Texas Instruments TPS3618-50DGKR

Overview

TPS3618-50DGKR from Texas Instruments is a battery-backup supervisor IC designed for RAM retention in 5-V systems. It provides precision 4.55-V supply monitoring, 800-ms watchdog timeout, 100-ms power-on reset delay, and seamless VDD-to-VBAT switchover with ≤1-Ω on-resistance (VDD→VOUT) and ≤15-Ω on-resistance (VBAT→VOUT). It serves as the critical power-fail and data-retention controller in portable battery-powered equipment.

For engineers reviewing the TPS3618-50DGKR datasheet, TPS3618-50DGKR pinout, TPS3618-50DGKR application, or TPS3618-50DGKR equivalent, key selection criteria include its 40 µA max supply current, 100 nA max battery supply current, −40°C to +85°C operating range, MSOP-8 package footprint, and dual-voltage supervision capability (VDD and PFI).

Technical Context

The TPS3618-50DGKR integrates a precision voltage monitor with 4.55-V trip threshold (VIT), a push-pull active-low RESET output with 100-ms fixed delay, and an independent power-fail comparator (PFI/PFO) referenced to 1.15 V. Its internal switchover logic ensures VOUT connects to VDD above VIT and switches to VBAT only when VDD falls below VIT and VBAT exceeds VDD.

It features a dedicated watchdog timer with 800-ms nominal timeout (0.48–1.12 s range), triggered by WDI transitions; unused WDI must be left floating. The device operates across 1.65–5.5 V on VDD and 1.5–5.5 V on VBAT, supporting lithium backup cells exceeding VDD voltage without reverse current flow.

Key Specifications

Pinout & Package

TPS3618-50DGKR is housed in an 8-pin VSSOP (DGK) package measuring 3.05 mm × 4.98 mm with 0.65-mm lead pitch and maximum height of 1.1 mm. The exposed pad is not electrically connected.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar battery-backup supervisor applications.

Compared with TPS3618-50DGKR, TPS3617-50DGKR adds factory battery isolation at no cost to performance, while TPS3618-50DGKT extends thermal qualification-neither offers pin-to-pin or functional substitution without verifying temperature and seal requirements.

Availability

TPS3618-50DGKR is available at Aetrix Electronics and suitable for portable battery powered equipment, fax machines, set-top boxes, and point-of-sale equipment requiring stable component supply, long-lifecycle support, and guaranteed traceable sourcing.

Supply support for TPS3618-50DGKR 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 specializing in analog and embedded processing technologies, with leadership in power management, signal chain, and interface solutions.

The TPS361x family was engineered specifically for nonvolatile memory retention in battery-backed systems, emphasizing ultra-low IBAT, precise VIT tolerance, and robust switchover reliability across industrial temperature ranges.

FAQ

What is the exact supply voltage threshold (VIT) for TPS3618-50DGKR?

The TPS3618-50DGKR has a nominal VDD supply voltage threshold (VIT) of 4.55 V, with a guaranteed range of 4.46 V to 4.64 V over −40°C to +85°C. This precision threshold ensures reliable brownout detection for 5-V systems without false resets during nominal ripple. The device uses internal trimming to achieve this accuracy, and VIT hysteresis is 60 mV to prevent chatter near the trip point.

Can TPS3618-50DGKR support a 3.6-V lithium backup battery while VDD is at 5 V?

Yes, TPS3618-50DGKR explicitly supports VBAT voltages exceeding VDD - including 3.6-V lithium cells - without reverse current flow or damage. Its internal PMOS/NMOS switchover architecture isolates VBAT from VOUT until VDD falls below VIT and VBAT > VDD. This allows safe use of higher-voltage backup sources while maintaining 100 nA max IBAT and preventing battery discharge during normal operation.

How does the watchdog timer in TPS3618-50DGKR operate, and what happens if WDI is unused?

The TPS3618-50DGKR watchdog timer has a nominal 800-ms timeout (0.48–1.12 s range) and resets on any WDI edge (rising or falling). If unused, WDI must be left floating - internally it is weakly pulled low, disabling the watchdog. Driving WDI externally high continuously draws ~125 µA; best practice is pulsing low-high-low once per timeout period to minimize current. The watchdog asserts RESET if no transition occurs within the timeout window.

What is the maximum continuous output current supported by TPS3618-50DGKR on VOUT?

TPS3618-50DGKR supports up to 300 mA continuous output current on VOUT in both VDD-mode and VBAT-mode. In VDD-mode, RDS(on) is ≤1 Ω, yielding <300 mV drop at 300 mA; in VBAT-mode, RDS(on) is ≤15 Ω, limiting usable current at lower VBAT (e.g., 200 mA at 3.3 V yields ~0.66 V drop). Exceeding 300 mA risks thermal shutdown or parametric shift outside datasheet limits.

Is TPS3618-50DGKR pin-compatible with other members of the TPS361x family?

Yes, TPS3618-50DGKR is fully pin-compatible with TPS3617-50DGKR and TPS3618-50DGKT - all share identical 8-pin VSSOP (DGK) pinout, terminal functions, and electrical behavior. Differences are limited to internal features (battery freshness seal in TPS3617) and temperature grading (TPS3618-50DGKT rated to +125°C junction). No PCB layout change is needed when substituting within the same package variant.