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參數資料
| 型號： | SC488 |
| 廠商： | Semtech Corporation |
| 英文描述： | Complete DDR1/2/3 Memory Power Supply |
| 中文描述： | 完全DDR1/2/3內存供電 |
| 文件頁數： | 1/24頁 |
| 文件大小： | 818K |
| 代理商： | SC488 |
www.semtech.com
1
POWER MANAGEMENT
Description
The SC488 is a combination switching regulator and lin-
ear source/sink regulator intended for DDR1/2 memory
systems. The purpose of the switching regulator is to gen-
erate the supply voltage, VDDQ, for the memory system.
It is a pseudo-
fi
xed frequency constant on-time controller
designed for high ef
fi
ciency, superior DC accuracy, and fast
transient response. The purpose of the linear source/sink
regulator is to generate the memory termination voltage,
VTT, with the ability to source and sink 2.8A peak cur-
rents.
SC488
Complete DDR1/2/3
Memory Power Supply
September 28, 2006
Features
For the VDDQ regulator, the switching frequency is constant
until a step in load or line voltage occurs at which time the
pulse density, i.e., frequency, will increase or decrease to
counter the transient change in output or input voltage.
After the transient, the frequency will return to steady-state
operation. At lighter loads, the selectable Power-Save
Mode enables the PWM converter to reduce its switching
frequency and improve ef
fi
ciency. The integrated gate
drivers feature adaptive shoot-through protection and soft-
switching. Additional features include cycle-by-cycle current
limiting, digital soft-start, over-voltage and under-voltage
protection and a power good
fl
ag.
For the VTT regulator, the output voltage tracks REF, which
is VDDQ to provide an accurate termination voltage.
The VTT output is generated from a 1.2V to VDDQ input by
a linear source/sink regulator which is designed for high
DC accuracy, fast transient response, and low external
component count. All three outputs (VDDQ, VTT and REF)
are actively discharged when VDDQ is disabled, reducing
external component count and cost. The SC488 is avail-
able in a 24-pin MLPQ (4x4 mm) package.
Constant On-Time Controller for Fast Dynamic
Response on VDDQ
DDR1/DDR2/DDR3 Compatible
VDDQ = Fixed 1.8V or 2.5V, or Adjustable From
1.5V to 3.0V
1.5% Internal Reference (2.5% System Accuracy)
Resistor Programmable On-Time for VDDQ
VCCA/VDDP Range = 4.5V to 5.5V
VIN Range = 2.5V to 25V
VDDQ DC Current Sense Using Low-Side R
DS(ON)
Sensing
External R
in Series with Low-Side FET
Cycle-by-Cycle Current Limit for VDDQ
Digital Soft-Start for VDDQ
Analog Soft-Start for VTT/REF
Smart Over-Voltage VDDQ Protection
Combined EN and PSAVE Pin for VDDQ
Over-Voltage/Under-Voltage Fault Protection
Power Good Output
Separate VCCA and VDDP Supplies
VTT/REF Range = 0.75V – 1.5V
VTT Source/Sink 2.8A Peak
Internal Resistor Divider for VTT/REF
VTT is High Impedance in S3
VDDQ, VTT, REF are Actively Discharged in S4/S5
24 Lead MLPQ (4x4 mm) Lead-Free Package
Product Is Fully WEEE and RoHS Compliant
Notebook Computers
CPU I/O Supplies
Handheld Terminals and PDAs
LCD Monitors
Network Power Supplies
Applications
Typical Application Circuit
REF
R7
10R
C10
1uF
VTT
C8
0.1uF
Q1
Q2
D1
C3
2x10uF
VBAT
R1
1Meg
L1
+
C6
VDDQ
VTT_EN
R6
10R
C9
1uF
VBAT
C7
1nF
C1
1uF
EN/PSV
C4
10uF
PGND2
1
VTTS
2
VSSA
3
TON
4
REF
5
VCCA
6
N
7
V
1
F
9
L
2
D
1
PGND1
18
PGND1
17
ILIM
16
VDDP
15
VDDP
14
N
1
E
1
V
8
PGD
13
V
2
V
2
B
2
D
2
PAD
U1
SC488
R4
VDDQ
5V
VTTSNS
PAD
C2
0.1uF
5V
PGOOD
RILIM
C11
1uF
C5
10uF
VDDQ
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相關代理商/技術參數 |
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|---|---|
| SC488ML.TRT | 制造商:SEMTECH 功能描述:I.C. |
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