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Analog Devices Inc. LTC1550LCS8-2.5#TRPBF
- Part No.:
- LTC1550LCS8-2.5#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 8-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
LTC1550LCS8-2.5#TRPBF.pdf
- Description:
- IC REG CHARG PUMP -2.5V 20MA 8SO
- Quantity:
- Payment:
- Shipping:
Inventory:4,468
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Product details
Overview
LTC1550LCS8-2.5#TRPBF from Analog Devices (formerly Linear Technology) is a fixed-output, low-noise switched-capacitor voltage inverter with integrated linear post-regulator, delivering –2.5V at up to 20mA load current with ±2.5% output regulation over line, load, and temperature. It operates from a single 3.05V–5.25V supply, features 900kHz charge pump frequency, <1mVP-P output ripple, and TTL-compatible active-low shutdown. It is optimized for GaAs FET bias generation in portable RF transmitters.
For engineers reviewing the LTC1550LCS8-2.5#TRPBF datasheet, LTC1550LCS8-2.5#TRPBF pinout, LTC1550LCS8-2.5#TRPBF application, or LTC1550LCS8-2.5#TRPBF equivalent, key selection criteria include guaranteed –2.5V output regulation across 3.05V–5.25V input range, 0.2µA shutdown current, MSOP-8 package compatibility, and minimal external component count (four capacitors only).
Technical Context
The LTC1550LCS8-2.5#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 load conditions.
It employs star-ground layout requirements for VCC bypass, CPOUT, and VOUT capacitors to minimize noise coupling. The REG pin provides open-drain power-valid indication (sinking 4mA), requiring external pull-up; it is not present in the 8-pin SO package variant but confirmed absent per datasheet package diagrams and pin function table.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | Fixed –2.5V with ±2.5% regulation over full operating range (3.05V ≤ VCC ≤ 5.25V, 0–20mA load) |
| Output Ripple | <1mVP-P typical with 10µF output capacitor + 0.1µF ceramic bypass - enables clean bias for sensitive RF FETs |
| Supply Range | 3.05V to 5.25V minimum input - ensures operation from Li-ion or regulated 3.3V/5V rails |
| Shutdown Current | 0.2µA typical - extends battery life in portable RF systems during idle periods |
| Charge Pump Freq | 900kHz - avoids IF bands (400–600kHz) and allows use of small 0.1µF ceramic flying capacitors |
| Max Output Current | 20mA at VCC ≥ 4.1V - sufficient for biasing multiple GaAs FETs in cellular front-end modules |
| Regulation Accuracy | ±2.5% over line, load, and temperature - meets tight bias voltage tolerance for GaAs device stability |
Pinout & Package
Package: 8-lead SO (Small Outline, narrow 0.150"), RoHS-compliant, tape-and-reel (#TRPBF). Pin pitch: 1.27mm. Body dimensions: 4.90mm × 3.90mm × 1.75mm (max height).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (REG) | Open-drain power-valid output | Asserts low when VOUT is within ±5% of –2.5V; requires external pull-up; not functional in SO-8 package per datasheet - omitted from pin function list for S8 variants |
| 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 path |
| 3 (GND) | Analog/power ground reference | Single ground pin shared for analog and power return; must connect directly to low-impedance PCB ground plane |
| 4 (C1–) | Negative flying capacitor terminal | Completes charge transfer path with C1+; connects to 0.1µF ceramic capacitor (C1) |
| 5 (SHDN) | Active-low shutdown control | Drives internal charge pump and regulator into ultra-low-power state (<1µA); high-impedance input requiring external pull-up resistor |
| 6 (VCC) | Positive input supply | Accepts 3.05–5.25V; requires ≥2.2µF low-ESR ceramic bypass capacitor placed adjacent to pin |
| 7 (C1+) | Positive flying capacitor terminal | Charges C1 to VCC on first clock phase; connects to same 0.1µF ceramic capacitor as C1– |
| 8 (VOUT) | Regulated negative output | Delivers –2.5V; requires ≥10µF output capacitor (moderate ESR) + 0.1µF ceramic bypass for ripple suppression and loop stability |
Key Features
| Feature | Design Value |
|---|---|
| Integrated linear post-regulator | Reduces charge pump ripple to <1mVP-P without external LDO, eliminating need for second-stage filtering |
| 900kHz switching frequency | Enables use of standard 0.1µF ceramic flying capacitors and avoids interference with common RF IF bands |
| Four-component solution | Requires only input bypass (2.2µF), two 0.1µF flying caps, and 10µF output cap - minimizes BOM count and board area |
| TTL-compatible SHDN | Direct interface with microcontroller GPIO without level-shifting; 0.2µA shutdown current extends battery runtime |
| Guaranteed –2.5V output accuracy | ±2.5% regulation across full temperature, line, and load range - eliminates need for calibration in production |
Applications
| Portable Cellular Transmitter Bias | GaAs FET Power Amplifier Supply |
|---|---|
Use Scenario: Generating stable negative gate bias for GaAs FETs in 2G/3G/4G handset power amplifiers operating from single-cell Li-ion battery. IC Role / Device Role / Timing Role: Fixed –2.5V regulated inverter providing precise DC bias voltage independent of battery voltage sag. Use Value: Enables consistent FET transconductance and gain flatness across 3.05–4.2V battery range while maintaining <1mVP-P noise floor. | Use Scenario: Supplying gate control voltage for discrete GaAs pHEMTs in LTE band-switched front-end modules. IC Role / Device Role / Timing Role: Low-noise negative voltage source synchronized to RF transmit bursts via SHDN pin toggling. Use Value: Achieves 20mA peak current delivery with fast turn-on time (≤5ms) and no overshoot, supporting burst-mode PA operation. |
| RF Test Equipment Local Bias | Low-Power IoT Sensor Node Bias |
Use Scenario: Providing calibrated –2.5V reference for mixer LO injection and local oscillator tuning diodes in handheld spectrum analyzers. IC Role / Device Role / Timing Role: Precision voltage inverter referenced to system ground, rejecting supply noise via internal linear regulation. Use Value: Delivers 1.225V internal reference-derived output with <2.5mV/V line regulation - critical for dBm-level measurement accuracy. | Use Scenario: Biasing low-current GaAs switches in NB-IoT or LTE-M sensor nodes powered by coin-cell batteries. IC Role / Device Role / Timing Role: Ultra-low-quiescent inverter enabling >10-year battery life via 0.2µA shutdown mode between wake cycles. Use Value: Maintains –2.5V regulation at 100µA load with <0.5mV ripple, ensuring reliable switch threshold control during brief active intervals. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar negative voltage inverter applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC1550LCMS8-2.5#TRPBF | Identical electrical specs; MSOP-8 package (3.0mm × 3.0mm) vs SO-8 (4.9mm × 3.9mm); same pinout except REG pin is NC in SO-8 | Preferred for space-constrained PCBs; requires different land pattern and stencil design | Select for miniaturized RF modules where board area is premium; verify REG functionality not required |
| LTC1551LCS8-2.5#TRPBF | Same output, regulation, and ripple; active-high SHDN (vs active-low in LTC1550L); identical SO-8 footprint and pinout | Required when host MCU GPIO drives high to enable - eliminates need for external inverter logic | Choose when system-level control architecture mandates active-high enable signaling |
Compared with LTC1550LCS8-2.5#TRPBF, the MSOP variant saves 40% board area but removes REG functionality, while the LTC1551L version retains identical performance and form factor but changes shutdown polarity - both require validation of control signal compatibility and layout adaptation.
Availability
LTC1550LCS8-2.5#TRPBF is available at Aetrix Electronics and suitable for portable RF transmitters, GaAs FET biasing, and low-power IoT sensor nodes requiring stable component supply with guaranteed long-term availability and traceable sourcing.
Supply support for LTC1550LCS8-2.5#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 the LTC portfolio.
The LTC1550L series was designed specifically for low-noise, compact negative voltage generation in battery-powered RF systems - emphasizing ultra-low ripple, minimal external components, and robust regulation under varying input conditions.
FAQ
What is the minimum input voltage required for LTC1550LCS8-2.5#TRPBF to regulate –2.5V at 10mA?
The LTC1550LCS8-2.5#TRPBF requires a minimum VCC of 3.45V to maintain ±2.5% regulation at 10mA load, as specified in the Electrical Characteristics table. Below this voltage, output accuracy degrades due to insufficient headroom for the internal linear regulator's dropout margin. Operation at 3.05V is only guaranteed for 5mA loads.
Does LTC1550LCS8-2.5#TRPBF include the REG pin functionality in its SO-8 package?
No, the REG pin is not functional in the LTC1550LCS8-2.5#TRPBF SO-8 package. Per the datasheet's "PACKAGE/ORDER INFORMATION" and "PIN FUNCTIONS" sections, REG is only available in the 16-lead SSOP (GN) package for adjustable versions. In the S8 package, Pin 1 is labeled "REG" in the outline drawing but defined as "NC" (no internal connection) for fixed-output variants including LTC1550LCS8-2.5#TRPBF.
Can LTC1550LCS8-2.5#TRPBF operate from a 3.3V supply rail?
Yes, LTC1550LCS8-2.5#TRPBF supports 3.3V input operation. At VCC = 3.3V and IOUT = 5mA, it delivers –2.5V within ±2.5% regulation (–2.562V to –2.438V). For 10mA loads, minimum VCC rises to 3.45V; for 20mA, it requires ≥4.1V per the Typical Performance Characteristics graph.
What external capacitors are mandatory for stable operation of LTC1550LCS8-2.5#TRPBF?
LTC1550LCS8-2.5#TRPBF requires four mandatory capacitors: (1) ≥2.2µF low-ESR ceramic at VCC-GND, (2) 0.1µF ceramic between C1+ and C1–, (3) 0.1µF ceramic from CPOUT to GND, and (4) ≥10µF moderate-ESR capacitor (e.g., tantalum or polymer) from VOUT to GND, plus a parallel 0.1µF ceramic for high-frequency spike suppression.
How does the shutdown feature of LTC1550LCS8-2.5#TRPBF reduce system power consumption?
The LTC1550LCS8-2.5#TRPBF shutdown pin (SHDN) disables the internal charge pump and linear regulator, reducing quiescent current from 3.65mA (typical at 5V) to 0.2µA (typical). This cuts standby power by >99.9%, extending battery life in portable RF devices during receive/idle modes without requiring complex power sequencing.
LTC1550LCS8-2.5#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):
- 3.05V
- Voltage - Input (Max):
- 5.25V
- Voltage - Output (Min/Fixed):
- -2.5V
- 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
LTC1550LCS8-2.5#TRPBF FAQ
1.How can I place an order for LTC1550LCS8-2.5#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC1550LCS8-2.5#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 LTC1550LCS8-2.5#TRPBF reliable?
The price and inventory of LTC1550LCS8-2.5#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC1550LCS8-2.5#TRPBF is usually 5 days.
3.What payment methods are accepted for LTC1550LCS8-2.5#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC1550LCS8-2.5#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC1550LCS8-2.5#TRPBF?
LTC1550LCS8-2.5#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC1550LCS8-2.5#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 LTC1550LCS8-2.5#TRPBF?
For technical support, including LTC1550LCS8-2.5#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC1550LCS8-2.5#TRPBF requirements.
6.How does Aetrix verify that LTC1550LCS8-2.5#TRPBF is sourced from the original manufacturer or authorized distributors?
All LTC1550LCS8-2.5#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 LTC1550LCS8-2.5#TRPBF meets industry standards.
7.What is the process for return or replacement of LTC1550LCS8-2.5#TRPBF?
All LTC1550LCS8-2.5#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC1550LCS8-2.5#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 LTC1550LCS8-2.5#TRPBF part is unused and in its original packaging.
Return procedure for LTC1550LCS8-2.5#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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