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LT1399CS#TRPBF 参数 Datasheet PDF下载

LT1399CS#TRPBF图片预览
型号: LT1399CS#TRPBF
PDF下载: 下载PDF文件 查看货源
内容描述: [LT1399 - Low Cost Dual and Triple 300MHz Current Feedback Amplifiers with Shutdown; Package: SO; Pins: 16; Temperature Range: 0°C to 70°C]
分类和应用: 放大器
文件页数/大小: 16 页 / 232 K
品牌: Linear [ Linear ]
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LT1398/LT1399/LT1399HV  
O U  
W
U
PPLICATI  
S I FOR ATIO  
A
will remain enabled at all times, then the EN pin should be  
tied to the Vsupply. The enable pin current is approxi-  
mately 30µA when activated. If using CMOS open-drain  
logic, an external 1k pull-up resistor is recommended to  
ensure that the LT1399 remains disabled in spite of any  
CMOS drain-leakage currents.  
Power Supplies  
The LT1398/LT1399 will operate from single or split  
supplies from ±2V (4V total) to ±6V (12V total). The  
LT1399HV will operate from single or split supplies from  
±2V (4V total) to ±7.5V (15V total). It is not necessary to  
use equal value split supplies, however the offset voltage  
and inverting input bias current will change. The offset  
voltage changes about 600µV per volt of supply mis-  
match. The inverting bias current will typically change  
about 2µA per volt of supply mismatch.  
5.0  
T
= 25°C  
A
+
4.5  
4.0  
3.5  
3.0  
2.5  
2.0  
1.5  
1.0  
0.5  
0
V
= 5V  
V
= 0V  
V
= 5V  
Slew Rate  
Unlike a traditional voltage feedback op amp, the slew rate  
of a current feedback amplifier is not independent of the  
amplifier gain configuration. In a current feedback ampli-  
fier,boththeinputstageandtheoutputstagehaveslewrate  
limitations.Intheinvertingmode,andforgainsof2ormore  
inthenoninvertingmode,thesignalamplitudebetweenthe  
input pins is small and the overall slew rate is that of the  
outputstage.Forgainslessthan2inthenoninvertingmode,  
the overall slew rate is limited by the input stage.  
0
2
3
+
4
5
6
7
1
V
– V (V)  
EN  
1398/99 F01  
Figure 1. +IS vs (V+ – VEN  
)
OUTPUT  
The input slew rate of the LT1398/LT1399/LT1399HV is  
approximately 600V/µs and is set by internal currents and  
capacitances.Theoutputslewrateissetbythevalueofthe  
feedback resistor and internal capacitance. At a gain of 2  
with 324feedback and gain resistors and ±5V supplies,  
the output slew rate is typically 800V/µs. Larger feedback  
resistors will reduce the slew rate as will lower supply  
voltages.  
EN  
1398/99 F02  
VS = ±5V RF = 324Ω  
IN = 1V G = 324Ω  
RL = 100Ω  
V
R
Enable/ Disable  
Figure 2. Amplifier Enable Time, AV = 2  
Each amplifier of the LT1398/LT1399/LT1399HV has a  
unique high impedance, zero supply current mode which  
is controlled by its own EN pin. These amplifiers are  
designed to operate with CMOS logic; the amplifiers draw  
zero current when these pins are high. To activate each  
amplifier, its EN pin is normally pulled to a logic low.  
However, supply current will vary as the voltage between  
the V+ supply and EN is varied. As seen in Figure 1, +IS  
does vary with (V+ – VEN), particularly when the voltage  
difference is less than 3V. For normal operation, it is  
important to keep the EN pin at least 3V below the V+  
supply. If a V+ of less than 3V is desired, and the amplifier  
OUTPUT  
EN  
1398/99 F03  
VS = ±5V RF = 324Ω  
VIN = 1V RG = 324Ω  
RL = 100Ω  
Figure 3. Amplifier Disable Time, AV = 2  
10