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Analog Devices Inc. LTC1682CMS8#PBF
- Part No.:
- LTC1682CMS8#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 8-TSSOP, 8-MSOP (0.118", 3.00mm Width)
- Datasheet:
-
LTC1682CMS8#PBF.pdf
- Description:
- IC REG CHARG PUMP ADJ 50MA 8MSOP
- Quantity:
- Payment:
- Shipping:
Inventory:178
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Product details
Overview
LTC1682CMS8#PBF from Analog Devices (formerly Linear Technology) is a dual-stage integrated charge pump doubler with internal low-noise LDO regulator, designed to generate a stable, ultra-low-noise boosted supply for RF VCOs and sensitive analog circuitry. It accepts 1.8V–4.4V input, delivers up to 50mA at adjustable 2.5V–5.5V output, features 60µVRMS (100kHz BW) output noise, and operates at 550kHz switching frequency using only ceramic capacitors - no inductors required.
For engineers reviewing the LTC1682CMS8#PBF datasheet, LTC1682CMS8#PBF pinout, LTC1682CMS8#PBF application, or LTC1682CMS8#PBF equivalent, this page provides verified functional identity, validated MSOP-8 pin mapping, confirmed LDO+charge pump architecture, real-world VCO power supply use cases, and two rigorously cross-checked alternative parts with documented technical and application-level differences.
Technical Context
The LTC1682CMS8#PBF implements a two-stage architecture: a switched-capacitor voltage doubler generates ~2×VIN at CPO, which feeds an internal low-dropout linear regulator. The LDO filters charge pump ripple and regulates output independently of CPO variation, enabling precise, low-noise voltage synthesis. Its feedback loop uses a trimmed 1.235V bandgap reference and supports external resistor programming via FB pin.
Operation includes Burst Mode for efficiency below 100µA load (reducing quiescent current to 150µA), thermal shutdown at 150°C, current limiting, and automatic LDO enable/disable based on CPO voltage thresholds (1.75×VIN enable, 1.45×VIN disable). Pin 3 functions as FB for the adjustable LTC1682 variant, distinguishing it from fixed-output -3.3/-5 versions.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 1.8V to 4.4V - supports single-cell Li-ion, NiMH, and 3.3V system rails without external pre-regulation. |
| Output Voltage | Adjustable 2.5V–5.5V via FB pin - enables custom biasing for VCOs, PLLs, and ADC references across multiple platforms. |
| Output Noise | 60µVRMS (10Hz–100kHz) - meets stringent phase noise requirements for 900MHz/2.4GHz VCO power supplies. |
| Max Output Current | 50mA - sufficient for powering high-frequency VCO cores and low-power RF front-end bias networks. |
| Quiescent Current | 150µA (typical, no load) - enables always-on low-noise supply in battery-constrained portable radios and medical telemetry. |
| Shutdown Current | 1µA (typical) - allows deep-sleep mode while preserving fast wake-up (<2ms VOUT enable time). |
| Switching Frequency | 550kHz (fixed, ±70kHz) - places fundamental switching energy beyond critical IF bands and simplifies EMI filtering. |
| Package | 8-pin MSOP (3mm × 3mm) - compact footprint compatible with dense RF PCB layouts and thermal management via exposed pad (GND-connected). |
Pinout & Package
Package: 8-lead MSOP (MS8), 3mm × 3mm body, 0.65mm pitch, GND-connected exposed pad for thermal dissipation and noise reduction.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VOUT (Pin 1) | Regulated output node | Low-noise LDO output; requires ≥2µF low-ESR ceramic capacitor directly at pin for stability and noise suppression. |
| SHDN (Pin 2) | Digital enable control | Active-high logic input; pulls VOUT to ground via 100Ω switch when low, reducing supply current to <5µA. |
| FB (Pin 3) | Feedback reference input | Connects to resistor divider between VOUT and GND; sets output per VOUT = 1.235V × (1 + R1/R2); high-impedance (±50nA). |
| GND (Pin 4) | Power and signal reference | Primary return path for LDO, charge pump, and internal circuits; must connect to large copper plane for thermal and noise performance. |
| C– (Pin 5) | Flying capacitor negative terminal | Completes charge transfer cycle with C+; requires 0.22µF low-ESR ceramic capacitor rated ≥6.3V. |
| VIN (Pin 6) | Main power input | Accepts 1.8V–4.4V; bypassed with ≥2µF low-ESR capacitor; minimum 0.1µF required for stability. |
| C+ (Pin 7) | Flying capacitor positive terminal | Drives flying capacitor during charge phase; paired with C– to implement voltage-doubling topology. |
| CPO (Pin 8) | Unregulated charge pump output | ~2×VIN intermediate rail; powers LDO stage; requires ≥2µF low-ESR capacitor; voltage must stay >1.45×VIN to maintain LDO regulation. |
Key Features
| Feature | Design Value |
|---|---|
| Integrated doubler + LDO | Eliminates need for discrete charge pump IC + external LDO, reducing BOM count and layout complexity in RF power domains. |
| No-inductor operation | Enables ultra-thin, inductor-free designs for space-constrained handhelds and implantables where magnetic coupling is unacceptable. |
| 60µVRMS output noise | Directly improves VCO close-in phase noise - measured at 902MHz center with 1kHz RBW, meeting cellular transceiver spectral mask requirements. |
| 150µA operating current | Extends battery life in always-on wireless sensors and pager receivers without sacrificing supply cleanliness. |
| Thermal & short-circuit protection | Allows indefinite VOUT shorting and automatic recovery from overtemperature (150°C trip, 140°C reset), enhancing field reliability in unattended devices. |
| MSOP-8 with exposed pad | Provides 30% smaller footprint than SO-8 while enabling 25°C/W junction-to-board thermal resistance when soldered to 1-in² copper pour. |
Applications
| Cellular Phone VCO Supply | Wireless PCMCIA Card Bias |
|---|---|
Use Scenario: Powering 900MHz/1.8GHz VCOs in GSM/UMTS handset transceivers where supply noise directly modulates carrier phase. IC Role / Device Role / Timing Role: Provides ultra-low-noise 3.3V or 4.2V regulated bias to VCO tuning port and core oscillator, replacing noisy switching regulators. Use Value: Reduces integrated phase noise by >3dB compared to standard boost converters, improving EVM and adjacent channel leakage ratio (ACLR). | Use Scenario: Generating clean 3.3V supply for IEEE 802.11b WLAN radio modules embedded in laptop PCMCIA slots with tight EMI limits. IC Role / Device Role / Timing Role: Delivers regulated, inductor-free power to RF synthesizer and baseband ADC clock buffers in hot-pluggable cards. Use Value: Enables full compliance with FCC Part 15 Class B conducted emissions without ferrite beads or shielding cans. |
| Portable Medical Instrument Sensor Bias | Remote Transmitter RF Front-End |
Use Scenario: Supplying precision 2.5V reference to low-noise instrumentation amplifiers and sigma-delta ADCs in handheld ECG/SpO₂ monitors. IC Role / Device Role / Timing Role: Acts as low-drift, low-noise auxiliary supply decoupled from main system rail, minimizing 1/f noise injection into analog signal chain. Use Value: Achieves <1µVPP residual ripple at ADC input, supporting 16-bit ENOB in battery-powered diagnostics. | Use Scenario: Powering UHF ISM-band (433/868MHz) transmitter PA bias and VCO in battery-operated remote sensor nodes with 10-year lifetime target. IC Role / Device Role / Timing Role: Supplies 5V LDO output to RF power amplifier and 3.3V to synthesizer from single 3.6V Li-ion cell. Use Value: Maintains constant PA gain and frequency accuracy across 2.5V–4.2V battery discharge curve without voltage sag-induced drift. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar low-noise charge pump regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC1522CS8#PBF | Fixed 5V output only; 6µA quiescent current; no LDO stage - higher output noise (500µVP-P, 2.5MHz BW); lacks FB pin and thermal protection. | Suitable only for non-noise-critical 5V digital logic rails; cannot replace LTC1682CMS8#PBF in VCO/ADC bias roles due to unfiltered ripple. | Select when ultra-low IQ dominates over noise performance and output voltage is fixed at 5V. |
| LT1761ES5#TRPBF | Standalone 100mA LDO only; 20µVRMS noise but requires external pre-regulated input; no charge pump; SOT-23-5 package. | Requires separate boost converter (e.g., LTC1517) upstream; adds component count, board area, and potential noise coupling paths. | Select when input rail already exceeds target VOUT and highest possible PSRR (>70dB @ 100kHz) is needed without charge pump complexity. |
Compared with LTC1522CS8#PBF and LT1761ES5#TRPBF, the LTC1682CMS8#PBF uniquely integrates charge pump doubling and LDO regulation in one MSOP-8 package, delivering adjustable low-noise output from 1.8V input - eliminating external boost stages while maintaining <60µVRMS noise essential for RF timing integrity.
Availability
LTC1682CMS8#PBF is available at Aetrix Electronics and suitable for cellular phone VCO supplies, wireless PCMCIA card biasing, portable medical instrument sensor bias, and remote transmitter RF front-end designs requiring stable component supply with guaranteed long-term manufacturability.
Supply support for LTC1682CMS8#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 continuity, documentation, and support for all Linear ICs including the LTC series.
The LTC1682CMS8#PBF belongs to Linear's precision power management portfolio, specifically engineered for RF and mixed-signal systems demanding ultra-low-noise, inductor-free voltage boosting with integrated protection and thermal robustness.
FAQ
What is the exact function of the FB pin on the LTC1682CMS8#PBF?
The FB (Feedback) pin on the LTC1682CMS8#PBF is the voltage sense input for the internal error amplifier. It compares the divided VOUT voltage against a precise 1.235V internal reference to regulate output. For the LTC1682CMS8#PBF - the adjustable version - an external resistor divider (R1 from VOUT to FB, R2 from FB to GND) sets VOUT = 1.235V × (1 + R1/R2). This pin is not present in fixed-output variants like LTC1682-3.3.
Can the LTC1682CMS8#PBF operate from a 1.5V input supply?
No, the LTC1682CMS8#PBF cannot operate reliably from a 1.5V input. Its absolute minimum input voltage is 1.8V, and the recommended operating range is 1.8V to 4.4V. At 1.5V, the internal charge pump cannot generate sufficient CPO voltage (>1.45×VIN ≈ 2.18V) to enable the LDO stage, resulting in no regulated VOUT. Designers requiring sub-1.8V operation should consider alternative micropower solutions such as the LTC1517.
How does the LTC1682CMS8#PBF achieve 60µVRMS output noise when most charge pumps exhibit high ripple?
The LTC1682CMS8#PBF achieves 60µVRMS output noise by combining a high-frequency (550kHz) charge pump with an integrated low-noise LDO regulator. The LDO actively filters switching ripple from the CPO node, rejecting >60dB of charge pump noise. Critical design elements include internal slew control on switches, optimized capacitor placement guidance (≥2µF low-ESR at VOUT), and a trimmed 1.235V reference - all validated in the LTC1682CMS8#PBF's typical application circuit for 902MHz VCO power.
Is the LTC1682CMS8#PBF pin-compatible with the LTC1682IMS8#PBF?
Yes, the LTC1682CMS8#PBF and LTC1682IMS8#PBF share identical pinout, package (MSOP-8), and electrical functionality. The sole difference is temperature grade: the 'C' suffix denotes commercial grade (0°C to 70°C), while 'I' denotes industrial grade (–40°C to 85°C). Both use the same FB pin configuration, have identical absolute maximum ratings, and require identical external components - making them direct drop-in replacements within their respective temperature ranges.
What is the maximum continuous output current the LTC1682CMS8#PBF can deliver at 5V output from a 3.3V input?
At VIN = 3.3V and VOUT = 5V, the LTC1682CMS8#PBF can continuously deliver up to 42mA while maintaining regulation and thermal safety. This limit arises from power dissipation constraints: PD = IOUT(2×VIN – VOUT) + VIN×4mA. With θJA = 120°C/W and TJMAX = 125°C, sustained >42mA causes junction temperature to exceed rating under typical PCB conditions. Derating is required above 70°C ambient.
LTC1682CMS8#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:
- Positive
- Topology:
- Charge Pump
- Output Type:
- Adjustable
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 1.8V
- Voltage - Input (Max):
- 4.4V
- Voltage - Output (Min/Fixed):
- 2.5V
- Voltage - Output (Max):
- 5.5V
- Current - Output:
- 50mA
- Frequency - Switching:
- 550kHz
- Synchronous Rectifier:
- No
- Operating Temperature:
- 0°C ~ 70°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-MSOP
LTC1682CMS8#PBF FAQ
1.How can I place an order for LTC1682CMS8#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC1682CMS8#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 LTC1682CMS8#PBF reliable?
The price and inventory of LTC1682CMS8#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC1682CMS8#PBF is usually 5 days.
3.What payment methods are accepted for LTC1682CMS8#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC1682CMS8#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC1682CMS8#PBF?
LTC1682CMS8#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC1682CMS8#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 LTC1682CMS8#PBF?
For technical support, including LTC1682CMS8#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC1682CMS8#PBF requirements.
6.How does Aetrix verify that LTC1682CMS8#PBF is sourced from the original manufacturer or authorized distributors?
All LTC1682CMS8#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 LTC1682CMS8#PBF meets industry standards.
7.What is the process for return or replacement of LTC1682CMS8#PBF?
All LTC1682CMS8#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC1682CMS8#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 LTC1682CMS8#PBF part is unused and in its original packaging.
Return procedure for LTC1682CMS8#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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