Texas Instruments TPS3421ECDRYR

Overview

TPS3421ECDRYR from Texas Instruments is a dual-input, low-power push-button reset controller with fixed 400-ms active-low open-drain reset pulse, operating from 1.6 V to 6.5 V supply and supporting –40°C to +125°C ambient. It monitors PB1 and PB2 simultaneously, asserts RST only after both inputs are held low ≥7.5 s (TS = GND), and deasserts RST after precisely 400 ms regardless of input state-enabling reliable hard-reset differentiation in portable consumer power management.

For engineers reviewing the TPS3421ECDRYR datasheet, TPS3421ECDRYR pinout, TPS3421ECDRYR application, or TPS3421ECDRYR equivalent, key selection criteria include its dual-pushbutton timing logic, factory-programmed 400-ms tRST, 250 nA standby current at 3.3 V, 6-pin USON (1.45 mm × 1.00 mm) package, and requirement for external pullup resistors on PB1/PB2-critical for battery-sensitive handheld systems requiring deterministic reset behavior.

Technical Context

The TPS3421ECDRYR implements a two-stage digital timing architecture: first, a configurable push-button timer (tTIMER) that validates simultaneous low states on PB1 and PB2 for ≥7.5 s (TS = GND) before asserting RST; second, a fixed-duration reset pulse generator that holds RST low for 400 ms (tRST) independent of input transitions. Its NMOS-based input threshold logic requires external pullups, and its open-drain RST output supports voltage-level translation up to 6.5 V.

This architecture eliminates false resets from transient button presses while ensuring system-level reset integrity-distinct from single-input alternatives like TPS3422 or input-dependent deassertion variants like TPS3420. The TS pin selects between 0 s and 7.5 s tTIMER options, but only the 7.5 s configuration is intended for normal operation per TI documentation.

Key Specifications

Pinout & Package

TPS3421ECDRYR uses a 6-pin ultra-thin small-outline no-lead (USON) package, 1.45 mm × 1.00 mm body size, with wettable flank terminations for automated optical inspection. Pin 1 is marked by a dot; top-side marking includes "C" (temperature grade), "D" (package), "R" (tape/reel), and "Y" (TI logo).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar push-button reset controller applications.

Compared with TPS3421ECDRYR, TPS3420ECDRYR offers input-dependent reset termination ideal for interactive diagnostics, while TPS3422ECDRYR reduces bill-of-materials complexity at the cost of dual-input security-making TPS3421ECDRYR the optimal choice for safety-critical hard-reset enforcement.

Availability

TPS3421ECDRYR is available at Aetrix Electronics and suitable for smartphone power management, medical wearable reset control, industrial tablet system recovery, and gaming handheld fault recovery requiring stable component supply across extended product lifecycles.

Supply support for TPS3421ECDRYR 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 headquartered in Dallas, Texas, delivering analog and embedded processing solutions for industrial, automotive, personal electronics, and communications markets.

The TPS342x family was designed specifically for ultra-low-power, space-constrained portable electronics requiring robust, deterministic push-button reset functionality-addressing the gap between mechanical switches and software-controlled reset schemes.

FAQ

What is the function of the TS pin on the TPS3421ECDRYR?

The TS pin on the TPS3421ECDRYR selects between two push-button timer durations: connecting TS to GND configures tTIMER = 7.5 s (typical), while TS = VCC sets tTIMER = 0 s. Only the 7.5 s option is intended for normal operation; TS must remain static during device operation and should be changed only during power-off to avoid false triggering. This pin does not affect the fixed 400-ms reset pulse duration (tRST) of the TPS3421ECDRYR.

Does the TPS3421ECDRYR require external pullup resistors on PB1 and PB2?

Yes, the TPS3421ECDRYR requires external pullup resistors on both PB1 and PB2 pins because it uses NMOS-based input threshold logic without internal pullups. These resistors must connect to VCC and establish valid high logic levels (VIH ≥ 0.85 V). Typical values range from 10 kΩ to 100 kΩ, balancing leakage current, noise immunity, and response time. This design requirement is intrinsic to the TPS3421ECDRYR's dual-input validation architecture.

What is the maximum sink current capability of the TPS3421ECDRYR RST output?

The TPS3421ECDRYR RST output supports a maximum sink current of 8 mA while maintaining VOL ≤ 0.4 V at VCC ≥ 4.5 V, per Electrical Characteristics table. At lower supply voltages (VCC ≥ 1.6 V), it sinks 3 mA with VOL ≤ 0.3 V. This specification defines the minimum pullup resistor value needed-for example, a 1-kΩ pullup to 3.3 V yields ~3.3 mA sink, staying within safe operating limits. Exceeding 8 mA risks violating VOL specs and compromising reset signal integrity in the TPS3421ECDRYR.

Can the TPS3421ECDRYR operate from a 1.8-V supply?

Yes, the TPS3421ECDRYR operates from 1.6 V to 6.5 V, so a 1.8-V supply is fully supported. At 1.8 V, standby current remains ≤1 µA (–40°C to +85°C), tTIMER stays within ±20% of 7.5 s, and tRST holds at 400 ms typical. The device maintains full functionality-including PB1/PB2 input thresholds and RST open-drain drive-across this range. This makes the TPS3421ECDRYR suitable for modern low-voltage SoC domains where 1.8-V rails are common.

How does the TPS3421ECDRYR differ from the TPS3420ECDRYR in reset behavior?

The TPS3421ECDRYR asserts RST after both PB1 and PB2 are held low for ≥7.5 s and deasserts RST after a fixed 400-ms pulse-regardless of input state. In contrast, the TPS3420ECDRYR deasserts RST immediately when either PB1 or PB2 transitions high. This fundamental difference means the TPS3421ECDRYR guarantees minimum reset hold time for microprocessor initialization, while the TPS3420ECDRYR enables user-terminated reset sequences. Both share identical pinout and supply specs, but their reset deassertion logic is mutually exclusive.