Analog Devices Inc. LTC2923IDE#TRPBF

Summary of LTC2923IDE#TRPBF Product

The LTC2923IDE#TRPBF, manufactured by Analog Devices Inc., is a versatile power supply controller designed to simplify complex power sequencing and tracking in systems with multiple supply rails. Housed in a compact 12-lead DFN (4mm x 3mm) package, the LTC2923IDE#TRPBF supports applications where orderly supply voltage ramp-up, ramp-down, and sequencing are critical for reliable system operation, such as servers, communications equipment, and microprocessor-based designs. The device stands out for its ability to manage two supplies directly and a third via a series FET, enabling flexible tracking profiles tailored to specific digital logic requirements.

Highlights of LTC2923IDE#TRPBF Power Supply Controller

At its core, the LTC2923IDE#TRPBF offers flexible supply tracking, covering coincident, ratiometric, offset, and sequenced power-up profiles. It tracks both up and down power events, ensuring stability is not compromised during operation. An integrated electronic circuit breaker adds fault protection when a series FET is used to control a supply. The device is capable of ramp rate adjustment via external components and supports systems requiring the coordination of up to three power supplies, enhancing usability across varied architectures—particularly those involving FPGAs, DSPs, and complex ASICs.

Structure and Functionality of LTC2923IDE#TRPBF

The LTC2923IDE#TRPBF utilizes a proprietary tracking cell employing a wide-range current mirror to synchronize “slave” supply outputs to a master signal. Currents into feedback nodes allow direct ramping without pass element losses or disrupting supply stability and transient response. Its open-loop control ensures that, once ramping is complete, the device presents high impedance, leaving supplies to operate independently. When a third rail must be sequenced, the controller charges the gate of an external N-channel FET, enabling the ramp and integrating circuit breaker protection to safeguard against short-circuit events. The device accommodates ramp profiles through simple passive components, making customization straightforward.

Pin Layout and Electrical Characteristics of LTC2923IDE#TRPBF

Operational reliability and configuration flexibility are assured via well-defined pin functions and electrical characteristics. LTC2923IDE#TRPBF runs on a supply voltage range of 2.9V to 5.5V and includes an undervoltage lockout that activates below 2.5V. Key pins include ON (logic threshold and hysteresis for ramp initiation), TRACK1/2 (tracking control), FB1/2 (feedback control outputs), RAMPBUF (buffered ramp output), GATE (drive for the external FET), and RAMP (buffer input). The open-drain SDO and STATUS pins provide system-level shutdown and “power good” indications, supporting integrated monitoring. The device is tolerant of typical pin currents up to 5mA and operates across industrial temperature ranges.

Use Cases for LTC2923IDE#TRPBF

The LTC2923IDE#TRPBF addresses power integrity and sequencing requirements for processing-centric platforms, including microprocessors, FPGAs, DSPs, servers, and communication infrastructure. It is highly suitable for:

VCORE and auxiliary supply coordination, avoiding destructive latch-up due to improper voltage differentials.

Systems demanding tight voltage tracking, whether coincident (identical ramp rates), ratiometric (proportional), offset (fixed voltage gap during ramp), or sequenced (staggered startup).

Designs with power modules, regulators lacking direct feedback access, or those requiring forced supply-to-ground conditions.

Integration Approach for LTC2923IDE#TRPBF in Designs

The LTC2923IDE#TRPBF simplifies application design through a three-step process:

Setting the master ramp rate, dictated by gate capacitance and current source characteristics.

Determining resistor values for slave supply tracking, based on desired ramp rates and feedback resistor parameters.

Introducing delays or voltage offsets through parallel resistor calculation, ensuring tracking profiles (coincident, ratiometric, offset, or sequencing) are met.

Formulas for these calculations are provided, allowing engineers to define ramp timing and synchronization with precision and minimal risk of impractical resistor values.

Application Examples Tracking, Offset Correction, Sequence Control with LTC2923IDE#TRPBF

The LTC2923IDE#TRPBF supports implementation of diverse multi-rail profiles:

Coincident tracking: All supplies ramp up (and down) together, used for dual-supply ASICs to prevent excessive potential differences.

Ratiometric tracking: Supplies ramp up proportionally but not necessarily at the same rate, allowing for tailored voltage relationships.

Offset tracking: A slave supply ramps with a fixed delay to maintain a specific voltage offset from the master.

Sequencing: Supplies ramp up in a controlled sequence (one after another), essential for systems where logic blocks or clocks require staged initialization.

Examples illustrate the design approach, selecting component values to implement various tracking and sequencing behaviors.

Essential Evaluation Criteria for LTC2923IDE#TRPBF Designs

For robust system design, engineers should verify:

That slave supplies fully ramp before the master reaches its final value.

TRACKx and RAMPBUF pin currents stay within specification (<1mA and <2mA, respectively).

Compatibility with boost and linear regulators: If a regulator’s output cannot be forced low via feedback manipulation, a series FET should be used.

Output load and capacitive conditions, ensuring the supply can sink current for required ramp-down rates.

That startup delays on slave supplies do not defeat overall sequencing or tracking objectives.

Board Layout and System Design Tips for LTC2923IDE#TRPBF

Effective PCB layout is essential for high-performance operation:

Place a 0.1μF bypass capacitor close to the supply pin.

Include a 10Ω resistor between the FET gate and the external ramp capacitor to suppress high frequency oscillations.

Minimize length and noise exposure of FBx traces, especially where supplies track sensitive signals.

If noise is a concern, add a resistor in series with the FBx pin, sized not to exceed feedback current constraints.

Available Packages and Technical Details for LTC2923IDE#TRPBF

The LTC2923IDE#TRPBF is available in 12-lead DFN (4mm x 3mm) and 10-lead MSOP packages, suiting both space-constrained designs and standard board layouts. Key package dimensions, coplanarity specifications, and solder pad recommendations ensure reliable assembly and thermal characteristics.

Alternative Comparable Models to LTC2923IDE#TRPBF

While the LTC2923IDE#TRPBF sits prominently in Analog Devices’ multi-rail tracking controller portfolio, engineers seeking alternatives may evaluate other LTC2923 variants (such as LTC2923CDE, or packages tailored for different operating temperatures), or similar tracking controllers within the Linear Technology (now part of Analog Devices) lineup, subject to matching supply voltage, control features, and fault protection needs. Care should be taken to verify reference voltages, ramp rates, and the number of supplies managed in alternative models.

Conclusion

The LTC2923IDE#TRPBF delivers a robust, highly configurable solution for power supply sequencing and tracking in multi-rail electronic systems. Its integration of flexible tracking profiles, reliable fault protection, and straightforward customization enables engineers to address the nuanced demands of advanced microprocessor, FPGA, and communication platforms with confidence. Thoughtful application of the LTC2923IDE#TRPBF ensures both the performance and reliability of critical supply rails, facilitating rapid design cycles and robust field operation in complex electronic environments.