onsemi CS5203-1GT3

Overview

CS5203-1GT3 from onsemi is a 3.0 A adjustable-output linear regulator in TO-220-3 package, delivering ±1.5% output voltage accuracy across −40°C to +70°C ambient, with dropout voltage as low as 1.15 V at full load and fast transient response for microprocessor post-regulation. It features internal current limiting and thermal shutdown, and uses two external resistors to set output between 1.25 V and 5.5 V.

For engineers reviewing the CS5203-1GT3 datasheet, pinout, applications, or equivalent options, key selection considerations include dropout performance at 3.0 A, thermal regulation stability under load transients, minimum load current requirements (0.6–2.0 mA), and compatibility with tantalum-based output capacitor networks for microprocessor supply rails.

Technical Context

The CS5203-1GT3 employs a composite PNP-NPN pass transistor architecture optimized for low-dropout operation and high-current capability. Its error amplifier maintains a precise 1.254 V reference between VOUT and ADJ pins, enabling accurate resistor-divider-based output programming.

Protection circuitry includes foldback current limiting (3.1–4.6 A trip range) and thermal shutdown activation at 150–210°C junction temperature with 25°C hysteresis. The device operates with input-to-output differential up to 7.0 V and requires ≥22 µF tantalum output capacitance for stability.

Key Specifications

Pinout & Package

CS5203-1GT3 is housed in a TO-220-3 package (Case 221A) with electrically connected tab tied to VOUT. The case serves as both thermal path and output terminal, requiring electrical isolation when mounting to heatsinks.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar adjustable high-current linear regulator applications.

Compared with LT1085CT-3.3#PBF and TLV1117-33CDCYR, the CS5203-1GT3 uniquely combines adjustable output, 3.0 A capability, and sub-1.2 V dropout in through-hole TO-220 packaging-enabling scalable, thermally robust power delivery where fixed-voltage or low-current alternatives fall short.

Availability

CS5203-1GT3 is available at Aetrix Electronics and suitable for microprocessor core supplies, FPGA I/O regulation, industrial PLC CPU modules, and medical imaging subsystems requiring stable component supply with long-term manufacturability.

Supply support for CS5203-1GT3 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 (formerly ON Semiconductor) is a global semiconductor supplier specializing in energy-efficient power management, analog, sensing, and connectivity solutions for automotive, industrial, cloud, and medical markets.

The CS5203-1GT3 belongs to onsemi's high-current linear regulator product line, engineered specifically for post-regulation of microprocessor and FPGA power rails where low dropout, fast transient response, and integrated protection are mandatory.

FAQ

What is the maximum input-to-output voltage differential allowed for the CS5203-1GT3?

The CS5203-1GT3 has an absolute maximum VIN–VOUT differential of 7.0 V per its datasheet. Exceeding this risks permanent damage, especially during short-circuit events where thermal or current protection may not activate quickly enough. Designers must ensure this limit is maintained under all operating conditions including startup and fault states.

Can the CS5203-1GT3 be used with ceramic output capacitors?

No - the CS5203-1GT3 requires output capacitors with sufficient ESR (e.g., tantalum or aluminum electrolytic) for loop stability. Ceramic capacitors typically have near-zero ESR and can cause oscillation. The datasheet explicitly recommends ≥22 µF tantalum; using ceramics without added series resistance risks instability and output voltage overshoot.

How does the adjust pin current affect output voltage accuracy in the CS5203-1GT3?

The CS5203-1GT3's adjust pin draws ~50 µA, which flows through R2 in the feedback divider and introduces an error term (I_ADJ × R2) in the output voltage equation. For example, with R2 = 10 kΩ, this adds 0.5 V error - requiring R2 ≤ 1 kΩ or active compensation to maintain ±1.5% accuracy. This effect is documented in the "Adjustable Operation" section of the datasheet.

Is a heat sink required for the CS5203-1GT3 at 3.0 A output current?

Yes - at 3.0 A and typical dropout voltages (≥1.15 V), power dissipation exceeds 3.5 W. With R_JA ≈ 50°C/W for TO-220-3 in still air, junction temperature rise would exceed safe limits. A properly mounted heat sink (with thermal compound) reducing R_JA to ≤20°C/W is necessary to keep T_J below 150°C under worst-case ambient conditions.

Does the CS5203-1GT3 support remote voltage sensing?

No - the CS5203-1GT3 is a three-terminal regulator without dedicated sense pins. Remote sensing is not supported. To minimize load regulation error from PCB trace resistance, the feedback divider's R1 must connect directly to the VOUT pin (not the load), as shown in Figure 15 of the datasheet. True Kelvin sensing requires four-terminal regulators like the LT308x series.