®
RT6220
6A, 23V, 500kHz, ACOT
TM
Synchronous Buck Converter
General Description
The RT6220 is a synchronous Buck converter with
Advanced Constant On-Time (ACOT
TM
) mode control,
which provides a very fast transient response with no
external compensators. The RT6220 operates from 4.5V
to 23V input voltage, provides complete protection
functions including Over Current Protection (OCP), Under
Voltage Protection (UVP) and Over Voltage Protection
(OVP). This IC also provides a 1.5ms internal soft-start
function and an open-drain power good indicator.
Features
4.5V to 23V Input Voltage Range
Adjustable from 0.6V to 5V Output Range
Up to 98% Duty for 2S Battery Application
500kHz Switching Frequency
ACOT
TM
Mode Performs Fast Transient Response
Integrated MOSFETs
½
31mΩ of High-Side MOSFET
Ω
½
20mΩ of Low-Side MOSFET
Ω
Supports MLCC Output Capacitors
Internal Soft-Start (1.5ms typ)
Built-in OVP/UVP/OCP
Power Good Indicator
Thermal Shutdown
Ordering Information
RT6220
Package Type
QUF : UQFN-16L 3x3 (FC) (U-Type)
Lead Plating System
G : Green (Halogen Free and Pb Free)
PWM Operation / VOUT Protection
A : with DEM/Latch
AH : with DEM/Hiccup
BL : without DEM/Latch
BH : without DEM/Hiccup
Note :
Richtek products are :
½
Applications
Laptop Computers
Tablet PCs
Networking Systems
Servers
Personal Video Recorders
Flat Panel Television and Monitors
Distributed Power Systems
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
Simplified Application Circuit
V
IN
C
IN
Chip Enable
C
EN
R
BYP
C
BYP
PGND
AGND
PGOOD
VCC
EN
VIN
RT6220
SW
VOUT
FB
R
PGOOD
V
CC
C
VCC
R1
R2
C
OUT
BOOT
R
B
C
B
L
V
OUT
V
SYS
VBYP
Copyright
©
2018 Richtek Technology Corporation. All rights reserved.
is a registered trademark of Richtek Technology Corporation.
DS6220-08 August 2018
www.richtek.com
1
RT6220
Marking Information
RT6220AGQUF
6J= : Product Code
RT6220BLGQUF
7M= : Product Code
YMDNN : Date Code
6J=YM
DNN
7M=YM
DNN
YMDNN : Date Code
RT6220AHGQUF
7P= : Product Code
RT6220BHGQUF
7N= : Product Code
YMDNN : Date Code
7P=YM
DNN
7N=YM
DNN
YMDNN : Date Code
Pin Configuration
(TOP VIEW)
AGND
EN
FB
VCC
BOOT
14 13 12 11 10
VIN
PGND
1
15
2
9
SW
16
SW
SW
SW
3
4
5
6
7
8
UQFN-16L 3x3 (FC)
Functional Pin Description
Pin No.
1
2
3
4
5, 6, 14
7
8, 9, 15, 16
10
11
12
13
Pin Name
VIN
PGND
VBYP
PGOOD
AGND
VOUT
SW
BOOT
VCC
FB
EN
Power ground.
Switch over input supply voltage for VCC. A low pass filter should be connected to
AGND, if VBYP is applied. If VBYP is not used, then connect to AGND. Do not connect
to VCC pin.
Open-Drain Power Good Indicator Output.
Analog ground.
Output voltage sense input. An internal discharging circuit is connected to this pin.
Switch node.
Bootstrap supply for high-side gate driver. A capacitor is needed to drive the power
switch's gate above the supply voltage. It is connected between the SW and BOOT
pins to form a floating supply across the power switch driver.
5V linear regulator output for internal control circuit. Bypass V
CC
to AGND with a 2.2F
capacitor. V
CC
can only supply internal circuits. Do not connect to external loads.
Feedback voltage input.
Enable control input. Do not leave this pin floating. The slew rate of EN is
recommended to be slower than 4.8V/s.
is a registered trademark of Richtek Technology Corporation.
VBYP
PGOOD
AGND
AGND
VOUT
Pin Function
Power input connect to high-side MOSFET drain.
Copyright
©
2018 Richtek Technology Corporation. All rights reserved.
www.richtek.com
2
DS6220-08 August 2018
RT6220
Functional Block Diagram
VCC
VBYP
Soft-Start
POR &
Reference
V
CC
Switch-Over
On-Time
One shot
Min off Time
V
CC
V
IN
BOOT
FB
V
REF
V
FB
+
+
-
Gate
Control
Logic
SW
V
CC
EN
VOUT
125% x V
REF
-
+
PGND
SW
V
OC
+
-
OCP
PGOOD
OVP
-
+
Fault
Logic
POK
58% x V
REF
+
-
AGND
91.5% x V
REF
UVP
V
CC
V
CC
Regulator
VIN
Operation
Overall
The RT6220 is a synchronous step-down converter with
advanced constant on-time control mode. Using the
ACOT
TM
control mode can reduce the output capacitance
and provide fast transient response. It can minimize the
component size without additional external compensation
network.
Internal VCC Regulator
The regulator provides 5V power to supply the internal
control circuit. Connecting a 2.2μF ceramic capacitor for
decoupling and stability is required.
Soft-Start
In order to prevent the converter output voltage from
overshooting during the startup period, the soft-start
function is necessary. The soft-start time is internal setting
and the duration is around 1.5ms.
VCC Switch-Over
The internal regulator output will switch over to VBYP if
VBYP level is higher than 4.6V.
Power Off
There is an internal discharging circuit to discharge the
residual charge of output capacitor when converter is power
off.
OCP
The inductor valley current is monitored cycle-by-cycle
via the internal swiches, preventing an on-time until the
current drops below the current limit.
Power Good
After soft-start is finished, the power good output goes
high. The PGOOD pin is an open-drain output.
Copyright
©
2018 Richtek Technology Corporation. All rights reserved.
is a registered trademark of Richtek Technology Corporation.
DS6220-08 August 2018
www.richtek.com
3
RT6220
Absolute Maximum Ratings
(Note 1)
−0.3V
to 27V
−0.3V
to 27.3V
−5V
to 28V
−0.6V
to 33.3V
−5V
to 34V
VIN to PGND --------------------------------------------------------------------------------------------------
SW to PGND
DC ----------------------------------------------------------------------------------------------------------------
AC (<30ns) -----------------------------------------------------------------------------------------------------
BOOT to PGND
DC ----------------------------------------------------------------------------------------------------------------
AC (<30ns) -----------------------------------------------------------------------------------------------------
BOOT to SW --------------------------------------------------------------------------------------------------
−0.3V
to 6V
EN, FB to AGND ---------------------------------------------------------------------------------------------
−0.3V
to 27V
VBYP to AGND -----------------------------------------------------------------------------------------------
−0.3V
to 5.3V
VCC, PGOOD, VOUT to AGND --------------------------------------------------------------------------
−0.3V
to 6V
PGND to AGND -----------------------------------------------------------------------------------------------
−0.3V
to 0.3V
Power Dissipation, P
D
@ T
A
= 25°C
UQFN-16L 3x3 (FC) ------------------------------------------------------------------------------------------ 1.4W
Package Thermal Resistance (Note 2)
UQFN-16L 3x3 (FC),
θ
JA
------------------------------------------------------------------------------------ 70°C/W
UQFN-16L 3x3 (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 ---------------------------------------------------------------------------------- 4.5V to 23V
Junction Temperature Range -------------------------------------------------------------------------------
−40°C
to 125°C
Ambient Temperature Range -------------------------------------------------------------------------------
−40°C
to 85°C
Electrical Characteristics
Parameter
Supply Current
Shutdown Current
Quiescent Current
BOOT to SW Leakage Current
BOOT to SW Leakage
Current
Switch On-Resistance
Switch On-Resistance
High Side MOSFET
Leakage Current
Symbol
(V
IN
= 12V, T
A
= 25°C, unless otherwise specified)
Test Conditions
V
EN
= 0V
V
EN
= 2V,
no switching
Min
--
--
--
Typ
2.5
100
110
Max
5
130
150
Unit
A
A
(RT6220A/AH)
(RT6220BL/BH)
V
BYP
= 5V, V
EN
= 0V
--
--
2.5
A
R
DS(ON)_H
V
BOOT
– V
SW
= 5V
R
DS(ON)_L
I
Leakage_H
V
IN
= 12V, V
EN
= 0V
--
--
--
31
20
--
--
--
1
m
A
Copyright
©
2018 Richtek Technology Corporation. All rights reserved.
is a registered trademark of Richtek Technology Corporation.
www.richtek.com
4
DS6220-08 August 2018
RT6220
Parameter
Supply Current
Shutdown Current
Quiescent Current
BOOT to SW Leakage Current
BOOT to SW Leakage
Current
Switch On-Resistance
Switch On-Resistance
High Side MOSFET
Leakage Current
Current Limit
Current Limit
Switching Frequency
Minimum Off-Time
Protections
OVP Trip Threshold
OVP Propagation Delay
UVP Trip Threshold
UVP Propagation Delay
Reference and Soft-Start
Feedback Reference
Voltage
Soft-Start Time
Enable and UVLO
EN Input High Voltage
EN Hysteresis
EN Input Current
VCC UVLO Rising
VCC UVLO Hysteresis
VCC Regulator
VCC Regulator
VCC Switch Over
Threshold to VBYP
VCC Switch Over
Hysteresis
Switch Over
On-Resistance
Copyright
©
2018 Richtek Technology Corporation. All rights reserved.
Symbol
Test Conditions
V
EN
= 0V
V
EN
= 2V,
no switching
Min
--
--
--
Typ
2.5
100
110
Max
5
130
150
Unit
A
A
(RT6220A/AH)
(RT6220BL/BH)
V
BYP
= 5V, V
EN
= 0V
--
--
--
--
--
31
20
--
2.5
--
--
1
A
R
DS(ON)_H
V
BOOT
– V
SW
= 5V
R
DS(ON)_L
I
Leakage_H
V
IN
= 12V, V
EN
= 0V
m
A
I
OC
f
SW
t
OFF_MIN
V
OVP
T
OVPDLY
V
UVP
T
UVPDLY
Valley current of low-side switch
7.6
450
--
--
500
200
125
5
58
5
11.4
550
--
130
--
63
--
A
kHz
ns
%
s
%
s
Switching Frequency and Minimum Off Timer
With respect to output voltage
With respect to output voltage
120
--
53
--
V
REF
T
SS
V
ENH
V
ENHYS
I
EN
V
CCUVLO
V
CCHYS
V
VCC
V
BYP
rising edge
V
EN
= 2V
V
EN
= 0V
From EN high to PGOOD high
0.594
1
1.25
50
--
--
3.8
75
4.805
4.4
150
--
0.600
1.5
1.35
200
1
0
4.2
400
5
4.6
200
3
0.606
2
1.45
250
--
--
4.45
650
5.295
4.8
400
5
V
ms
V
mV
A
V
mV
V
V
mV
is a registered trademark of Richtek Technology Corporation.
DS6220-08 August 2018
www.richtek.com
5
