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參數(shù)資料
| 型號(hào)： | TC7650CPD |
| 廠商： | TelCom Semiconductor, Inc. |
| 元件分類： | 運(yùn)算放大器 |
| 英文描述： | CHOPPER-STABILIZED OPERATIONAL AMPLIFIER |
| 中文描述： | 斬波穩(wěn)定運(yùn)算放大器 |
| 文件頁(yè)數(shù)： | 3/7頁(yè) |
| 文件大小： | 90K |
| 代理商： | TC7650CPD |
3-275
TELCOM SEMICONDUCTOR, INC.
7
6
5
4
3
1
2
8
ELECTRICAL CHARACTERISTICS:
V
DD
= +5V, V
SS
= – 5V, C
A
= C
B
= 0.1
μ
F, T
A
= 25
°
C, unless otherwise
specified.
Symbol
Parameter
Test Conditions
Min
Typ
Max
Units
Supply
V
DD
, V
SS
I
S
PSRR
Operating Supply Range
Supply Current
Power Supply
Rejection Ratio
4.5
—
120
—
2
130
16
3.5
V
No Load
V
S
=
±
3V to
±
8V
mA
dB
NOTES:
1. See "Output Clamp" discussion.
2. Output clamp not connected. See typical characteristics curves for output swing versus clamp current characteristics.
3. Limiting input current to 100
μ
A is recommended to avoid latch-up problems.
Theory of Operation
Figure 1 shows the major elements of the TC7650.
There are two amplifiers (the main amplifier and the nulling
amplifier), and both have offset-null capability. The main
amplifier is connected full-time from the input to the output.
The nulling amplifier, under the control of the chopping
frequency oscillator and clock circuit, alternately nulls itself
and the main amplifier. Two external capacitors provide the
required storage of the nulling potentials and the necessary
nulling-loop time constants. The nulling arrangement oper-
ates over the full common-mode and power-supply ranges,
and is also independent of the output level, thus giving
exceptionally high CMRR, PSRR, and A
VOL
.
Careful balancing of the input switches minimizes chop-
per frequency charge injection at the input terminals, and the
feed-forward-type injection into the compensation capacitor
that can cause output spikes in this type of circuit.
The circuit's offset voltage compensation is easily shown.
With the nulling inputs shorted, a voltage almost identical to
the nulling amplifier offset voltage is stored on C
A
. The
effective offset voltage at the null amplifier input is:
CHOPPER-STABILIZED
OPERATIONAL AMPLIFIER
TC7650
V
OSE
= 1
OSN
A
N
+ 1
(1)
After the nulling amplifier is zeroed, the main amplifier is
zeroed; the A switches open and B switches close.
The output voltage equation is:
V
OUT
= A
M
[V
OSM
+(V
+
– V
–
) + A
N
(V
+
– V
–
) + A
N
V
OSE
]
(2)
(3)
As desired, the device offset voltages are reduced by
the high open-loop gain of the nulling amplifier.
Output Stage/Loading
The output circuit is a high-impedance stage (approxi-
mately 18k
). With loads less than this, the chopper ampli-
fier behaves in some ways like a transconductance amplifier
whose open-loop gain is proportional to load resistance. For
example, the open-loop gain will be 17dB lower with a 1k
load than with a 10k
load. If the amplifier is used strictly for
DC, the lower gain is of little consequence, since the DC gain
is typically greater than 120dB, even with a 1k
load. In
wideband applications, the best frequency response will be
achieved with a load resistor of 10k
or higher. This results
in a smooth 6 dB/octave response from 0.1Hz to 2 MHz, with
phase shifts of less than 10
°
in the transition region, where
the main amplifier takes over from the null amplifier. The
clock frequency sets the transition region.
Intermodulation
Previous chopper-stabilized amplifiers have suffered
from intermodulation effects between the chopper frequency
and input signals. These arise because the finite AC gain of
the amplifier results in a small AC signal at the input. This is
seen by the zeroing circuit as an error signal, which is
chopped and fed back, thus injecting sum and difference
frequencies, and causing disturbances to the gain and
phase versus frequency characteristics near the chopping
frequency. These effects are substantially reduced in the
TC7650 by feeding the nulling circuit with a dynamic current
corresponding to the compensation capacitor current in
such a way as to cancel that portion of the input signal due
to a finite AC gain. The intermodulation and gain/phase
disturbances are held to very low values, and can generally
be ignored.
Substituting (1)
→
(2) and assuming A
N
>>
1:
[
V
OUT
= A
M
A
N
(V
+
– V
–
) +
]
V
OSM
+ V
OSN
A
N
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PDF描述 |
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| TC7650 | Wallmount ULTRX Series Fiberglass Enclosure; NEMA Type:1, 2, 4, 4X, 12, 13; Enclosure Material:Fiberglass; External Height:20.2"; External Width:16.22"; External Depth:12.64"; Enclosure Color:Light Gray; Leaded Process Compatible:No |
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| TC7650IJA | 功能描述:運(yùn)算放大器 - 運(yùn)放 Low VOS CMOS RoHS:否 制造商:STMicroelectronics 通道數(shù)量:4 共模抑制比（最小值）:63 dB 輸入補(bǔ)償電壓:1 mV 輸入偏流（最大值）:10 pA 工作電源電壓:2.7 V to 5.5 V 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:QFN-16 轉(zhuǎn)換速度:0.89 V/us 關(guān)閉:No 輸出電流:55 mA 最大工作溫度:+ 125 C 封裝:Reel |
| TC7650IJD | 功能描述:運(yùn)算放大器 - 運(yùn)放 Low VOS CMOS RoHS:否 制造商:STMicroelectronics 通道數(shù)量:4 共模抑制比（最小值）:63 dB 輸入補(bǔ)償電壓:1 mV 輸入偏流（最大值）:10 pA 工作電源電壓:2.7 V to 5.5 V 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:QFN-16 轉(zhuǎn)換速度:0.89 V/us 關(guān)閉:No 輸出電流:55 mA 最大工作溫度:+ 125 C 封裝:Reel |
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| TC7652_13 | 制造商:MICROCHIP 制造商全稱:Microchip Technology 功能描述:Low Noise, Chopper Stabilized Operational Amplifier |
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