RT5710B
Operation
The RT5710B is a synchronous low voltage step-down
converter that can support the input voltage range from
2.5V to 6V and the output current can be up to 1A. The
RT5710B uses a constant on-time, current mode
architecture. In normal operation, the high-side
P-MOSFET is turned on when the switch controller is
set by the comparator and is turned off when the Ton
comparator resets the switch controller.
Low-side MOSFET peak current is measured by
internal RSENSE. The error amplifier EA adjusts
COMP voltage by comparing the feedback signal (V
FB
)
from the output voltage with the internal 0.6V reference.
When the load current increases, it causes a drop in
the feedback voltage relative to the reference, then the
COMP voltage rises to allow higher inductor current to
match the load current.
UV Comparator
If the feedback voltage (V
FB
) is lower than threshold
voltage 0.2V, the UV comparator's output will go high
and the switch controller will turn off the high-side
MOSFET. The output under-voltage protection is
designed to operate in Hiccup mode.
Enable Comparator
A logic-high enables the converter; a logic-low forces
the IC into shutdown mode.
Soft-Start (SS)
An internal current source charges an internal capacitor
to build the soft-start ramp voltage. The V
FB
voltage will
track the internal ramp voltage during soft-start interval.
The typical soft-start time is 1.2ms.
Over-Current Protection (OCP)
The RT5710B provides over-current protection by
detecting low-side MOSFET valley inductor current. If
the sensed valley inductor current is over the current
limit threshold (1.5A typ.), the OCP will be triggered.
When OCP is tripped, the RT5710B will keep the over
current threshold level until the over current condition is
removed.
Thermal Shutdown (OTP)
The device implements an internal thermal shutdown
function when the junction temperature exceeds 150°C.
The thermal shutdown forces the device to stop
switching when the junction temperature exceeds the
thermal shutdown threshold. Once the die temperature
decreases below the hysteresis of 20°C, the device
reinstates the power up sequence.
Copyright © 2019 Richtek Technology Corporation. All rights reserved.
is a registered trademark of Richtek Technology Corporation.
DS5710B-05
November 2019
www.richtek.com
3
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