RT6203E
Input Under-Voltage Lockout
The protection is activated outside of the absolute
maximum range of operation as a secondary fail-safe and
therefore should not be relied upon operationally.
Continuous operation above the specified absolute
maximum operating junction temperature may impair
device reliability or permanently damage the device.
In addition to the EN pin, the RT6203E also provides enable
control through the VIN pin. It features an under-voltage
lockout (UVLO) function that monitors the internal linear
regulator. If VEN rises above VIH first, switching will still be
inhibited until the VIN voltage rises above VUVLO. It is to
ensure that the internal regulator is ready so that operation
with not-fully-enhanced internal MOSFET switches can
be prevented. After the device is powered up, if the input
voltage VIN goes below the UVLO falling threshold voltage
(VUVLO − ΔVUVLO), this switching will be inhibited; if VIN
rises above the UVLO rising threshold (VUVLO), the device
will resume normal operation with a complete soft-start.
The Over-Current Protection
The RT6203E features cycle-by-cycle current-limit
protection on low-side MOSFETs and prevents the device
from the catastrophic damage in output short circuit and
over current.
The low-side MOSFET over-current protection is achieved
by measuring the inductor current through the
synchronous rectifier (low-side switch) during the low-side
on-time. Once the current rises above the low-side switch
valley current limit (ILIM_L), the on-time one-shot will be
inhibited until the inductor current ramps down to the
current limit level (ILIM_L), that is, another on-time can only
be triggered when the inductor current goes below the
low-side current limit. If the output load current exceeds
the available inductor current (clamped by the low-side
current limit), the output capacitor needs to supply the
extra current such that the output voltage will begin to
drop.
Thermal Shutdown
The RT6203E 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 (20°C,
typically), the IC will resume normal operation with a
complete soft-start.
Note that the over temperature protection is intended to
protect the device during momentary overload conditions.
Copyright 2019 Richtek Technology Corporation. All rights reserved.
©
is a registered trademark of Richtek Technology Corporation.
DS6203E-00 January 2019
www.richtek.com
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