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参数资料
| 型号： | DS1381 |
| 厂商： | DALLAS SEMICONDUCTOR |
| 元件分类： | DRAM |
| 英文描述： | NV RAMport(非易失性RAM口) |
| 中文描述： | 2K X 8 NON-VOLATILE SRAM, 100 ns, PDIP24 |
| 文件页数： | 10/16页 |
| 文件大小： | 353K |
| 代理商： | DS1381 |
BUF04
REV. 0
–10–
A two-terminal equivalent circuit of the BUF04 is shown in
Figure 30 where the transistor-level equivalent circuit is reduced
to its essential elements. The input stage develops a signal
current, I
IN
, that is replicated by an internal current conveyor so
as to flow through R
t
, the transimpedance of the BUF04. The
voltage developed across R
t
is buffered by a unity-gain output
voltage follower. With an open-loop R
t
of 400 k
and an R
IN
of
30
, the voltage gain of the BUF04, given by the ratio R
t
/R
IN
is
approximately 13,000—accurate to approximately 13.5 bits.
The BUF04’s open-loop ac transimpedance response is
determined by the open-loop pole formed by R
t
and C
t
. Since
C
t
is typically 8 pF, the open-loop pole occurs at approximately
50 kHz.
X1
I
IN
R
t
I
IN
R
IN
V
OUT
C
t
V
IN
XI
R
FB
R
IN
= 30
R
t
= 400 k
C
= 8pF
RFB = 100
Figure 30. Current-Feedback Functional Equivalent
Circuit of the BUF04
Grounding and Bypassing Considerations
To take full advantage of the BUF04’s very wide bandwidth,
high slew rates, and dynamic range capabilities requires due
diligence with regard to supply bypassing. In high speed circuits,
the supply bypassing network must provide a very low impedance
return path for currents flowing to and from the load network.
As with any high speed application, multiple bypassing is always
recommended. A 10
μ
F tantalum electrolytic in parallel with a
0.1
μ
F ceramic capacitor is sufficient for most applications. For
those high speed applications where output load currents
approach 50 mA, small valued resistors (1.1
to 4.7
) in
series with the tantalum capacitors may improve circuit
transient response by damping out the capacitor’s self-
inductance. Figure 31 illustrates bypassing recommendations.
BUF04
7
6
10μF
R1
0.1μF
V+
0.1μF
V–
10μF
R2
4
3
R
S
R
L
KELVIN RETURN
FOR LOAD CURRENT
KELVIN RETURN
FOR LOAD CURRENT
V
IN
V
OUT
NOTE
USE SHORT LEAD LENGTHS (<5mm)
Figure 31. Recommended Power-Supply Bypassing
To minimize the effects of high-frequency coupling, circuits
must be built with short interconnect leads, and large ground
planes should he used whenever possible to provide a low
resistance, low-inductance circuit path. Sockets should be
avoided because the increased interlead capacitance can degrade
bandwidth and stability. If sockets are necessary, individual pin
sockets (oftentimes called “cage jacks,” AMP Part No.
5-330808-3 or 5-330808-6) should be used. They contribute far
less stray reactance than molded socket assemblies.
Offset Voltage Nulling
Although the offset voltage of the BUF04 is very low (1 mV,
maximum) for such a high speed buffer, the circuit shown in
Figure 32 can be used if additional offset voltage nulling is
required. A potentiometer ranging from 1 k to 10 k can be used
for V
OS
nulling; with a 10 k
potentiometer, the trim range is
±
30 mV.
V+
BUF04
7
6
0.1μF
10μF
0.1μF
V–
10μF
4
3
V
IN
10k
1
V
OUT
TRIM RANGE
±30mV
8
Figure 32. Optional Offset Voltage Nulling Scheme
APPLICATIONS
Output Short-Circuit Protection
To optimize the transient response and output voltage swing of
the BUF04, internal output short-circuit current limiting was
omitted. Although the BUF04 can provide continuous output
currents of 50 mA without protection, direct connection of the
BUF04’s output to ground or to the supplies will destroy the
device. An active current limit technique, illustrated in Figure
33, provides the necessary short-circuit protection while
retaining full dc output voltage swing to the load.
BUF04
7
6
10μF
0.1μF
0.1μF
–15V
10μF
4
3
V
IN
V
OUT
+15V
RSC2
≥
10
2N2219
2N2219
2N2905
2N2905
RSC1
≥
10
0.01μF
SET ISC +(ISC–) <60mA,
CONTINUOUS
RSC1 (RSC2) =
0.6V
ISC + (ISC–)
6.2k
Figure 33. Short-Circuit Current Limiting Using
Current Sources
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相关代理商/技术参数 |
参数描述 |
|---|---|
| DS1384 | 制造商:DALLAS 制造商全称:Dallas Semiconductor 功能描述:Watchdog Timekeeping Controller |
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| DS1384FP-12 | 功能描述:IC CTRLR RTC WDOG 120NS 44-MQFP RoHS:否 类别:集成电路 (IC) >> 时钟/计时 - 实时时钟 系列:- 产品培训模块:Obsolescence Mitigation Program 标准包装:1 系列:- 类型:时钟/日历 特点:警报器，闰年，SRAM 存储容量:- 时间格式:HH:MM:SS（12/24 小时） 数据格式:YY-MM-DD-dd 接口:SPI 电源电压:2 V ~ 5.5 V 电压 - 电源，电池:- 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:8-WDFN 裸露焊盘 供应商设备封装:8-TDFN EP 包装:管件 |
| DS1384FP-12+ | 功能描述:实时时钟 RoHS:否 制造商:Microchip Technology 功能:Clock, Calendar. Alarm RTC 总线接口:I2C 日期格式:DW:DM:M:Y 时间格式:HH:MM:SS RTC 存储容量:64 B 电源电压-最大:5.5 V 电源电压-最小:1.8 V 最大工作温度:+ 85 C 最小工作温度: 安装风格:Through Hole 封装 / 箱体:PDIP-8 封装:Tube |
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