Texas Instruments TPS7148QD

Overview

TPS7148QD from Texas Instruments is a 4.85-V fixed-output micropower low-dropout (LDO) voltage regulator featuring PMOS pass element architecture, 30 mV typical dropout at 100 mA, 285 µA quiescent current independent of load, 0.5 µA sleep-state current, and ±2% output voltage tolerance over –40°C to 125°C. It delivers up to 500 mA output current and integrates power-good (PG) monitoring for battery-powered instrumentation and portable medical devices.

For engineers reviewing the TPS7148QD datasheet, TPS7148QD pinout, TPS7148QD application, or TPS7148QD equivalent, key selection criteria include its ultra-low dropout under high load, rail-to-rail enable logic compatibility, PG threshold accuracy at 4.5–4.7 V, and TSSOP-20 package suitability for space-constrained PCB layouts with thermal derating considerations.

Technical Context

The TPS7148QD employs a PMOS pass transistor instead of conventional PNP, enabling dropout voltage directly proportional to output current (V_DO = I_O × r_DS(on)) and eliminating load-dependent quiescent current. Its internal 1.178-V reference feeds a precision error amplifier driving the gate of the PMOS element.

Power-good functionality uses a dedicated comparator monitoring the SENSE pin (tied to OUT in fixed-voltage configurations), asserting PG low when output falls below 4.5–4.7 V with 50-mV hysteresis. Enable input supports TTL-compatible active-low control with 50-mV hysteresis and 0.5-V logic-low threshold.

Key Specifications

Pinout & Package

TSSOP-20 package (PW), 6.5 mm × 4.4 mm footprint, 1.2 mm max height, with exposed thermal pad (not electrically connected). Pin 1 marked by dot; top-side view per datasheet Figure 1.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar LDO regulator applications.

Compared with TPS7148QPW, the TPS7148QD offers identical performance in tube packaging for prototyping and low-volume builds; versus TPS7A20485PDBVR, it trades higher IQ for significantly lower dropout-critical when input voltage approaches 4.9 V.

Availability

TPS7148QD is available at Aetrix Electronics and suitable for portable medical sensors, industrial data acquisition systems, automotive body control modules, and smart energy meters requiring stable component supply across extended temperature ranges and long production lifecycles.

Supply support for TPS7148QD 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 designing analog ICs, embedded processors, and connectivity solutions for industrial, automotive, and personal electronics markets.

The TPS71xx family was engineered specifically for micropower, low-dropout regulation in battery-operated systems where extended runtime and tight voltage tolerance are essential-exemplified by the TPS7148QD's 4.85-V fixed output and sub-1-µA shutdown capability.

FAQ

What is the minimum input voltage required for stable operation of the TPS7148QD?

The minimum input voltage for TPS7148QD is 5.2 V under maximum 500-mA load, calculated as V_OUT + V_DO(max) = 4.85 V + 250 mV = 5.1 V (rounded to 5.2 V per datasheet recommended conditions). At lighter loads, input can be reduced-e.g., 4.88 V suffices at 100 mA where dropout is 30 mV. Always verify with worst-case V_DO curves in Figure 1 of the TPS7148QD datasheet.

How should the SENSE pin be connected on the TPS7148QD?

The SENSE pin on the TPS7148QD must be connected directly to the OUT pin as close as physically possible to the device package-ideally with a short, wide copper trace-to ensure accurate feedback and maintain ±2% output tolerance. Do not route SENSE through vias or shared traces; this connection is mandatory for fixed-output operation and referenced in datasheet Note A and Figure 2.

Does the TPS7148QD support reverse current protection?

No, the TPS7148QD does not integrate reverse current protection. Its PMOS pass transistor inherently blocks reverse current flow from OUT to IN when disabled, but during active regulation, no internal circuitry prevents backfeed if V_OUT exceeds V_IN. External Schottky diodes or ideal diode controllers are required in systems where output voltage may exceed input (e.g., hot-swap or dual-supply redundancy).

What is the thermal resistance (θ_JA) of the TPS7148QD in its TSSOP-20 package?

The TPS7148QD in TSSOP-20 (PW) package has a junction-to-ambient thermal resistance (θ_JA) of 178°C/W under standard JEDEC 2-layer board conditions, as specified in Figure 3 of the datasheet. With proper PCB copper pour on the exposed pad (though non-electrical), θ_JA can be reduced to ~60°C/W in optimized layouts-enabling 448 mW dissipation at 70°C ambient before derating.

Can the TPS7148QD be used without the PG pin connected?

Yes, the PG pin on the TPS7148QD is optional and may be left unconnected if power-good monitoring is not required. It is an open-drain output requiring an external pull-up resistor (typically 10–100 kΩ to V_OUT or system rail) to function. Leaving PG floating has no effect on regulation performance, but forfeits undervoltage detection capability critical for system reset integrity.