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PDF RT9204A Data sheet ( Hoja de datos )
| Número de pieza | RT9204A | |
| Descripción | Dual Regulators - Standard Buck PWM DC-DC and Linear Controller | |
| Fabricantes | Richtek | |
| Logotipo |  |
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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.
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.
Features
l Operate from 5V
l 0.8V Internal Reference
l Voltage Mode PWM Control
l Fast Transient Response
l Fixed 600kHz Oscillator Frequency
l Full 0 to 100% Duty Cycle
l Internal Soft Start
l Internal PWM Loop Compensation
l RoHS Compliant and 100% Lead (Pb)-Free
Applications
l Motherboard Power Regulation for Computers
l Subsystems Power Supplies
l Cable Modems, Set Top Box, and DSL Modems
l DSP and Core Communications Processor Supplies
l Memory Power Supplies
l Personal Computer Peripherals
l Industrial Power Supplies
l 5V-Input DC-DC Regulators
l Low Voltage Distributed Power Supplies
Pin Configurations
(TOP VIEW)
GND
VCC
DRV
FBL
2
3
4
8 UGATE
7 BOOT
6 SD
5 FB
SOP-8
DS9204/A-08 March 2007
www.richtek.com
1
Free Datasheet http://www.datasheet4u.com/
1 page  
Preliminary
RT9204/A
Absolute Maximum Ratings
l Supply Voltage VCC ------------------------------------------------------------------------------------------------ 7V
l BOOT & UGATE to GND ------------------------------------------------------------------------------------------- 15V
l Input, Output or I/O Voltage --------------------------------------------------------------------------------------- GND-0.3V to 7V
l Power Dissipation, PD @ TA = 25°C
SOP-8 ------------------------------------------------------------------------------------------------------------------ 0.625W
l Package Thermal Resistance
SOP-8, θJA ------------------------------------------------------------------------------------------------------------------------------------------------------- 160° C/W
l Ambient Temperature Range -------------------------------------------------------------------------------------- 0° C to +70° C
l Junction Temperature Range -------------------------------------------------------------------------------------- −40° C to +125° C
l Storage Temperature Range --------------------------------------------------------------------------------------- −65° C to +150° C
l 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
(VCC = 5V, TA = 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
ICC UGATE, LGATE open
VCC VBOOT=12V
-- 3 -- mA
-- 6 -- V
3.75 4.1 4.35
-- 0.5 --
V
V
Both FB & FBL
0.784 0.8 0.816 V
∆ VOSC
550 600 650 kHz
-- 1.75 -- VP-P
-- 35 -- dB
RUGATE VBOOT = 12V; VBOOT - VUGATE = 1V -- 7 -- Ω
RUGATE VUGATE = 1V
-- 5 -- Ω
VDRV = 2V
100 --
-- mA
To be continued
DS9204/A-08 March 2007
www.richtek.com
5
Free Datasheet http://www.datasheet4u.com
5 Page 
Preliminary
RT9204/A
Input / Output Capacitor
High frequency/long life decoupling capacitors should be
placed as close to the power pins of the load as physically
possible. Be careful not to add inductance to the PCB
trace, as it could eliminate the performance from utilizing
these low inductance components. Consult with the
manuf acturer of the load on specific decoupling
requirements.
The output capacitors are necessary for filtering output
and stabilizing the close loop (see the PWM loop stability).
For powering advanced, high-speed processors, it is
required to meet with the requirement of fast load transient,
high frequency capacitors with low ESR/ESL capacitors
are recommended.
Another concern is high ESR induced ripple may trigger
UV or OV protections.
Linear Regulator Driver
The linear regulator of RT9204/A was designed to drive
bipolar NPN or MOSFET pass transistor. For MOSFET
pass transistor, normally DRV need to provide minimum
VOUT2+VT+gate-drive voltage to keep VOUT2 as setting
voltage. When driving MOSFET operating at 5V power
supply system, the gate-drive will be limited at 5V. In this
situation shown in Figure 5, low VT threshold MOSFET
(VT = 1V) and Vout2 setting below 2.5V were suggested.
In VBOOT = 12V operation condition as Figure 8, VCC is
regulated as higher to 6V providing more gate-drive for
pass MOSFET transistor, VOUT2 can be set as ≤ 3.3V.
VOUT2 < 3.3V
VBOOT = 12V
DRV
BOOT
FBL
6V VCC
RT9204/A
R3
R4
R4<1K
Figure 8
PWM Loop Stability
The RT9204/A is a voltage mode buck controller designed
for 5V step-down applications. The gain of error amplifier
is fixed at 35dB for simplified design.
The output amplitude of ramp oscillator is 1.6V, the loop
gain and loop pole/zero are calculated as follows:
5 0.8
DC loop gain GA = 35 dB × ×
1.6 VOUT
1
LC filter pole PO =
2π LC
Error Amp pole PA = 300kHz
1
ESR zero ZO =
2πESR × C
The RT9204/A Bode plot as shown Figure 9. is stable in
most of application conditions.
VCC = 5V
VOUT2 < 2.5V
DRV
BOOT
FBL
VCC
RT9204/A
R3
R4 R4<1K
Figure 7
VOUT = 3.3V
COUT = 1500uF(33mΩ)
L = 2uH
40
VOUT = 1.5V
VOUT = 2.5V
30 VOUT = 3.3V
PO = 2.9kHz
ZO = 3.2kHz
20
Loop Gain
10
100 1k 10k 100k
Figure 9
1M
DS9204/A-08 March 2007
www.richtek.com
11
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11 Page | ||
| Páginas | Total 14 Páginas | |
| PDF Descargar | [ Datasheet RT9204A.PDF ] | |
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