onsemi CAT824YSDI-GT3

Overview

CAT824YSDI-GT3 from onsemi is a system supervisory voltage reset IC with watchdog timer and active-high reset output, designed for brownout detection and power-on reset in 2.25 V systems. It provides 140–400 ms reset timeout, 1.12–3.20 s watchdog timeout, ±40 ppm/°C reset threshold tempco, and operates across −40°C to +85°C. Used in microcontroller-based portable equipment requiring reliable power sequencing.

For engineers reviewing the CAT824YSDI-GT3 datasheet, pinout, applications, or equivalent options, key selection criteria include reset threshold accuracy (2.13–2.25 V), TSOT-23-5 package compatibility, watchdog input timing tolerance, and MR-free architecture versus CAT823 variants.

Technical Context

The CAT824YSDI-GT3 implements a precision bandgap reference with comparator-based voltage monitoring and a digital delay timer for reset assertion. Its watchdog circuit monitors WDI transitions with a fixed timeout window and supports disable-by-tristate operation.

Unlike the CAT823, it omits the manual reset (MR) input and provides only an active-high RESET output - eliminating external pushbutton interface but simplifying layout where manual override is unnecessary. Reset assertion occurs when VCC falls below 2.19 V (typ) or rises above VRST with ≥140 ms delay.

Key Specifications

Pinout & Package

Supplied in TSOT-23-5 package (Case 419AE), 2.90 mm × 1.60 mm × 0.95 mm body, with 0.95 mm lead pitch and NiPdAu finish.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar voltage supervisor applications.

Compared with MAX824YUR+T and TPS3808G12QDBVRQ1, the CAT824YSDI-GT3 offers lowest quiescent current (4 µA), fixed minimal footprint (TSOT-23-5), and simplified WDI interface - ideal for cost- and space-constrained portable designs where automotive or programmable features are unnecessary.

Availability

CAT824YSDI-GT3 is available at Aetrix Electronics and suitable for portable medical sensors, industrial PLC I/O modules, and smart meter communication units requiring stable component supply across multi-year production cycles.

Supply support for CAT824YSDI-GT3 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 CAT823/CAT824 family was engineered specifically for robust, low-power system supervision in space-constrained embedded systems - emphasizing precision voltage thresholds, integrated watchdog functionality, and minimal external component count.

FAQ

What is the exact reset threshold voltage range for CAT824YSDI-GT3 over temperature?

The CAT824YSDI-GT3 has a guaranteed reset threshold range of 2.13 V (min) to 2.25 V (max) across −40°C to +85°C ambient, with typical value 2.19 V at 25°C. This 120 mV window reflects factory-trimmed bandgap reference accuracy and ±40 ppm/°C tempco - critical for stable operation in battery-powered 2.2 V systems where rail tolerance is tight.

Does CAT824YSDI-GT3 support manual reset functionality like the CAT823 series?

No, CAT824YSDI-GT3 does not include a manual reset (MR) input. Unlike CAT823 variants, it is designed exclusively with watchdog (WDI) and power-supply monitoring functions. The absence of MR simplifies PCB routing and eliminates pushbutton debounce circuitry - making CAT824YSDI-GT3 optimal for applications where operator-initiated reset is unnecessary or handled elsewhere in the system.

Can CAT824YSDI-GT3 be used with a 1.8 V supply rail?

No, CAT824YSDI-GT3 is not specified for 1.8 V operation. Its minimum recommended VCC is 1.2 V per datasheet Table 2, but its 2.19 V reset threshold means it will assert RESET continuously below that level. For 1.8 V systems, use CAT824UTDI-GT3 (2.00 V threshold) or verify actual trip behavior under load - the CAT824YSDI-GT3 is intended for 2.2 V nominal rails.

How does the watchdog timeout behave when WDI is left floating?

When WDI is left floating or tri-stated, CAT824YSDI-GT3 detects the open condition and pulls WDI low for 7/8 of the watchdog period (≈2.8 s) then high for 1/8 (≈0.4 s), repeating indefinitely. This prevents unintended reset while signaling invalid drive - allowing safe watchdog disable without external pull-down resistors. No reset is issued unless WDI remains static beyond full timeout.

Is CAT824YSDI-GT3 RoHS-compliant and lead-free?

Yes, CAT824YSDI-GT3 is RoHS-compliant, lead-free, halogen-free, and BFR-free per onsemi documentation. It features NiPdAu terminal finish and meets JEDEC MO-193 mechanical standards for TSOT-23-5 packaging. Full compliance data is available in the official onsemi Product Compliance Database under order number CAT824YSDI-GT3.