®
RT6206A
5.5A, 18V, 650kHz, ACOT
TM
Synchronous Step-Down Converter
General Description
The RT6206A is a synchronous step-down DC/DC converter
with Advanced Constant On-Time (ACOT
TM
) mode control.
It achieves high power density to deliver up to 5.5A output
current from a 4.5V to 18V input supply. The proprietary
ACOT
TM
mode offers an optimal transient response over a
wide range of loads and all kinds of ceramic capacitors,
which allows the device to adopt very low ESR output
capacitor for ensuring performance stabilization. In
addition, RT6206A keeps an excellent constant switching
frequency under line and load variation and the integrated
synchronous power switches with the ACOT
TM
mode
operation provides high efficiency in whole output current
load range. Cycle-by-cycle current limit provides an
accurate protection by a valley detection of low side
MOSFET and external soft-start setting eliminates input
current surge during startup. Protection functions include
thermal shutdown for RT6206A.
The RT6206A are available in the TSSOP-14 (Exposed
pad), SOP-8 (Exposed Pad) and WDFN-10L 3x3
packages.
Features
ACOT
TM
Mode Enables Fast Transient Response
4.5V to 18V Input Voltage Range
5.5A Output Current
35mΩ Internal Low Side N-MOSFET
Ω
Advanced Constant On-Time Control
Support All Ceramic Capacitors
Up to 95% Efficiency
Adjustable Output Voltage from 0.765V to 7V
Adjustable Soft-Start
Cycle-by-Cycle Current Limit
Input Under-Voltage Lockout
Thermal Shutdown
RoHS Compliant and Halogen Free
Applications
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
Simplified Application Circuit
RT6206A
V
IN
VIN
VINR*
Enable
Power Good
EN
PGOOD*
VREG5
GND*
SW
BOOT
FB
SS
V
OUT
PGND
* : VINR, GND pin for TSSOP-14 (Exposed Pad) only.
* : PGOOD pin for TSSOP-14 (Exposed Pad) and WDFN-10L 3x3 only.
Copyright
©
2015 Richtek Technology Corporation. All rights reserved.
is a registered trademark of Richtek Technology Corporation.
DS6206A-03
September 2015
www.richtek.com
1
RT6206A
Ordering Information
RT6206A
Package Type
CP : TSSOP-14 (Exposed Pad)
Lead Plating System
G : Green (Halogen Free and Pb Free)
UVP Trim Operation
L : Latch-Off
PWM/PSM Mode
A : Force-PWM
EN
FB
VREG5
SS
2
3
4
Pin Configurations
(TOP VIEW)
8
VIN
BOOT
SW
PGND
PGND
9
7
6
5
SOP-8 (Exposed Pad)
EN
FB
VREG5
SS
PGOOD
1
2
3
4
5
PGND
10
9
8
7
6
RT6206A
Package Type
SP : SOP-8 (Exposed Pad-Option 2)
QW : WDFN-10L 3x3 (W-Type)
Lead Plating System
G : Green (Halogen Free and Pb Free)
UVP Trim Operation
H : Hiccup
PWM/PSM Mode
A : Force-PWM
Note :
Richtek products are :
½
11
VIN
VIN
BOOT
SW
SW
WDFN-10L 3x3
VOUT
FB
VREG5
SS
GND
PGOOD
EN
2
14
13
PGND
3
4
5
6
7
12
11
10
15
9
8
VINR
VIN
BOOT
SW
SW
PGND
PGND
TSSOP-14 (Exposed Pad)
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.
Marking Information
RT6206AHGSP
RT6206AHGSP : Product Number
½
RT6206AH
GSPYMDNN
YMDNN : Date Code
RT6206AHGQW
5K= : Product Code
5K=YM
DNN
YMDNN : Date Code
RT6206ALGCP
RT6206ALGCP : Product Number
YMDNN : Date Code
RT6206AL
GCPYMDNN
Copyright
©
2015 Richtek Technology Corporation. All rights reserved.
is a registered trademark of Richtek Technology Corporation.
www.richtek.com
2
DS6206A-03
September 2015
RT6206A
Functional Pin Description
Pin No.
TSSOP-14
SOP-8
WDFN-10L 3x3
(Exposed Pad) (Exposed Pad)
1
--
--
Pin
Name
Pin Function
VOUT
Optional Output Voltage Discharge Connection. This
open drain output connects to ground when the
device is disabled. If output voltage discharge is
desired, connect VOUT to the output voltage.
Feedback Voltage Input. It is used to regulate the
output of the converter to a set value via an external
resistive voltage divider. The feedback threshold
voltage is 0.765V typically.
Internal Regulator Output. Connect a 1F capacitor
to GND to stabilize output voltage.
Soft-Start Time Setting. Connect an external capacitor
between this pin and GND to set the soft- start time.
Analog Ground.
Open Drain Power Good Indicator Output.
Enable Control Input. A logic-high enables the
converter; a logic-low forces the IC into shutdown
mode reducing the supply current to less than 10A.
Power Ground. The exposed pad must be soldered
to a large PCB and connected to PGND for
maximum power dissipation.
Switch Node. Connect this pin to an external L-C
filter.
Bootstrap Supply for High Side Gate Driver. Connect
a 0.1F capacitor between the BOOT and SW pin.
Power Input. The input voltage range is from 4.5V to
18V. Must bypass with a suitably large ( 10F x 2)
ceramic capacitor.
Internal Linear Regulator Supply Input. For the
TSSOP-14 (Exposed Pad) package, VINR supplies
power for the internal linear regulator that powers
the IC. Connect VIN to the input voltage and bypass
to ground with a 0.1F ceramic capacitor.
2
2
2
FB
3
4
5
6
7
3
4
--
--
1
3
4
--
5
1
VREG5
SS
GND
PGOOD
EN
8, 9, 15
5, 9
11
PGND
(Exposed Pad) (Exposed Pad) (Exposed Pad)
10, 11
12
13
6
7
8
6, 7
8
9, 10
SW
BOOT
VIN
14
--
--
VINR
Copyright
©
2015 Richtek Technology Corporation. All rights reserved.
is a registered trademark of Richtek Technology Corporation.
DS6206A-03
September 2015
www.richtek.com
3
RT6206A
Function Block Diagram
VINR*
VREG5
BOOT
EN
POR &
Reg
VBIAS
OC
UV & OV
V
REG5
6µA
V
REF
Min.
Off-Time
VREG5
VIN
SW
Control
Driver
SW
Ripple
Gen.
FB
+
+
-
Comparator
ZC
PGND
GND*
SS
V
IN
FB
On-Time
Comparator
FB
0.9 x V
REF
-
+
PGOOD*
* : VINR, GND pin for TSSOP-14 (Exposed Pad) only.
* : PGOOD pin for TSSOP-14 (Exposed Pad) and WDFN-10L 3x3 only.
Operation
The RT6206A 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 Regulator
The regulator provides 5.1V power to supply the internal
control circuit. Connecting a 1μF 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 adjustable
and can be set by an external capacitor.
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 latch-off.
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
automatically resume switching
Power Good (for TSSOP-14 (Exposed Pad) and
WDFN-10L 3x3 only)
After soft-start is finished, the power good function will be
activated. When the FB is activated, the PGOOD will
become an open-drain output. If the FB is below, the
PGOOD pin will be pulled low.
Copyright
©
2015 Richtek Technology Corporation. All rights reserved.
is a registered trademark of Richtek Technology Corporation.
www.richtek.com
4
DS6206A-03
September 2015
RT6206A
Absolute Maximum Ratings
(Note 1)
−0.3V
to 20V
−0.3V
to (V
IN
+ 0.3V)
−5V
to 25V
−0.3V
to 6V
−0.3V
to 20V
−0.3V
to 6V
Supply Voltage, VIN, VINR ---------------------------------------------------------------------------------------
Switch Voltage, SW -----------------------------------------------------------------------------------------------
< 10ns ----------------------------------------------------------------------------------------------------------------
BOOT to SW --------------------------------------------------------------------------------------------------------
EN, VOUT ------------------------------------------------------------------------------------------------------------
Other Pins ------------------------------------------------------------------------------------------------------------
Power Dissipation, P
D
@ T
A
= 25°C
TSSOP-14 (Exposed Pad) --------------------------------------------------------------------------------------- 2.5W
SOP-8 (Exposed Pad) -------------------------------------------------------------------------------------------- 2.041W
WDFN-10L 3x3 ------------------------------------------------------------------------------------------------------ 1.667W
Package Thermal Resistance (Note 2)
TSSOP-14 (Exposed Pad),
θ
JA
--------------------------------------------------------------------------------- 40°C/W
SOP-8 (Exposed Pad),
θ
JA
--------------------------------------------------------------------------------------- 49°C/W
SOP-8 (Exposed Pad),
θ
JC
-------------------------------------------------------------------------------------- 15°C/W
WDFN-10L 3x3,
θ
JA
------------------------------------------------------------------------------------------------ 60°C/W
WDFN-10L 3x3,
θ
JC
------------------------------------------------------------------------------------------------ 7.5°C/W
Junction Temperature Range ------------------------------------------------------------------------------------- 150°C
Lead Temperature (Soldering, 10 sec.) ------------------------------------------------------------------------ 260°C
Storage Temperature Range -------------------------------------------------------------------------------------
−65°C
to 150°C
(Note 3)
Recommended Operating Conditions
Supply Voltage, VIN ----------------------------------------------------------------------------------------------- 4.5V 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
Supply Current
Shutdown Current
Quiescent Current
Logic Threshold
EN Input Voltage
V
FB
Voltage
Feedback Threshold Voltage
Feedback Input Current
V
REG5
Output
V
REG5
Output Voltage
Line Regulation
Logic-High
Logic-Low
Symbol
I
SHDN
I
Q
V
EN
= 0V
Test Conditions
Min
--
--
2
--
Typ
1
1
--
--
Max
10
1.3
18
0.4
Unit
A
mA
V
EN
= 5V, V
FB
= 0.8V
V
V
FB
I
FB
V
REG5
T
A
= 25C
T
A
=
40C
to 85C
V
FB
= 0.8V
6V
V
IN
18V, 0 < I
VREG5
5mA
6V
V
IN
18V, I
VREG5
= 5mA
0.757 0.765 0.773
0.755
--
4.8
--
--
0.01
5.1
--
0.775
0.1
5.4
20
V
A
V
mV
Copyright
©
2015 Richtek Technology Corporation. All rights reserved.
is a registered trademark of Richtek Technology Corporation.
DS6206A-03
September 2015
www.richtek.com
5
