RT7255
18V, 1.5A, 500kHz ACOT
TM
Step-down Converter in 8 Pin TSOT-23
General Description
The RT7255 is a simple, easy-to-use, 1.5A
synchronous step-down DC-DC converter with an input
supply voltage range of 4.3V to 18V. The device
build-in an accurate 0.6V reference voltage and
integrates low R
DS(ON)
power MOSFETs to achieve
high efficiency in a TSOT-23-8 package.
The RT7255 adopts Advanced Constant On-Time
(ACOT
TM
) control architecture to provide an ultrafast
transient response with few external components and
to operate in nearly constant switching frequency over
the line, load, and output voltage range. The RT7255A
operates in automatic PSM that maintains high
efficiency during light load operation. The RT7255C
operates in Forced PWM that helps meet tight voltage
regulation accuracy requirements.
The RT7255 senses low-side FETs current for a robust
over-current protection. It features cycle-by-cycle
current limit protection and prevent the device from the
catastrophic damage in output short circuit, over
current or inductor saturation. An externally adjustable
soft-start function prevents inrush current during
start-up. The device also includes input under-voltage
lockout, output under-voltage protection, and
over-temperature protection (thermal shutdown) to
provide safe and smooth operation in all operating
conditions. The RT7255 is offered in a TSOT-23-8
package.
Features
1.5A Converter With Built-In 230m/130m Low
R
DS(ON)
Power FETs
Input Supply Voltage Range : 4.3V to 18V
Output Voltage Range : 0.6 to 8V
Advanced Constant On-Time (ACOT
TM
) Control
Ultrafast Transient Response
No Needs For External Compensations
Optimized
for Low-ESR Ceramic Output
Capacitors
0.6V
1.5%
High-Accuracy Feedback Reference
Voltage
Low Quiescent Current (500A typ.)
Optional for Operation Modes :
Power Saving Mode (PSM) at Light Load
(RT7255A)
Forced PWM Mode (RT7255C)
Light-load V
OUT
Ripple Reduction Technology in
PSM
Fixed Switching Frequency : 500kHz
Externally Adjustable Soft-Start
Monotonic Start-Up for Pre-Biased Output
Input Under-Voltage Lockout (UVLO)
Output Under-Voltage Protection (UVP) with
Hiccup Mode
Power Good Indication
Enable Control
Available In TSOT-23-8 Package
Simplified Application Circuit
RT7255
V
IN
C
IN
BOOT
R
PG
5V
Enable
C
SS
PGOOD
EN
SS
FB
R2
GND
VIN
SW
C
BOOT
C
FF
R1
C
OUT
L
V
OUT
Copyright © 2017 Richtek Technology Corporation. All rights reserved.
is a registered trademark of Richtek Technology Corporation.
DS7255-01
November 2017
www.richtek.com
1
RICHTEK [ RICHTEK TECHNOLOGY CORPORATION ]
