Analog Devices Inc. LTC3265IDHC#PBF

Summary of Analog Devices LTC3265IDHC#PBF Charge Pump Switching Regulator

The Analog Devices LTC3265IDHC#PBF is an advanced charge pump switching regulator IC specifically engineered to deliver positive and negative output voltage rails from a single supply. Housed in an 18-lead WFDFN Exposed Pad package, this device is optimized for low noise performance and supports up to 100 mA combined current output. Its core function centers around efficient generation of dual rail power supplies, integrating boost and inverting charge pump topologies alongside high-performance LDO post regulators. With input voltage flexibility and programmable switching frequency, the LTC3265IDHC#PBF targets precision bias generator and industrial instrumentation applications where noise minimization and compact size are critical.

Primary Functional Attributes of the LTC3265IDHC#PBF

The LTC3265IDHC#PBF stands out for its combination of boost and inverting charge pumps working in concert with low noise positive and negative LDOs. The boost charge pump supports input voltages from 4.5V to 16V, generating up to twice the input voltage for the positive rail. The inverting charge pump accepts inputs from 4.5V to 32V, delivering a negative output up to the magnitude of its input. Both charge pumps employ either Burst Mode® for ultralow quiescent current (135 μA with both LDOs active) or fixed frequency operation for predictable EMI/ripple. LDO output voltages are adjustable via external resistor dividers, providing up to 50 mA per rail with excellent ripple rejection. The programmable oscillator frequency (50 kHz to 500 kHz) enables engineers to finely balance efficiency, noise, and dynamic response. Short-circuit and thermal protection mechanisms guarantee robust operation in demanding environments.

Electrical Specifications and Performance Metrics of the LTC3265IDHC#PBF

Detailed performance specifications of the LTC3265IDHC#PBF reveal its adaptability and suitability for precision supply generation. In boost mode, the device can double the positive input voltage, regulated to 0.94 × twice the supply during Burst Mode for optimal efficiency. The inverting charge pump supplies up to –0.94 × the negative input voltage, with a maximum negative rail up to –32V. Quiescent supply currents as low as 3 μA (shutdown) and competitive dropout voltages for LDOs (as low as 400 mV at 50 mA for positive rail) underscore the device’s balance of power and noise performance. Output noise can be minimized with external capacitors at the BYP+ and BYP– pins, yielding typical voltage noise levels on the order of 100 μVRMS. Fast transient response and excellent line/load regulation facilitate stable operation under dynamic loading. The programmable oscillator is referenced to a fixed voltage, adjustable via external resistor at the RT pin for frequency fine-tuning.

Pin Details and Functional Structure of the LTC3265IDHC#PBF

Understanding the pin layout and functional blocks of the LTC3265IDHC#PBF is key for effective PCB integration. Critical charge pump flying capacitor connections (CBST+, CBST–, CINV+, CINV–) allow designers to optimize pump efficiency and ripple. The dual input arrangement (VIN_P and VIN_N) gives flexible polarity generation, with VIN_N configurable to either VIN_P or VOUT+—enabling symmetric or asymmetric supply designs as required. The RT pin provides easy interface for oscillator frequency adjustment, using a resistor to GND. Enable controls (EN+ and EN–), along with the MODE selector, give system-level control over burst or constant-frequency operation. The LDO outputs (LDO+, LDO–) demand low ESR capacitance at their pins, while the BYP+ and BYP– reference bypass facilitate ultra-low-noise performance. All logic pins are designed for straightforward digital interfacing, critical in mixed-signal systems.

Packaging Specifications and Thermal Management for LTC3265IDHC#PBF

The LTC3265IDHC#PBF is offered in a compact, thermally optimized 18-lead WFDFN package (5 × 3 × 0.75 mm), featuring an exposed pad for enhanced thermal dissipation. Such a low-profile form factor is advantageous for dense industrial layouts and instrumentation where board space is premium. The ambient-to-junction thermal impedance (θJA) of 42°C/W, along with an operating junction temperature range of –40°C to 125°C (LTC3265I variant), allows for reliable performance across most commercial and industrial environments. The exposed pad must be properly soldered to the PCB ground for effective heat transfer and electrical stability. Additional versions for extended temperature ranges are available, allowing system designers to select the optimal part for harsh applications.

Use Cases and Applications for the LTC3265IDHC#PBF

The LTC3265IDHC#PBF is purpose-built for applications demanding low noise bipolar or inverting supplies, such as high-precision analog bias generators, industrial measurement instrumentation, and mixed-signal sensor systems. Its dual rail configuration is ideal for op amp, ADC/DAC backend circuits requiring both positive and negative supplies with high voltage rejection and minimal ripple. For example, generating ±15V rails from a single 12V input is straightforward, simplifying both power tree architecture and system debugging. The device’s operating flexibility, compact footprint, and quiet output suit it well for instrumentation amplifiers, bridge sensor biasing, medical measurement equipment, and wherever symmetrical supply rails are mandatory.

Alternative or Substitute Models for LTC3265IDHC#PBF

When evaluating alternatives for the LTC3265IDHC#PBF, engineers may consider analogous low noise dual charge pump regulator ICs, notably those within the Linear Technology (now Analog Devices) family, such as the LTC3260 and LTC3261 series, which offer similar dual-supply generation with different performance envelopes. Within the Analog Devices LDO and charge pump lines, the LTC3245 or LTC3232 may provide partial functional overlap, though with differing voltage/current capabilities. Selection must be made based on rail voltage requirements, output current, package constraints, and system noise sensitivity. For extended temperature applications, LTC3265H or LTC3265MP variants of the LTC3265 series can be considered, ensuring compliance with the environmental demands of the end application. Proper review of datasheet specifications is essential for accurate model substitution.

Conclusion

The Analog Devices LTC3265IDHC#PBF charge pump switching regulator is a versatile and technically advanced solution for engineers seeking low noise, compact, dual-polarity power supplies. Its blend of boost and inverting charge pump topologies, robust LDO performance, and wide programmable frequency range empower system designers to achieve precise, quiet bias rails in demanding analog and mixed-signal environments. Consideration of detailed electrical characteristics, pin assignments, available packages, application flexibility, and qualified replacements ensures optimal part selection for both new designs and legacy replacements. The LTC3265IDHC#PBF remains a reference standard in power management solutions for modern instrumentation systems.