参数资料
| 型号： | NE57811S/N1,518 |
| 厂商： | NXP Semiconductors |
| 文件页数： | 8/13页 |
| 文件大小： | 0K |
| 描述： | IC DDR TERMINATION SPAK-5 |
| 标准包装： | 2,000 |
| 应用： | 转换器，DDR，DDR2 |
| 输入电压： | 1.6 V ~ 3.6 V |
| 输出数： | 1 |
| 工作温度： | 0°C ~ 70°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | SPAK-5 |
| 供应商设备封装： | 5-SPAK |
| 包装： | 带卷 (TR) |
| 其它名称： | 935284748518 NE57811S/N1-T NE57811S/N1-T-ND |
Philips Semiconductors
Advanced DDR memory termination power
with shutdown
APPLICATION INFORMATION
Product data
NE57811
The NE57811 can be used in a variety of DDR memory
configurations. Its small footprint, fast transient response and
lessened need for large bulk output capacitance, makes it highly
adaptable. Some of these methods of use are given below.
Normal operating mode (V TT = V DDR /2)
The most common implementation of a DDR terminator regulator
using the NE57811 is shown in Figure 10. The NE57811 has an
internal resistor divider between the V DD (pin 2) and V SS (pin 3) pins
which maintains the output voltage, V TT , at V DD /2. Typically, the V DD
voltage is the DDR RAM supply voltage, which can range from 1.8 V
to 2.5 V. The center node of this resistor divider is the reference for
the V TT output voltage and the buffered RefOut signal (pin 5).
There are two components to the memory signal load: a high
frequency component caused by the 266 MHz plus speed of the
address, data, and control buses, and a low frequency component
caused by the time-average skew of all of the bus states away from
an equal number of 1s and 0s. Electrolytic and tantalum capacitor
appear inductive at the high frequencies. Therefore two types of
capacitors are needed for the output filtering.
A very good, low ESR electrolyic capacitor of no less than 470 μ F
should be placed next to the terminator, which should be placed as
close as possible to the memory array. One half of the high
frequency filter capacitors should be to V DD and the other half to
SHTDWN
V DD
2
V SS so that the output will better track any variations in the V DD
voltage.
For different memory sizes, the values of the recommended output
filter capacitances will change. For a 256 MByte memory space, for
example, approximately 100 μ F of ceramic surface mount chip
capacitors should be evenly distributed across the physical memory
layout. Depending upon the PCB noise environment, this could be
10 pieces of 10 μ F, 20 pieces of 5 μ F, and so on.
It might be possible to reduce the total capacitance, provided the
performance remains stable. Examine the behavior of the V TT bus
carefully when the system is operating and verify that deviations in
the bus voltage do not exceed the DDR specification ( ± 40 mV).
Use of the SHTDWN signal and low power mode
The NE57811 provides an optional SHTDWN pin that may be used
to put the device into low power mode. When SHUTDOWN is
asserted (LOW), the V TT power amplifier is turned off and the output
is 3-Stated. This brings the quiescent current of the entire device to
less than 800 μ A.
If the pin is not externally connected, and internal 10 k ? resistor
biases the control logic to V DD causing the output sections to be
turned on and the NE57811 operates normally.
(HF)
V DD
V TT
1
+V TT
NE57811
C IN
4
SHTDWN
C OUT
(LF)
C OUT
(HF)
GND
V SS
3
RefOut
5
GND
V REF
SL01694
Figure 10. Normal operating method (V TT = V DD /2)
2003 Apr 02
8
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相关代理商/技术参数 |
参数描述 |
|---|---|
| NE57814 | 制造商:PHILIPS 制造商全称:NXP Semiconductors 功能描述:DDR memory termination regulator with standby mode and enhanced efficiency |
| NE57814DD | 制造商:NXP Semiconductors 功能描述: 制造商:NXP Semiconductors 功能描述:DDR TERM W/STANDBY 8SOIC |
| 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 |
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