RT7285B
Functional Pin Description
Pin No.
1
2
3
4
5
6
Pin Name
BOOT
GND
FB
EN
VIN
SW
Pin Function
Bootstrap Supply for High-Side Gate Driver. Connect a 0.1μF ceramic capacitor
between the BOOT and SW pins.
Power Ground.
Feedback Voltage Input. The pin is used to set the output voltage of the converter
via a resistive divider. The converter regulates V
FB
to 0.6V
Enable Control Input. Connect EN to a logic-high voltage to enable the IC or to a
logic-low voltage to disable. Do not leave this high impedance input unconnected.
Power Input. The input voltage range is from 4.3V to 18V. Must bypass with a
suitable large ceramic capacitor at this pin.
Switch Node. Connect to external L-C filter.
Function Block Diagram
BOOT
V
IN
Reg
VIBIAS
PVCC
V
REF
Min off
PVCC
UGATE
Control
UV & OV
PVCC
SW
Ripple
Gen.
+
-
-
Comparator
EN
GND SW
V
IN
On-Time
SW
Driver
LGATE
GND
SW
VIN
OC
FB
EN
Operation
The RT7285B is a synchronous step-down converter with
advanced constant on-time control mode. Using the ACOT
control mode can reduce the output capacitance and fast
transient response. It can minimize the component size
without additional external compensation network.
Current Protection
The inductor current is monitored via the internal switches
cycle-by-cycle.
UVLO Protection
To protect the chip from operating at insufficient supply
voltage, the UVLO is needed. When the input voltage of
VIN is lower than the UVLO falling threshold voltage, the
device will be lockout.
Thermal Shutdown
When the junction temperature exceeds the OTP
threshold value, the IC will shut down the switching
operation. Once the junction temperature cools down and
is lower than the OTP lower threshold, the converter will
autocratically resume switching.
is a registered trademark of Richtek Technology Corporation.
Copyright
©
2018 Richtek Technology Corporation. All rights reserved.
www.richtek.com
2
DS7285B-03 March 2018
RICHTEK [ RICHTEK TECHNOLOGY CORPORATION ]
