Texas Instruments TPS3421ECDRYT

Overview

TPS3421ECDRYT 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 consuming only 250 nA typical standby current. It monitors PB1 and PB2 simultaneously, asserts RST only after both inputs are held low for ≥7.5 s (TS = GND), and deasserts RST after the fixed pulse-enabling reliable hard-reset differentiation in portable power management systems.

For engineers reviewing the TPS3421ECDRYT datasheet, TPS3421ECDRYT pinout, TPS3421ECDRYT application, or TPS3421ECDRYT equivalent, key selection criteria include its dual-pushbutton timing logic, factory-programmed 400-ms tRST, USON-6 package footprint, ultra-low ICC standby, and open-drain RST compatibility with mixed-voltage microprocessor reset rails.

Technical Context

The TPS3421ECDRYT implements dual-input synchronous detection logic: both PB1 and PB2 must be driven low for the full tTIMER duration (7.5 s typical, TS = GND) before RST assertion. Its internal timing generator uses an oscillator-based delay circuit with temperature-compensated stability across –40°C to +125°C.

RST output behavior is decoupled from input release: once asserted, it remains low for exactly 400 ms (tRST, typical) regardless of PB1/PB2 state changes during that window-ensuring deterministic reset hold time for microprocessor initialization sequences.

Key Specifications

Pinout & Package

TPS3421ECDRYT is housed in a 1.45-mm × 1.00-mm, 6-pin USON (DRY) package with wettable flanks for automated optical inspection.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TPS3421ECDRYT, TPS3420ECDRYT offers input-dependent reset deassertion ideal for interactive diagnostics, while TPS3422ECDRYT reduces component count for single-button designs-both share identical ultra-low power, timing accuracy, and thermal range but differ fundamentally in input architecture and reset control model.

Availability

TPS3421ECDRYT is available at Aetrix Electronics and suitable for smartphone power sequencing, industrial HMI emergency shutdown, and medical wearable recovery mode requiring stable component supply across extended product lifecycles.

Supply support for TPS3421ECDRYT 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 leader delivering analog and embedded processing solutions, with over 90 years of innovation in power management, signal chain, and microcontroller technologies.

The TPS342x family was designed specifically for ultra-low-power, space-constrained push-button reset applications in portable and automotive electronics-emphasizing timing precision, supply voltage flexibility, and robust ESD immunity.

FAQ

What is the function of the TS pin on the TPS3421ECDRYT?

The TS pin on the TPS3421ECDRYT selects between two push-button timer durations: connecting TS to GND configures tTIMER = 7.5 s (typical), while TS = VCC sets tTIMER = 0 s (factory test mode only). For normal operation, TS must be permanently tied to GND or VCC-dynamic switching is not supported and may cause erratic behavior. This configuration is sampled at power-up and when PB inputs are high.

Does the TPS3421ECDRYT require external pullup resistors on PB1 and PB2?

Yes, the TPS3421ECDRYT requires external pullup resistors on both PB1 and PB2 pins to VCC. The device does not include internal pullups on these inputs-unlike the TPS3422ECDRYT-and relies on external resistors to ensure defined high-state logic levels. Typical values range from 10 kΩ to 100 kΩ, selected based on system noise immunity and leakage requirements.

How long does the RST output remain active after assertion in the TPS3421ECDRYT?

The RST output of the TPS3421ECDRYT remains low for a factory-programmed fixed duration of 400 ms (typical), with guaranteed minimum 320 ms and maximum 480 ms across temperature and supply voltage. This fixed pulse is independent of PB1/PB2 release timing-ensuring predictable microprocessor reset hold time even if buttons are released early.

Can the TPS3421ECDRYT operate from a 1.8-V supply?

Yes, the TPS3421ECDRYT fully supports 1.8-V operation within its specified 1.6-V to 6.5-V supply range. At 1.8 V, standby current remains ≤1 µA (–40°C to +85°C), tTIMER retains ±20% accuracy, and tRST stays within 320–480 ms. The open-drain RST output can be pulled up to a higher voltage rail (e.g., 3.3 V) independently of VCC.

What is the maximum sink current capability of the RST pin on the TPS3421ECDRYT?

The RST pin on the TPS3421ECDRYT can sink up to 8 mA while maintaining VOL ≤0.4 V at VCC ≥4.5 V, ≤0.3 V at VCC ≥3.3 V, and ≤0.3 V at VCC ≥1.6 V. This ensures reliable logic-low signaling into standard CMOS reset inputs. Leakage current in high-impedance state is ±0.35 µA at VRST = 6.5 V, minimizing unintended loading on shared reset buses.