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PDF SC2447 Data sheet ( Hoja de datos )
| Número de pieza | SC2447 | |
| Descripción | Dual-Phase Single or Two Output Synchronous Step-Down Controller | |
| Fabricantes | Semtech Corporation | |
| Logotipo |  |
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SC2447
Dual-Phase, Single or Dual Output
Synchronous Step-Dwowww.DnataCShoeent4Ut.rcoomller
POWER MANAGEMENT
Description
Features
The SC2447 is a versatile high-frequency dual phase PWM
step-down controller optimized for Philips and Renesas
DrMOSTM. Both phases are capable of sourcing or sink-
ing load currents, making the SC2447 suitable for net-
working system power and DDR applications.
The SC2447 employs fixed frequency, continuous-con-
duction peak current-mode control for easy compensa-
tion and fast transient response.
The SC2447 can be used to generate two independent
outputs (up to 30A per output) or a single 60A output
with shared phase current. The PWM signals are 180°
out of phase to minimize input/output ripple.
Either inductor DC resistance or precision sense resistor
can be used for current-mode control. Inductor DC resis-
tance sensing has the advantage of being lossless.
Each phase has individual closed-loop soft-start and over-
load shutdown timer. The SC2447 powers up neatly with
pre-biased output. It has tri-state shutdown and hiccup
overload protection. In two-phase single-output configu-
ration, the master timer controls the soft-start and over-
load shutdown functions. The SC2447 is in a lead-free,
WEEE and RoHS compliant, TSSOP-28 package.
2-Phase Step-down Controller optimized for Philips
or Renesas DrMOSTM
Out of Phase Operation for Low Input Current Ripple
Outputs Source and Sink Current
Fixed Frequency Peak Current-Mode Control
Lossless Inductor DCR Current Sensing
Optional Resistor Current-Sensing for Precise Cur-
rent-Limit
Dual 30A Outputs or 2-Phase 60A Single Output
Operation
Wide Input Voltage Range: 4.65V to 15V
Individual Closed-Loop Soft-Start, Overload Shut-
down Timer and Enable
Output Voltage as Low as 0.5V
Starts into Pre-Bias Output
Tri-State PWM Output during Shutdown
Programmable Frequency Up to 1MHz Per Phase
External Synchronization
TSSOP-28 Lead-free Package. Fully WEEE and RoHS
Compliant
Applications
Telecommunication Power Supplies
DDR Memory Power Supplies
Graphic Power Supplies
Servers and Base Stations
Typical Application Circuit
VIN
12V
VOUT1
2.5V/20A
CO1
100µF
x3
RFB1A
10KΩ
RFB1B
2.49KΩ
Figure 1
CIN1
22µF
x4
CB1
L1 100nF
1µH/1.8mΩ
RS1B
22.1KΩ
RS1A
22.1KΩ
CCS1
100nF
RS1C , 11KΩ
VDDO
CBP
VDDC
VDDG
CBN
VO
REG5V
VI
DISABLE
VSSO VSSC
PIP212-12M
R1
10Ω
C5
1µF
C3
1µF
CVCC
4.7µF
CCMP1
10pF
RA1
24.9KΩ
CA1
3.3nF
CREF
0.1uF
RVCC
10Ω
AVCC
R2
10Ω
C4
1µF C6
1µF
GDH1
GDL1
GDH2
GDL2
SC2447
VDDC
VDDG
VDDO
CBP
REG5V
VI
CBN
VO
DISABLE
VSSC VSSO
PIP212-12M
CIN2
22µF
x4
CB2
100nF
L2
0.4µH/1mΩ
RS2B
200KΩ
RS2A
22.1KΩ
CS1+
CS2+
CCS2
68nF
CS1-
IN1-
CS2-
IN2-
RS2C , 20KΩ
COMP1
REFOUT
REF
REFIN
COMP2
ROSC , 51.1KΩ
ROSC
AGND
SS1/EN1
RA2
16.9KΩ
CA2
3.3nF
CCMP2
10pF
SYNC
SS2/EN2
CSS2
CSS1
0.1µF 0.1µF
VOUT2
1.2V/25A
CO2
100µF
x3
RFB2A
10KΩ
RFB2B
7.15KΩ
Revision: December 15, 2006
1
www.semtech.com
1 page  
SC2447
POWER MANAGEMENT
Electrical Characteristics (Cont.)
Unless specified: AVCC = 12V, SYNC = 0, ROSC = 51.1kΩ, -40°C < TA = TJ < 125°C
Parameter
Symbol
Conditions
Output High Voltage
Output Low Voltage
Maximum Tri-State Leakage
Current
Propagation delay time from
current sense inputs to PWM
output(1)
TDLPWM
Soft-Start, Overload Hiccup and Enable
Source IO = 1.2mA, 0 ~ 70° C
Sink IO = 1mA
GDH in High Impedance State
TA =25° C
Soft-Start Charging Current
Overload Hiccup Enabling
Voltage
ISS1, ISS2
Soft-Start Discharging Current
at Over Current Condition
ISS1(DIS),
ISS2(DIS)
Overload Hiccup Threshold
Voltage
Overload Hiccup Recovery
Soft-Start Voltage
PWM Output Disable SS/EN
Voltage
PWM Output Enable SS/EN
Voltage
VSSRCV1,
VSSRCV2
Internal 0.5V Reference Buffer
VSS1 = VSS2 = 1.5V
VSS1 and VSS2 Increasing
VIN1-= 0.5VREF,VIN2-= 0.5VREFIN ,
VSS1 = VSS2 > 2.85V
VIN1-= 0.5VREF,VIN2-= 0.5VREFIN ,
VSS1 = VSS2 < 2.85V
VSS1 and VSS2 Decreasing
VSS1 and VSS2 Decreasing
www.DataSheet4U.com
Min Typ Max Units
4.1 5 V
0 0.4 V
2 µA
85 ns
9.5
3.2
37
7.5
2.85
0.5
0.6
1.2 1.5
µA
V
µA
µA
V
V
V
V
Output Voltage
Load Regulation
VREFOUT
Line Regulation
Notes:
(1) Guaranteed by design, not tested in production.
IREFOUT = -1mA, 0° C < TA = TJ < 70° C 495 500
0 < I < -5mA
REFOUT
0.05
AVCCTH < AVCC < 15V, IREFOUT = -1mA
505
0.02%
mV
%/mA
%V
© 2006 Semtech Corp.
5
www.semtech.com
5 Page 
POWER MANAGEMENT
Block Diagram
SC2447
www.DataSheet4U.com
SYNC
6
ROSC
3
COMP1
5
IN1
4
REF
8
CS1+
1
CS1-
2
OSCILLATOR
CLK
CLK2
FREQUENCY
DIVIDER CLK1
SLOPE COMP.
-
+ EA1
+
REFSS1
+
ISEN1
-
SLOPE1
+
+
Σ
50mV
+
ILIM1+
-
SLOPE2
-
PWM1
+
CLK1
OC1
SSL1
REFOUT
9
0.5V
1.25V
REFERENCE
R
Q
S
TGON1
UV
0.5V
PRE-BIAS
SOFT-START
&
OVERLOAD
HICCUP
CONTROL 1
OL1
DSBL1
SS1/EN1
1.25V
2R
R
TRI-STATE1
UVLO
4.3/4.5V
COMP2
11
IN2
12
REFIN
10
2.5V
-
+
-
+ EA2
+
CS2+
14
CS2-
13
REFSS2
+
ISEN2
-
SLOPE2
+
+
Σ
50mV
+
ILIM2+
-
SEL
ANALOG
SWITCH
-
PWM2
+
CLK2
R
Q
S
TGON2
UV
CLK2
OC2
SSL2
PRE-BIAS
SOFT-START
&
OVERLOAD
HICCUP
CONTROL 2
OL2
DSBL2
SS2/EN2
BA
MUX
Y
TRI-STATE2
R 2R 1.25V
REFSS2
AVCC
16
GDH1
25
GDL1
24
SS1/EN1
28
AGND
7
GDH2
20
GDL2
21
SS2/EN2
15
© 2006 Semtech Corp.
Figure 3. SC2447 Block Diagram
11
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11 Page | ||
| Páginas | Total 26 Páginas | |
| PDF Descargar | [ Datasheet SC2447.PDF ] | |
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