Overview

The TPS54331 (commonly supplied in 8-pin SOIC TPS54331DR) is a 3.0 A3.0\text{ A} step-down (buck) switching regulator from Texas Instruments. Featuring an integrated 80 mΩ80\text{ m}\Omega high-side N-channel MOSFET, it operates across an input voltage range of 3.5 V3.5\text{ V} to 28.0 V28.0\text{ V} and regulates output voltage down to 0.8 V0.8\text{ V}.

To maximize efficiency across all load conditions, the TPS54331 features Eco-mode™ pulse skipping, which automatically reduces switching frequency under light loads (such as standby MCU modes) to maintain high efficiency down to milliamp currents.

Quick reference

Regulator TypeEco-mode™ Step-Down (Buck) DC-DC Converter
PackageSOIC-8 (D) / SO PowerPAD-8 (DDA)
Input Voltage Range (VINV_{IN})3.5 V3.5\text{ V} to 28.0 V28.0\text{ V} DC
Output Voltage Range (VOUTV_{OUT})0.8 V0.8\text{ V} to 25.0 V25.0\text{ V} DC (Adjustable)
Continuous Output Current (IOUTI_{OUT})Up to 3.0 A3.0\text{ A}
Switching Frequency570 kHz570\text{ kHz} fixed internal oscillator
Conversion Efficiency88%…92%88\% \dots 92\% (with light-load pulse skipping)
FeaturesAdjustable soft-start (SS), precision UVLO enable (EN), Eco-mode

Pinout (SOIC-8 / SO PowerPAD-8)

text
        ┌─────────────┐
   BOOT ─│ 1         8 │─ PH
    VIN ─│ 2         7 │─ GND
     EN ─│ 3    EP   6 │─ COMP
     SS ─│ 4         5 │─ VSENSE
        └─────────────┘
PinNameDescription
1BOOTBootstrap capacitor connection to PH (0.1 μF0.1\ \mu\text{F} cap) for high-side gate drive
2VINUnregulated DC input voltage (+3.5V to +28V DC)
3ENEnable control input pin with internal precision threshold for UVLO tuning
4SSSoft-start programming pin (capacitor to GND sets soft-start ramp time)
5VSENSEVoltage sense feedback input (0.8V0.8\text{V} internal reference)
6COMPError amplifier output pin for external loop frequency compensation
7GNDGround reference pin
8PHPhase / Switch node output connected to internal high-side MOSFET drain

Specifications

ParameterSymbolMinTypMaxUnitConditions
Input Voltage RangeVINV_{IN}3.51228VOperating range
Feedback Reference VoltsVREFV_{REF}0.7840.8000.816VTJ=25∘CT_J = 25^\circ\text{C}
Continuous Output CurrentIOUTI_{OUT}—3.0—AVIN=12V,VOUT=3.3VV_{IN} = 12\text{V}, V_{OUT} = 3.3\text{V}
Switch On-ResistanceRDS(ON)R_{DS(ON)}—80135mΩ\text{m}\OmegaVBOOT−VPH=6VV_{BOOT} - V_{PH} = 6\text{V}
Switching FrequencyfSWf_{SW}450570690kHzInternal clock
Quiescent CurrentIQI_Q—110160μA\mu\text{A}Non-switching Eco-mode state
Shutdown CurrentISDI_{SD}—1.02.5μA\mu\text{A}VEN=0VV_{EN} = 0\text{V}

Typical Application Circuit

text
       +V_IN (3.5V - 28V DC Input)
          │
       [Pin 2: VIN]
        TPS54331DR ──── [Pin 8: PH] ──── [ 6.8µH - 10µH Inductor ] ──┬─── +V_OUT Regulated DC Output
          │                                   │                       │
       [Pin 7: GND]                [B340A Schottky Diode]          [ R1 ]
          │                                   │                       │
         GND ─────────────────────────────────┴───────────────────────┼─── [Pin 5: VSENSE]
                                                                      │
                                                                    [ R2 ]
                                                                      │
                                                                     GND

VOUT=0.8V×(1+R1R2)V_{OUT} = 0.8\text{V} \times \left( 1 + \frac{R_1}{R_2} \right)

Common mistakes

  • Floating the SS pin: Leaving SS floating results in instantaneous startup current spikes. Always connect a small ceramic capacitor (e.g., 10nF) between SS and GND for smooth soft-start output ramp.
  • Incorrect COMP component values: The TPS54331 relies on external RC compensation on the COMP pin (Pin 6). Leaving COMP unconnected or using arbitrary RC values can cause control loop instability or output ripple.

Notes

  • Eco-mode Advantage: Unlike standard buck switchers that consume 3–5mA idling, the TPS54331 drops quiescent current to ~110µA under light load, making it ideal for battery-backed systems.

Assets & downloads