0.1µF CPOUT storage capacitor, and a ≥10µF output filter capacitor (with parallel 0.1µF ceramic) to achieve <1mVP-P ripple. The REG pin provides open-drain power-good indication when VOUT is within ±5% of nominal.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | Fixed –4.1V, regulated to ±2.5% over line/load/temperature - ensures stable GaAs FET gate bias across operating conditions. |
| Max Output Current | 20mA at VCC ≥ 4.75V - supports moderate-power RF front-end biasing without external amplification. |
| Output Ripple | <1mVP-P typical (with 10µF + 0.1µF output cap) - meets low-noise requirements for sensitive RF transmitter stages. |
| Supply Range | 4.5V to 5.25V - mandates use with regulated 5V rails; insufficient for 3.3V-only systems without boost. |
| Shutdown Current | 0.2µA typical - enables ultra-low-power sleep mode in battery-operated handheld RF devices. |
| Charge Pump Freq | 900kHz - places switching energy outside common IF bands (400–600kHz), reducing RF interference. |
| Quiescent Current | 3.65mA typical at 5V - balances efficiency and startup speed for intermittent bias applications. |
Pinout & Package
Package: 8-lead MSOP (MS8), 3.0mm × 3.0mm × 0.85mm, thermal pad optional, RoHS-compliant, tape-and-reel (#TRPBF).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (REG) | Open-drain power-good indicator | Pulls low when VOUT is within ±5% of –4.1V; requires external pull-up to VCC or higher (≤6V); enables system-level power sequencing validation. |
| 2 (CPOUT) | Negative charge pump output | Intermediate node supplying linear regulator input; requires 0.1µF capacitor to GND with star-ground connection to minimize AC current loop area. |
| 3 (GND) | Analog/power ground reference | Single ground pin for 8-lead MSOP; must connect directly to low-impedance ground plane to avoid regulation error and noise coupling. |
| 4 (C1–) | Negative flying capacitor terminal | Completes charge transfer path with C1+; connects to 0.1µF ceramic capacitor (C1) - polarity-sensitive in layout. |
| 5 (SHDN) | Active-low shutdown control | TTL-compatible input; pulls low to disable charge pump and reduce IQ to 0.2µA; no internal pull-up - external resistor required for default-on operation. |
| 6 (VCC) | Positive input supply | Accepts 4.5V–5.25V; requires ≥2.2µF low-ESR ceramic bypass capacitor placed adjacent to pin and GND for stable charge pump operation. |
| 7 (C1+) | Positive flying capacitor terminal | Drives 0.1µF flying capacitor (C1) during charge phase; forms switched-capacitor inverter core with C1– and internal switches. |
| 8 (VOUT) | Regulated negative output | Delivers –4.1V; requires ≥10µF output capacitor (moderate ESR) + parallel 0.1µF ceramic to ensure loop stability and sub-mV ripple. |
Key Features
| Feature | Design Value |
|---|---|
| Integrated linear post-regulator | Eliminates need for external LDO; achieves ±2.5% output accuracy and <1mVP-P ripple without inductors or complex compensation. |
| 900kHz charge pump frequency | Enables use of small 0.1µF ceramic flying capacitors and avoids IF band interference in cellular/RF applications. |
| Four-component solution | Requires only CIN (2.2µF), C1 (0.1µF), CCP (0.1µF), and COUT (10µF + 0.1µF) - reduces BOM cost and PCB area vs. inductor-based inverters. |
| Active-low TTL-compatible SHDN | Supports direct interfacing with baseband processors or PMICs without level-shifting; 0.2µA shutdown current extends battery life. |
| Power-good (REG) output | Provides system-level fault detection and sequencing capability - critical for reliable RF transmitter enable/disable timing. |
Applications
| GaAs FET Bias Generator | Negative Supply for RF ICs |
|---|---|
|
Use Scenario: Providing stable gate bias voltage to GaAs pHEMT power amplifier stages in GSM/UMTS/WCDMA handset transmitters. IC Role / Device Role / Timing Role: Fixed –4.1V regulated inverter generating precise negative gate control voltage independent of battery droop. Use Value: Enables consistent PA gain and linearity across 3.4V–4.2V Li-ion battery range while maintaining <1mVP-P noise floor. |
Use Scenario: Generating clean negative supply for RF front-end ICs requiring dual-rail operation (e.g., mixer LO buffers, IF amplifiers). IC Role / Device Role / Timing Role: Low-noise charge-pump inverter with linear post-regulation serving as dedicated auxiliary rail. Use Value: Eliminates need for discrete inductor-based converters, reducing EMI and board space while meeting –4.1V ±2.5% tolerance. |
| Battery-Powered Portable Radio | Low-Power Sensor Biasing |
|
Use Scenario: Powering analog sections of handheld two-way radios where compact size and low quiescent current are critical. IC Role / Device Role / Timing Role: Efficient negative voltage source enabling full functionality during transmit bursts and deep-sleep modes. Use Value: 0.2µA shutdown current and 3.65mA operating current extend runtime; MSOP-8 footprint fits tight RF module layouts. |
Use Scenario: Biasing precision analog sensors (e.g., MEMS microphones, current-sense amplifiers) requiring symmetric dual supplies. IC Role / Device Role / Timing Role: Compact, low-noise inverter generating stable negative rail from single positive battery source. Use Value: Sub-mV ripple prevents sensor offset drift; ±2.5% regulation ensures consistent ADC reference tracking across temperature. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar switched-capacitor inverter applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC1551LCMS8-4.1#TRPBF | Identical specs except active-high SHDN pin; same MSOP-8 package and –4.1V output. | Suitable when host controller drives active-high enable signals; no change to bias circuitry or layout. | Select when system logic uses active-high control; otherwise LTC1550LCMS8-4.1#TRPBF is preferred for active-low compatibility. |
| LTC1261LCS8-4.1#PBF | Lower max output current (15mA), higher typical ripple (2mVP-P), no REG pin, SO-8 package. | Acceptable for lower-current GaAs bias or non-critical analog rails where power-good signaling is unnecessary. | Choose for cost-sensitive designs with relaxed ripple/regulation specs and SO-8 assembly infrastructure. |
Compared with LTC1551LCMS8-4.1#TRPBF, the LTC1550LCMS8-4.1#TRPBF offers identical performance with active-low control - simplifying interface to most baseband processors. Versus LTC1261LCS8-4.1#PBF, it delivers tighter regulation, lower noise, and power-good signaling in a smaller MSOP package, justifying premium for RF-critical biasing.
Availability
LTC1550LCMS8-4.1#TRPBF is available at Aetrix Electronics and suitable for GaAs FET biasing, portable RF transmitter power, and low-noise negative supply generation requiring stable component supply, long-term lifecycle support, and traceable sourcing.
Supply support for LTC1550LCMS8-4.1#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, documentation, and manufacturing continuity for legacy Linear parts including the LTC series.
The LTC1550L family was designed specifically for low-noise, inductorless negative voltage generation in portable RF systems - emphasizing GaAs FET biasing, minimal external components, and robust regulation under dynamic load conditions.
FAQ
What is the minimum input voltage required for LTC1550LCMS8-4.1#TRPBF to regulate –4.1V at 20mA?
The LTC1550LCMS8-4.1#TRPBF requires VCC ≥ 4.75V to guarantee –4.1V output regulation at 20mA load, per the Electrical Characteristics table. Below 4.75V, output voltage may drop out of specification; operation at 4.5V is only guaranteed up to 5mA load. Always verify against the "Minimum Required VCC vs VOUT and IOUT" graph in the datasheet.
Can LTC1550LCMS8-4.1#TRPBF be used with a 3.3V supply?
No - the LTC1550LCMS8-4.1#TRPBF is not rated for 3.3V operation. Its absolute minimum VCC for –4.1V output is 4.5V, and full 20mA regulation requires ≥4.75V. Using 3.3V will result in failure to reach –4.1V or complete regulation loss. For 3.3V-input inverters, consider LTC1555 or LTC1556 instead.
Why does LTC1550LCMS8-4.1#TRPBF require a specific ESR range for the output capacitor?
The LTC1550LCMS8-4.1#TRPBF's linear regulator loop relies on the zero formed by the output capacitor's ESR and capacitance for phase lead. Very low-ESR capacitors (e.g., polymer or ultra-low-ESR ceramics) remove this zero, causing instability and oscillation. A moderate-ESR capacitor (e.g., standard tantalum or aluminum electrolytic) combined with a parallel 0.1µF ceramic ensures both stability and high-frequency noise suppression.
Is the REG pin on LTC1550LCMS8-4.1#TRPBF internally pulled up?
No - the REG pin on LTC1550LCMS8-4.1#TRPBF is open-drain and has no internal pull-up. An external pull-up resistor (typically 10kΩ to VCC or another logic rail ≤6V) is mandatory to observe valid high/low transitions. Without it, REG remains floating and cannot signal power-good status to the system.
How does the SHDN pin behavior differ between LTC1550LCMS8-4.1#TRPBF and LTC1551LCMS8-4.1#TRPBF?
The LTC1550LCMS8-4.1#TRPBF SHDN pin is active-low: pulling it to GND disables the device. The LTC1551LCMS8-4.1#TRPBF SHDN pin is active-high: pulling it to VCC disables it. Both have identical electrical specs otherwise. The LTC1550L version includes an internal pull-down on SHDN in the 16-lead SSOP variant, but the MSOP-8 version (including LTC1550LCMS8-4.1#TRPBF) has no internal pull-up or pull-down - external biasing is required.
LTC1550LCMS8-4.1#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 8-TSSOP, 8-MSOP (0.118", 3.00mm 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-MSOP
LTC1550LCMS8-4.1#TRPBF FAQ
1.How can I place an order for LTC1550LCMS8-4.1#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC1550LCMS8-4.1#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 LTC1550LCMS8-4.1#TRPBF reliable?
The price and inventory of LTC1550LCMS8-4.1#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC1550LCMS8-4.1#TRPBF is usually 5 days.
3.What payment methods are accepted for LTC1550LCMS8-4.1#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC1550LCMS8-4.1#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC1550LCMS8-4.1#TRPBF?
LTC1550LCMS8-4.1#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC1550LCMS8-4.1#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 LTC1550LCMS8-4.1#TRPBF?
For technical support, including LTC1550LCMS8-4.1#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC1550LCMS8-4.1#TRPBF requirements.
6.How does Aetrix verify that LTC1550LCMS8-4.1#TRPBF is sourced from the original manufacturer or authorized distributors?
All LTC1550LCMS8-4.1#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 LTC1550LCMS8-4.1#TRPBF meets industry standards.
7.What is the process for return or replacement of LTC1550LCMS8-4.1#TRPBF?
All LTC1550LCMS8-4.1#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC1550LCMS8-4.1#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 LTC1550LCMS8-4.1#TRPBF part is unused and in its original packaging.
Return procedure for LTC1550LCMS8-4.1#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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