®
RT8299
3A, 24V, 500kHz Synchronous Step-Down Converter
General Description
The RT8299 is a high efficiency, monolithic synchronous
step-down DC/DC converter with internal power MOSFETs.
It achieves 3A of continuous output current over a wide
input supply range from 3V to 24V with excellent load and
line regulation. Current mode operation provides fast
transient response and eases loop stabilization. Cycle-
by-cycle current limit provides protection against shorted
outputs and soft-start eliminates input current surge during
start-up. Thermal shutdown provides reliable, fault tolerant
operation. The low current shutdown mode provides output
disconnection, enabling easy power management in battery
powered systems.
Features
3V to 24V Input Voltage Range
3A Output Current
Internal N-MOSFETs
Current Mode Control
Fixed Frequency Operation : 500kHz
Output Adjustable from 0.8V to 15V
Up to 95% Efficiency
Stable with Low ESR Ceramic Output Capacitors
Cycle-by-Cycle Over Current Protection
Input Under Voltage Lockout
Output Under Voltage Protection
Thermal Shutdown Protection
SOP-8 (Exposed Pad) and 10-Lead WDFN Packages
RoHS Compliant and Halogen Free
Ordering Information
RT8299
Package Type
SP : SOP-8 (Exposed Pad-Option 1)
QW: WDFN-10L 3x3 (W-Type)
Lead Plating System
G : Green (Halogen Free and Pb Free)
Z : ECO (Ecological Element with
Halogen Free and Pb free)
Note :
Richtek products are :
½
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
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.
Pin Configurations
(TOP VIEW)
BOOT
VIN
SW
GND
2
3
4
8
½
VCC
PGOOD
EN
FB
GND
9
7
6
5
SOP-8 (Exposed Pad)
FB
PGOOD
EN
VCC
BOOT
1
2
3
4
5
10
9
8
7
6
11
GND
SW
SW
VIN
VIN
WDFN-10L 3x3
Copyright
©
2014 Richtek Technology Corporation. All rights reserved.
is a registered trademark of Richtek Technology Corporation.
DS8299-04
October 2014
GND
www.richtek.com
1
RT8299
Marking Information
RT8299GSP
RT8299GSP : Product Number
RT8299GQW
56= : Product Number
YMDNN : Date Code
RT8299
GSPYMDNN
56=YM
DNN
YMDNN : Date Code
RT8299ZSP
RT8299ZSP : Product Number
RT8299ZQW
56 : Product Number
YMDNN : Date Code
RT8299
ZSPYMDNN
56 YM
DNN
YMDNN : Date Code
Typical Application Circuit
RT8299
V
IN
C
IN
10µF x 2
VIN
BOOT
C
BOOT
L1
EN
VCC
C
VCC
1µF
GND
SW
FB
PGODD
R
T
Power Good
R1
C
OUT
R2
V
OUT
Chip Enable
Table 1. Recommended Component Selection
V
OUT
(V)
1.2
2.5
3.3
5
R1 (k) R2 (k) R
T
(k)
15
30
50
25.5
16
27
12
5.1
5.1
40
30
18
L (H) C
OUT
(F)
2
22 x 2
3.6
4.7
6.8
22 x 2
22 x 2
22 x 2
Copyright
©
2014 Richtek Technology Corporation. All rights reserved.
is a registered trademark of Richtek Technology Corporation.
www.richtek.com
2
DS8299-04
October 2014
RT8299
Functional Pin Description
Pin No.
SOP-8
WDFN-10L 3x3
(Exposed Pad)
1
2
3
4, 9
(Exposed Pad)
5
5
6, 7
Pin Name
BOOT
VIN
Pin Function
Bootstrap for High Side Gate Driver. Connect a 0.1F or greater
ceramic capacitor from BOOT to SW pin.
Supply Input Voltage. Must bypass with a suitably large ceramic
capacitor.
Switch Node. Connect to external LC filter.
Ground. The exposed pad must be soldered to a large PCB and
connected to GND for maximum power dissipation.
Feedback Input. This pin is connected to the converter output. It
is used to regulate the output of the converter to a desired value
via an internal resistive voltage divider. For an adjustable output,
an external resistive voltage divider is connected to this pin.
Enable Input. A logic high enables the converter; a logic low
forces the RT8299 into shutdown mode, reducing the supply
current to less than 3A. Attach this pin to VIN with a 100k pull
up resistor for automatic startup.
Power Good Output. The output of this pin is open drain.
Bias Supply.
8, 9
SW
10, 11
GND
(Exposed Pad)
1
FB
6
7
8
3
2
4
EN
PGOOD
VCC
Function Block Diagram
VIN
Ramp
Generator
Current Sense
Amplifier
-
+
EN
5k
3V
Comparator
-
Regulator
+
2V
BOOT
Oscillator
500kHz
+
-
S
R
Q
Driver
Q
VCC
Reference
FB
+
-
Error
Amplifier
PWM
Comparator
SW
OC Limit
Clamp
GND
PGOOD
PGOOD
Generator
300k
30pF
1pF
Copyright
©
2014 Richtek Technology Corporation. All rights reserved.
is a registered trademark of Richtek Technology Corporation.
DS8299-04
October 2014
www.richtek.com
3
RT8299
Absolute Maximum Ratings
(Note 1)
−0.3
to 26V
−0.6
to (V
IN
+ 0.3V)
−5V
to 30V
(V
SW
−
0.3V) to (V
SW
+ 6V)
−0.3
to 6V
1.333W
Supply Input Voltage, V
IN
----------------------------------------------------------------------------------
Switching Voltage, SW ------------------------------------------------------------------------------------
< 20ns ----------------------------------------------------------------------------------------------------------
Boot Voltage, BOOT ----------------------------------------------------------------------------------------
All Other Pins ------------------------------------------------------------------------------------------------
Power Dissipation, P
D
@ T
A
= 25°C
SOP-8 (Exposed Pad) -------------------------------------------------------------------------------------
WDFN-10L 3x3 ----------------------------------------------------------------------------------------------- 1.429W
Package Thermal Resistance (Note 2)
SOP-8 (Exposed Pad),
θ
JA
-------------------------------------------------------------------------------- 75°C/W
SOP-8 (Exposed Pad),
θ
JC
------------------------------------------------------------------------------- 15°C/W
WDFN-10L 3x3,
θ
JA
----------------------------------------------------------------------------------------- 70°C/W
WDFN-10L 3x3,
θ
JC
----------------------------------------------------------------------------------------- 8.2°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
MM (Machine Model) ---------------------------------------------------------------------------------------- 200V
(Note 4)
Recommended Operating Conditions
Supply Voltage, V
IN
----------------------------------------------------------------------------------------- 3V to 24V
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
Supply Current
Upper Switch On Resistance
Lower Switch On Resistance
Switch Leakage
Current Limit
Oscillator Frequency
Short Circuit Frequency
Maximum Duty Cycle
Minimum On-Time
Feedback Voltage
Logic-High
EN Input
Threshold Voltage Logic-Low
Symbol
I
SHDN
Test Conditions
V
EN
= 0V
V
EN
= 3V, V
FB
= 1V
Min
--
--
--
--
Typ
--
1
100
100
0
5.5
500
150
93
100
800
--
--
Max
3
--
--
--
10
--
575
--
--
--
812
5.5
0.4
Unit
A
mA
m
m
A
A
kHz
kHz
%
ns
mV
V
V
EN
= 0V, V
SW
= 0V or 12V
I
LIM
f
OSC
D
MAX
t
ON
V
FB
V
IH
V
IL
4.5V
V
IN
24V
V
BOOT
V
SW
= 4.8V
V
FB
= 0.75V
V
FB
= 0V
V
FB
= 0.8V
--
--
425
--
--
--
788
2
--
Copyright
©
2014 Richtek Technology Corporation. All rights reserved.
is a registered trademark of Richtek Technology Corporation.
www.richtek.com
4
DS8299-04
October 2014
RT8299
Parameter
Under Voltage Lockout
Threshold
Under Voltage Lockout
Threshold Hysteresis
Power Good Threshold
VCC Regulator
VCC Load Regulation
Soft-Start Period
Thermal Shutdown
t
SS
T
SD
I
CC
= 5mA
Symbol
V
UVLO
V
UVLO
VOUT Rising, with Respect to V
FB
VOUT Falling, with Respect to V
FB
Test Conditions
V
IN
Rising
Min
--
--
--
--
--
4
--
--
Typ
2.8
300
90
70
5
--
2
150
Max
--
--
--
--
--
4
--
--
Unit
V
mV
%
V
%
ms
C
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
©
2014 Richtek Technology Corporation. All rights reserved.
is a registered trademark of Richtek Technology Corporation.
DS8299-04
October 2014
www.richtek.com
5
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