®
RT5789A/B
6V, 6A, 1.5MHz ACOT
TM
Synchronous Step-Down Converter
in 2.5mm x 2mm Package
General Description
The RT5789A/B is a simple, easy-to-use, 6A synchronous
step-down DC-DC converter with an input supply voltage
range of 2.5V to 6V. The device build-in an accurate 0.6V
(±1.5%) reference voltage and can operate in 100% duty
cycle as a very low dropout voltage regulator. the
RT5789A/B integrates low R
DS(ON)
power MOSFETs to
achieve high efficiency and is available in TSOT-23-8 (FC)
package and UDFN-8L 2.5x2(FC) package.
The RT5789A/B 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 RT5789A/B is
designed to operate at 1.5MHz fixed frequency. While
the RT5789A automatically enters power saving mode
(PSM) operation at light load to maintain high efficiency.
RT5789B operates in Forced PWM over the loading range,
that helps meet tight voltage regulation accuracy
requirements.
The RT5789A/B senses both FETs current for a robust
over-current protection. It prevents the device from the
catastrophic damage in output short circuit, over current
or inductor saturation. The individual enable control input
and power good indicator provides flexible system power
sequence control a built-in 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.
Features
6A Converter With Built-In 18mΩ/16mΩ Low R
DS(ON)
Ω
Ω
Power FETs
Input Supply Voltage Range : 2.5V to 6V
Output Voltage Range : 0.6V to 6V
Operates Up to 100% Duty Cycle
Advanced Constant On-Time (ACOT
TM
) Control
Ultrafast Transient Response
�½
No Needs For External Compensations
�½
�½
Optimized for Low-ESR Ceramic Output Capacitors
0.6V
±
1.5% High-Accuracy Feedback Reference
Voltage
35μA Operation Quiescent Current (RT5789A)
μ
Robust Over-Current Protection for Both FETs
Optional for Operation Modes :
�½
Power Saving Mode (PSM) (RT5789A)
�½
Forced PWM Mode (RT5789B)
Fixed Switching Frequency : 1.5MHz
Monotonic Start-Up for Pre-Biased Output
Individual Enable Control Input
Power Good Indicator
Built-In Internally Fixed Soft-Start (Typ. 1.5ms)
100% Duty Cycle Mode
Internal Output Discharge
Input Under-Voltage Lockout (UVLO)
Output Under-Voltage Protection (UVP) with Hiccup
Mode
Over-Temperature Protection
Available in TSOT-23-8 (FC) Package and UDFN-8L
2.5x2 (FC) Package
Simplified Application Circuit
V
IN
R
PGOOD
PGOOD
Enable
C
IN
RT5789A/B
PGOOD
EN
VOUT
PGND
AGND
FB
R2
R1
C
OUT
VIN
LX
L
V
OUT
Copyright
©
2018 Richtek Technology Corporation. All rights reserved.
is a registered trademark of Richtek Technology Corporation.
DS5789A/B-02 March 2018
www.richtek.com
1
RICHTEK [ RICHTEK TECHNOLOGY CORPORATION ]
