onsemi CS51414EDR8G

Overview

CS51414EDR8G from onsemi is a 1.5 A, 520 kHz fixed-frequency buck regulator IC with external bias capability, operating from 4.5 V to 40 V input and delivering tightly regulated output voltage via V2 control architecture. It integrates an on-chip NPN power switch, supports BOOST pin bootstrapping for reduced saturation voltage (0.4–1.0 V at 1.5 A), and includes thermal shutdown, cycle-by-cycle current limiting, and frequency foldback for short-circuit protection. It is used in industrial power supplies requiring high efficiency at light loads and wide VIN ranges.

For engineers reviewing the CS51414EDR8G datasheet, pinout, applications, or equivalent options, key selection considerations include its 520 kHz switching frequency, BIAS pin support for 3.3–6.0 V auxiliary supply, VFB foldback threshold of 0.29–0.36 V, 85 µA shutdown quiescent current, and SOIC-8 package compatibility with LT1376.

Technical Context

The CS51414EDR8G implements V2 control architecture-using both DC and AC components of the feedback signal (VFB) as PWM inputs-to achieve ultrafast transient response independent of error amplifier bandwidth. Its transconductance error amplifier (6.4 mA/V) drives the VC node, enabling simple compensation with a single 0.1 µF capacitor.

It features dual protection modes: when VFB drops below 0.29 V, it reduces switching frequency to 130 kHz (¼ of nominal) and folds back current limit to 0.9–2.1 A; the BIAS pin allows internal circuitry to be powered from an external low-voltage rail (3.3–6.0 V), reducing power dissipation under high-VIN, light-load conditions.

Key Specifications

Pinout & Package

CS51414EDR8G is housed in an SOIC-8 (Case 751) package with exposed pad for thermal enhancement. Pin 1 is BOOST; Pin 2 is VIN; Pin 3 is VSW; Pin 4 is BIAS; Pin 5 is GND; Pin 6 is VFB; Pin 7 is VC; Pin 8 is SHDNB. No pins are NC or unused in this variant.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar buck regulator applications.

Compared with LT1376CS8#PBF and MP2451DT-LF-Z, CS51414EDR8G uniquely combines BIAS-assisted efficiency, V2 transient performance, and integrated foldback-making it optimal for thermally constrained, wide-input industrial converters where reliability under fault conditions is critical.

Availability

CS51414EDR8G is available at Aetrix Electronics and suitable for industrial power supplies, automotive body electronics, and programmable logic controllers requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for CS51414EDR8G 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

onsemi (Nasdaq: ON) is a global semiconductor leader delivering energy-efficient, intelligent power and sensing solutions for automotive, industrial, cloud, medical, and IoT applications.

The CS5141X product line was designed specifically for high-efficiency, wide-input-voltage buck conversion in space-constrained industrial systems-emphasizing robustness, simplified design, and fault resilience over generic switching regulator functionality.

FAQ

What is the function of the BIAS pin on the CS51414EDR8G?

The BIAS pin on the CS51414EDR8G allows the internal control circuitry-including the error amplifier, oscillator, and comparators-to be powered from an external 3.3 V to 6.0 V supply instead of VIN. This reduces power dissipation significantly under high-input-voltage, light-load conditions. For example, at VIN = 24 V and I_LOAD = 100 mA, using the BIAS pin can lower total IC power loss by over 30% compared to VIN-only biasing. The CS51414EDR8G automatically selects the BIAS source when voltage exceeds 3.3 V.

Does the CS51414EDR8G support synchronization with an external clock?

No, the CS51414EDR8G does not support external synchronization. It belongs to the "Bias" variant group (CS51412/CS51414), which omits the SYNC pin in favor of the BIAS pin. Only CS51411 and CS51413 variants include the SYNC function. Attempting to drive a clock signal into any pin other than SHDNB, BOOST, or BIAS may damage the CS51414EDR8G. Its 520 kHz oscillator is factory-trimmed and requires no external components.

What protection features are built into the CS51414EDR8G?

The CS51414EDR8G integrates three core protections: (1) cycle-by-cycle current limiting with 120–160 ns delay, triggering at 1.6–3.0 A; (2) thermal shutdown with 175–195 °C trip point and 42 °C hysteresis; and (3) frequency/current foldback-activated when VFB falls below 0.29 V-which reduces switching frequency to 130 kHz and limits peak current to 0.9–2.1 A. These functions collectively prevent destructive overheating and component stress during sustained overload or short-circuit events.

Can the CS51414EDR8G operate with a 4.5 V input voltage?

Yes, the CS51414EDR8G guarantees operation down to 4.5 V input, with a startup voltage range of 2.2–4.4 V. However, at VIN = 4.5 V, BOOST pin functionality is limited because the required headroom (VIN + 2.5 V) cannot be achieved-so saturation voltage increases and efficiency drops. For reliable BOOST operation, VIN should be ≥6 V. At 4.5 V, the device remains functional but operates in non-bootstrapped mode with higher V_CE(sat), and BIAS pin usage is not recommended due to insufficient headroom.

Is the CS51414EDR8G pin-compatible with the LT1376?

Yes, the CS51414EDR8G is functionally pin-compatible with the LT1376 in SOIC-8 package, as confirmed in the onsemi datasheet (Rev. 22, p.1). Pin mapping matches exactly: BOOST→BOOST, VIN→VIN, VSW→SW, BIAS→BIAS, GND→GND, VFB→FB, VC→COMP, SHDNB→SHDN. No PCB layout changes are required for drop-in replacement, though design validation of loop stability and thermal performance is recommended due to differences in V2 vs. current-mode control behavior.