參數(shù)資料
型號: L6997S
廠商: 意法半導體
英文描述: STEP DOWN CONTROLLER FOR LOW VOLTAGE OPERATIONS
中文描述: 降壓控制器低電壓運作
文件頁數(shù): 25/30頁
文件大小: 515K
代理商: L6997S
25/30
L6997S
Figure 25. Efficiency Vs Output Current
Figure 26. Efficiency Vs Output Current
50
55
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90
95
100
0
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Output Current [A]
E
VOUT= 12V
VIN = 25V
VCC= 5V
FSW= 200KHz
VOUT= 5V
VOUT= 3.3V
0
10
20
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0
1
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Output Current [A]
E
VOUT= 12V
VIN = 33V
7.5 DDR MEMORY AND TERMINATION SUPPLY
Double data rate (DDR) memories require a particular Power Management Architecture. This is due to fact that
the trace between the driving chipset and the memory input must be terminated with resistors. Since the Chipset
driving the Memory has a push pull output buffer, the Termination voltage must be capable of sourcing and sink-
ing current. Moreover, the Termination voltage must be equal to one half of the memory supply (the input of the
memory is a differential stage requiring a reference bias midpoint) and in tracking with it. For DDRI the Memory
Supply is 2.5V and the Termination voltage is 1.25Vwhile for the DDRII the Memory Supply is 1.8V and the Ter-
mination voltage is 0.9V. Figure 27 shows a complete DDRII Memory and Termination Supply realized by using
2 x L6997S. The 1.8V section is powering the memory, while the 0.9V section is providing the termination voltage.
Figure 27. Application Idea: DDRII Memory Supply
L6997S
PGND
FB
PHASE
GNDSENSE
OVP
VSENSE
LGATE
BOOT
HGATE
VCCDR
OSC
SS
VCC
VREF
NOSKIP
PGOOD
SHDN
VCC
L6997S
GND
ILIM
U2
GNDSENSE
VSENSE
FB
PGND
LGATE
PHASE
HGATE
BOOT
VCCDR
VCC
OSC
SS
NOSKIP
INT
VREF
SHDN
PGOOD
OVP
GND
U1
ILIM
VIN
VCC
INT
+
-
CHIPSET
MEMORY
SUPPLY
V
BUS
TERMINATION
NETWORK
Vddq
1.8V@15A
Vtt
0.9V+
R
2R
2R
R
STS8DNF3LL
STS11NF3LL
STS11NF3LL
相關PDF資料
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相關代理商/技術參數(shù)
參數(shù)描述
L6997STR 功能描述:DC/DC 開關控制器 3.0 to 5.5V Step-Dwn RoHS:否 制造商:Texas Instruments 輸入電壓:6 V to 100 V 開關頻率: 輸出電壓:1.215 V to 80 V 輸出電流:3.5 A 輸出端數(shù)量:1 最大工作溫度:+ 125 C 安裝風格: 封裝 / 箱體:CPAK
L6998-0 制造商:Johanson Manufacturing 功能描述:TUNING ELEMENT
L6998-1 制造商:Johanson Manufacturing 功能描述:TUNING ELEMENT
L6998-5 制造商:Johanson Manufacturing 功能描述:TUNING ELEMENT
L6998-6 制造商:Johanson Manufacturing 功能描述:TUNING ELEMENT