component

TPS61221

Public Unreviewed

by Ray

TI low-input-voltage boost converter, SC70-6. Starts from 0.7 V, adjustable output, tiny. Datasheet-verified.

componentpowerboost-converterswitching-regulatordc-dcsc70-6texas-instruments
Overview Files Discover Packages Releases Dependencies Issues Breadcrumbs Pull Requests Activity

3D Model

Open in new tab ↗

Symbol & Footprint

Schematic Symbol

Open full view ↗

PCB Footprint

Open full view ↗
Contents

README

markdown

TPS61221

Texas Instruments · Switching regulator (boost) · SC70-6

Boosts a low input up to a regulated rail, starting from 0.7 V once running so it works from a single alkaline or NiMH cell or a nearly-flat battery. A resistor divider at FB sets the output, EN gates it, and the whole thing fits a six-pin SC70 with just an inductor and two capacitors. A low quiescent current keeps standby efficiency high. Common where a 1.5 V cell must make 3.3 V for a sensor or radio.

Pinout

Pin Name Type Function
1 VIN power_in Boost converter input voltage supply pin. Operating range 0.7 V to 5.5 V (startup guaranteed from 0.7 V with R_LOAD >= 150 ohm). Bypass locally with a 10 µF ceramic capacitor to GND.
2 FB input Feedback input for the adjustable version. On this fixed-3.3 V TPS61221 variant this pin must be tied directly to VOUT (V_FB typical 500 mV on adjustable variant, I_FB <= 10 nA).
3 GND power_in Control-logic and power ground. Common return for input capacitor, output capacitor, and inductor current.
4 VOUT power_out Boost converter regulated output. Fixed 3.3 V nominal (3.20 V min / 3.41 V max). Also senses output for the internal feedback divider and provides the pass-through path when the converter is shut down. Requires a 10 µF ceramic output capacitor.
5 L passive Switching node / inductor connection. Ties to the free end of the boost inductor (typ. 4.7 µH); the other inductor terminal returns to VIN. Internal main (low-side) and rectifying (high-side) MOSFETs switch this node between GND and VOUT.
6 EN input Enable input. Drive high to enable the converter, low to disable (pass-through mode from VIN to VOUT via the rectifying switch's body diode). Must be actively driven, do not leave floating. Thresholds: for V_IN <= 1.5 V, V_IL <= 0.2V_IN, V_IH >= 0.8V_IN; for V_IN > 1.5 V, V_IL <= 0.4 V, V_IH >= 1.2 V. I_EN <= 0.1 µA.

Key specifications

Parameter Value
Type Boost (step-up) converter
Input 0.7-5.5 V (start-up from 0.7 V)
Output Up to 5.5 V (adjustable)
Quiescent current 5.5 uA (typ)
Light load Power-save mode
Enable EN pin
Package SC70-6

Ordering variants

Same part, different packaging or reel option.

  • TPS61222DCKR (fixed 3.3 V)
  • TPS61220DCKR (fixed 1.8 V)

The extractor listed these alongside TPS61221, but they are different parts with different electrical characteristics. Do not order them as substitutes.

  • TPS61221DCKR (adjustable, SC70-6)

CAD (KiCad official)

  • Symbol: Regulator_Switching:TPS61221DCK (KiCad official)
  • Footprint: Package_TO_SOT_SMD:Texas_R-PDSO-G6
  • 3D model: SC70-6 (KiCad packages3D, STEP)

Provenance

Data extracted from the manufacturer datasheet, not a distributor listing:

  • Datasheet: Texas Instruments datasheet (28 pp, sha256 ca17c38d6ed40a7a, retrieved 2026-08-17, tier: manufacturer)
  • Extractor: ds2sf (Claude). Every pin and dimension is cited to a datasheet page; it refuses to fabricate.
  • CAD: KiCad official libraries (CC-BY-SA 4.0).

Datasheet PDF