TPS543320RPYR

The TPS543320RPYR from Texas Instruments is a 3A synchronous step-down converter with a wide 4.5V to 22V input range, designed for industrial and automotive point-of-load power applications. The device features TI’s HotRod QFN package technology, which flips the die and attaches it directly to the leadframe without wire bonds, reducing parasitic inductance and on-resistance for improved efficiency and lower EMI. The converter operates at an adjustable switching frequency from 500kHz to 2.2MHz, allowing designers to balance efficiency and solution size. A unique spread spectrum feature (pin-selectable) modulates the switching frequency by +/-6% with a pseudo-random pattern, reducing peak EMI emissions and helping systems pass CISPR 25 and other EMI standards without additional shielding or filtering. The DCS-Control topology provides seamless transition between forced PWM mode (for tight regulation and constant frequency) and PFM mode (for high efficiency at light loads with only 5uA quiescent current). The 0.6V +/-1% reference voltage enables output voltages as low as 0.6V for modern low-voltage processors and FPGAs. Integrated high-side and low-side MOSFETs deliver up to 3A continuous output current. Protection features include cycle-by-cycle current limit, undervoltage lockout with programmable threshold via EN pin, output overvoltage protection, and thermal shutdown. The compact 3x3mm HotRod QFN-12 package provides excellent thermal performance with a low junction-to-ambient thermal resistance.

The TPS543320RPYR operates as a synchronous buck converter using DCS-Control topology. Key subsystems include: (1) DCS-Control – a proprietary control scheme providing fast transient response through direct feedforward of input and output voltage; the control loop operates in voltage mode with internal compensation; in PWM mode, the device switches at the programmed frequency; in PFM mode at light loads, switching pulses are skipped to reduce losses; (2) Integrated Power MOSFETs – the HotRod QFN package mounts the die with copper pillars directly to the leadframe, eliminating bond wire resistance and inductance; the high-side MOSFET connects VIN to SW, the low-side MOSFET connects SW to GND; (3) Spread Spectrum – when the SS pin is pulled high, a pseudo-random number generator modulates the switching frequency by +/-6% around the center frequency; this spreads the switching harmonic energy across a wider bandwidth, reducing peak emissions in the EMI spectrum; when SS is low, the device operates at the fixed frequency set by the RT resistor; (4) Mode Selection – the MODE pin selects between forced PWM (constant frequency across all loads) and auto PFM/PWM (high efficiency at light loads); forced PWM is preferred for EMI-sensitive or audio applications where variable frequency is undesirable; (5) Protection – cycle-by-cycle current limit (typically 4.5A-6A); OVP (overvoltage protection) activates the low-side MOSFET to discharge the output if VOUT exceeds the setpoint by 8%; thermal shutdown at approximately 165C.

• Automotive infotainment: 12V battery to 3.3V/5V with spread spectrum for CISPR 25 compliance
• Industrial PLC: 24V to 1.2V for FPGA core, PFM mode for low standby power
• Test equipment: 12V to 1.8V/0.9V for ADC/DAC rails, FPWM for low output ripple
• Battery-powered IoT: 3-cell Li-Ion (9-12.6V) to 3.3V, 5uA IQ in PFM sleep mode