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參數(shù)資料
| 型號(hào)： | 3656BG |
| 元件分類： | 隔離放大器 |
| 英文描述： | Transformer Coupled ISOLATION AMPLIFIER |
| 中文描述： | 變壓器耦合隔離放大器 |
| 文件頁數(shù)： | 3/17頁 |
| 文件大小： | 149K |
| 代理商： | 3656BG |
3656
11
Step 2: Output stage trim (RA = RB = 20M, RC = 100k,
RF = 0, RX = 100k, RK = ∞, R1 and R2 connected);
A1 low, A2 low gain. Adjust R2 for 0V ±1mV or
desired setting at VOUT, pin 15 (±110mV approxi-
mate total range).
NOTE: Other circuit component values can be used with
valid results.
APPLICATIONS
ECG AMPLIFIER
Although the features of the circuit shown in Figure 6 are
important in patient monitoring applications, they may also
be useful in other applications. The input circuitry uses an
external, low quiescent current op amp (OPA177 type)
powered by the isolated power of the input stage to form a
high impedance instrumentation amplifier input (true three-
wire input). R
3 and R4 give the input stage amplifier of the
3656 a noninverting gain of 10 and an inverting gain of –9.
R
1 and R2 give the external amplifier a noninverting gain of
1 + 1/9. The inputs are applied to the noninverting inputs of
the two amplifiers and the composite input stage amplifier
has a gain of 10.
The 330k
, 1W, carbon resistors and diodes D
1 - D4 provide
protection for the input amplifiers from defibrillation pulses.
The output stage in Figure 6 is configured to provide a
bandpass filter with a gain of 22.7 (68M
/3M). The high-
pass section (0.05Hz cutoff) is formed by the 1
F capacitor
and 3M
resistor which are connected in series between the
output demodulator and the inverting input of the output
stage amplifier. The low-pass section (100Hz cutoff) is
formed by the 68M
resistor and 22pF capacitor located in
the feedback loop of the output stage. The diodes provide for
quick recovery of the high-pass filter to overvoltages at the
input. The 100k
pot and the 100M resistor allow the
output voltage to be trimmed to compensate for increased
offset voltage caused by unbalanced impedances seen by the
inputs of the output stage amplifier.
In many modern electrocardiographic systems, the patient is
not grounded. Instead, the right-leg electrode is connected to
the output of an auxiliary operational amplifier as shown in
Figure 7. In this circuit, the common-mode voltage on the
body is sensed by the two averaging resistors, R1 and R2,
inverted, amplified, and fed back to the right-leg through
resistor R4. This negative feedback drives the common-
mode voltage to a low value. The body’s displacement
current id does not flow to ground, but rather to the output
circuit of A
3. This reduces the pickup as far as the ECG
amplifier is concerned and effectively grounds the patient.
The value of R4 should be as large as practical to isolate the
patient from ground. The resistors R3 and R4 may be se-
lected by these equations:
R
3 = (R1/2) (VO/VCM) and R4 = (VCM – VO)/id
(–10V
≤ V
O ≤ +10V and –10V ≤ VCM ≤+10V)
D
M
R
C
I/P PWR
R
X
+
–
0.47F
–
+
19
20
R
F
R
A
V
OUT
R
B
R
K
R
1
100k
R
2
100k
+
–
15V
7
4
6
9
2
10
15
11
13
17
16
12
O/P PWR
Pulse GEN
1
3
14
8
5
A
1
A
2
FIGURE 5. Optional Offset Voltage Trim.
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| 3656F | 制造商:JT&T Products 功能描述: |
| 3656F1 | 制造商: 功能描述: |
| 3656HG | 功能描述:特殊用途放大器 Transformer Coupled Iso Amp RoHS:否 制造商:Texas Instruments 通道數(shù)量:Single 共模抑制比（最小值）: 輸入補(bǔ)償電壓: 工作電源電壓:3 V to 5.5 V 電源電流:5 mA 最大功率耗散: 最大工作溫度:+ 70 C 最小工作溫度:- 40 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:QFN-20 封裝:Reel |
| 3656JG | 功能描述:特殊用途放大器 Transformer Coupled Iso Amp RoHS:否 制造商:Texas Instruments 通道數(shù)量:Single 共模抑制比（最小值）: 輸入補(bǔ)償電壓: 工作電源電壓:3 V to 5.5 V 電源電流:5 mA 最大功率耗散: 最大工作溫度:+ 70 C 最小工作溫度:- 40 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:QFN-20 封裝:Reel |
| 3656KG | 功能描述:特殊用途放大器 Transformer Coupled Iso Amp RoHS:否 制造商:Texas Instruments 通道數(shù)量:Single 共模抑制比（最小值）: 輸入補(bǔ)償電壓: 工作電源電壓:3 V to 5.5 V 電源電流:5 mA 最大功率耗散: 最大工作溫度:+ 70 C 最小工作溫度:- 40 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:QFN-20 封裝:Reel |
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