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RT7294C
2.5A, 18V, 500kHz ACOT
TM
Synchronous Step-Down Converter
General Description
The RT7294C is a synchronous step-down converter with
Advanced Constant On-Time (ACOT
TM
) mode control. The
ACOT
TM
provides a very fast transient response with few
external components. The low impedance internal
MOSFET supports high efficiency operation with wide input
voltage range from 4.3V to 18V. The proprietary circuit of
the RT7294C enables to support all ceramic capacitors.
Features
4.3V to 18V Input Voltage Range
2.5A Output Current
Advanced Constant On-Time Control
Fast Transient Response
Support All Ceramic Capacitors
Up to 95% Efficiency
500kHz Switching Frequency
Adjustable Output Voltage from 0.6V to 8V
Cycle-by-Cycle Current Limit
Input Under-Voltage Lockout
Hiccup Mode Under-Voltage Protection
Thermal Shutdown
RoHS Compliant and Halogen Free
Ordering Information
RT7294C
Package Type
J6F : TSOT-23-6 (FC)
Lead Plating System
G : Green (Halogen Free and Pb Free)
Note :
Richtek products are :
½
Applications
RoHS compliant and compatible with the current require-
ments of IPC/JEDEC J-STD-020.
Suitable for use in SnPb or Pb-free soldering processes.
½
Pin Configurations
(TOP VIEW)
SW VIN EN
6
5
2
4
3
Industrial and Commercial Low Power Systems
Computer Peripherals
LCD Monitors and TVs
Green Electronics/Appliances
Point of Load Regulation for High-Performance DSPs,
FPGAs, and ASICs
Marking Information
04= : Product Code
04=DNN
DNN : Date Code
BOOT GND FB
TSOT-23-6 (FC)
Simplified Application Circuit
RT7294C
V
IN
VIN
BOOT
SW
Enable
EN
GND
FB
V
OUT
Copyright
©
2016 Richtek Technology Corporation. All rights reserved.
is a registered trademark of Richtek Technology Corporation.
DS7294C-06
October 2016
www.richtek.com
1
RT7294C
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 0.1F 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 RT7294C 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. Once the output voltage drops under UV
threshold, the RT7294C will enter hiccup mode.
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
©
2016 Richtek Technology Corporation. All rights reserved.
www.richtek.com
2
DS7294C-06
October 2016
RT7294C
Absolute Maximum Ratings
(Note 1)
−0.3V
to 20V
−0.3V
to (V
IN
+ 0.3V)
−5V
to 25V
(V
SW
−
0.3V) to (V
SW
+ 6V)
−0.3V
to 6V
VIN to GND -----------------------------------------------------------------------------------------------------
SW to GND ----------------------------------------------------------------------------------------------------
< 10ns -----------------------------------------------------------------------------------------------------------
BOOT to GND -------------------------------------------------------------------------------------------------
Other Pins ------------------------------------------------------------------------------------------------------
Power Dissipation, P
D
@ T
A
= 25°C
TSOT-23-6 (FC) ----------------------------------------------------------------------------------------------- 1.429W
Package Thermal Resistance (Note 2)
TSOT-23-6 (FC),
θ
JA
------------------------------------------------------------------------------------------ 70°C/W
TSOT-23-6 (FC),
θ
JC
----------------------------------------------------------------------------------------- 15°C/W
Lead Temperature (Soldering, 10 sec.) ------------------------------------------------------------------ 260°C
Junction Temperature ---------------------------------------------------------------------------------------- 150°C
Storage Temperature Range -------------------------------------------------------------------------------
−65°C
to 150°C
ESD Susceptibility (Note 3)
HBM (Human Body Model) --------------------------------------------------------------------------------- 2kV
(Note 4)
Recommended Operating Conditions
Supply Input Voltage, VIN ---------------------------------------------------------------------------------- 4.3V to 18V
Junction Temperature Range -------------------------------------------------------------------------------
−40°C
to 125°C
Ambient Temperature Range -------------------------------------------------------------------------------
−40°C
to 85°C
Electrical Characteristics
(V
IN
= 12V, T
A
= 25°C, unless otherwise specified)
Parameter
Shutdown Current
Quiescent Current
Switch-On
Resistance
Current Limit
Oscillator Frequency
Maximum Duty Cycle
Minimum On-Time
Feedback Threshold Voltage
EN Input Threshold
Logic-High
Logic-Low
High-Side
Low-Side
Symbol
I
SHDN
I
Q
R
DS(ON)_H
R
DS(ON)_L
I
LIM
f
SW
D
MAX
t
ON
V
FB
V
EN_H
V
EN_L
V
UVLO
Test Conditions
V
EN
= 0V
V
EN
= 2V, V
FB
= 1V
V
BOOTSW
= 4.8V
V
IN
= 5V
Valley Current
Min
--
--
--
--
2.7
--
--
--
Typ
--
0.5
150
90
3.4
500
90
60
600
1.29
1.03
3.9
340
800
160
Max
4
--
--
--
4
--
--
--
609
1.39
1.13
4.25
--
--
--
Unit
A
mA
m
A
kHz
%
ns
mV
V
V
mV
s
C
In CCM Mode
591
1.19
0.93
VIN Under-Voltage Lockout
Threshold
VIN Under-Voltage Lockout
Threshold Hysteresis
Soft-Start Time
Thermal Shutdown Threshold
VIN Rising
3.55
--
t
SS
T
SD
--
--
Copyright
©
2016 Richtek Technology Corporation. All rights reserved.
is a registered trademark of Richtek Technology Corporation.
DS7294C-06
October 2016
www.richtek.com
3
RT7294C
Parameter
Thermal Shutdown Hysteresis
V
OUT
Discharge Resistance
Output Under-Voltage Trip
Threshold
Output Under-Voltage Delay
Time
Symbol
T
SD
R
DISCHG
EN = 0V, V
OUT
= 0.5V
UVP detect
Hysteresis
Test Conditions
Min
--
--
70
--
--
Typ
20
50
75
10
250
Max
--
100
80
--
--
Unit
C
%
s
Note 1.
Stresses beyond those listed
“Absolute
Maximum Ratings” may cause permanent damage to the device. These are
stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in
the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions may
affect device reliability.
Note 2.
θ
JA
is measured at T
A
= 25°C on a high effective thermal conductivity four-layer test board per JEDEC 51-7.
θ
JC
is
measured at the exposed pad of the package.
Note 3.
Devices are ESD sensitive. Handling precaution is recommended.
Note 4.
The device is not guaranteed to function outside its operating conditions.
Copyright
©
2016 Richtek Technology Corporation. All rights reserved.
is a registered trademark of Richtek Technology Corporation.
www.richtek.com
4
DS7294C-06
October 2016
RT7294C
Typical Application Circuit
RT7294C
V
IN
4.3V to 18V
5
C
IN
10µF
VIN
BOOT
1
C
BOOT
100nF
L
2µH
C
FF
R1
10k
R2
10k
V
OUT
1.2V
C
OUT
22µF
SW 6
4 EN
FB 3
GND 2
Enable
Table 1. Suggested Component Values
V
OUT
(V)
5
3.3
2.5
1.2
R1 (k)
110
115
25.5
10
R2 (k)
15
25.5
8.06
10
L (H)
4.7
3.6
3.6
2
C
OUT
(F)
22
22
22
22
C
FF
(pF)
39
33
NC
NC
Copyright
©
2016 Richtek Technology Corporation. All rights reserved.
is a registered trademark of Richtek Technology Corporation.
DS7294C-06
October 2016
www.richtek.com
5
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