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Número de pieza | RT9205A | |
Descripción | Dual Regulators - Synchronous Buck PWM DC-DC and Linear Controller | |
Fabricantes | Richiek | |
Logotipo | ||
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Preliminary
RT9205/A
Dual Regulators - Synchronous Buck PWM DC-DC and
Linear Controller
General Description
The RT9205/A is a dual-output power controllers
designed for high performance graphics cards and
personal computers. The IC integrates a
synchronous buck controller, a linear controller and
protection functions into a small 14-pin package.
The RT9205/A uses an internal compensated voltage
mode PWM control for simplying design. An internal
0.8V reference allows the output voltage to be
precisely regulated to meet low output voltage
requirement. A fixed 300kHz oscillation frequency
reduces the component size for saving board area.
The RT9205/A also features over voltage protection
(OVP) and under voltage lock-out (UVLO).
Applications
PC Motherboard
Cable Modems, Set-Top-Box, and XDSL 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
Graphic Cards
Features
Operates at 5V
0.8V Internal Reference
Drives Two N-channel MOSFET
Voltage Mode PWM Control
Fast Transient Response
Fixed 300kHz Oscillator Frequency
Dynamic 0~100% Duty Cycle
Internal PWM Loop Compensation
Internal Soft-Start
Adaptive Non-overlapping Gate Driver
Over-voltage Protection Uses Lower MOSFET
Pin Configurations
Part Number
Pin Configurations
RT9205/ACS
(Plastic SOP-14)
TOP VIEW
LGATE 1
PGND 2
GND 3
VCC 4
DRV 5
FBL 6
NC 7
14 UGATE
13 BOOT
12 NC
11 NC
10 NC
9 FB
8 NC
Ordering Information
RT9205/A
Package Type
S : SOP-14
Operating Temperature Range
C : Commercial Standard
UVP : Hiccup Mode
UVP : Latch Mode
DS9205/A-03 May 2003
www.richtek.com
1
1 page Preliminary
RT9205/A
Absolute Maximum Ratings
Supply Voltage VCC
7V
BOOT & UGATE to GND
19V
Input, Output or I/O Voltage
Package Thermal Resistance
GND−0.3V ~ 7V
SOP-14, θJA
Ambient Temperature Range
Junction Temperature Range
Storage Temperature Range
160°C/W
0°C ~ +70°C
-40°C ~ +125°C
−65°C ~ +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
(VCC = 5V, TA = 25°C, Unless otherwise specified.)
Parameter
Symbol
Test Conditions
VCC Supply Current
Nominal Supply Current
VCC Regulated Voltage
Power-On Reset
ICC UGATE, LGATE open
ICC VBOOT = 12V
Rising VCC Threshold
VCC Threshold Hysteresis
Reference
Reference Voltage
VFB Both PWM and linear regulator
Oscillator
Free Running Frequency
Ramp Amplitude
PWM Error Amplifier
∆ VOSC
DC gain
PWM Controller Gate Driver
Upper Drive Source
RUGATE
BOOT= 12V
BOOT-VUGATE = 1V
Upper Drive Sink
RUGATE VUGATE = 1V
Lower Drive Source
RLGATE VCC - VLGATE = 1V,
Lower Drive Sink
Linear Regulator
RLGATE VLGATE = 1V
DRV Driver Source
Protection
VDRV = 2V
FB Over-Voltage Trip
FB Rising
FB & FBL Under-Voltage Trip
FB & FBL Falling
Soft-Start Interval
Min Typ Max Units
-- 3 -- mA
567 V
3.8 4.1 4.4
-- 0.5 --
V
V
0.784 0.8 0.816 V
250 300 350 KHz
-- 1.75 -- VP-P
32 35 38 dB
-- 7.5 11
-- 5
8
-- 3.5 6
-- 2
5
Ω
Ω
Ω
Ω
100 --
-- mA
0.9 1
--
V
-- 0.5 0.65 V
-- 2.5 -- mS
DS9205/A-03 May 2003
www.richtek.com
5
5 Page COUNT = 1 COUNT = 2 COUNT = 3
4V
2V
0V
OVERLOAD
APPLIED
Preliminary
RT9205/A
Q
VI
L
VL
D
C
R VO
0A
T0T1
T2
TIME
Fig. 5
T3
Applications Information
Inductor Selection
The RT9205/A was designed for VIN = 5V, step-down
application mainly. Fig.6 shows the typical topology
and waveforms of step-down converter.
The ripple current of inductor can be calculated as
follows:
ILRIPPLE = (5V - VOUT)/L × TON
Because operation frequency is fixed at 300kHz,
TON = 3.33 × VOUT/5V
The VOUT ripple is
VOUT RIPPLE = ILRIPPLE × ESR
ESR is the equivalent series resistor of output
capacitor
Table 1 shows the ripple voltage of VOUT at VIN = 5V
Table 1
C.C.M.
TS
TON TOFF
VI - VO
VL
- VO
iL µQ
µIL
IL = IO
iQ
IQ
iD
ID
Fig. 6
VOUT
3.3V
2.5V
Inductor
2µH 5µH 2µH 5µH
1000µF (ESR=53mΩ) 100mV 40mV 110mV 44mV
1500µF (ESR=33mΩ)
62mV 25mV 68mV 28mV
3000µF (ESR=21mΩ)
40mV 16mV 43mV 18mV
*Refer to Sanyo low ESR series (CE, DX, PX…)
The suggested L and C are as follows:
2µH with ≥ 1500µF COUT
5µH with ≥ 1000µF COUT
1.5V
2µH 5µH
93mV 37mV
58mV 23mV
37mV 15mV
DS9205/A-03 May 2003
www.richtek.com
11
11 Page |
Páginas | Total 16 Páginas | |
PDF Descargar | [ Datasheet RT9205A.PDF ] |
Número de pieza | Descripción | Fabricantes |
RT9205 | Dual Regulators - Synchronous Buck PWM DC-DC and Linear Controller | Richiek |
RT9205A | Dual Regulators - Synchronous Buck PWM DC-DC and Linear Controller | Richiek |
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