參數(shù)資料
型號(hào)： ISPPAC30-01P
廠商： Lattice Semiconductor Corporation
英文描述： In-System Programmable Analog Circuit
中文描述： 在系統(tǒng)可編程模擬電路
文件頁數(shù)： 18/30頁
文件大?。?/td> 379K
代理商： ISPPAC30-01P
Lattice Semiconductor
ispPAC30 Preliminary Data Sheet
18
other as necessary to achieve higher gains, for example. Precision gain and offset con
fi
gurations can be imple-
mented using different combinations of IA’s, MDAC’s and VREF’s to condition signals using a common summing
junction to deliver the desired output result. The combination of analog input and summing node route options
make the ispPAC30 very powerful in enabling so many different circuit possibilities. Examples of possible circuits
are included in the ispPAC30 applications literature.
Output Ampli
fi
er Functional Modes
The ispPAC30 output ampli
fi
ers (OA’s) can be con
fi
gured to act as wideband ampli
fi
ers, lowpass
fi
lters, integrators
or comparators. Each mode is determined by SRAM (or E
2
con
fi
guration memory at turn-on) control bits that open
and close feedback elements around the OA’s. All available modes of OA operation can be con
fi
gured during the
design phase using PAC-Designer software or during normal operation via JTAG or SPI serial interface control.
Ampli
fi
er/Filter Mode
When con
fi
gured as a wideband ampli
fi
er, an ispPAC30’s OA feedback resistor connection is closed and the feed-
back capacitor set to its minimum value. The feedback capacitance set is required to maintain necessary stability.
When used in
fi
lter mode, the ispPAC30 differs from the wideband ampli
fi
er in that it has seven alternative feedback
capacitor values available to form the lowpass
fi
lter corner frequencies. See Table 3 for these values (listed as the
maximum corner frequencies in the precision
fi
lter range table). The capacitor values are trimmed for each device
to achieve an absolute pole frequency with an accuracy guaranteed to that given in the speci
fi
cations section. The
fi
rst order
fi
lter formed using the OA in this manner is not the only way a
fi
lter can be implemented using the
ispPAC30. In the following precision
fi
ltering section, an example is given for using an OA in integrator mode and
providing proportional feedback by putting one of the MDAC’s into the feedback loop. When calculating equivalent
time constants for ispPAC30 in
fi
lter mode, a nominal resistance of 50k
can be assumed. The frequencies called
out in PAC-Designer that are associated with individual feedback capacitor values are computed based on the
measured –3dB frequency of a single IA/OA combination (gain=1). Again, absolute accuracy is guaranteed as
listed in the
fi
lter speci
fi
cations section for all devices shipped.
Integrator Mode
In integrator mode, an OA’s feedback capacitor is closed and the feedback resistor is open. Operation then
becomes that of an integrator, with the expected non-ideal effects of a real operational ampli
fi
er (having
fi
nite gain-
bandwidth properties). The gain-phase simulator in the PAC-Designer will give the user a very good representation
of these
fi
rst-order effects on ideal operation. The effective time-constant of any given integrator con
fi
guration can
be computed knowing the feedback capacitor value and that an IA in a gain =1 will yield an effective input resis-
tance, R, equal to 50k
(1 time constant = 2 x
π
x RC). This value of R is divided by the gain setting of the IA, so in
a gain of 10 for example, R is equal to 5k
. When an MDAC is used as the input to an OA con
fi
gured as an integra-
tor, the effective R is equal to 50k
divided by the fraction of the input signal passed by the MDAC. For example, if
the MDAC is set to a code that results in passing 50% of the input signal, then R is equal to 50k
/0.5 or 100k
.
This can, of course, be used to advantage to either extend the effective time constant range or to
fi
ne tune it.
Comparator Mode
In comparator mode, both the feedback capacitor and resistor are opened around the OA. Also, the internal com-
pensation of the OA is altered to improve comparator output characteristics. Since only one input is available to the
OA in comparator mode, instead of the normally expected two, a slightly different approach is required to realize a
true comparison function. This is done by using the reference voltage and summing it with the value it is to be com-
pared with. Whenever the input to be compared is greater than the reference input value the OA output is high and
when it is less, the OA output is low. The logic sense of this comparator output can be controlled at will by selecting
either plus or minus gains in the IA/MDAC input sections. When examined closely, it may be observed that compar-
ator mode operation appears identical to that of the integrator mode with a minimum feedback capacitance. This is
true except in comparator mode the output compensation of the OA is altered to get optimum switching times. That
means using the OA in other linear modes without this compensation enabled will likely result in unstable opera-
tion. In PAC-Designer, the default con
fi
guration modes will not allow this to happen.
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ISPPAC30-01PI In-System Programmable Analog Circuit
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ISPPAC30-01PI 功能描述:SPLD - 簡(jiǎn)單可編程邏輯器件 PROGRAMMABLE ANALOG CIRCUIT RoHS:否 制造商:Texas Instruments 邏輯系列:TICPAL22V10Z 大電池?cái)?shù)量:10 最大工作頻率:66 MHz 延遲時(shí)間:25 ns 工作電源電壓:4.75 V to 5.25 V 電源電流:100 uA 最大工作溫度:+ 75 C 最小工作溫度:0 C 安裝風(fēng)格:Through Hole 封裝 / 箱體:DIP-24
ISPPAC30-01S 制造商:LATTICE 制造商全稱:Lattice Semiconductor 功能描述:In-System Programmable Analog Circuit
ISPPAC30-01SI 功能描述:SPLD - 簡(jiǎn)單可編程邏輯器件 Not Upgrade Device CIRCUIT RoHS:否 制造商:Texas Instruments 邏輯系列:TICPAL22V10Z 大電池?cái)?shù)量:10 最大工作頻率:66 MHz 延遲時(shí)間:25 ns 工作電源電壓:4.75 V to 5.25 V 電源電流:100 uA 最大工作溫度:+ 75 C 最小工作溫度:0 C 安裝風(fēng)格:Through Hole 封裝 / 箱體:DIP-24
ISPPAC80-01PI 功能描述:SPLD - 簡(jiǎn)單可編程邏輯器件 PROGRAMMABLE ANALOG CIRCUIT RoHS:否 制造商:Texas Instruments 邏輯系列:TICPAL22V10Z 大電池?cái)?shù)量:10 最大工作頻率:66 MHz 延遲時(shí)間:25 ns 工作電源電壓:4.75 V to 5.25 V 電源電流:100 uA 最大工作溫度:+ 75 C 最小工作溫度:0 C 安裝風(fēng)格:Through Hole 封裝 / 箱體:DIP-24
ISPPAC80-01SI 功能描述:SPLD - 簡(jiǎn)單可編程邏輯器件 PROGRAMMABLE ANALOG CIRCUIT RoHS:否 制造商:Texas Instruments 邏輯系列:TICPAL22V10Z 大電池?cái)?shù)量:10 最大工作頻率:66 MHz 延遲時(shí)間:25 ns 工作電源電壓:4.75 V to 5.25 V 電源電流:100 uA 最大工作溫度:+ 75 C 最小工作溫度:0 C 安裝風(fēng)格:Through Hole 封裝 / 箱體:DIP-24
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