The TPS61236RWLT is a step-up (boost) converter from Texas Instruments, built around a 6.5 A internal switch — that switch current is the headline number for a boost regulator because it directly sets the maximum output power you can deliver from a given input voltage. The output is adjustable from 2.9 V up to 5.5 V, so it can produce a regulated 3.3 V rail or a 5 V USB power bus from a single cell.
Switching frequency and package
Switching at 1 MHz, the TPS61236RWLT lets you use a small inductor and ceramic capacitors — the 1 MHz rate keeps the ripple current low enough that the output capacitor bank can be 10 µF class, saving board space in a compact handheld or IoT endpoint. The synchronous rectifier improves efficiency by replacing the external Schottky diode with an internal low-side FET — expect >90 % efficiency across most of the load range, though the exact number depends on the inductor and input voltage. Housed in a 9-pin VFQFN package measuring 2.5 mm × 2.5 mm, this is a small-footprint part — the 0.50 mm pitch demands careful solder-paste stencil design and a good thermal via pattern under the exposed pad to pull heat out of the switch.
Obsolete — sourcing reality
The TPS61236RWLT is listed as obsolete. That means Texas Instruments has stopped manufacturing it — no last-time-buy window remains open, and the only available units are those already in the distribution channel or on the spot market. If you need a pin-compatible drop-in, expect to requalify the board — the TPS6123x family shares the same base number but the RWLT suffix is unique to this variant, and TI's current boost portfolio (e.g. TPS61089 or TPS6125x) uses a different pinout and package. Sourcing this part means working with an independent distributor who can verify date-code authenticity and screen for counterfeit units — the spot market for obsolete TI boost converters carries risk, and a known-good date-code lot from the original TI factory is the only safe buy.