onsemi CS403GT5

Overview

CS403GT5 from onsemi is a 5.0 V ±3% fixed-output linear regulator designed as a post-regulator for switching power supplies. It delivers 750 mA output current, features active delayed reset with 10–30 ms programmable delay via external capacitor, and achieves 1.4 V typical dropout at full load. Its PNP–NPN output stage enables low quiescent current (4.0 mA typ. at 750 mA) and high PSRR (70 dB at 120 Hz), making it ideal for microprocessor supply rails requiring clean, stable voltage and reliable power-on reset.

For engineers reviewing the CS403GT5 datasheet, pinout, applications, or equivalent options, key selection criteria include its 5-lead TO-220 package with GND-tab, RESET open-collector output behavior, delay capacitor timing interface, dropout voltage vs. load/temperature performance, and thermal derating requirements in high-power applications.

Technical Context

The CS403GT5 integrates dual comparator-based reset logic with hysteresis on both RESET and Delay thresholds (VRTL = 4.75 V, VDH = 200–1000 mV), ensuring glitch-free reset assertion during brownout recovery. Its internal reference switches from VIN to VOUT once regulation is achieved-optimizing supply rejection without sacrificing transient response.

It employs a latching Delay capacitor discharge circuit that fully discharges Cd whenever VOUT falls below VRTL, guaranteeing a controlled RESET pulse after any fault. The RESET output is open-collector NPN with 0.08–0.40 V saturation voltage at 1.6 mA sink, compatible with CMOS logic inputs.

Key Specifications

Pinout & Package

CS403GT5 uses a 5-lead TO-220 package (Case 314D) with tab connected to Pin 3 (GND). The straight leadform supports through-hole mounting and direct heatsinking via the metal tab.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar linear regulator with reset applications.

Compared with TLV70250DBVR and TPS76350QDBVRQ1, the CS403GT5 uniquely combines 750 mA drive, programmable reset delay, latching discharge behavior, and TO-220 thermal capability-making it optimal for industrial and medical systems demanding robust, field-configurable power supervision.

Availability

CS403GT5 is available at Aetrix Electronics and suitable for microprocessor power supply, industrial PLC I/O modules, medical sensor signal chains, and automotive body control modules requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for CS403GT5 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 delivering energy-efficient silicon solutions for automotive, industrial, cloud, medical, and IoT applications.

The CS403GT5 belongs to onsemi's precision linear regulator family, engineered specifically for post-regulation of switching supplies in systems requiring simultaneous voltage accuracy, low noise, and intelligent power-good supervision.

FAQ

What is the maximum input voltage rating for the CS403GT5?

The CS403GT5 has an absolute maximum forward input voltage rating of 18 V. Operation above this level risks permanent damage. Electrical characteristics are specified for 7.0 V ≤ VIN ≤ 10 V, but the device remains functional up to 18 V within thermal limits. Always observe maximum power dissipation constraints-especially at high VIN and high IOUT-using R_ΘJA = 50°C/W and ambient temperature derating curves from the datasheet.

How does the CS403GT5 generate its reset delay time?

The CS403GT5 generates reset delay using an external capacitor (Cd) connected to the Delay pin. An internal current source (10–40 µA) charges Cd until it reaches VDTC (3.7–4.4 V); when exceeded, the RESET output is released. If VOUT falls below VRTL (4.75 V), the Delay pin actively discharges Cd to ground. This latching discharge ensures the delay timer resets completely on every fault, guaranteeing consistent RESET pulse width for the CS403GT5 in real-world transient conditions.

Can the CS403GT5 operate without an output capacitor?

No, the CS403GT5 requires an output capacitor (COUT ≥ 10 µF) for stability, as confirmed in the test circuit (Figure 6) and Application Notes. Aluminum or tantalum electrolytics are mandated-ceramic or film capacitors with near-zero ESR cause oscillation due to loop instability. Omitting COUT or using inappropriate types will result in sustained ringing or sustained oscillation on VOUT, compromising regulation and potentially damaging downstream loads powered by the CS403GT5.

What is the function of the GND pin (Pin 3) on the CS403GT5?

Pin 3 (GND) serves as the electrical reference for all internal circuitry and the thermal path to the metal tab in the TO-220 package. It is directly bonded to the tab, enabling direct heatsinking. All voltage measurements-including VOUT, RESET, and Delay-are referenced to this pin. Improper grounding (e.g., high-impedance traces or shared noisy return paths) degrades PSRR, increases output noise, and can destabilize the reset threshold comparators. For optimal performance, connect Pin 3 to a low-impedance ground plane and mount the CS403GT5 with the tab thermally coupled to a heatsink.

Does the CS403GT5 support adjustable output voltage configurations?

No, the CS403GT5 is a fixed 5.0 V ±3% output regulator and does not support external feedback resistors or adjustment. Its internal voltage reference and error amplifier are trimmed for 5 V operation only. Attempting to modify the output via external components violates the design intent and voids all guaranteed specifications-including line/load regulation, dropout, and reset thresholds. For adjustable outputs, consider onsemi's CS402 series or other members of the same family explicitly rated for variable configurations.