TI TPS54478RTET

The TPS54478 is a fully-featured 6-V, 4-A synchronous step-down current mode converter with two integrated MOSFETs.

The TPS54478 achieves compact designs by integrating MOSFETs, implementing current mode control to reduce external component count, enabling switching frequencies up to 2MHz to minimize inductor size, and utilizing a small 3mm×3mm thermally enhanced WQFN package to minimize IC package size.

The TPS54478 provides accurate regulation for various loads across the operating temperature range with a precise (±1%) voltage reference (V_REF). Efficiency is maximized through the integrated 30mΩ MOSFETs and a typical supply current of 525μA. The device can enter shutdown mode via the enable pin, reducing shutdown supply current to 2.5μA.

The UVLO threshold is internally set at 2.6V but can be raised by configuring a resistor network on the enable pin. The output voltage startup ramp is controlled by the soft-start pin. An open-drain power-good signal indicates that the output is within 93% to 107% of its nominal voltage.

Cycle-by-cycle current limiting, hiccup overcurrent protection, and thermal shutdown protect the device from damage under overcurrent conditions.

The TPS54478 is a 6-V, 4-A, synchronous step-down (buck) converter with two integrated n-channel MOSFETs. To improve performance during line and load transients the device implements a constant frequency, peak current mode control which reduces output capacitance and simplifies external frequency compensation design. The wide switching frequency of 200kHz to 2000kHz allows for efficiency and size optimization when selecting the output filter components. The switching frequency is adjusted using a resistor to ground on the RT/CLK pin. The device has an internal phase lock loop (PLL) on the RT/CLK pin that is used to synchronize the power switch turn on to a falling edge of an external system clock.

The TPS54478 has a typical default start up voltage of 2.6V. The EN pin has an internal pull-up current source that can be used to adjust the input voltage under voltage lockout (UVLO) with two external resistors. In addition, the pull up current provides a default condition when the EN pin is floating for the device to operate. The total operating current for the TPS54478 is typically 525μA when not switching and under no load. When the device is disabled, the supply current is less than 2.5μA.

The integrated 30mΩ MOSFETs allow for high efficiency power supply designs with continuous output currents up to 4 amperes.

The TPS54478 reduces the external component count by integrating the boot recharge diode. The bias voltage for the integrated high side MO

• Two 30mΩ (typical) MOSFETs with high efficiency at 4A load
• 200kHz to 2MHz switching frequency
• 0.6V ±1% voltage reference over operating temperature range (-40°C to +150°C)
• Pre-biased output startup
• External clock synchronization
• Adjustable soft-start/sequencing
• Undervoltage (UV) and overvoltage (OV) power-good output
• Cycle-by-cycle current limiting and hiccup current protection
• Thermally enhanced 3mm×3mm 16-pin WQFN (RTE) package
• Pin-compatible with TPS54418
• Create custom designs using TPS54478 with WEBENCH Power Designer

• Low-voltage, high-density power systems
• Point-of-load regulation for high-performance DSP, FPGA, ASIC, and microprocessors
• Broadband, networking, and fiber optic communication infrastructure