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参数资料
| 型号： | LOG114AIRGVR |
| 厂商： | TEXAS INSTRUMENTS INC |
| 元件分类： | 模拟运算功能 |
| 英文描述： | LOG OR ANTILOG AMPLIFIER, PQCC16 |
| 封装： | 4 X 4 MM, GREEN, PLASTIC, QFN-16 |
| 文件页数： | 3/29页 |
| 文件大小： | 637K |
| 代理商： | LOG114AIRGVR |
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LOG114
SBOS301A MAY 2004 REVISED MARCH 2007
www.ti.com
11
APPLICATIONS INFORMATION
OVERVIEW
The LOG114 is a precision logarithmic amplifier that is
capable of measuring currents over a dynamic range of
eight decades. It computes the logarithm, or log ratio,
of an input current relative to a reference current ac-
cording to equation (1).
V
LOGOUT + 0.375
log
10
I
1
I
2
The output at VLOGOUT can be digitized directly, or scaled
for an ADC input using an uncommitted or external op
amp.
An offsetting voltage (VCom) can be connected to the
Com pin to raise the voltage at VLOGOUT. When an
offsetting voltage is used, the transfer function
becomes:
V
LOGOUT + 0.375
log
10
I
1
I
2
) V
Com
Either I1 or I2 can be held constant to serve as the refer-
ence current, with the other input being used for the in-
put signal. The value of the reference current is selected
such that the output at VLOGOUT (pin 9) is zero when the
reference current and input current are equal. An on-
chip 2.5V reference is provided for use in generating the
reference current.
Two additional amplifiers, A4 and A5, are included in the
LOG114 for use in scaling, offsetting, filtering, threshold
detection, or other functions.
BASIC CONNECTIONS
Figure 1 and Figure 2 show the LOG114 in typical dual
and single-supply configurations, respectively. To re-
duce the influence of lead inductance of power-supply
lines, it is recommended that each supply be bypassed
with a 10
F tantalum capacitor in parallel with a 1000pF
ceramic capacitor as shown in Figure 1 and Figure 2.
Connecting these capacitors as close to the LOG114
V+ supply pin to ground as possible improves supply
related noise rejection.
Q1
R1
R2
R5
100k
R6
66.5k
R7
100k
R
8
56.2k
R3
R
REF
2.5M
R4
V
O4
(2)
IN4
+IN4
V
LOGOUT
(1)
+IN5
IN
5
VO5
V
CM IN
I
1
4
11
10
9
14
5
3
15
13
12
16 VREF
2.5V
REF
V
Com
VREF GND
Q2
A3
A
1
A
2
A
4
A5
I
REF
1
F
Input Signal
100pA to 10mA
I2
V+
1
86
7
+5V
++
5V
1000pF
10
F10F
LOG114
NOTE: (1) V
LOGOUT = 0.375 × log(I1/I2)
(2) VO4 = 0.249 × log(I1/I2)+ 1.5V
Figure 1. Dual Supply Configuration Example for Best Accuracy Over Eight Decades.
(1)
(2)
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LOG114AIRGVRG4 | 功能描述:对数放大器 Prec High-Speed Logarithmic Amp RoHS:否 制造商:Texas Instruments 通道数量:3 带宽:3 dB 共模抑制比（最小值）: 输入补偿电压:+/- 7 mV 输入电压范围（最大值）:5.5 V 工作电源电压:4.5 V to 5.5 V 电源电流:+/- 15 mA 工作温度范围:- 40 C to +85 C 安装风格:SMD/SMT 封装 / 箱体:VQFN-16 封装:Reel |
| LOG114AIRGVT | 功能描述:对数放大器 Precision High-Speed RoHS:否 制造商:Texas Instruments 通道数量:3 带宽:3 dB 共模抑制比（最小值）: 输入补偿电压:+/- 7 mV 输入电压范围（最大值）:5.5 V 工作电源电压:4.5 V to 5.5 V 电源电流:+/- 15 mA 工作温度范围:- 40 C to +85 C 安装风格:SMD/SMT 封装 / 箱体:VQFN-16 封装:Reel |
| LOG114AIRGVTG4 | 功能描述:对数放大器 Prec High-Speed Logarithmic Amp RoHS:否 制造商:Texas Instruments 通道数量:3 带宽:3 dB 共模抑制比（最小值）: 输入补偿电压:+/- 7 mV 输入电压范围（最大值）:5.5 V 工作电源电压:4.5 V to 5.5 V 电源电流:+/- 15 mA 工作温度范围:- 40 C to +85 C 安装风格:SMD/SMT 封装 / 箱体:VQFN-16 封装:Reel |
| LOG114EVM | 功能描述:放大器 IC 开发工具 LOG114 Eval Mod RoHS:否 制造商:International Rectifier 产品:Demonstration Boards 类型:Power Amplifiers 工具用于评估:IR4302 工作电源电压:13 V to 23 V |
| LOG1527 | 制造商:未知厂家 制造商全称:未知厂家 功能描述:由CMOS工艺设计制造的可内烧的学习码编码IC. |
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