Texas Instruments LM34923EVAL/NOPB

Overview

LM34923EVAL/NOPB from Texas Instruments is an evaluation board for the LM34923 80-V 600-mA constant on-time (COT) buck switching regulator IC. It delivers a regulated 5 V output from 6 V to 75 V input, supports up to 500 mA load current, features 200 kHz nominal switching frequency, and achieves 94.75% efficiency at 6 V input/100 mA load - designed for high-input-voltage industrial power supply validation.

For engineers reviewing the LM34923EVAL/NOPB datasheet, LM34923EVAL/NOPB pinout, LM34923EVAL/NOPB application, or LM34923EVAL/NOPB equivalent, this board enables rapid characterization of COT-based buck regulation under wide VIN, variable load, ripple-sensitive feedback, and UVLO/SD control conditions - with integrated test points, configurable ripple networks, and thermal-aware layout.

Technical Context

The LM34923EVAL/NOPB implements the LM34923's constant on-time control architecture, where on-time (t_ON) varies inversely with input voltage per t_ON = (V_IN − 0.5 V) / (1.25 × 10⁻¹⁰ × (R1 + 500 Ω)) + 30 ns - yielding 4.38 µs at 6 V and 351 ns at 75 V. A minimum off-time timer enforces ≥260 ns off-periods to stabilize switching frequency near 200 kHz.

It integrates full functional support for the LM34923's key subsystems: FB-pin ripple generation (≥25 mV_p-p required), under-voltage detection (11 V–12 V hysteresis via R2/R3), shutdown control (TP1-SD), and UVO status reporting (TP3-Status). The board provides three selectable output ripple configurations (Options A–C) using R7/C8/R8-C6-C7 networks.

Key Specifications

Availability

LM34923EVAL/NOPB is available at Aetrix Electronics and suitable for industrial power supply validation, high-voltage DC-DC prototyping, and COT control algorithm evaluation requiring stable component supply, traceable sourcing, and long-term design-in support.

Supply support for LM34923EVAL/NOPB 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 headquartered in Dallas, Texas, specializing in analog, embedded processing, and power management technologies with over 90 years of innovation in industrial, automotive, and communications markets.

The LM34923EVAL/NOPB belongs to TI's high-voltage buck regulator evaluation platform family, engineered to accelerate adoption of constant-on-time topology in ruggedized 6–75 V input applications such as factory automation, railway electronics, and telecom power systems.

FAQ

What is the primary function of the LM34923EVAL/NOPB?

The LM34923EVAL/NOPB is a fully assembled evaluation board for the LM34923 buck regulator IC. It demonstrates and validates the constant-on-time (COT) control scheme across 6–75 V input, delivering a stable 5 V/500 mA output. Engineers use LM34923EVAL/NOPB to verify loop stability, efficiency, thermal behavior, and ripple performance before committing to custom PCB designs.

Does the LM34923EVAL/NOPB include the LM34923 IC?

Yes, the LM34923EVAL/NOPB includes the LM34923 IC mounted in a VSSOP-10 package (U1 on schematic). The board uses the exact production-grade LM34923 device, not a placeholder or emulator, enabling direct correlation between evaluation results and final system performance.

How is output voltage ripple controlled on the LM34923EVAL/NOPB?

The LM34923EVAL/NOPB offers three hardware-configurable ripple options: Option A (R7 only) yields 51–280 mV_p-p; Option B (R7 + C8) reduces it to 28–159 mV_p-p; Option C (R8/C6/C7 network) achieves <10 mV_p-p. All rely on injecting ≥25 mV_p-p ripple at the FB pin - a mandatory condition for stable COT operation of the LM34923 IC.

Can the LM34923EVAL/NOPB be used to evaluate under-voltage lockout (UVLO) behavior?

Yes, the LM34923EVAL/NOPB implements a user-adjustable under-voltage detector using R2 and R3 to monitor VIN. By default, UVO asserts low when VIN exceeds 12 V and high when VIN drops below 11 V. Test points TP2-UVO and TP3-Status allow real-time monitoring of UVLO status independent of regulator operation - a key feature verified during LM34923EVAL/NOPB testing.

What are the recommended operating conditions to avoid thermal stress on the LM34923EVAL/NOPB?

At high input voltage (>48 V) and high load current (>300 mA), the LM34923 IC on LM34923EVAL/NOPB may become hot to the touch. Texas Instruments recommends forced air flow in such conditions and cautions against prolonged operation above 60°C ambient without thermal derating. Input voltage must never exceed 75 V, and load wiring must minimize voltage drop to maintain regulation accuracy.