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參數資料
| 型號： | ISO121 |
| 元件分類： | 隔離放大器 |
| 英文描述： | Precision Low Cost ISOLATION AMPLIFIER |
| 中文描述： | 精密低成本隔離放大器 |
| 文件頁數： | 9/16頁 |
| 文件大小： | 184K |
| 代理商： | ISO121 |
9
ISO120/121
output are not significant under these circumstances unless
the input signal contains significant components above
250kHz.
There are two ways to use these characteristics. One is to
move the carrier frequency low enough that the troublesome
signal components are attenuated to an acceptable level as
shown in Signal Response vs Carrier Frequency. This in
effect limits the bandwidth of the amplifier. The Synchroni-
zation Range performance curve shows the relationship
between carrier frequency and the value of C
. To maintain
stability, C
must also be connected and must be equal to or
larger in value than C
. C
may be further increased in value
for additional attenuation of the undesired signal compo-
nents and provides the additional benefit of reducing the
residual carrier ripple at the output. See the Bandwidth vs C
2
performance curve.
When periodic noise from external sources such as system
clocks and DC/DC converters are a problem, ISO120 and
ISO121 can be used to reject this noise. The amplifier can be
synchronized to an external frequency source, f
, placing
the amplifier response curve at one of the frequency and
amplitude nulls indicated in the Signal Response vs Carrier
Frequency performance curve. For proper synchronization,
choose C
as shown in the Synchronization Range perfor-
mance curve. Remember that C
≥
C
is a necessary condi-
tion for stability of the isolation amplifier. This curve shows
the range of lock at the fundamental frequency for a 4V
sinusoidal signal source. The applications section shows the
ISO120 and ISO121 synchronized to isolation power sup-
plies, while Figure 6 shows circuitry with opto-isolation
suitable for driving the Ext Osc input from TTL levels.
FIGURE 4a. Gain Adjust.
FIGURE 4b. Gain Setting.
+V
S1
or +V
S2
Signal Com 1
or
Signal Com 2
–V
S1
or –V
S2
100k
1M
10k
FIGURE 5. V
OS
Adjust.
resolution with a typical trim potentiometer. The output will
have some sensitivity to power supply variations. For a
±
100mV trim, power supply sensitivity is 8mV/V at the
output.
CARRIER FREQUENCY CONSIDERATIONS
As previously discussed, the ISO120 and ISO121 amplifiers
transmit the signal across the iso-barrier by a duty-cycle
modulation technique. This system works like any linear
amplifier for input signals having frequencies below one
half the carrier frequency, f
. For signal frequencies above
f
/2, the behavior becomes more complex. The Signal Re-
sponse vs Carrier Frequency performance curve describes
this behavior graphically. The upper curve illustrates the
response for input signals varying from DC to f
/2. At input
frequencies at or above f
/2, the device generates an output
signal component that varies in both amplitude and fre-
quency, as shown by the lower curve. The lower horizontal
scale shows the periodic variation in the frequency of the
output component. Note that at the carrier frequency and its
harmonics, both the frequency and amplitude of the re-
sponse go the zero. These characteristics can be exploited in
certain applications. It should be noted that when C
is zero,
the carrier frequency is nominally 500kHz and the –3dB
point of the amplifier is 60kHz. Spurious signals at the
FIGURE 6. Synchronization with Isolated Drive Circuit for
Ext Osc Pin.
C
1
Ext Osc on
ISO120 (pin 22)
C
2
10k
6
5
8
2
3
TTL
f
IN
2.5k
200
+15V
+5V
IN
(
)
C
1
= 140E-6
C
2
= 10
X
C
1
, with a minimum 10nF
2.5k
6N136
ISOLATION MODE VOLTAGE
Isolation mode voltage (IMV) is the voltage appearing be-
tween isolated grounds Gnd 1 and Gnd 2. IMV can induce
error at the output as indicated by the plots of IMV vs
Frequency. It should be noted that if the IMV frequency
exceeds f
/2, the output will display spurious outputs in a
manner similar to that described above, and the amplifier
response will be identical to that shown in the Signal Re-
sponse vs Carrier Frequency performance curve. This occurs
R
2
V
IN
V
OUT
R
1
Sense
R
2
1
200k
Gain = 1 + R
R
1
(
)
R
1
||
R
2
GND1
1k
2k
R
1
R
2
V
IN
V
OUT
GND1
Sense
相關PDF資料 |
PDF描述 |
|---|---|
| ISO121BG | Precision Low Cost ISOLATION AMPLIFIER |
| ISO121G | Precision Low Cost ISOLATION AMPLIFIER |
| ISO130 | |
| ISO130P | Amplifier. Other |
| ISO130PB | Amplifier. Other |
相關代理商/技術參數 |
參數描述 |
|---|---|
| ISO1211D | 功能描述:ISOLATED 24-V DIGITAL INPUT RECE 制造商:texas instruments 系列:- 包裝:管件 零件狀態:在售 應用:PLC 數字輸入模塊 接口:數字 電壓 - 電源:2.25 V ~ 5.5 V 封裝/外殼:8-SOIC（0.154"，3.90mm 寬） 供應商器件封裝:8-SOIC 安裝類型:表面貼裝 標準包裝:75 |
| ISO1211EVM | 功能描述:EVAL BOARD FOR ISO1211 制造商:texas instruments 系列:- 零件狀態:在售 主要用途:接口，數字式隔離器 嵌入式:- 使用的 IC/零件:ISO1211 主要屬性:板載測試點 輔助屬性:- 所含物品:板 標準包裝:1 |
| ISO1212DBQ | 功能描述:INDUSTRIAL IO 制造商:texas instruments 系列:- 包裝:管件 零件狀態:在售 應用:PLC 數字輸入模塊 接口:數字 電壓 - 電源:2.25 V ~ 5.5 V 封裝/外殼:16-SSOP（0.154"，3.90mm 寬） 供應商器件封裝:16-SSOP 安裝類型:表面貼裝 標準包裝:75 |
| ISO1212DBQR | 功能描述:ISOLATED 24-V TO 60-V DIGITAL IN 制造商:texas instruments 系列:- 包裝:剪切帶（CT） 零件狀態:在售 應用:PLC 數字輸入模塊 接口:數字 電壓 - 電源:2.25 V ~ 5.5 V 封裝/外殼:16-SSOP（0.154"，3.90mm 寬） 供應商器件封裝:16-SSOP 安裝類型:表面貼裝 標準包裝:1 |
| ISO1212EVM | 功能描述:EVAL BOARD FOR ISO1212 制造商:texas instruments 系列:- 零件狀態:在售 主要用途:接口，數字式隔離器 嵌入式:- 使用的 IC/零件:ISO1212 主要屬性:板載測試點 輔助屬性:- 所含物品:板 標準包裝:1 |
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