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EN29A0QI-Slide5

The EN29A0QI supports input voltages from 9V to 16V and output voltages from 0.75 to 3.3V making it an excellent choice for powering low-voltage FPGA power rails and for generating a 3.3V intermediate bus voltage. The part will support up to 10A of continuous output current over the full industrial ambient temperature range of -40°C to 85°C without the need for any thermal derating. The output voltage accuracy is ±1% over the full input voltage range, output current range, and the full operational junction temperature range making it suitable for powering loads requiring a high degree of accuracy. The switching frequency is programmable from 450kHz up to 2MHz by adjusting a single external resistor value allowing the user to optimize between efficiency, ripple, or load transient response. The part supports synchronization to an external clock source, as long as the clock is a higher frequency and within 15% of the switching frequency setpoint value. The soft-start ramp time is adjustable over a wide range from 0.1ms up to 20ms by adjusting the soft-start capacitor value, and the soft-shutdown time is also adjustable via an external resistor value. When the ENABLE input goes “low”, this resistor forms an RC circuit with the soft-start capacitor to determine the soft-shutdown time. The output power good indicator provides accurate voltage monitoring for precision sequencing, and the output overvoltage and overcurrent threshold values are also tightly controlled allowing for more predictable protection of critical loads. The EN29A0QI also provides accurate undervoltage lockout rising and falling thresholds assuring that the part is not attempting to operate when the input voltage is outside of its operational range. The overcurrent protection, OCP, is implemented using a proprietary dual threshold hysteretic approach that guarantees no current runaway which can occur with cycle by cycle limiting. When the peak current exceeds the upper threshold, typically 150% of the rated current, the high side switch shuts off and the low side switch comes on and ramps the inductor current down to the second threshold, typically, 115% of the rated current. The drivers ignore the PWM signal during this limiting period; when the current ramps down to the lower threshold, the drivers respond to the PWM signal again. At first occurrence of an overcurrent condition, two timers start counting; an overcurrent timer and a reset timer. The overcurrent timer will continue to count unless it gets reset by the reset timer. The reset timer will reset if no overcurrent events occur in a 10ms period and the overcurrent timer will fault-out after 20ms of overcurrent events and no reset. This enables the device to power through short duration overcurrent events such as starting up into large amounts of bulk capacitance, or supporting burst loads like Hybrid Memory Cube.

PTM Published on: 2019-02-05