参数资料
型号: LOG101
英文描述: Precision LOGARITHMIC AND LOG RATIO AMPLIFIER
中文描述: 精密对数和对数比率放大器
文件页数: 11/13页
文件大小: 281K
代理商: LOG101
www.ti.com
LOG101
7
SBOS242B
FIGURE 7. Precision Current Inverter/Current Source.
1.5k
Photodiode
10nA to 1mA
+5V
1.5k
+3.3V
1/2 OPA2335
OPA2335
1
2
BSH203
TLV271 or
Back Bias
LOG101
Pin 1 or Pin 8
FIGURE 8. Precision Current Inverter/Current Source.
1.5k
+5V
1.5k
1.5k
100k
10nA to 1mA
LOG101
10nA to 1mA
100k
100k
+3.3V
1/2
OPA2335
1/2
OPA2335
Photodiode
Back Bias
Pin 1 or Pin 8
100k
VOLTAGE INPUTS
The LOG101 gives the best performance with current inputs.
Voltage inputs may be handled directly with series resistors,
but the dynamic input range is limited to approximately three
decades of input voltage by voltage noise and offsets. The
transfer function of Equation (13) applies to this configuration.
APPLICATION CIRCUITS
LOG RATIO
One of the more common uses of log ratio amplifiers is
to measure absorbance. A typical application is shown in
Figure 9.
Absorbance of the sample is A = log
λ
1/ λ1
(3)
If D1 and D2 are matched A ∝ (1V) logI1/I2
(4)
DATA COMPRESSION
In many applications the compressive effects of the logarith-
mic transfer function are useful. For example, a LOG101
preceding a 12-bit Analog-to-Digital (A/D) converter can
produce the dynamic range equivalent to a 20-bit converter.
FIGURE 9. Absorbance Measurement.
I
2
I
1
8
1
5
6
3
V
OUT
4
V+
V–
C
LOG101
D
2
D
1
Sample
λ
1
λ
1
λ
1
Light
Source
OPERATION ON SINGLE SUPPLY
Many applications do not have the dual supplies required to
operate the LOG101. Figure 10 shows the LOG101 config-
ured for operation with a single +5V supply.
8
1
3
6
4
5
1
2
35
4
–5V
1
F
LOG101
1
F
I
1
I
2
V
OUT
C
1
F
TPS(1)
Single Supply +5V
NOTE: (1) TPS60402DBV negative charge pump.
FIGURE 10. Single +5V Power-Supply Operation.
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LOG101AID 功能描述:对数放大器 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
LOG101AIDE4 功能描述:对数放大器 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
LOG101AIDR 功能描述:对数放大器 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
LOG101AIDRE4 功能描述:对数放大器 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
LOG102 制造商:TI 制造商全称:Texas Instruments 功能描述:LOGARITHMIC AND LOG RATIO AMPLIFIER