參數(shù)資料
型號(hào): ADA4092-4ARUZ
廠商: Analog Devices Inc
文件頁(yè)數(shù): 7/20頁(yè)
文件大?。?/td> 0K
描述: IC OPAMP 1.4MHZ QUAD 14TSSOP
標(biāo)準(zhǔn)包裝: 96
放大器類型: 通用
電路數(shù): 4
輸出類型: 滿擺幅
轉(zhuǎn)換速率: 0.4 V/µs
增益帶寬積: 1.4MHz
電流 - 輸入偏壓: 50nA
電壓 - 輸入偏移: 200µV
電流 - 電源: 200µA
電流 - 輸出 / 通道: 20mA
電壓 - 電源,單路/雙路(±): 2.7 V ~ 30 V,±1.35 V ~ 15 V
工作溫度: -40°C ~ 125°C
安裝類型: 表面貼裝
封裝/外殼: 14-TSSOP(0.173",4.40mm 寬)
供應(yīng)商設(shè)備封裝: 14-TSSOP
包裝: 管件
ADA4092-4
Rev. B | Page 15 of 20
THEORY OF OPERATION
The ADA4092-4 is a single-supply, micropower amplifier
featuring rail-to-rail inputs and outputs. To achieve wide input
and output ranges, these amplifiers employ unique input and
output stages.
INPUT STAGE
In Figure 48, the input stage comprises two differential pairs, a
PNP pair (PNP input stage) and an NPN pair (NPN input stage).
These input stages do not work in parallel. Instead, only one
stage is on for any given input common-mode signal level. The
PNP stage (Transistor Q1 and Transistor Q2) is required to ensure
that the amplifier remains in the linear region when the input
voltage approaches and reaches the negative rail. Alternatively,
the NPN stage (Transistor Q5 and Transistor Q6) is needed for
input voltages up to, and including, the positive rail.
For the majority of the input common-mode range, the PNP
stage is active, as shown in Figure 8 through Figure 13. Notice
that the VOS shifts and that the bias current switches direction at
approximately 1.5 V below the positive rail. At voltages below this
level, the bias current flows out of the ADA4092-4 input, from
the PNP input stage. However, above this voltage, the bias
current enters the device due to the NPN stage. The actual
mechanism within the amplifier for switching between the input
stages comprises Q3, Q4, and Q7. As the input common-mode
voltage increases, the emitters of Q1 and Q2 follow that voltage
plus a diode drop. Eventually, the emitters of Q1 and Q2 are
high enough to turn on Q3, which diverts the tail current away
from the PNP input stage, turning it off. The tail current of the
PNP pair is diverted to the Q4/Q7 current mirror to activate the
NPN input stage, as shown in Figure 48.
A common practice in bipolar amplifiers to protect the input
transistors from large differential voltages is to include series
resistors and differential diodes. See Figure 49 for the full input
protection circuitry. These diodes turn on whenever the differential
voltage exceeds approximately 0.6 V. In this condition, current
flows between the input pins, limited only by the two 5 k
resistors. Evaluate each application carefully to make sure that
the increase in current does not affect performance.
OUTPUT STAGE
The output stage in the ADA4092-4 device uses a PNP and an
NPN transistor, as do most output stages. However, Q32 and
Q33, the output transistors, connect with their collectors to an
output pin to achieve the rail-to-rail output swing.
As the output voltage approaches either the positive or the
negative rail, these transistors begin to saturate. Thus, the final
limit on output voltage is the saturation voltage of these transistors,
which is about 50 mV. The output stage has inherent gain arising
from the transistor output impedance, as well as any external load
impedance; consequently, the open-loop gain of the op amp is
dependent on the load resistance and decreases when the output
voltage is close to either rail.
08803-
124
Q1
Q3
–IN
Q5
Q6
Q11
Q10
Q8
Q7
Q4
Q13
Q15
Q14
Q12
Q9
Q16
Q17
Q18
Q19
Q32
OUT
Q33
+IN
Q2
Figure 48. Simplified Schematic Without Input Protection (See Figure 49)
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ADA4092-4ARUZ-RL 功能描述:IC OPAMP 1.4MHZ QUAD 14TSSOP RoHS:是 類別:集成電路 (IC) >> Linear - Amplifiers - Instrumentation 系列:- 標(biāo)準(zhǔn)包裝:100 系列:- 放大器類型:通用 電路數(shù):1 輸出類型:- 轉(zhuǎn)換速率:0.2 V/µs 增益帶寬積:- -3db帶寬:- 電流 - 輸入偏壓:100pA 電壓 - 輸入偏移:30µV 電流 - 電源:380µA 電流 - 輸出 / 通道:- 電壓 - 電源,單路/雙路(±):±2 V ~ 18 V 工作溫度:0°C ~ 70°C 安裝類型:表面貼裝 封裝/外殼:8-SOIC(0.154",3.90mm 寬) 供應(yīng)商設(shè)備封裝:8-SO 包裝:管件
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