AT1382A
Preliminary Product Information
4-Channel DC-DC Converter for DSC
8. Setting the triangular oscillator frequency
The triangular oscillator frequency is determined by the timing capacitor (CT) connected to the CT
terminal, and the timing resistor (RT) connected to the RT terminal.
1000000
CT (PF) × RT (kΩ)
f
OSC (kHz) =
9. Setting the DEAD time
When using step up or SEPIC or flyback DC/DC converter, it must prevent that output transistor
works at full-ON state (ON duty = 100%). To prevent this situation, set the maximum duty of these
channels. To set it, set the voltage at the DTC terminal by applying a resistive voltage divider to
the VREF as shown below.
When the voltage at the DTC pin is higher than the triangular wave voltage (CT), the output
transistor is turned on. The maximum duty calculation formula assuming that triangular wave
amplitude = ∆V1(CH4=0.45,CH1~3=0.4) and triangular wave minimum voltage = Vx
(CH4=0.3,CH1~3=0.25).
Vd −Vx
∆V1
DUTY(ON)max =
×100﹪
If don't setting maximum duty, connect DTC terminal directly to the VREF terminal.
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