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參數(shù)資料
| 型號(hào)： | MAX4242EUA |
| 廠商： | MAXIM INTEGRATED PRODUCTS INC |
| 元件分類： | 運(yùn)動(dòng)控制電子 |
| 英文描述： | Single/Dual/Quad, !.8V/10レA, SOT23, Beyond-the-Rails Op Amps |
| 中文描述： | DUAL OP-AMP, 2000 uV OFFSET-MAX, 0.09 MHz BAND WIDTH, PDSO8 |
| 封裝： | 3 X 3 MM, MICRO, SOP-8 |
| 文件頁數(shù)： | 14/16頁 |
| 文件大?。?/td> | 174K |
| 代理商： | MAX4242EUA |
M
Using the MAX 4240–MAX 4244
as Comparators
Although optimized for use as operational amplifiers,
the MAX4240–MAX4244 can also be used as rail-to-rail
I/O comparators. Typical propagation delay depends
on the input overdrive voltage, as shown in Figure 9.
External hysteresis can be used to minimize the risk of
output oscillation. The positive feedback circuit, shown
in Figure 10, causes the input threshold to change
when the output voltage changes state. The two thresh-
olds create a hysteresis band that can be calculated by
the following equations:
V
HYST
= V
HI
- V
LO
V
LO
= V
IN
x R2 / (R1 + (R1 x R2 / R
HYST
) + R2)
V
HI
= [(R2 / R1 x V
IN
) + (R2 / R
HYST
) x V
CC
] /
(1 + R1 / R2 + R2 / R
HYST
)
The MAX4240–MAX4244 contain special circuitry to
boost internal drive currents to the amplifier output
stage. This maximizes the output voltage range over
which the amplifiers are linear. In an open-loop com-
parator application, the excursion of the output voltage
is so close to the supply rails that the output stage tran-
sistors will saturate, causing the quiescent current to
increase from the normal 10μA. Typical quiescent cur-
rents increase to 35μA for the output saturating at V
CC
and 28μA for the output at V
EE
.
Using the MAX 4240–MAX 4244
as Ultra-Low-Power Current Monitors
The MAX4240–MAX4244 are ideal for applications
powered from a 2-cell battery stack. Figure 11 shows
an application circuit in which the MAX4240 is used for
monitoring the current of a 2-cell battery stack. In this
circuit, a current load is applied, and the voltage drop
at the battery terminal is sensed.
The voltage on the load side of the battery stack is
equal to the voltage at the emitter of Q1, due to the
feedback loop containing the op amp. As the load cur-
rent increases, the voltage drop across R1 and R2
increases. Thus, R2 provides a fraction of the load cur-
rent (set by the ratio of R1 and R2) that flows into the
emitter of the PNP transistor. Neglecting PNP base cur-
rent, this current flows into R3, producing a ground-ref-
erenced voltage proportional to the load current. Scale
R1 to give a voltage drop large enough in comparison
to V
OS
of the op amp, in order to minimize errors.
The output voltage of the application can be calculated
using the following equation:
V
OUT
= [I
LOAD
x (R1 / R2)] x R3
For a 1V output and a current load of 50mA, the choice
of resistors can be R1 = 2
, R2 = 100k
, R3 = 1M
.
The circuit consumes less power (but is more suscepti-
ble to noise) with higher values of R1, R2, and R3.
S ingle/Dual/Quad, +1.8V /10μA, S OT 23,
Beyond-the-Rails Op Amps
14
______________________________________________________________________________________
R2
R1
V
IN
OUTPUT
INPUT
V
OH
V
OH
V
OL
V
EE
V
CC
V
OUT
R
HYST
V
EE
MAX4240
MAX4241
MAX4242
MAX4243
MAX4244
HYSTERESIS
V
LO
V
HI
Figure 10. Hysteresis Comparator Circuit
10,000
10
0
20 30
10
100
100
1000
M
V
OD
(mV)
t
P
μ
s
40 50 60 70 80
90
t
PD
-; V
CC
= +5V
t
PD
+; V
CC
= +1.8V
t
PD
-; V
CC
= +1.8V
t
PD
+; V
CC
= +5V
Figure 9. Propagation Delay vs. Input Overdrive
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| MAX4282 | SOT23, Rail-to-Rail, Fixed-Gain GainAmps/Open-Loop Op Amps |
| MAX4175 | SOT23, Rail-to-Rail, Fixed-Gain GainAmps/Open-Loop Op Amps |
| MAX4274 | SOT23, Rail-to-Rail, Fixed-Gain GainAmps/Open-Loop Op Amps |
| MAX4274_ESA | SOT23, Rail-to-Rail, Fixed-Gain GainAmps/Open-Loop Op Amps |
| MAX4274_EUA | SOT23, Rail-to-Rail, Fixed-Gain GainAmps/Open-Loop Op Amps |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| MAX4242EUA+ | 功能描述:運(yùn)算放大器 - 運(yùn)放 1.8V 10uA Beyond the-Rails 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 |
| MAX4242EUA+T | 功能描述:運(yùn)算放大器 - 運(yùn)放 1.8V 10uA Beyond the-Rails 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 |
| MAX4242EUA-T | 功能描述:運(yùn)算放大器 - 運(yùn)放 1.8V 10uA Beyond the-Rails 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 |
| MAX4243ESD | 功能描述:運(yùn)算放大器 - 運(yùn)放 1.8V 10uA Beyond the-Rails 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 |
| MAX4243ESD+ | 制造商:Maxim Integrated Products 功能描述:- Rail/Tube |
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