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参数资料
| 型号： | NE57814DD |
| 厂商： | NXP Semiconductors N.V. |
| 元件分类： | 基准电压源/电流源 |
| 英文描述： | DDR memory termination regulator with standby mode and enhanced efficiency |
| 封装： | NE57814DD<SOT786-2 (HSO8)|<<http://www.nxp.com/packages/SOT786-2.html<1<week 13, 2004,; |
| 文件页数： | 9/16页 |
| 文件大小： | 203K |
| 代理商： | NE57814DD |
Philips Semiconductors
Product data
NE57814
DDR memory termination regulator with
standby mode and enhanced efficiency
2003 Apr 03
9
High efficiency operating mode
The NE57814 is designed for portable applications such as laptop
computers and other battery operated computer systems requiring
DDR memory. The standby mode 3-states the V
TT
output and
unpowers most of the NE57814, which is very desirable for portable
applications. The RefOut pin is still active for use elsewhere within
the system.
The V
D
pin on the NE57814 allows the DDR termination system to
operate with reduced output power dissipation. The V
D
voltage can
be lowered to approximately +0.25 volts above the V
TT
output
voltage.
The high-efficiency method draws its V
TT
current, not from the
memory V
DD
line but from a lower voltage, V
D
. This will decrease
the loss within the terminator when it sources current to the V
TT
line.
The V
D
voltage required depends on the load current sourced and is
given by V
D(min)
= V
TT
+ 0.3(I
TT(source)
). I
TT
is expressed in amps.
The V
DD
voltage is still used to set the V
ref
voltage to the memory
devices.
As much as a 65 percent overall efficiency can be gained by
operating the output stage from a voltage source of 0.25 V above
the output V
TT
voltage during the sourcing condition. This gives it a
distinct benefit in portable applications.
The efficiency of the DDR terminator during the sourcing and sinking
states of the NE57814 can be determined by the following
calculations:
Sourcing:
Efficiency(sourcing)
(V
TT
) (I
TT
)
(V
D
(I
Q
) (V
DD
)
V
TT
) (I
TT
)
100
This can be between 81 and 82.5 percent when the NE57814 is
sourcing current.
Sinking:
Efficiency(sinking)
(V
TT
) (I
TT
)
(I
Q
) (V
DD
)
(V
TT
) (I
TT
)
100
This is approximately 49.5 percent.
SL01884
V
DD
5
ExtRefIn
6
V
SS
1
V
TT
3
V
TT
SENSE
2
RefOut
8
V
D
4
V
ref
V
TT
50
μ
F
(Y5V)
0.1
μ
F
(Y5V)
NE57814
470
μ
F
(Electro)
0.1
μ
F
(Y5V)
0.1
μ
F
(Y5V)
INPUT VOLTAGE
( > V
TT
+ 0.25 V )
10
μ
F
(Y5V)
V
DD
VOLTAGE
Figure 10. High efficiency operation.
Less than +0.25 V between V
D
and V
TT
A voltage difference between V
D
and V
TT
of less than +0.25 V
reduces the maximum sourcing current capability of the V
TT
power
amplifier.
This reduction in output sourcing current capability can many times
be compensated for within the termination system by adding
additional low ESR electrolytic capacitors on the V
TT
output. The
typical performance of the NE57814 as the V
D
voltage approaches
V
TT
voltage (decreasing headroom voltage) can be seen in
Figure 11.
T
T
SL01885
HEADROOM VOLTAGE (mV)
0
50
100
150
200
250
2.5
2.0
1.5
1.0
0.5
0
Figure 11. Typical output source current versus V
D
(at 25
°
C).
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相关代理商/技术参数 |
参数描述 |
|---|---|
| NE57814DD,518 | 功能描述:线性稳压器 - 标准 DDR TERMINATOR REG RoHS:否 制造商:STMicroelectronics 输出类型: 极性: 输出电压:1.8 V 输出电流:150 mA 负载调节: 最大输入电压:5.5 V 线路调整率: 最大工作温度:+ 125 C 安装风格:SMD/SMT 封装 / 箱体:SOT-323-5L |
| NE57814DD518 | 制造商:Rochester Electronics LLC 功能描述: 制造商:NXP 功能描述: 制造商:NXP Semiconductors 功能描述: |
| NE57835 | 制造商:未知厂家 制造商全称:未知厂家 功能描述:TRANSISTOR | BJT | NPN | 11V V(BR)CEO | 30MA I(C) | SOT-173 |
| NE578D | 制造商:未知厂家 制造商全称:未知厂家 功能描述:Compander |
| NE-58 | 制造商:Visual Communications Company (VCC) 功能描述:NE-58 /Refer New Part # F4A |
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