RT6215F
External Bootstrap Capacitor
VOUT, 2V/DIV
Output short
Connect a 0.1μF low-ESR ceramic capacitor between the
BOOT and SW pins. This bootstrap capacitor supplies for
the gate driver of the high-sideN-channel MOSFET switch.
Fault condition removed
Resume normal operation
ISW, 4A/DIV
Over-Temperature Protection (Thermal Shutdown)
The RT6215F includes an over-temperature protection
(OTP) circuitry to prevent overheating due to excessive
power dissipation. The OTP will shut down switching
operation when junction temperature exceeds a thermal
shutdown threshold TSD. Once the junction temperature
cools down by a thermal shutdown hysteresis (ΔTSD), the
IC will resume normal operation with a complete soft-start.
tHICCUP_ON = 2.1ms
VSW, 10V/DIV
10ms/DIV
tHICCUP_OFF = 5.7ms
Soft-Start (SS)
The RT6215F provides an internal soft-start feature for
inrush control. At power up, the internal capacitor is
charged by an internal current source to generate a soft-
start ramp voltage as a reference voltage to the PWM
comparator. The device will initiate switching and the
output voltage will smoothly ramp up to its targeted
regulation voltage only after this ramp voltage is greater
than the feedback voltage VFB to ensure the converters
have a smooth start-up. The output voltage starts to rise
in 0.4ms from EN rising, and the soft-start ramp-up time
(VFB from 0V to 0.791V) is 1.5ms.
VIN = 12V
VIN
0.4ms
1.5ms
EN
VOUT
Copyright 2018 Richtek Technology Corporation. All rights reserved.
©
is a registered trademark of Richtek Technology Corporation.
DS6215F-00 September 2018
www.richtek.com
5
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