RT7285/A
Functional Pin Description
Pin No.
Pin Name
BOOT
GND
Pin Function
Bootstrap Supply for High-Side Gate Driver. Connect a 0.1μF ceramic capacitor
1
2
3
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 VFB to 0.6V
FB
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.
4
EN
Power Input. The input voltage range is from 4.3V to 18V. Must bypass with a
suitable large ceramic capacitor at this pin.
5
6
VIN
SW
Switch Node. Connect to external L-C filter.
Function Block Diagram
BOOT VIN
V
IN
Reg
PVCC
VIBIAS
Min off
Control
V
REF
PVCC
UGATE
LGATE
OC
SW
Driver
UV & OV
GND
PVCC
Ripple
Gen.
GND SW
SW
V
IN
+
-
EN
EN
On-Time
SW
-
Comparator
FB
Operation
The RT7285/A is a synchronous step-down converter with
advanced constant on-time control mode. Using theACOT
control mode can reduce the output capacitance and fast
transient response. It can minimize the component size
without additional external compensation network.
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.
Current Protection
Thermal Shutdown
The inductor current is monitored via the internal switches
cycle-by-cycle. Once the output voltage drops under UV
threshold, the RT7285/A will enter hiccup mode.
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.
Copyright 2018 Richtek Technology Corporation. All rights reserved.
©
is a registered trademark of Richtek Technology Corporation.
www.richtek.com
2
DS7285/A-03 March 2018
RICHTEK [ RICHTEK TECHNOLOGY CORPORATION ]
