TI TPS54339EDDAR

The TPS54339E is an adaptive on-time D-CAP2™ mode synchronous buck converter. It helps system designers complete the power bus regulator set for various end equipment with a low-cost, low component count, low standby current solution. The main control loop employs D-CAP2™ mode control, achieving extremely fast transient response without external compensation components. Adaptive on-time control enables seamless transition between PWM mode under heavy load conditions and Eco-mode™ operation under light load. Eco-mode™ allows the TPS54339E to maintain high efficiency under lighter load conditions. Proprietary circuitry also helps the device accommodate low ESR output capacitors such as POSCAP or SP-CAP, as well as ultra-low ESR ceramic capacitors. The operating input voltage ranges from 4.5V to 18V, output voltage is adjustable between 0.76V and 7V, features an adjustable soft-start time, comes in an 8-pin DDA package, and is designed for operation over a -40°C to 85°C temperature range.

The TPS54339E is a 3-A synchronous step-down (buck) converter with two integrated N-channel MOSFETs. It operates using D-CAP2™ mode control. The fast transient response of D-CAP2™ control reduces the output capacitance required to meet a specific level of performance. Proprietary internal circuitry allows the use of low ESR output capacitors including ceramic and special polymer types.

The main control loop of the TPS54339E is an adaptive on-time pulse width modulation (PWM) controller that supports a proprietary D-CAP2™ mode control. D-CAP2™ mode control combines constant on-time control with an internal compensation circuit for pseudo-fixed frequency and low external component count configuration with both low ESR and ceramic output capacitors. It is stable even with virtually no ripple at the output.

TPS54339E uses an adaptive on-time control scheme and does not have a dedicated on board oscillator. The TPS54339E runs with a pseudo-constant frequency of 600 kHz by using the input voltage and output voltage to set the on-time one-shot timer. The on-time is inversely proportional to the input voltage and proportional to the output voltage; therefore, when the duty ratio is VOUT/VIN, the frequency is constant.

The TPS54339E is designed with Auto-Skip Eco-mode™ to increase light load efficiency. As the output current decreases from heavy load condition, the inductor current is also reduced and eventually comes to point that its rippled valley touches zero level, which is the boundary between continuous conduction and discontinuous conduction modes. The rectifying MOSFET is turned off when its zero inductor current is detected. As the load current further decreases the converter run into discontinuous conduction mode. The on-time is kept almost the same as is was in the continuous conduction mode so that it takes longer time to discharge the output capacitor with smaller load current to the level of the reference voltage.

The soft start function is adjustable. When the EN pin becomes high, 6 μA current begins charging the capacitor which is connected from the SS pin to GND. Smooth control of the output voltage is maintained during start up.

• D-CAP2™ mode for fast transient response
• Low output ripple, compatible with ceramic output capacitors
• Wide input voltage range: 4.5V to 23V
• Output voltage range: 0.76V to 7.0V
• High-efficiency integrated FET
• Optimized for lower duty cycle applications
• -140mΩ (high-side) and 70mΩ (low-side)
• High efficiency, quiescent current less than 10μA in shutdown
• High initial bandgap reference accuracy
• Adjustable soft-start
• Pre-bias soft-start
• 600kHz switching frequency (fSW)
• Cycle-by-cycle current limiting
• Automatic skip Eco-mode™ for high efficiency at light load

• Wide application in low-voltage systems
• Digital TV power supplies
• High-definition Blu-ray Disc players
• Home network terminal equipment
• Digital set-top boxes (STB)