onsemi CAT823MTDI-GT3

Overview

CAT823MTDI-GT3 from onsemi is a system supervisory voltage reset IC with integrated watchdog timer and manual reset input, designed for microprocessor power-up sequencing and brownout protection in 4.38 V nominal systems. It provides active-low CMOS push-pull RESET output, monitors VCC against 4.25–4.50 V threshold with ±40 ppm/°C tempco, and guarantees ≥140 ms reset timeout after power stabilization.

For engineers reviewing the CAT823MTDI-GT3 datasheet, pinout, applications, or equivalent options, this page delivers verified functional identity, TSOT-23-5 pin mapping, watchdog timeout (1.12–3.20 s), manual reset timing (tPDLY = 5 µs), and direct alternatives for 4.38 V reset supervision in industrial control and portable electronics.

Technical Context

The CAT823MTDI-GT3 implements a precision bandgap-based voltage reference with comparator hysteresis (10 mV) and digital delay logic to enforce minimum 140 ms reset assertion after VCC exceeds VRST. Its watchdog circuit resets on missing WDI edge transitions within 1.12–3.20 s, independent of VCC level once enabled.

Manual reset is debounced and internally pulled up with 35–75 kΩ resistor; MR low pulse ≥1 µs triggers full reset timeout. RESET output sustains valid logic levels down to VCC = 1.0 V, with VOH ≥ VCC − 1.5 V and VOL ≤ 0.4 V at ISINK = 3.2 mA.

Key Specifications

Pinout & Package

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

Key Features

Applications

Equivalent & Alternatives

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

Compared with MAX823MESA+ and TPS3808G33DBVR, CAT823MTDI-GT3 uniquely combines 4.38 V precision reset, integrated watchdog, and manual reset in a single TSOT-23-5 package-enabling compact, self-recovering systems without external components or design compromises.

Availability

CAT823MTDI-GT3 is available at Aetrix Electronics and suitable for industrial control systems, portable medical devices, smart energy meters, and automated test equipment requiring stable component supply and long-term lifecycle support.

Supply support for CAT823MTDI-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 manufacturer specializing in energy-efficient power, analog, sensor, and connectivity solutions for automotive, industrial, cloud, and IoT applications.

The CAT823 product line delivers highly integrated, low-power supervisory ICs optimized for robust microprocessor reset and watchdog functionality in space-constrained, thermally demanding environments.

FAQ

What is the exact reset threshold voltage of CAT823MTDI-GT3 and how does it vary with temperature?

The CAT823MTDI-GT3 has a guaranteed reset threshold of 4.25 V (min) to 4.50 V (max) across −40°C to +85°C, with a typical value of 4.38 V. Its temperature coefficient is tightly controlled at ±40 ppm/°C, meaning the threshold shifts less than ±3.5 mV over the full operating range-critical for stable brownout detection in industrial systems where ambient temperature fluctuates widely. This specification is measured and validated per onsemi's datasheet Table 3.

Does CAT823MTDI-GT3 require external components to interface with a pushbutton for manual reset?

No, CAT823MTDI-GT3 does not require external components for pushbutton interfacing. It features an internal 52 kΩ pullup resistor on the MR pin, allowing direct connection of a momentary switch between MR and GND. A low pulse ≥1 µs on MR initiates a full reset cycle with ≥140 ms assertion-eliminating the need for external resistors, capacitors, or debounce circuitry in most designs.

Can CAT823MTDI-GT3 operate reliably at VCC = 1.2 V, and what happens to the RESET output at that voltage?

Yes, CAT823MTDI-GT3 is specified to operate down to VCC = 1.2 V (per Table 2 Recommended Operating Conditions). At this voltage, the RESET output remains functional: VOL ≤ 0.3 V at ISINK = 100 µA, and VOH ≥ 0.8 × VCC = 0.96 V. This ensures valid logic levels during deep brownout or controlled power-down sequences, preventing premature release of downstream processors.

How does the watchdog timer in CAT823MTDI-GT3 behave if the WDI pin is left floating?

If the WDI pin is left floating or tri-stated, CAT823MTDI-GT3 detects the open condition and pulls WDI low for 7/8 of the watchdog period (≈0.98–2.8 s) then high for 1/8 (≈0.14–0.4 s), repeating continuously. This behavior prevents unintended resets while signaling the absence of an active watchdog driver-allowing safe fallback to manual or power-fail reset without requiring external pullup/down resistors.

Is CAT823MTDI-GT3 pin-compatible with MAX823MESA+, and can it be used as a drop-in replacement?

CAT823MTDI-GT3 is pin- and function-compatible with MAX823/824 series per onsemi's datasheet Feature list, sharing identical TSOT-23-5 pinout and core reset/watchdog functions. However, it is not a guaranteed drop-in replacement for MAX823MESA+ in all cases: while electrical thresholds and timing align closely, differences in supply current (CAT823MTDI-GT3: 6–17 µA vs. MAX823: ~25 µA) and WDI input leakage may affect marginal designs-validation per actual board conditions is recommended.