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PDF RT9259 Data sheet ( Hoja de datos )
| Número de pieza | RT9259 | |
| Descripción | 12V Synchronous Buck PWM DC-DC and Linear Power Controller | |
| Fabricantes | Richtek Technology | |
| Logotipo |  |
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RT9259
12V Synchronous Buck PWM DC-DC and
Linear Power Controller
General Description
Features
The RT9259 is a dual-channel DC/DC controller specifically
designed to deliver high quality power where 12V power
source is available. This part consists of a synchronous
buck controller and an LDO controller. The synchronous
buck controller integrates MOSFET drivers that support
12V+12V bootstrapped voltage for high efficiency power
conversion. The bootstrap diode is built-in to simplify the
circuit design and minimize external part count. The LDO
controller drives an external N-MOSFET for lower power
requirement.
Other features include adjustable operation frequency,
internal soft start, under voltage protection, over current
protection and shut down function. With the above
functions, this part provides customers a compact, high
efficiency, well-protected and cost-effective solution. This
part comes to VQFN-16L 4x4, SOP14 and SSOP-16
packages.
Ordering Information
RT9259
Package Type
S : SOP-14
A : SSOP-16
QV : VQFN-16 4x4 (V-Type)
Operating Temperature Range
P : Pb Free with Commercial Standard
G : Green (Halogen Free with Commer-
cial Standard)
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.
z Single 12V Bias Supply
z Support Dual Channel Power Conversion
`One Synchronous Rectified Buck PWM Controller
`One Linear Controller
z Both Controllers Drive Low Cost N-MOSFETs
z Adjustable Frequency from 150kHz to 1MHz
and Free-Run Frequency at 230kHz
z Small External Component Count
z Output Voltage Regulation
`PWM Controller : ±1% Accuracy
`LDO Controller : ±2% Accuracy
z Two Internal VREF Power Support Lower to 0.8V
z Adjustable External Compensation
z Linear Controller Drives N-MOSFET Pass
Transistor
z Fully-Adjustable Outputs
z Under Voltage Protection for Both Outputs
z Over Current Fault Monitor on MOSFET; No Current
Sense Resistor is Required.
z RoHS Compliant and 100% Lead (Pb)-Free
Applications
z Graphic Card GPU, Memory Core Power
z Graphic Card Interface Power
z Motherboard, Desktop and Servers Chipset and Memory
Core Power
z IA Equipments
z Telecomm Equipments
z High Power DC-DC Regulators
Marking Information
For marking information, contact our sales representative
www.DataSheet4U.com
directly or through a Richtek distributor located in your
area, otherwise visit our website for detail.
DS9259-03T00 August 2007
www.richtek.com
1
1 page  
RT9259
Parameter
Symbol
Test Conditions
Min Typ Max Units
Oscillator
Free Running Frequency
Ramp Amplitude
fOSC
Reference Voltage
PWM Error Amplifier Reference
Linear Driver Reference
Error Amplifier
VREF1
VREF2
RRT = 110kΩ
250 300 350 kHz
-- 1.6 --
V
0.792 0.8 0.808
0.784 0.8 0.816
V
V
DC Gain
70 88 -- dB
Gain-Bandwidth Product
Slew Rate
GBW
SR
CLOAD = 5pF
6 15 -- MHz
3 6 -- V/us
Gate Driver
Upper Drive Source
Upper Drive Sink
Lower Drive Source
Lower Drive Sink
Protection
RUGATE
RUGATE
RLGATE
RLGATE
VBOOT − VPHASE = 12V,
VBOOT − VUGATE = 1V
VUGATE = 1V
VCC – VLGATE = 1V
VLGATE = 1V
-- 4 8 Ω
-- 4 8 Ω
-- 4 6 Ω
-- 2 4 Ω
Under Voltage Protection
Soft-Start Time Interval
Over Current Threshold
RT_DIS Shutdown Threshold
VUVP
TSS
VOC
0.36 0.4 0.45
234
-- -400 --
0.35 0.4
--
V
ms
mV
V
Linear Regulator
Output High Voltage
Output Low Voltage
Source Current
Sink Current
VDRV
VDRV
IDRVSR
IDRVSC
9.5 10.3
-- 0.1
2 --
0.5 --
--
1
--
--
V
V
mA
mA
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. Devices are ESD sensitive. Handling precaution recommended.
Note 3. The device is not guaranteed to function outside its operating conditions.
Note 4. θJA is measured in the natural convection at TA = 25°C on a high effective 4-layers 2S2P thermal conductivity test board
www.DataSohfeetJ4EUD.cEoCm51-7 thermal measurement standard.
DS9259-03T00 August 2007
www.richtek.com
5
5 Page 
RT9259
The ESR zero is contributed by the ESR associated with
the output capacitance. Note that this requires that the
output capacitor should have enough ESR to satisfy stability
requirements. The ESR zero of the output capacitor
expressed as follows :
fESR
=
2π
1
× COUT
× ESR
2) Compensation Frequency Equations
The compensation network consists of the error amplifier
and the impedance networks ZC and ZF as shown in
Figure 9.
ZF
C1
R2 C2
ZC
R1
VOUT
-
COMP EA+
FB
VREF
RF
Figure 9. Compensation Loop
fZ1
=
2π
1
x R2
x
C2
fP1
=
2π
x R2
1
x
C1 x
C1 +
C2
C2
80 80
Loop Gain
60
40 40
Compensation
Gain
20
00
Modulator
-20 Gain
-40-40
-60-60
110H0zvdb(vo) vdb(comp2)11000vHd0zb(lo)
11.0kKHz 110K0Hzk
FrequFreequnenccyy (Hz)
11000K0Hzk
Figure 10. Bode Plot
1.01MHMz
wwFwig.Duareta1S0hesehto4Uw.scothme DC-DC converter's gain vs. frequency.
The compensation gain uses external impedance networks
ZC and ZF to provide a stable, high bandwidth loop. High
crossover frequency is desirable for fast transient response,
but often jeopardize the system stability. In order to cancel
one of the LC filter poles, place the zero before the LC
filter resonant frequency. In the experience, place the zero
at 75% LC filter resonant frequency. Crossover frequency
should be higher than the ESR zero but less than 1/5 of
the switching frequency. The second pole is placed at half
the switching frequency.
Thermal Considerations
For continuous operation, do not exceed absolute
maximum operation junction temperature 125°C. The
maximum power dissipation depends on the thermal
resistance of IC package, PCB layout, the rate of
surroundings airflow and temperature difference between
junction to ambient. The maximum power dissipation can
be calculated by following formula :
PD(MAX) = ( TJ(MAX) − TA ) / θJA
Where TJ(MAX) is the maximum operation junction
temperature 125°C, TA is the ambient temperature and the
θJA is the junction to ambient thermal resistance.
For recommended operating conditions specification of
RT9259, where TJ(MAX) is the maximum junction
temperature of the die (125°C) and TA is the maximum
ambient temperature. The junction to ambient thermal
resistance θJA is layout dependent. For VQFN-16L 4x4
packages, the thermal resistance θJA is 54°C/W on the
standard JEDEC 51-7 four-layers thermal test board.
The maximum power dissipation at TA = 25°C can be
calculated by following formula :
PD(MAX) = ( 125°C − 25°C ) / 54°C/W = 1.852 W for
QFN-16L 4x4 packages
PD(MAX) = ( 125°C − 25°C) / 100°C/W = 1.000 W for
SOP-14 packages
PD(MAX) = ( 125°C − 25°C ) / 110°C/W = 0.909 W for
SSOP-16 packages
The maximum power dissipation depends on operating
ambient temperature for fixed TJ (MAX) and thermal resistance
θJA. For RT9259 packages, the Figure 11 of derating curves
allows the designer to see the effect of rising ambient
temperature on the maximum power allowed.
DS9259-03T00 August 2007
www.richtek.com
11
11 Page | ||
| Páginas | Total 15 Páginas | |
| PDF Descargar | [ Datasheet RT9259.PDF ] | |
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