Texas Instruments TPS3620-50DGKT

Overview

TPS3620-50DGKT from Texas Instruments is a 5-V backup-battery supervisor IC with integrated switchover MOSFET, precision 4.55 V reset threshold (±1%), 100 ms power-on reset delay, and ultra-low 40 µA VDD supply current. It monitors main supply (VDD) and backup battery (VBAT), automatically switching RAM to battery during brownout or power failure in portable medical monitors and point-of-sale terminals.

For engineers reviewing the TPS3620-50DGKT datasheet, TPS3620-50DGKT pinout, TPS3620-50DGKT application, or TPS3620-50DGKT equivalent, key selection criteria include its 4.55 V reset threshold tolerance, VBAT-to-VOUT on-resistance of 8–15 Ω at 3.3 V, 100 nA max battery-supply current, and compatibility with lithium backup cells exceeding VDD voltage.

Technical Context

The TPS3620-50DGKT implements dual-supply supervision using an internal 1.15 V reference for both VDD and PFI monitoring, with hysteresis of 60 mV on VDD and 12 mV on PFI. Its switchover logic ensures VBAT only connects to VOUT when VDD falls below VIT and VBAT > VDD, preventing backfeed.

Reset assertion occurs at VDD ≥ 1.1 V during power-up, then remains active until VDD exceeds 4.55 V and sustains that level for 100 ms; subsequent undervoltage events trigger immediate RESET low with no additional delay. The MR input supports manual reset with 100 ns/V minimum slew rate immunity.

Key Specifications

Pinout & Package

TPS3620-50DGKT uses an 8-pin VSSOP (DGK) package, 3.05 mm × 4.98 mm footprint, 1.1 mm max height, RoHS-compliant NiPdAu lead finish, MSL Level-1.

Key Features

Applications

Equivalent & Alternatives

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

Compared with TPS3620-33DGKT, the TPS3620-50DGKT provides higher reset threshold matching 5 V systems, while MAX6420XS33+T offers lower IQ but omits critical backup switchover and auxiliary monitoring needed for RAM retention.

Availability

TPS3620-50DGKT is available at Aetrix Electronics and suitable for medical vital sign monitors, point-of-sale terminals, and automotive telematics units requiring stable component supply with long-term lifecycle support.

Supply support for TPS3620-50DGKT 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, with leadership in power management, signal chain, and microcontrollers.

The TPS36xx family was designed specifically for battery-backed RAM retention in portable and industrial systems, integrating precision voltage supervision, power-fail detection, and seamless switchover into a single 8-pin VSSOP device.

FAQ

What is the exact reset threshold voltage of the TPS3620-50DGKT and how tightly is it specified?

The TPS3620-50DGKT has a nominal reset threshold of 4.55 V, with a guaranteed tolerance of ±1% over the full operating temperature range of –40°C to +85°C. This value is measured at the VDD pin and defines the voltage at which the RESET output transitions from active-low to inactive-high after the 100 ms delay timer expires. The TPS3620-50DGKT datasheet specifies min/max values of 4.46 V and 4.64 V respectively, confirming the ±1% band.

Can the TPS3620-50DGKT support a 3.6 V lithium thionyl chloride battery while supervising a 5 V main supply?

Yes, the TPS3620-50DGKT explicitly supports VBAT voltages exceeding VDD, including 3.6 V LiSOCl₂ cells on 5 V systems. Its switchover architecture connects VBAT to VOUT only when VDD falls below 4.55 V and VBAT > VDD, preventing backfeed. The absolute maximum VBAT rating is 5.5 V, and the device draws just 100 nA from VBAT in backup mode - ideal for multi-year shelf life. The TPS3620-50DGKT's VBAT-to-VOUT rDS(on) is 8–15 Ω at 3.3 V, ensuring low dropout under load.

Does the TPS3620-50DGKT require external components to generate its 100 ms power-on reset delay?

No, the TPS3620-50DGKT integrates a factory-trimmed 100 ms reset delay timer - no external capacitor or resistor is needed. This fixed delay begins counting only after VDD rises above the 4.55 V threshold and remains valid across temperature and supply variations. The TPS3620-50DGKT's internal timer eliminates timing uncertainty from component tolerances and PCB parasitics, ensuring consistent reset behavior in high-reliability applications like medical monitors and POS terminals.

How does the PFI/PFO function work on the TPS3620-50DGKT and what external components are needed?

The PFI pin on the TPS3620-50DGKT compares an external voltage against an internal 1.15 V reference; when PFI falls below this threshold, PFO goes low. To monitor a voltage other than 1.15 V (e.g., 12 V), use a precision 1% resistor divider with total resistance ~1 MΩ to minimize loading. The TPS3620-50DGKT's PFI input draws only ±25 nA, so divider current dominates error. If unused, tie PFI to GND and leave PFO floating. No external hysteresis components are required - the TPS3620-50DGKT provides built-in 12 mV hysteresis.

Is the TPS3620-50DGKT pin-compatible with legacy Maxim supervisors like the MAX704?

Yes, the TPS3620-50DGKT is explicitly advertised as pin-for-pin compatible with MAX819, MAX703, and MAX704 in the 8-pin MSOP (DGK) package. Pin mapping matches exactly: VOUT (1), VDD (2), GND (3), PFI (4), PFO (5), MR (6), RESET (7), VBAT (8). However, note functional differences - the TPS3620-50DGKT adds PFI/PFO monitoring and battery switchover not present in MAX704, and its 4.55 V threshold differs from MAX704's 4.63 V. System validation is recommended before drop-in replacement.