Texas Instruments TPS3435AFACADDFRQ1

Overview

TPS3435AFACADDFRQ1 from Texas Instruments is an AEC-Q100 Grade 1 automotive watchdog timer IC with factory- or capacitor-programmable timeout (adjustable), ±10% timer accuracy, 10s startup delay, and open-drain active-low WDO output - used in battery management systems and front camera ECUs to prevent system lockup during firmware updates or boot sequences.

For engineers reviewing the TPS3435AFACADDFRQ1 datasheet, TPS3435AFACADDFRQ1 pinout, TPS3435AFACADDFRQ1 application, or TPS3435AFACADDFRQ1 equivalent, key selection criteria include its adjustable watchdog timeout via CWD capacitor, 10s programmable startup delay, ultra-low 250nA supply current, SOT-23-8 DDF package, and MR input support for manual reset assertion.

Technical Context

The TPS3435AFACADDFRQ1 implements a precision timeout watchdog using internal capacitance-sensing circuitry that measures CWD pin capacitance at power-up to set tWD without continuous charge/discharge cycles - eliminating dead time and enabling stable monitoring across temperature. Its timing accuracy remains within ±10% over –40°C to 125°C ambient.

This variant uses Pinout Option A (per TI documentation), featuring dedicated CWD and CRST pins for capacitor-based programming of both watchdog timeout and WDO assert time, plus MR, WDI, SET0, WDO, VDD, and GND terminals - supporting latched open-drain operation and on-the-fly timer scaling via SET0 logic control.

Key Specifications

Pinout & Package

TPS3435AFACADDFRQ1 is housed in an 8-pin SOT-23 (DDF) package measuring 2.90 mm × 1.60 mm, optimized for space-constrained automotive PCBs and compatible with standard pick-and-place assembly.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar timeout watchdog timer applications.

Compared with TPS3435AFACADDFRQ1, TPS3435CAKAGDDFRQ1 offers simpler integration but lacks field-adjustability, while TPS3435CECAJDDFRQ1 trades timeout flexibility for latched fault signaling - making TPS3435AFACADDFRQ1 optimal for designs requiring both programmability and guaranteed boot margin.

Availability

TPS3435AFACADDFRQ1 is available at Aetrix Electronics and suitable for battery management systems, front camera ECUs, on-board chargers, and surround view systems requiring stable component supply across automotive production lifecycles.

Supply support for TPS3435AFACADDFRQ1 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 deep expertise in automotive-grade reliability and functional safety.

The TPS3435-Q1 product line delivers ultra-low-power, AEC-Q100-qualified watchdog timers specifically engineered for automotive electronic control units where deterministic fault detection and long-term supply stability are mandatory.

FAQ

What is the watchdog timeout range supported by TPS3435AFACADDFRQ1?

TPS3435AFACADDFRQ1 supports adjustable watchdog timeout via external capacitor on the CWD pin, covering approximately 7.4 ms to 5 seconds based on 1.5–1000 nF capacitor values per TI Equation 1. This differs from fixed-timer variants and enables precise tuning to application-specific firmware execution windows without changing the bill of materials.

How does the 10 s startup delay function in TPS3435AFACADDFRQ1?

The 10 s startup delay in TPS3435AFACADDFRQ1 is factory-programmed and begins at power-up or after WDO assertion. During this period, the device monitors WDI but suppresses WDO output - ensuring the host microcontroller completes boot initialization before watchdog supervision activates. This prevents spurious resets during cold start or recovery sequences.

Can TPS3435AFACADDFRQ1 be used without external capacitors?

No - TPS3435AFACADDFRQ1 requires external capacitors on both CWD (for watchdog timeout) and CRST (for WDO assert time) pins to operate as specified. The device uses capacitance-sensing circuitry at power-up to determine timing parameters; omitting either capacitor results in undefined or disabled watchdog functionality per TI documentation.

What is the role of the MR pin in TPS3435AFACADDFRQ1?

The MR pin in TPS3435AFACADDFRQ1 is an active-low manual reset input with internal 100 kΩ pull-up. Driving MR low immediately asserts the WDO output for the programmed tWDO duration, enabling host MCU-initiated recovery independent of watchdog state - critical for controlled system restarts during diagnostics or firmware updates.

Does TPS3435AFACADDFRQ1 support on-the-fly watchdog timeout adjustment?

Yes - TPS3435AFACADDFRQ1 supports on-the-fly timeout scaling via the SET0 pin, offering 1×, 8×, or 16× multiplication of the base tWD value determined by the CWD capacitor. This allows dynamic adaptation between operational modes (e.g., extended timeout during sleep, shorter timeout during active processing) without hardware changes.