Preliminary
RT9204/A
Dual Regulators - Standard Buck PWM DC-DC and
Linear Controller
General Description
The RT9204/A is a dual power controllers designed for
high performance graphics cards and computer
applications. The IC integrates a standard buck controller,
a linear regulator driver and protection functions into a
small 8-pin package.
The RT9204/A uses an internal compensated voltage
mode PWM control for simple application design. An
internal 0.8V reference allows the output voltage to be
precisely regulated to low voltage requirement. A fixed
600kHz oscillator reduce the component size for saving
board area.
The RT9204/A protects the converter and regulator by
monitoring the output under voltage.
Features
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Operate from 5V
0.8V Internal Reference
Voltage Mode PWM Control
Fast Transient Response
Fixed 600kHz Oscillator Frequency
Full 0 to 100% Duty Cycle
Internal Soft Start
Internal PWM Loop Compensation
RoHS Compliant and 100% Lead (Pb)-Free
Applications
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Ordering Information
RT9204/A
Package Type
S : SOP-8
Operating Temperature Range
P : Pb Free with Commercial Standard
G : Green (Halogen Free with Commer-
cial Standard)
UVP : Hiccup Mode
UVP : Latch Mode
Note :
RichTek Pb-free and Green products are :
}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.
}100%matte
tin (Sn) plating.
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Motherboard Power Regulation for Computers
Subsystems Power Supplies
Cable Modems, Set Top Box, and DSL Modems
DSP and Core Communications Processor Supplies
Memory Power Supplies
Personal Computer Peripherals
Industrial Power Supplies
5V-Input DC-DC Regulators
Low Voltage Distributed Power Supplies
Pin Configurations
(TOP VIEW)
GND
VCC
DRV
FBL
2
3
4
8
7
6
5
UGATE
BOOT
SD
FB
SOP-8
DS9204/A-08 March 2007
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1
RT9204/A
Typical Application Circuit
V
AUX
3.3V
Q1
2SD1802
V
OUT2
1.6V
R4
100
R5
100
C5
1uF
+
Preliminary
R1
10
1
2
3
4
GND
VCC
DRV
FBL
RT9204/A
UGATE
BOOT
SD
FB
8
7
6
5
C3
+
5V
BAT54A
0.1uF
V
OUT1
2.5V
R3
+
L1
5uH
C4
1000uF
MU
D1
SS34
C2
1uF
C1
470uF
C6
220uF
250
R2
120
C7
10nF
Figure1. RT9204/A powered from 5V only
5V
R1
0
V
AUX
3.3V
Q1
Suggest use Transistor
2SD5706
V
OUT2
1.6V
R4
100
R5
100
+
C7
1uF
1
2
3
4
8
7
R6
C5
1uF
GND
VCC
DRV
FBL
RT9204/A
UGATE
BOOT
SD
FB
10
12V
5V
+
6
5
V
OUT1
2.5V
R3
+
L1
5uH
C4
1000uF
MU
D1
SS34
C2
1uF
C1
470uF
C6
220uF
250
R2
120
C7
10nF
Figure2. RT9204/A powered from 12V
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2
DS9204/A-08 March 2007
Preliminary
MU
C
OUT
1000uF
GND
C
VCC
1uF
C
BOOT
VCC
BOOT
0.1uF
RT9203/A
GND Return
Diode
D
L
5uH
G
S
+
+
RT9204/A
C
IN1
1uF
C
IN2
470uF
Layout Placement
Layout Notes
1. Put C
1
& C
2
to be near the MU drain and ML source nodes.
2. Put RT9204/A to be near the C
OUT
3. Put C
BOOT
as close as to BOOT pin
4. Put C
VCC
as close as to VCC pin
Function Block Diagram
6.0V
Regulation
Power on
Reset
DRV
FBL
0.8
Reference
-
+
1V -
+
OVP
UVP
LDO
VCC
BOOT
+
-
0.8V
FB
+
35dB
-
Error
Amplifier
GND
DS9204/A-08 March 2007
+
Soft Start
-
0.5V +
UVP
+
+
PWM
-
Control
Logic
UGATE
SS
600kHz
Oscillator
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RT9204/A
Functional Pin Description
GND (Pin 1)
Preliminary
Signal and power ground for the IC. All voltage levels are
measured with respect to this pin.
VCC (Pin 2)
This is the main bias supply for the RT9204/A. This pin
also provides the gate bias charge for the lower MOSFETs
gate. The voltage at this pin monitored for power-on reset
(POR) purpose. This pin is also the internal 6.0V regulator
output powered from BOOT pin when BOOT pin is directly
powered from ATX 12V.
DRV (Pin 3)
This pin is linear regulator output driver. Connect to external
bypass NPN transistor base or NMOSFET gate terminal.
FBL (Pin 4)
This pin is connected to the linear regulator output divider.
This pin also connects to internal linear regulator error
amplifier inverting input and protection monitor.
FB (Pin 5)
This pin is connected to the PWM converter's output divider.
This pin also connects to internal PWM error amplifier
inverting input and protection monitor.
SD (Pin 6)
Active low design with a 40µA pull low current source.
Pull this pin to VCC to shutdown both PWM and linear
regulator.
BOOT (Pin 7)
This pin provides ground referenced bias voltage to the
upper MOSFET driver. A bootstrap circuit is used to create
a voltage suitable to drive a logic-level N-Channel
MOSFET when operating at a single 5V power supply.
This pin also could be powered from ATX 12V, in this
situation, an internal 6.0V regulator will supply to VCC
pin for internal voltage bias.
UGATE (Pin 8)
Connect UGATE pin to the PWM converter's upper
MOSFET gate. This pin provides the gate drive for the
upper MOSFET.
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DS9204/A-08 March 2007
Preliminary
Absolute Maximum Ratings
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RT9204/A
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Supply Voltage VCC ------------------------------------------------------------------------------------------------ 7V
BOOT & UGATE to GND ------------------------------------------------------------------------------------------- 15V
Input, Output or I/O Voltage --------------------------------------------------------------------------------------- GND-0.3V to 7V
Power Dissipation, P
D
@ T
A
= 25°C
SOP-8 ------------------------------------------------------------------------------------------------------------------ 0.625W
Package Thermal Resistance
SOP-8,
θ
JA -------------------------------------------------------------------------------------------------------------------------------------------------------
160° C/W
Ambient Temperature Range -------------------------------------------------------------------------------------- 0°C to +70°C
Junction Temperature Range --------------------------------------------------------------------------------------
−
40°C to +125°C
Storage Temperature Range ---------------------------------------------------------------------------------------
−
65°C to +150°C
Lead Temperature (Soldering, 10 sec.)-------------------------------------------------------------------------- 260°C
CAUTION:
Stresses beyond the ratings specified in
“
Absolute Maximum Ratings
”
may cause permanent damage to the device.
This is a stress only rating and operation of the device at these or any other conditions above those indicated in the
operational sections of this specification is not implied.
Electrical Characteristics
(V
CC
= 5V, T
A
= 25° C, Unless otherwise specified.)
Parameter
VCC Supply Current
Nominal Supply Current
VCC Regulated Voltage
Power-On Reset
Rising VCC Threshold
VCC Threshold Hysteresis
Reference
Reference Voltage
Oscillator
Free Running Frequency
Ramp Amplitude
PWM Error Amplifier
DC Gain
PWM Controller Gate Driver
Upper Drive Source
Upper Drive Sink
Linear Regulator
DRV Driver Source
Symbol
Test Conditions
Min
Typ
Max
Units
I
CC
V
CC
UGATE, LGATE open
VBOOT=12V
--
--
3
6
--
--
mA
V
3.75
--
Both FB & FBL
0.784
550
∆
V
OSC
--
4.1
0.5
0.8
600
1.75
4.35
--
0.816
650
--
V
V
V
kHz
V
P-P
--
R
UGATE
R
UGATE
V
BOOT
= 12V; V
BOOT
-
V
UGATE
= 1V
V
UGATE
= 1V
--
--
35
7
5
--
--
--
dB
Ω
Ω
V
DRV
= 2V
100
--
--
mA
To be continued
DS9204/A-08 March 2007
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