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TC9400 参数 Datasheet PDF下载

TC9400图片预览
型号: TC9400
PDF下载: 下载PDF文件 查看货源
内容描述: 电压 - 频率/频率 - 电压转换器 [VOLTAGE-TO-FREQUENCY/FREQUENCY-TO-VOLTAGE CONVERTERS]
分类和应用: 转换器
文件页数/大小: 13 页 / 155 K
品牌: TELCOM [ TELCOM SEMICONDUCTOR, INC ]
 浏览型号TC9400的Datasheet PDF文件第1页浏览型号TC9400的Datasheet PDF文件第2页浏览型号TC9400的Datasheet PDF文件第3页浏览型号TC9400的Datasheet PDF文件第4页浏览型号TC9400的Datasheet PDF文件第6页浏览型号TC9400的Datasheet PDF文件第7页浏览型号TC9400的Datasheet PDF文件第8页浏览型号TC9400的Datasheet PDF文件第9页  
VOLTAGE-TO-FREQUENCY/  
FREQUENCY-TO-VOLTAGECONVERTERS  
3
TC9400  
TC9401  
TC9402  
+5V  
14  
+
5V  
V
R
10kΩ  
L
DD  
f
THRESHOLD  
DETECT  
OUT 8  
11  
3µsec  
DELAY  
+
5V  
THRESHOLD  
DETECTOR  
R
L
10kΩ  
f
/2  
OUT  
10  
9
SELF-  
START  
÷2  
OUTPUT  
COMMON  
–3V  
12 AMP OUT  
V
OUT  
REF  
5
20kΩ  
C
INT  
C
REF  
820pF  
12pF  
180pF  
TC9400  
TC9401  
TC9402  
R
1MΩ  
IN  
INPUT  
60pF  
I
IN  
3
V
IN  
+5V  
OpAmp  
+
ZERO  
ADJUST  
0V –10V  
50kΩ  
510kΩ  
2
V
V
7
I
GND  
6
SS  
REF  
BIAS  
–5V  
1
4
OFFSET  
ADJUST  
10kΩ  
R
BIAS  
100kΩ  
REFERENCE  
VOLTAGE  
(TYPICALLY –5V)  
–5V  
Figure 1. 10 Hz to 10 kHz V/F Converter  
VOLTAGE-TO-FREQUENCY (V/F)  
CIRCUIT DESCRIPTION  
At the end of the charging period, CREF is shorted out.  
This dissipates the charge stored on the reference capaci-  
tor, so that when the output again crosses zero the system  
is ready to recycle. In this manner, the continued discharg-  
ing of the integrating capacitor by the input is balanced out  
by fixed charges from the reference voltage. As the input  
voltage is increased, the number of reference pulses re-  
quired to maintain balance increases, which causes the  
output frequency to also increase. Since each charge in-  
crement is fixed, the increase in frequency with voltage is  
linear. In addition, the accuracy of the output pulse width  
does not directly affect the linearity of the V/F. The pulse  
must simply be long enough for full charge transfer to take  
place.  
The TC9400 V/F converter operates on the principal  
of charge balancing. The operation of the TC9400 is easily  
understood by referring to Figure 1. The input voltage (VIN)  
is converted to a current (IIN) by the input resistor. This  
current is then converted to a charge on the integrating  
capacitor and shows up as a linearly decreasing voltage at  
the output of the op amp. The lower limit of the output  
swing is set by the threshold detector, which causes the  
reference voltage to be applied to the reference capacitor  
for a time period long enough to charge the capacitor to  
the reference voltage. This action reduces the charge on  
the integrating capacitor by a fixed amount (q = CREF  
×
VREF), causing the op amp output to step up a finite  
amount.  
TELCOM SEMICONDUCTOR, INC.  
3-291  
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