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Analog Devices Inc. LTC1551LCMS8#TRPBF
- Part No.:
- LTC1551LCMS8#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 8-TSSOP, 8-MSOP (0.118", 3.00mm Width)
- Datasheet:
-
LTC1551LCMS8#TRPBF.pdf
- Description:
- IC REG CHARG PUMP ADJ 20MA 8MSOP
- Quantity:
- Payment:
- Shipping:
Inventory:1,131
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Product details
Overview
LTC1551LCMS8#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-high shutdown (SHDN). It is optimized for GaAs FET bias generation in portable RF and cellular telephone transmitters.
For engineers reviewing the LTC1551LCMS8#TRPBF datasheet, LTC1551LCMS8#TRPBF pinout, LTC1551LCMS8#TRPBF application, or LTC1551LCMS8#TRPBF equivalent, key selection criteria include guaranteed –4.1V output regulation under 20mA load, shutdown quiescent current <1µA, MSOP-8 package compatibility, and minimal external component count (four capacitors only).
Technical Context
The LTC1551LCMS8#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.
Unlike the LTC1550L variant, the LTC1551LCMS8#TRPBF uses an active-high SHDN pin with internal 5µA pull-down, eliminating need for external pull-up. The device requires no ADJ or REG pins in the 8-pin MSOP package-REG is omitted, and output is fixed at –4.1V, simplifying layout and reducing BOM count.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | Fixed –4.1V, regulated to ±2.5% over 4.5V–5.25V input and 0–20mA load - ensures stable GaAs FET gate bias across battery discharge. |
| Output Ripple | <1mVP-P typical with 10µF + 0.1µF output capacitor - meets low-noise RF bias requirements without additional filtering. |
| Supply Range | 4.5V to 5.25V minimum for –4.1V/20mA operation - aligns with Li-ion or regulated 5V rail in portable transceivers. |
| Shutdown Current | 0.2µA typical (active-high SHDN pulled to GND) - enables ultra-low-power sleep mode in battery-powered systems. |
| Charge Pump Freq | 900kHz fixed - avoids IF bands (400–600kHz), reduces EMI, and allows use of compact 0.1µF ceramic flying capacitors. |
| Max Output Current | 20mA at VCC ≥ 4.75V - sufficient for biasing multiple GaAs FETs or medium-power RF front-end stages. |
| Line Regulation | ±2.5% over full VCC range - maintains precise bias voltage despite supply sag during transmit bursts. |
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, Pb-free, halogen-free.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (REG) | Power-Valid Output | Omitted in LTC1551LCMS8#TRPBF - not bonded out in MS8 package; unused pin. |
| 2 (CPOUT) | Negative Charge Pump Output | Intermediate node supplying linear regulator input; requires 0.1µF capacitor to GND with star-grounded return path. |
| 3 (GND) | Analog Ground | Common reference for regulator feedback and charge pump; must connect directly to low-impedance ground plane. |
| 4 (C1–) | Flying Capacitor Negative Terminal | Connects to negative side of 0.1µF flying capacitor (C1); forms charge transfer path with C1+. |
| 5 (SHDN) | Active-High Shutdown Control | Pull to GND to disable; internal 5µA pull-down ensures default-on operation - no external resistor needed. |
| 6 (VCC) | Positive Supply Input | Accepts 4.5–5.25V; requires ≥2.2µF low-ESR ceramic bypass capacitor placed adjacent to pin. |
| 7 (C1+) | Flying Capacitor Positive Terminal | Connects to positive side of 0.1µF flying capacitor (C1); alternately charged/discharged at 900kHz. |
| 8 (VOUT) | Regulated Negative Output | Delivers –4.1V; requires ≥10µF output capacitor (tantalum or polymer) + 0.1µF ceramic in parallel for stability and ripple suppression. |
Key Features
| Feature | Design Value |
|---|---|
| Integrated Linear Post-Regulator | Eliminates need for external LDO; delivers low-noise –4.1V with fast transient response and no external compensation. |
| 900kHz Switching Frequency | Enables use of small 0.1µF ceramic flying capacitors and avoids interference with common IF bands in RF receivers. |
| Four-Component Solution | Only input bypass (2.2µF), two flying caps (0.1µF each), and output filter (10µF + 0.1µF) required - minimizes PCB area and BOM cost. |
| Active-High Shutdown | Internal 5µA pull-down on SHDN ensures reliable power-on default without external components - simplifies control logic interface. |
| Guaranteed –4.1V Output | Specified over full temperature and load range (0–20mA, –40°C to 85°C) - eliminates need for post-production calibration in GaAs bias circuits. |
Applications
| GaAs FET Transmitter Bias | Portable Cellular RF Front-End |
|---|---|
Use Scenario: Generating stable negative gate bias for GaAs pHEMT power amplifiers in 2G/3G/4G handset transmitters. IC Role / Device Role / Timing Role: Fixed –4.1V regulated voltage source providing gate control voltage to RF power FETs. Use Value: Maintains consistent amplifier gain and efficiency across battery voltage drop and temperature variation, with <1mVP-P noise preventing AM-to-PM distortion. |
Use Scenario: Supplying clean negative bias to low-noise amplifiers (LNAs) and mixer diodes in compact cellular radio modules. IC Role / Device Role / Timing Role: Compact, low-EMI inverter replacing discrete charge pump + LDO solutions in space-constrained RF subsystems. Use Value: Reduces component count by 4–6 parts versus discrete alternatives while meeting stringent RF spectral purity requirements. |
| Battery-Powered RF Test Equipment | ISM Band Transceiver Bias |
Use Scenario: Providing calibrated –4.1V supply for handheld spectrum analyzers and RF signal generators operating from single-cell Li-ion. IC Role / Device Role / Timing Role: Low-quiescent-current (0.2µA shutdown) inverter enabling multi-day battery life in portable test gear. Use Value: Enables deep-sleep modes without compromising startup time (<5ms turn-on) or output accuracy during measurement cycles. |
Use Scenario: Biasing GaAs switches and drivers in 915MHz/2.4GHz ISM band IoT transceivers (e.g., Zigbee, Bluetooth LE). IC Role / Device Role / Timing Role: Integrated charge pump + regulator delivering precise –4.1V for RF switch control and PA enable/disable sequencing. Use Value: Ensures repeatable RF performance across wide ambient temperatures (–40°C to +85°C) without derating. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar negative voltage regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC1550LCMS8-4.1#TRPBF | Active-low SHDN, identical electrical specs and pinout - differs only in shutdown polarity and internal pull configuration. | Requires external pull-up resistor for default-on operation; incompatible with direct GPIO-driven active-high control. | Select when system MCU GPIO defaults high or when legacy design uses active-low enable signals. |
| LTC1261LCS8#TRPBF | Adjustable output (via external resistors), lower max output current (15mA), higher typical ripple (2mVP-P), no linear post-regulator. | Suitable for non-critical bias where –4.1V is derived via resistor divider; less suitable for noise-sensitive GaAs FET gates. | Choose only if adjustable output is required and ripple tolerance >1mVP-P; avoid for precision RF bias. |
Compared with LTC1550LCMS8-4.1#TRPBF, the LTC1551LCMS8#TRPBF eliminates external pull-up needs and simplifies control logic; compared with LTC1261LCS8#TRPBF, it delivers superior noise performance and tighter regulation essential for GaAs transmitter linearity.
Availability
LTC1551LCMS8#TRPBF is available at Aetrix Electronics and suitable for GaAs FET bias generation, portable RF front-end power, and battery-powered test equipment requiring stable component supply, full-temperature-range performance, and RoHS-compliant packaging.
Supply support for LTC1551LCMS8#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, datasheet documentation, and long-term manufacturing commitment for legacy Linear parts.
The LTC1551L series was designed specifically for low-noise, high-efficiency negative voltage generation in portable RF systems - emphasizing minimal external components, guaranteed regulation, and robust EMI behavior in crowded wireless environments.
FAQ
What is the minimum input voltage required for LTC1551LCMS8#TRPBF to deliver –4.1V at 20mA?
The LTC1551LCMS8#TRPBF requires a minimum VCC of 4.75V to guarantee –4.1V output regulation at 20mA load, as specified in the Electrical Characteristics table. Below this, output voltage may droop outside ±2.5% tolerance. Operation down to 4.5V is supported at ≤10mA load.
Does LTC1551LCMS8#TRPBF require an external resistor on the SHDN pin?
No. The LTC1551LCMS8#TRPBF includes an internal 5µA pull-down on the SHDN pin, ensuring default-on operation when left unconnected. An external resistor is unnecessary - unlike the LTC1550L variant, which requires a pull-up.
Can LTC1551LCMS8#TRPBF be used with ceramic output capacitors only?
No. The LTC1551LCMS8#TRPBF requires a moderate-ESR output capacitor (e.g., tantalum or polymer) ≥10µF for loop stability. A low-ESR 0.1µF ceramic capacitor must be added in parallel to suppress high-frequency spikes - using ceramic-only risks oscillation.
Is the REG pin available on LTC1551LCMS8#TRPBF in the MS8 package?
No. The REG pin is not bonded out in the 8-lead MSOP (MS8) package used by LTC1551LCMS8#TRPBF. It is only available on the 16-lead SSOP (GN) package for adjustable versions. This pin is omitted entirely in fixed-output MS8 variants.
What is the typical startup time for LTC1551LCMS8#TRPBF?
The LTC1551LCMS8#TRPBF has a typical turn-on time of 1–5ms (measured from SHDN rising edge to VOUT settling within 1% of –4.1V) under 5V supply and 10mA load conditions, as confirmed in the Electrical Characteristics table and Figure G05.
LTC1551LCMS8#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:
- 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-MSOP
LTC1551LCMS8#TRPBF FAQ
1.How can I place an order for LTC1551LCMS8#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC1551LCMS8#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 LTC1551LCMS8#TRPBF reliable?
The price and inventory of LTC1551LCMS8#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC1551LCMS8#TRPBF is usually 5 days.
3.What payment methods are accepted for LTC1551LCMS8#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC1551LCMS8#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC1551LCMS8#TRPBF?
LTC1551LCMS8#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC1551LCMS8#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 LTC1551LCMS8#TRPBF?
For technical support, including LTC1551LCMS8#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC1551LCMS8#TRPBF requirements.
6.How does Aetrix verify that LTC1551LCMS8#TRPBF is sourced from the original manufacturer or authorized distributors?
All LTC1551LCMS8#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 LTC1551LCMS8#TRPBF meets industry standards.
7.What is the process for return or replacement of LTC1551LCMS8#TRPBF?
All LTC1551LCMS8#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC1551LCMS8#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 LTC1551LCMS8#TRPBF part is unused and in its original packaging.
Return procedure for LTC1551LCMS8#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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