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RT8292B
2A, 23V, 1.2MHz Synchronous Step-Down Converter
General Description
The RT8292B is a high efficiency, monolithic synchronous
step-down DC/DC converter that can deliver up to 2A
output current from a 4.5V to 23V input supply. The
RT8292B's current mode architecture and external
compensation allow the transient response to be
optimized over a wide range of loads and output
capacitors. Cycle-by-cycle current limit provides
protection against shorted outputs and soft-start
eliminates input current surge during start-up. The
RT8292B also provides under voltage protection and
thermal shutdown protection. The low current (<3μA)
shutdown mode provides output disconnction, enabling
easy power management in battery-powered systems.
The RT8292B is available in a SOP-8 (Exposed Pad)
package.
Features
±
1.5% High Accuracy Feedback Voltage
4.5V to 23V Input Voltage Range
2A Output Current
Integrated N-MOSFET Switches
Current Mode Control
Fixed Frequency Operation : 1.2MHz
Adjustable Output from 0.8V to 15V
Up to 95% Efficiency
Programmable Soft-Start
Stable with Low ESR Ceramic Output Capacitors
Cycle-by-Cycle Over Current Protection
Input Under Voltage Lockout
Output Under Voltage Protection
Thermal Shutdown Protection
RoHS Compliant and Halogen Free
Ordering Information
RT8292B
Package Type
SP : SOP-8 (Exposed Pad-Option 1)
Lead Plating System
G : Green (Halogen Free and Pb Free)
Z : ECO (Ecological Element with
Halogen Free and Pb free)
H : UVP Hiccup
L : UVP Latch-Off
Note :
Richtek products are :
½
Applications
Wireless AP/Router
Set-Top-Box
Industrial and Commercial Low Power Systems
LCD Monitors and TVs
Green Electronics/Appliances
Point of Load Regulation of High-Performance DSPs
Pin Configurations
(TOP VIEW)
BOOT
VIN
SW
GND
2
3
4
8
SS
EN
COMP
FB
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.
GND
9
7
6
5
½
SOP-8 (Exposed Pad)
Marking Information
RT8292BxGSP
RT8292BxGSP : Product Number
RT8292BxZSP
RT8292BxZSP : Product Number
x : H or L
YMDNN : Date Code
RT8292Bx
GSPYMDNN
RT8292Bx
ZSPYMDNN
x : H or L
YMDNN : Date Code
Copyright
©
2016 Richtek Technology Corporation. All rights reserved.
is a registered trademark of Richtek Technology Corporation.
DS8292B-04
October 2016
www.richtek.com
1
RT8292B
Typical Application Circuit
V
IN
4.5V to 23V
2
C
IN
10µF
R
EN
100k
VIN
BOOT
RT8292B
SW 3
7 EN
8 SS
GND
1
C
BOOT
L
100nF 3.6µH
R1
75k
FB 5
COMP
6
C
C
R
C
0.82nF 32k
R2
24k
V
OUT
3.3V/2A
C
OUT
22µF x 2
C
SS
0.1µF
4, 9 (Exposed Pad)
C
P
Open
Table 1. Recommended Component Selection
V
OUT
(V) R1 (k) R2 (k) R
C
(k) C
C
(nF) L (H)
8
27
3
75
0.82
10
5
62
11.8
47
0.82
6.8
3.3
75
24
32
0.82
3.6
2.5
25.5
12
25.5
0.82
3.6
1.5
10.5
12
15
0.82
2
1.2
12
24
12
0.82
2
1
3
12
10
0.82
2
C
OUT
(F)
22 x 2
22 x 2
22 x 2
22 x 2
22 x 2
22 x 2
22 x 2
Functional Pin Description
Pin No.
1
2
3
4,
9 (Exposed Pad)
5
Pin Name
BOOT
VIN
SW
GND
Pin Function
Bootstrap for High Side Gate Driver. Connect a 0.1F or greater ceramic
capacitor from BOOT to SW pins.
Input Supply Voltage 4.5V to 23V. Must bypass with a suitably large ceramic
capacitor.
Switch Node. Connect this pin to an external L-C 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 set
the output of the converter to regulate to the desired value via an internal
resistive voltage divider. For an adjustable output, an external resistive
voltage divider is connected to this pin.
Compensation Node. COMP is used to compensate the regulation control
loop. Connect a series RC network from COMP to GND. In some cases, an
additional capacitor from COMP to GND is required.
Chip Enable (Active High). A logic low forces the RT8292B 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.
Soft-Start Control Input. SS controls the soft-start period. Connect a capacitor
from SS to GND to set the soft-start period. A 0.1F capacitor sets the
soft-start period to 13.5ms.
FB
6
COMP
7
EN
8
SS
Copyright
©
2016 Richtek Technology Corporation. All rights reserved.
is a registered trademark of Richtek Technology Corporation.
www.richtek.com
2
DS8292B-03 March 2011
RT8292B
Function Block Diagram
VIN
Internal
Regulator
Shutdown
Comparator V
A
V
CC
1.2V
+
-
Lockout
Comparator
-
+
2.7V
V
CC
6µA
SS
0.8V
+
+EA
-
Oscillator
Foldback
Control
0.4V
+
Current Sense
Amplifier
Slope Comp
+
-
V
A
BOOT
S
+
R
-
Current
Comparator
Q
Q
130m
5k
EN
3V
-
UV
Comparator
SW
130m
GND
FB
COMP
Copyright
©
2016 Richtek Technology Corporation. All rights reserved.
is a registered trademark of Richtek Technology Corporation.
DS8292B-03 March 2011
www.richtek.com
3
RT8292B
Absolute Maximum Ratings
(Note 1)
−0.3V
to 25V
−0.3V
to (V
IN
+ 0.3V)
−0.3V
to 6V
−0.3V
to 6V
Supply Voltage, V
IN
-------------------------------------------------------------------------------------------------
Input Voltage, SW ---------------------------------------------------------------------------------------------------
V
BOOT
- V
SW
-----------------------------------------------------------------------------------------------------------
Other Pin Voltages -------------------------------------------------------------------------------------------------
Power Dissipation, P
D
@ T
A
= 25°C
SOP-8 (Exposed Pad) --------------------------------------------------------------------------------------------- 1.333W
Package Thermal Resistance (Note 2)
SOP-8 (Exposed Pad),
θ
JA
---------------------------------------------------------------------------------------- 75°C/W
SOP-8
(Εxposed
Pad),
θ
JC
---------------------------------------------------------------------------------------
Lead Temperature (Soldering, 10 sec.) -------------------------------------------------------------------------
Junction Temperature -----------------------------------------------------------------------------------------------
Storage Temperature Range --------------------------------------------------------------------------------------
15°C/W
260°C
150°C
−65°C
to 150°C
ESD Susceptibility (Note 3)
HBM (Human Body Mode) ---------------------------------------------------------------------------------------- 2kV
MM (Machine Mode) ------------------------------------------------------------------------------------------------ 200V
(Note 4)
Recommended Operating Conditions
Supply Voltage, V
IN
------------------------------------------------------------------------------------------------- 4.5V to 23V
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 Supply Current
Supply Current
Feedback Voltage
Error Amplifier
Transconductance
High Side Switch
On-Resistance
Low Side Switch
On-Resistance
High Side Switch Leakage
Current
Upper Switch Current Limit
Lower Switch Current Limit
COMP to Current Sense
Transconductance
Oscillation Frequency
Short Circuit Oscillation
Frequency
Maximum Duty Cycle
Minimum On Time
Symbol
V
EN
= 0V
Test Conditions
Min
--
--
0.788
--
--
--
Typ
0.5
0.8
0.8
940
130
130
0
4.3
1.3
4
1.2
270
75
100
Max
3
1.2
0.812
--
--
--
10
--
--
--
1.4
--
--
--
Unit
A
mA
V
A/V
m
m
A
A
A
A/V
MHz
kHz
%
ns
V
EN
= 3V, V
FB
= 0.9V
V
FB
G
EA
R
DS(ON)1
R
DS(ON)2
V
EN
= 0V, V
SW
= 0V
Min. Duty Cycle, V
BOOT
V
SW
= 4.8V
From Drain to Source
G
CS
f
OSC1
f
OSC2
D
MAX
t
ON
V
FB
= 0V
V
FB
= 0.7V
4.5V
V
IN
23V
I
C
= ±10A
--
--
--
--
1
--
--
--
Copyright
©
2016 Richtek Technology Corporation. All rights reserved.
is a registered trademark of Richtek Technology Corporation.
www.richtek.com
4
DS8292B-03 March 2011
RT8292B
Parameter
EN Input Threshold
Voltage
Logic-High
Logic-Low
Symbol
V
IH
V
IL
V
UVLO
V
UVLO
I
SS
t
SS
T
SD
V
SS
= 0V
C
SS
= 0.1F
V
IN
Rising
Test Conditions
Min
2.7
--
3.8
--
--
--
--
Typ
--
--
4.2
320
6
13.5
150
Max
5.5
0.4
4.5
--
--
--
--
Unit
V
V
mV
A
ms
C
Input Under Voltage Lockout Threshold
Input Under Voltage Lockout Hysteresis
Soft-Start Current
Soft-Start Period
Thermal Shutdown
Note 1.
Stresses listed as the above
"Absolute
Maximum Ratings" may cause permanent damage to the device. These are for
stress ratings. 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 for extended
periods may remain possibility to affect device reliability.
Note 2.
θ
JA
is measured in natural convection at T
A
= 25°C on a high effective thermal conductivity four-layer test board of
JEDEC 51-7 thermal measurement standard. The measurement case position of
θ
JC
is on 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.
DS8292B-03 March 2011
www.richtek.com
5
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