Texas Instruments TPS61221DCKT

Overview

TPS61221DCKT from Texas Instruments is a fixed-output 3.3 V synchronous boost converter optimized for ultra-low-input-voltage battery-powered systems. It operates from 0.7 V to 5.5 V input, delivers up to 126 mA output current at 3.3 V (VIN = 2.4 V), achieves ≥90% efficiency at 50 mA load, and consumes only 5.5 μA quiescent current - enabling long runtime in single-cell alkaline/NiMH or Li-ion applications such as portable medical sensors and LED indicators.

For engineers reviewing the TPS61221DCKT datasheet, TPS61221DCKT pinout, TPS61221DCKT application, or TPS61221DCKT equivalent, key selection criteria include its 0.7 V startup capability, SC-70 (6-pin) package footprint, pass-through behavior during shutdown, integrated overvoltage/overtemperature/undervoltage protection, and compatibility with standard 4.7 μH inductors and 10 μF ceramic output capacitors.

Technical Context

The TPS61221DCKT implements a hysteretic current-mode control architecture with synchronous rectification, using two internal MOSFETs (R_DS(on) = 600 mΩ main switch, 700 mΩ rectifier at V_OUT = 5 V). It regulates output voltage by maintaining constant 200 mA inductor ripple current and dynamically adjusting conduction time based on load demand.

Startup begins at 0.7 V input via an internal oscillator that limits switch current until V_OUT reaches ~1.8 V, then transitions to normal hysteretic operation. During shutdown (EN = low), the device disables switching but allows passive conduction through the rectifier's body diode - resulting in V_OUT ≈ V_IN − 0.3 V under light load.

Key Specifications

Pinout & Package

TPS61221DCKT is housed in a 6-pin SC-70 package (2.00 mm × 1.25 mm, 0.95 mm height), optimized for high-density PCB layouts in portable electronics. The thermally enhanced bottom-side pad improves power dissipation in ambient temperatures up to +125 °C.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar boost converter applications.

Compared with TPS61221DCKT, TPS61222DCKT provides higher output voltage at the cost of reduced efficiency below 2.4 V input, while MAX17222ETA+ trades integrated protection and output drive strength for minimal IQ and footprint - making TPS61221DCKT optimal for balanced performance in alkaline/NiMH-powered 3.3 V systems.

Availability

TPS61221DCKT is available at Aetrix Electronics and suitable for portable medical devices, smart wearables, low-power IoT sensors, and LED lighting applications requiring stable component supply across extended production lifecycles.

Supply support for TPS61221DCKT 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 specializing in analog, embedded processing, and power management technologies, with decades of expertise in high-efficiency DC/DC conversion.

The TPS6122x product line was designed specifically for ultra-low-input-voltage battery-powered applications - targeting single-cell alkaline, NiMH, and Li-ion systems where startup voltage, quiescent current, and small footprint are critical design constraints.

FAQ

What is the minimum input voltage required for TPS61221DCKT to start up and regulate?

The TPS61221DCKT starts up and begins regulation at 0.7 V input voltage under load conditions (RLoad ≥150 Ω), as confirmed in the Electrical Characteristics table. This enables reliable operation even as single-cell alkaline batteries discharge below 1.0 V. Startup time depends on input voltage and output load, with typical values shown in Figure 19 of the datasheet.

Does TPS61221DCKT require external feedback resistors to set its output voltage?

No, the TPS61221DCKT is a fixed-output variant with internally programmed 3.3 V regulation. Its FB pin is internally connected to the output divider, so it must be shorted directly to VOUT - no external resistors are needed or permitted. This simplifies design, reduces BOM count, and improves accuracy versus adjustable versions.

How does TPS61221DCKT behave when the EN pin is pulled low?

When EN is pulled low, the TPS61221DCKT enters shutdown mode: switching stops, internal control circuitry powers down, and quiescent current drops to 0.2–0.5 μA. However, the rectifying MOSFET's body diode remains conductive, allowing VOUT to follow VIN minus ~0.3 V - enabling partial system operation without additional diodes.

What protection features are integrated into TPS61221DCKT?

The TPS61221DCKT integrates four hardware protections: undervoltage lockout (UVLO) triggers at 0.5–0.7 V input, overvoltage protection (OVP) clamps output at 6.0–7.5 V, overtemperature protection (OTP) shuts down at 140 °C with 20 °C hysteresis, and internal switch current limiting prevents destructive inductor saturation during overload.

Can TPS61221DCKT drive a 100 mA load continuously at 3.3 V from a 1.2 V input?

Yes - at VIN = 1.2 V and VOUT = 3.3 V, the TPS61221DCKT delivers up to 60 mA continuously (Figure 3), but maximum output current increases with higher input voltage: it supports 126 mA at VIN = 2.4 V. For 100 mA at 1.2 V input, the device would operate in overload, causing VOUT to droop; a higher-input-voltage source or alternative regulator is recommended.