Texas Instruments LM2695EVAL

Overview

The LM2695EVAL evaluation board from Texas Instruments provides a fully functional, constant-on-time (COT) buck regulator reference design based on the LM2695 step-down switching controller. It delivers a regulated 10 V output from a 12–30 V input, supports up to 1 A load current with 1.3 A current limit, achieves 96.3% efficiency at 12 V_IN/300 mA, and operates at a nominal 380 kHz switching frequency.

For engineers reviewing the LM2695EVAL datasheet, LM2695EVAL board layout, LM2695EVAL application notes, or LM2695EVAL alternative evaluation platforms, this page details its verified performance envelope, ripple control options, thermal behavior under load, start-up procedure, and component-level configuration flexibility for power supply validation and design iteration.

Technical Context

The LM2695EVAL implements the LM2695's constant-on-time control architecture, where on-time is dynamically adjusted per cycle using Equation t_ON = V_IN / (1.3 × 10⁻¹⁰ × R1), yielding ≈2300 ns at 12 V_IN and ≈900 ns at 30 V_IN. A minimum off-time timer enforces ≥250 ns off-periods to ensure stable operation.

Regulation relies on feedback voltage at the FB pin requiring ≥25 mV_p-p ripple in-phase with the SW node waveform. The board supports three configurable ripple-generation methods-using R6/C9/C10 (minimum ripple), R4/C8 (intermediate), or R4 alone (lowest cost)-each validated across the full 12–30 V input range and 0–1 A load.

Key Specifications

Availability

LM2695EVAL is available at Aetrix Electronics and suitable for industrial power validation, DC-DC converter qualification, and embedded system prototyping requiring stable component supply, traceable sourcing, and documented thermal and efficiency performance.

Supply support for LM2695EVAL 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

Texas Instruments is a global semiconductor company specializing in analog, embedded processing, and power management technologies, with decades of leadership in high-reliability power conversion solutions.

The LM2695EVAL belongs to TI's evaluation board portfolio for high-voltage buck regulators, designed specifically to accelerate development of 10–30 V input, 10 V output power supplies using the LM2695 COT controller in industrial, test equipment, and distributed power architectures.

FAQ

What is the primary function of the LM2695EVAL evaluation board?

The LM2695EVAL evaluation board is a fully assembled, tested reference design that demonstrates the LM2695 constant-on-time buck regulator in operation. It delivers a stable 10 V output from 12–30 V input, supports up to 1 A load, and enables rapid validation of efficiency, ripple, transient response, and thermal behavior-without requiring custom PCB design. The LM2695EVAL includes all populated components except R5, C8, and C11, allowing users to modify current limit and output ripple per application needs.

How does the LM2695EVAL achieve stable regulation with constant-on-time control?

The LM2695EVAL achieves regulation by leveraging the LM2695's internal COT architecture: each switching cycle begins with a VIN-dependent on-time determined by R1 and Equation t_ON = V_IN/(1.3×10⁻¹⁰×R1), followed by a minimum 250 ns off-time enforced by an internal timer. Regulation occurs when FB voltage drops below 2.5 V, triggering the next on-pulse. The LM2695EVAL ensures ≥25 mV_p-p ripple at FB-via R4, R6/C9/C10, or C8-to reliably toggle the comparator and maintain steady-state operation across line and load variations.

What are the three output ripple configuration options on the LM2695EVAL, and how do they differ?

The LM2695EVAL offers three validated ripple configurations: (A) R6/C9/C10 yields 3–8 mV_p-p at VOUT1 for ultra-low-noise applications; (B) R4/C8 produces 27–105 mV_p-p, balancing cost and performance; (C) R4-only gives ≊110–420 mV_p-p, the lowest-cost option. Each method directly injects phase-aligned ripple into the FB node to satisfy the LM2695's 25 mV_p-p minimum requirement. The LM2695EVAL documentation provides exact calculations and component values for all three, enabling precise trade-off selection during design review.

Can the LM2695EVAL be used to evaluate higher current limits, and if so, how?

Yes-the LM2695EVAL supports current limit adjustment up to ≊1.5 A via optional resistor R5 between SGND and ISEN. The board's nominal limit is 1.3 A; adding R5 diverts recirculating current away from the internal sense resistor, raising the effective threshold. R5 value is calculated using Equation R5 = (I_PK− − 1.0 A)/(1.0 A × 0.11 Ω), where I_PK− is the lower inductor current peak derived from input voltage, inductance tolerance, and switching frequency. The LM2695EVAL User's Guide (SNVA147A) provides full derivation, verification steps, and peak/average current checks to ensure safe operation within the LM2695's 2 A SW-pin rating.

What thermal considerations apply when operating the LM2695EVAL at maximum load and input voltage?

At 30 V_IN and 1 A load, the LM2695 IC and Schottky diode D1 on the LM2695EVAL become hot to the touch due to increased conduction and switching losses. The User's Guide recommends forced airflow under these conditions to maintain safe junction temperatures and sustained output regulation. Board layout places U1 (LM2695 in TSSOP-14EP) and D1 (DLFS160 Power DI 123) with thermal relief pads and copper pours; however, no heatsink is included. Users must monitor temperature rise during extended full-load tests and consider ambient derating-especially in enclosed enclosures-when deploying the LM2695EVAL as a prototype power stage.