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  • Brief description of the ISL6754 pin function?

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    Brief description of the ISL6754 pin function?


    (1) VDD: IC power supply terminal.Add a bypass capacitor to GND and a ceramic capacitor close to VDD and GND.

    (2) GND: IC common terminal, signal ground.A terminal is used for power. Since high-peak current and high-frequency operation are required, a low-impedance layout is required, and the grounding wire is as short as possible.

    (3) VREF: 5V reference voltage terminal.Determine the cT current discharge amplitude, the minimum is 20Q resistance multiplied by the resistance current.The PWM dead band is given by the timing capacitor discharge time.The RTD voltage is typically 2V.(6) CS: This input is sent to the overcurrent comparator. The overcurrent comparator threshold is set to 1V. When the CS terminal is shorted to ground, the PWM output will be terminated depending on the source impedance.When the AMP terminal is short-circuited to ground, the PWM signal is terminated. A sawtooth voltage waveform is sent at the upper end. For current-type control, this terminal is connected to cs as a feedback signal of the current loop and added to both inputs. For voltage-type control, the oscillator is controlled.The sawtooth wave can be buffered and used to generate the appropriate signal.This is the delay of the upper MOS and the bottom MOS open shoulder. The voltage applied to the RESDEL determines the delay of the high-side MOS switch when the low-side MOS switch is turned on. The control voltage is changed from 0 to 2V, and the resonant delay is from 0 to 100%..

    (1 1) OUTLLN and OUTLRN: These two are complementary signals to the PWM bridge controlled low-side MOS drive, suitable for controlling secondary side synchronous rectification, and the phase relationship of each output is controlled by the voltage applied to VADJ.

    (12) VADJ: is added to this terminal from a control voltage of 0 to 5V.When 50% divided from the VREF terminal is internally applied to this terminal, there is no phase delay, and the terminal is suspended externally.When the PWM output delay is relative to the SR output, the delay time will not exceed 90% of the dead time, which is determined by the RTD and CT terminals.

    (13) VERR: Control voltage input.When VERR is driven by a photocrow or other current source, a pull-up Resistors is connected from VREF to it, giving a linear gain, typically 5kΩ.

    (14) FB: Inverting input of the error amplifier.The soft-start capacitor value of the control IC and the internal current source determine the rate of increase of the duty cycle during startup.SS can also be used to disable the output, using a small signal transistor to form an open collector structure.(17) CTBUF: buffered output of the CT waveform of the sawtooth oscillator.


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