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參數(shù)資料
| 型號(hào)： | MAX471ESA |
| 廠商： | MAXIM INTEGRATED PRODUCTS INC |
| 元件分類： | 電源管理 |
| 英文描述： | Extended Common-mode RS-485 Transceiver 8-SOIC -40 to 85 |
| 中文描述： | 1-CHANNEL POWER SUPPLY SUPPORT CKT, PDSO8 |
| 封裝： | SOP-8 |
| 文件頁數(shù)： | 9/12頁 |
| 文件大小： | 120K |
| 代理商： | MAX471ESA |
Peak Sense Current
The MAX471’s maximum sense current is 3A
RMS
. For
power-up, fault conditions, or other infrequent events,
larger peak currents are allowed, provided they are
short—that is, within a safe operating region, as shown
in Figure 5.
MAX 472
R
SENSE
, RG1, and RG2 are externally connected on
the MAX472. V
CC
can be connected to either the
load/charge or power-source/battery side of the sense
resistor. Connect V
CC
to the load/charge side of
R
SENSE
if you want to include the MAX472 current drain
in the measured current.
Suggested Component Values
for Various Applications
The general circuit of Figure 4 is useful in a wide variety
of applications. It can be used for high-current applica-
tions (greater than 3A), and also for those where the full-
scale load current is less than the 3A of the MAX471.
Table 1 shows suggested component values and indi-
cates the resulting scale factors for various applications
required to sense currents from 100mA to 10A.
Higher or lower sense-current circuits can also be built.
Select components and calculate circuit errors using
the guidelines and formulas in the following section.
R
SENSE
Choose R
SENSE
based on the following criteria:
a)
Voltage Loss:
A high R
SENSE
value will cause the
power-source voltage to degrade through IR loss.
For least voltage loss, use the lowest R
SENSE
value.
b)
Accuracy:
A high R
SENSE
value allows lower
currents to be measured more accurately. This is
because offsets become less significant when the
sense voltage is larger.
c)
Efficiency and Power Dissipation:
At high current
levels, the I
2
R losses in R
SENSE
may be significant.
Take this into consideration when choosing the
resistor value and power dissipation (wattage) rat-
ing. Also, if the sense resistor is allowed to heat up
excessively, its value may drift.
d)
Inductance:
If there is a large high-frequency com-
ponent to I
SENSE
, you will want to keep inductance
low. Wire-wound resistors have the highest induc-
tance, while metal film is somewhat better. Low-
inductance metal-film resistors are available. Instead
of being spiral wrapped around a core, as in metal-
film or wire-wound resistors, these are a straight
band of metal. They are made in values under 1
.
e)
Cost:
If the cost of R
SENSE
becomes an issue, you
may want to use an alternative solution, as shown in
Figure 6. This solution uses the PC board traces to
create a sense resistor. Because of the inaccuracies
of the copper “resistor,” you will need to adjust the
full-scale current value with a potentiometer. Also,
the resistance temperature coefficient of copper is
fairly high (approximately 0.4%/°C), so systems that
experience a wide temperature variance should take
this into account.
M
Prec ision, High-S ide
Current-S ense Amplifiers
_______________________________________________________________________________________
9
Table 1. Suggested Component Values for the MAX472
FULL-SCALE
LOAD
CURRENT,
I
SENSE
(A)
CURRENT-
SENSE
RESISTOR,
R
SENSE
(m
)
500
50
10
5
GAIN-SETTING
RESISTORS,
RG1 = RG2
(
)
OUTPUT
RESISTOR,
R
OUT
(k
)
FULL-SCALE
OUTPUT
VOLTAGE,
V
OUT
(V)
SCALE
FACTOR,
V
OUT
/I
SENSE
(V/A)
0.1
1
5
10
200
200
100
50
10
10
5
2
2.5
2.5
2.5
2
25
2.5
0.5
0.2
0.9
0.9
1.1
1.6
14
14
13
12
2.5
2.5
2.0
2.0
TYPICAL ERROR AT X%
OF FULL LOAD (%)
1%
100%
10%
50
45
0
10
μ
5
40
PULSE WIDTH (sec)
DIP safe
operating region
Small Outline safe
operating region
S
100
μ
1m
10m
30
35
15
20
25
10
DIP
fuse
Small
Outline
fuse
ti time
T
A
= +25°C
Figure 5. MAX471 Pulse Current Safe Operation for 10,000
Pulses and Fuse Time for Continuous Current. Pulse tests done
with 250mW average power dissipation.
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| MAX472 | Extended Common-mode RS-485 Transceiver 8-PDIP -40 to 85 |
| MAX471 | Precision, High-Side Current-Sense Amplifiers |
| MAX472CSA | Precision, High-Side Current-Sense Amplifiers |
| MAX472EPA | Precision, High-Side Current-Sense Amplifiers |
| MAX472ESA | Precision, High-Side Current-Sense Amplifiers |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| MAX471ESA+ | 功能描述:特殊用途放大器 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 |
| MAX471ESA+T | 功能描述:特殊用途放大器 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 |
| MAX471ESA-T | 功能描述:特殊用途放大器 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 |
| MAX4720ELT+ | 制造商:Rochester Electronics LLC 功能描述: 制造商:Maxim Integrated Products 功能描述: |
| MAX4720ELT+T | 功能描述:模擬開關(guān) IC Single-Supply SPDT Analog Switch RoHS:否 制造商:Texas Instruments 開關(guān)數(shù)量:2 開關(guān)配置:SPDT 開啟電阻（最大值）:0.1 Ohms 切換電壓（最大）: 開啟時(shí)間（最大值）: 關(guān)閉時(shí)間（最大值）: 工作電源電壓:2.7 V to 4.5 V 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:DSBGA-16 |
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