Texas Instruments Power Management ICs: DC-DC, LDO & PMIC

A Texas Instruments power management IC converts, regulates and sequences the voltage rails on your board: buck and boost converters, LDO regulators, PMICs, battery chargers, gate drivers, load switches and supervisors. Choosing the right one is a trade between efficiency, noise, size and cost, and the layout around it matters as much as the part you pick.

This guide separates switching from linear regulation, puts real TI part numbers against their specs, and covers the thermal and layout work where power designs actually fail.

• Buck/boost converters (switching) are efficient but generate ripple and EMI. The TPS54331 delivers 3 A from a 3.5–28 V input.
• LDOs are quiet and simple but burn the voltage difference as heat. The TPS7A47 reaches 4 µVRMS noise at 36 V, 1 A.
• PMICs integrate several rails plus charging — the BQ25150 combines charger, power path and LDO in one chip.
• The classic clean-rail trick is a switcher followed by a low-noise LDO to feed sensitive analog and ADC supplies.

What a TI Power Management IC Does and the Main Types

Every board starts with an input source — a wall adapter, a battery, a USB port — and needs one or more regulated rails at the right voltage and current. A power management IC does that conversion and protects the system around it. TI’s portfolio breaks into a few working types: step-down (buck) and step-up (boost) switching converters, buck-boost converters for rails that cross the input voltage, linear LDO regulators, integrated PMICs, battery chargers and fuel gauges, gate drivers, load switches, and supervisor/reset ICs.

The first decision is topology. The second is integration. The third — and the one most likely to bite a first prototype — is thermal layout.

Switching vs. Linear: DC-DC Converter or LDO?

The instinct that an LDO is “quieter” so it must be better is only half true. An LDO has excellent low-frequency power-supply rejection, but its PSRR rolls off at higher frequencies, so it does not magically clean up high-frequency switching noise. And it dissipates power equal to the dropout voltage times the load current — drop 5 V to 3.3 V at 1 A and you are burning 1.7 W as heat in the package.

Choose	When	Representative TI part	Watch out for
Buck converter	Stepping a higher rail down efficiently at >100 mA	TPS54331 (3 A, 3.5–28 V)	Ripple, EMI, inductor and layout
Nano-power buck	Battery rails that must sip current at light load	TPS62840 (~60 nA quiescent, up to 750 mA)	Light-load mode behaviour
LDO	Small step-down, low noise, simple	TPS7A47 (36 V, 1 A, 4 µVRMS)	Heat = (Vin−Vout) × Iload
Low-Iq LDO	Always-on rails in battery products	TPS7A25 (<340 mV dropout at 300 mA)	Dropout at peak load

So the right answer is often both. Use a buck converter to do the bulk step-down efficiently, then a low-noise LDO such as the TPS7A47 as a post-regulator to feed the analog and converter rails. That combination is why the data-converter and amplifier sections of a board so often have their own dedicated LDO.

The headline trade-off: raising the switching frequency shrinks the inductor and capacitors, saving board space, but it increases switching losses and can worsen EMI. There is no free lunch — you are trading size for efficiency and emissions.

TI PMICs and Battery Chargers for Portable Designs

In a space-constrained portable product, a PMIC collapses what would be several discrete regulators and a charger into one device. The TPS6507x and TPS65217 families pair a single-cell Li-ion charger and power path with multiple step-down converters and LDOs — the TPS65217 was designed specifically to power the Sitara AM335x processor. For smaller systems, the BQ25150 and BQ25120A integrate a linear charger, power path and a buck or LDO with ship-mode for shelf life.

The integration trade-off is real: a PMIC shrinks the board and the BOM line count, but it ties you to one vendor’s exact rail configuration and creates a single point of failure during a shortage. If the product is high-volume and long-lived, identify the fallback before you commit. PMICs frequently sit alongside Texas Instruments microcontrollers, which they sequence and supervise, and they connect to TI digital isolators when a rail must cross an isolation barrier.

Power IC Layout and Thermal Design: Where Boards Fail

More power designs fail on the board than in the schematic. The recurring culprits:

1. The exposed thermal pad. Most TI power QFNs dump heat through a bottom pad that must be soldered down and stitched with thermal vias into internal copper. A paste-starved or unstitched pad is the number-one reason a buck converter overheats on a first prototype.
2. Copper weight and trace width. Size high-current traces using the IPC-2221 conductor-current guidance, and step up to 2 oz copper where a 1 oz pour would run hot.
3. The input loop. Keep the input capacitor, switch node and ground in the tightest possible loop to control ripple and radiated noise. A sloppy input loop adds EMI no filter fully fixes.
4. Void control. Voids under the thermal pad raise junction temperature; inspect them with X-ray and grade against the voiding criteria in IPC-A-610 and IPC-7093.

An IoT client once shipped a buck design that failed thermal testing intermittently. The schematic was correct; the exposed pad had only two thermal vias and a 1 oz pour. Adding a 3-by-3 thermal-via array and moving to 2 oz copper dropped the measured junction temperature by roughly 15 °C and the failures disappeared. The regulator never changed — the copper did.

Common TI Power Management Mistakes

1. Choosing an LDO for a large step-down and then fighting the heat it creates.
2. Under-stitching or starving the exposed thermal pad of paste.
3. Violating an LDO’s output-capacitor ESR window, which can make it unstable.
4. Ignoring light-load efficiency on a battery rail, where quiescent current dominates run time.
5. Sizing the inductor for nominal load and ignoring saturation current at peak.

Frequently Asked Questions About TI Power Management ICs

What is the difference between a buck converter and an LDO?

A buck converter switches energy through an inductor and is efficient even with a large voltage drop. An LDO is a linear regulator that dissipates the voltage difference as heat, so it is simpler and quieter but inefficient for big steps. Use a buck for efficiency, an LDO for a small, clean step.

Which TI part is best for a low-noise analog rail?

A low-noise LDO such as the TPS7A47, at around 4 µVRMS, is the standard choice for analog and data-converter rails. It is usually fed from a buck converter that does the efficient bulk step-down upstream.

What is a PMIC?

A power management IC integrates several functions — multiple regulators, a battery charger, power path and sometimes supervision — into one device. TI examples include the TPS65217 for Sitara processors and the BQ25150 for compact portable systems.

Why does my TI buck converter run hot?

Usually the exposed thermal pad is not soldered down or stitched with enough thermal vias, so heat cannot leave the package. Adding a thermal-via array and heavier copper, and checking for voids by X-ray, typically fixes it.

How do I pick the switching frequency?

Higher frequency means smaller inductors and capacitors but more switching loss and potentially more EMI. Lower frequency is more efficient but larger. Choose based on your space, efficiency and emissions budget rather than a default value.

Design Your TI Power Stage, Then Get the Copper Right

Lock the topology from your efficiency and noise budget, choose the part, and then treat the thermal layout as part of the design. Send your Gerber and BOM for a DFM review so the thermal pad, via stitching and copper weight are checked before the first build, and return to the Texas Instruments component hub to align the rest of the board. For acceptance and voiding criteria, see IPC.