Texas Instruments TPS3820-33DBVT

Overview

TPS3820-33DBVT from Texas Instruments is a 3.3V fixed-threshold voltage supervisor IC with integrated watchdog timer, active-low push-pull reset output, manual reset input (MR), and 25ms reset delay. It monitors VDD supply rail in microcontroller-based systems, asserts RESET when VDD drops below 2.86–3.00V (−40°C to 85°C), and triggers system reset upon watchdog timeout or manual assertion. Used in portable equipment and industrial controllers requiring reliable power-on initialization.

For engineers reviewing the TPS3820-33DBVT datasheet, TPS3820-33DBVT pinout, TPS3820-33DBVT application, or TPS3820-33DBVT equivalent, key selection criteria include its 25ms delay (vs. 200ms in TPS3823), 3.3V threshold accuracy, 15μA quiescent current, SOT-23-5 package footprint, and MR/WDI signal timing compatibility with MSP430 and similar low-power MCUs.

Technical Context

The TPS3820-33DBVT implements a fixed-threshold supervision architecture with internal voltage divider setting V_IT− = 2.93V (nominal) and hysteresis of 50mV. Its watchdog timer times out after 112–300ms if WDI sees no falling edge, and reset delay (t_d) is 15–37ms after VDD exceeds V_IT− + V_HYS. The device operates from 1.1V to 5.5V and asserts RESET low when VDD falls below V_IT−.

It features a dedicated manual reset input (MR) that forces active-low RESET regardless of VDD level or watchdog state, and uses push-pull output stage capable of sinking 3mA at 0.4V (VOL) and sourcing 120μA at 0.8×VDD (VOH). No external components are required for basic operation.

Key Specifications

Pinout & Package

TPS3820-33DBVT is housed in a 5-pin SOT-23 (DBV) package measuring 2.90mm × 1.60mm, optimized for space-constrained PCB layouts.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TPS3823-33DBVT, the TPS3820-33DBVT reduces reset delay from 200ms to 25ms-critical for fast-booting systems-while maintaining identical 3.3V threshold accuracy and watchdog functionality; compared with TPS3820-33DBVR, it differs only in packaging format, not performance or interface.

Availability

TPS3820-33DBVT is available at Aetrix Electronics and suitable for microcontroller power-up sequencing, portable equipment supervision, and industrial programmable controllers requiring stable component supply with guaranteed long-term availability.

Supply support for TPS3820-33DBVT 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

Texas Instruments is a global semiconductor company delivering analog and embedded processing solutions for industrial, automotive, and personal electronics markets.

The TPS382x product line delivers compact, low-power voltage supervisors with integrated watchdog timers, designed specifically for reliable power-on reset and runtime fault detection in microcontroller and DSP-based systems.

FAQ

What is the exact reset threshold voltage range for TPS3820-33DBVT over temperature?

The TPS3820-33DBVT has a negative-going input threshold voltage (V_IT−) of 2.86V to 3.00V across the full operating temperature range of −40°C to 85°C. This 3.3V nominal threshold is set by an internal precision voltage divider and includes 50mV hysteresis to prevent chatter near the trip point. The TPS3820-33DBVT datasheet specifies these values under Electrical Characteristics section 6.5.

Does TPS3820-33DBVT require external components for basic operation?

No, the TPS3820-33DBVT requires no external components for fundamental voltage supervision and watchdog functionality. Its fixed 3.3V threshold, 25ms reset delay, and internal WDI pulse generator eliminate the need for resistors, capacitors, or timing elements. A 0.1μF ceramic bypass capacitor at VDD is recommended for noise immunity but not mandatory for DC operation.

How does the watchdog timer in TPS3820-33DBVT respond to a floating WDI pin?

When the WDI pin of the TPS3820-33DBVT is left unconnected, the device generates internal pulses to prevent unintended watchdog timeout. This behavior avoids false resets in systems where WDI is unused. If continuous pulsing is undesirable, a 1kΩ pull-down resistor to GND ensures the WDI pin is recognized as actively driven low rather than floating.

Can TPS3820-33DBVT drive a microcontroller reset pin directly without a pull-up resistor?

Yes, the TPS3820-33DBVT features a push-pull RESET output capable of actively driving both high and low states. It can directly assert active-low reset to standard microcontrollers (e.g., MSP430, STM32) without requiring an external pull-up resistor. The output sinks up to 3mA at 0.4V (VOL) and sources 120μA at 0.8×VDD (VOH), meeting typical MCU reset input requirements.

What is the function of the MR pin on TPS3820-33DBVT and how should it be handled if unused?

The MR (manual reset) pin on TPS3820-33DBVT is an asynchronous active-low input that forces RESET low regardless of VDD level or watchdog status. When unused, it may be left floating because the device includes an internal 90kΩ pull-up resistor connecting MR to VDD. Alternatively, it can be tied directly to VDD for explicit disable. Pulling MR low for ≥1µs initiates a full reset cycle including the 25ms delay.