onsemi CS8122YTHA5

Overview

CS8122YTHA5 from onsemi is a precision 5.0 V ±2.0% low-dropout linear regulator delivering up to 750 mA output current with 0.6 V dropout at 0.5 A, integrated delayed RESET function programmable via external RC network, and robust fault protection including −50 V reverse transient, 60 V load dump, short-circuit (1.2 A typ), and thermal shutdown - deployed in automotive power management for engine control units requiring stable 5 V supply under harsh electrical conditions.

For engineers reviewing the CS8122YTHA5 datasheet, pinout, applications, or equivalent options, key selection criteria include guaranteed RESET hysteresis (150–250 mV), operation down to 1.0 V output, externally adjustable delay time (16–48 ms with 0.1 µF), and TO-220 horizontal-mount copper-tab package enabling direct heatsink attachment for high-power dissipation scenarios.

Technical Context

The CS8122YTHA5 integrates a bandgap reference, error amplifier, anti-saturation transistor stage, and latching discharge circuit for the delay capacitor - enabling reliable RESET assertion during brief output faults while maintaining immunity to noise via hysteresis in both RESET and delay comparators. Its pre-regulator architecture supports input voltages from −0.5 V to 26 V and tolerates transients up to −50 V and +60 V.

RESET functionality is implemented as an open-collector NPN output with TTL/CMOS compatibility, triggered when VOUT falls below 4.65 V (ON threshold) and released only after VOUT rises above 4.90 V (OFF threshold) and the delay capacitor charges past 3.50 V - ensuring clean power-on sequencing and brown-out recovery without chatter.

Key Specifications

Pinout & Package

CS8122YTHA5 is housed in a TO-220 5-lead horizontal-mount package (Case 314A) with copper tab for thermal conduction. The tab is electrically connected to Pin 3 (GND) and serves as primary heat path to external heatsink.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 5 V LDO with RESET applications.

Compared with TL750L05ACD and LM2940CT-5.0/NOPB, the CS8122YTHA5 uniquely combines 2% output accuracy, 750 mA drive, programmable RESET delay, and −50 V reverse transient immunity - making it the only single-package solution qualified for demanding power domains in modern ECU and ADAS designs.

Availability

CS8122YTHA5 is available at Aetrix Electronics and suitable for automotive engine control, body electronics, ADAS camera modules, and telematics systems requiring stable component supply across extended temperature and high-reliability operational life.

Supply support for CS8122YTHA5 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, sensors, and connectivity solutions for automotive, industrial, and cloud infrastructure markets.

The CS8122YTHA5 belongs to onsemi's SMART REGULATOR® family - engineered specifically for automotive power systems requiring high transient immunity, precise voltage regulation, and integrated supervisory functions in harsh environments.

FAQ

What is the minimum input voltage required for CS8122YTHA5 to maintain regulation?

The CS8122YTHA5 maintains regulation as long as VIN ≥ VOUT + Dropout. With a typical dropout of 0.6 V at 500 mA and nominal VOUT = 5.0 V, the minimum VIN is 5.6 V. However, the RESET function remains active down to VOUT = 1.0 V - meaning CS8122YTHA5 continues asserting RESET even if input drops below 5.6 V, provided internal bias remains above 1.0 V.

Can CS8122YTHA5 be used without an external delay capacitor?

Yes, CS8122YTHA5 operates without an external delay capacitor - in that configuration, the RESET output goes low immediately upon VOUT falling below 4.65 V, with no intentional delay. The delay capacitor (Pin 4) is optional and added only when programmable timing is required; its absence does not impair basic regulation or RESET functionality.

What thermal performance can be expected from CS8122YTHA5 in a TO-220 horizontal mount without heatsink?

In TO-220 horizontal-mount configuration (Case 314A), CS8122YTHA5 has RJA = 50°C/W. At 750 mA output and 12 V input, power dissipation is ~5.25 W - resulting in ~262°C junction rise above ambient, exceeding the 150°C limit. Therefore, a heatsink is mandatory for full-load operation; the copper tab must be thermally coupled to a heatsink achieving ≤20°C/W total RJA to stay within safe operating limits.

Does CS8122YTHA5 require input and output capacitors, and what types are recommended?

Yes, CS8122YTHA5 requires both input (CIN ≥ 100 nF) and output (COUT ≥ 10 µF) capacitors. COUT must be aluminum or tantalum electrolytic with ESR between 0.1 Ω and 1.0 Ω - ceramic or film capacitors with near-zero ESR cause instability. The datasheet specifies COUT = 10 µF, 1.0 Ω ESR as baseline; stability testing per Figure 13 is required for final design validation.

How does the latching discharge circuit in CS8122YTHA5 improve system reliability?

The latching discharge circuit in CS8122YTHA5 forces full discharge of the external delay capacitor whenever VOUT falls below 4.50 V - even for sub-millisecond faults. This guarantees that every valid fault condition produces a full-duration RESET pulse, eliminating missed resets due to partial capacitor discharge. It ensures deterministic behavior in noisy environments where brief transients could otherwise leave residual charge and suppress RESET assertion.