TPS65288RHAR

TPS65288 is a power management IC featuring 3 buck converters. It integrates high-side and low-side MOSFETs to provide fully synchronous conversion with higher efficiency. The converters are designed to simplify application while allowing designers to optimize their usage for target applications. The converters operate in 5V, 9V, 12V, or 15V systems. The output voltage can be externally set via a resistor divider to any value between 0.8V and the input voltage minus the resistive voltage drop across the converter path. Each converter features a dedicated enable pin that allows delayed startup for sequencing purposes, a soft-start pin that enables adjustable soft-start time through selection of a soft-start capacitor, and a current limit (RLIM) pin that allows designers to adjust the current limit threshold and optimize inductor selection by choosing an external resistor. All converters operate in "hiccup mode": once an overcurrent condition lasting more than 10ms is detected in any converter, they are shut down for 10ms, then retry the startup sequence. If the overload has been removed, the converter ramps up and operates normally. Otherwise, the converter detects another overcurrent event, shuts down again, and repeats this cycle (hiccup) until the fault is cleared. If the overload condition lasts less than 10ms, only the affected converter is shut down and restarted — global hiccup mode is not triggered. The switching frequency of these converters is set by an external resistor connected to the ROSC pin. The switching regulators are designed to operate over a frequency range of 300kHz to 2.2MHz. The converters operate with a 180° phase offset to significantly reduce input filtering requirements. All converters feature peak current mode control, which simplifies external frequency compensation. The device incorporates a built-in slope compensation ramp. Slope compensation prevents sub-harmonic oscillation in peak current mode control. A conventional Type II compensation network stabilizes the system and achieves fast transient response. Additionally, an optional capacitor in parallel with the upper resistor of the feedback divider provides an extra zero, enabling the crossover frequency to exceed 100kHz. All converters feature an automatic low-power pulse skip mode (PSM), which improves efficiency during light load and standby operation while maintaining extremely low output ripple — achieving less than 2% at low output voltages. The device incorporates an overvoltage transient protection circuit to significantly reduce voltage overshoot. The OVP feature reduces output overshoot by implementing a circuit that compares the FB pin voltage against the OVP threshold (106% of the internal voltage reference). If the FB pin voltage exceeds the OVTP threshold, the high-side MOSFET is disabled to prevent current from flowing into the output, significantly reducing output overshoot. When the FB voltage drops below the lower OVP threshold (104% of the internal voltage reference), the high-side MOSFET is allowed to turn on at the next clock cycle. The TPS65288 features a monitoring circuit that monitors the output of each buck converter, with the PGOOD pin asserted upon completion of sequencing. The PGOOD pin is an open-drain output. It is pulled low when any buck converter output is pulled below 85% of its nominal output voltage. PGOOD is pulled high when all converter outputs exceed 90% of their respective nominal output voltages. The default reset time is 100ms. PGOOD polarity is active high. Two USB switches supply up to 1.2A of current required by downstream USB devices. When the output load exceeds the current limit threshold or a short circuit occurs, the PMU limits the output current to a safe level by switching to constant current mode and pulling the overcurrent logic output low. When sustained heavy load or short circuit increases power dissipation in the switch and causes the junction temperature to rise, an overtemperature protection circuit shuts down the USB switches while allowing the buck converters to continue operating. The device implements an internal thermal shutdown to protect itself from damage when the junction temperature exceeds 160°C. When the junction temperature exceeds the thermal shutdown threshold, the device is forced to stop operating. Once the die temperature drops below 140°C, the device restarts the power-on sequence. The thermal shutdown hysteresis is 20°C.

Key features

• Wide input supply voltage range: 4.5V - 18V
• 0.8V reference with ±1% accuracy
• Continuous load current: 3A (Buck 1), 2A (Buck 2 and Buck 3)
• Peak current: 3.5A (Buck 1), 2.5A (Buck 2 and Buck 3)
• Switching frequency 300kHz - 2.2MHz set by external resistor
• External enable pin with built-in current source for easy sequencing
• External soft-start pin
• Adjustable cycle-by-cycle current limit set by external resistor
• Current mode control with simple compensation network
• Pulse skip mode for high light-load efficiency with output ripple better than 2%
• Forced PWM mode
• Pre-biased output supported
• Power-good monitor and reset generator
• 2 USB power switch current limit typical 1.2A (factory trim options: 0.8/1.0/1.4/1.6/1.8/2.0/2.2A)
• Compact, thermally efficient 40-pin 6mm x 6mm RHA (QFN) package
• Junction temperature range: -40°C to 125°C