RT5712A
Functional Pin Description
Pin No.
1
2
3
4
Pin Name
NC
EN
VIN
LX
No internal connection.
Enable control input.
Supply voltage input. The RT5712A operates from a 2.7V to 6V input.
Switch node.
Ground. The exposed pad must be soldered to a large PCB and connected to
GND for maximum thermal dissipation.
Feedback.
Pin Function
5, 7 (Exposed Pad) GND
6
FB
Functional Block Diagram
EN
VIN
UVLO
OTP
Shut Down
Control
Error
Amplifier
R
C
C
COMP
Comparator
+
-
Ton
LX
VIN
FB
V
REF
-
+
Logic
Control
Current
Limit
Detector
Current
Sense
Driver
LX
GND
LX
Operation
The RT5712A is a synchronous low voltage step-down
converter that can support the input voltage range from
2.7V to 6V and the output current can be up to 2A. The
RT5712A 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 and Latch-off 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.
Copyright © 2019 Richtek Technology Corporation. All rights reserved.
is a registered trademark of Richtek Technology Corporation.
www.richtek.com
2
DS5712A-04
June 2019
RICHTEK [ RICHTEK TECHNOLOGY CORPORATION ]
