isppac20 Lattice Semiconductor Corp., isppac20 Datasheet - Page 18

• Manufacturer Part Number: isppac20
• Description: In-system Programmable Analog Circuit
• Manufacturer: Lattice Semiconductor Corp.

and becomes a factor in the overall output noise voltage,
causing it to increase.
Input Common-Mode Voltage Range
For the ispPAC20, both maximum input signal range and
corresponding common-mode voltage range are a func-
tion of the input gain setting. The maximum input voltage
times the gain of an individual PACblock cannot exceed
the output range of that block or clipping will occur. The
maximum guaranteed input range is 1V to 4V, with an
extended typical range of 0.7V to 4.3V for a 5V supply
voltage.
The input common-mode voltage is V
When the value of V
restrictions other than the previously mentioned clipping
consideration. This is easily achieved when the input
signal is true differential and referenced to 2.5V.
Table 1. Input Common-Mode Voltage Range Limitations
*Peak input voltage for guaranteed performance at a given gain setting.
Theory of Operation (Continued)
1.000
1.100
1.200
1.300
1.400
1.500
1.600
1.700
1.800
1.900
2.000
2.100
2.200
2.300
2.400
2.426
2.500
V
CM-
4.000
3.900
3.800
3.700
3.600
3.500
3.400
3.300
3.200
3.100
3.000
2.900
2.800
2.700
2.600
2.574
2.500
V
CM+
CM
is 2.5V, there are no further input
3.000*
0.557
0.728
0.899
1.071
1.242
1.413
1.584
1.756
1.927
2.098
2.270
2.441
2.612
2.783
2.955
3.126
G=1
1.500*
CM
0.278
0.364
0.450
0.535
0.621
0.707
0.792
0.878
0.964
1.049
1.135
1.220
1.306
1.392
1.477
1.563
G=2
= (V
Input Voltage Magnitude (Volts-Peak)
CM+
1.000*
0.186
0.243
0.300
0.357
0.414
0.471
0.528
0.585
0.642
0.699
0.757
0.814
0.871
0.928
0.985
1.042
G=3
+ V
CM-
0.750*
0.139
0.182
0.225
0.268
0.310
0.353
0.396
0.439
0.482
0.525
0.567
0.610
0.653
0.696
0.739
0.782
)/2.
G=4
18
When V
one, distortion will occur when the maximum input limit is
reached for a particular gain. The lowest V
gain setting is expressed by the formula, V
+ 0.584G·V
peak input voltage, expressed as |V
highest V
nominal supply voltage.
In Table 1, the maximum V
range is given. If the maximum V
equivalent or greater value under the appropriate gain
column and the widest range for V
horizontally across in the left-most two columns. Only a
V
free performance. Conversely, if the maximum V
range is known, the largest acceptable peak value of V
can be found in the corresponding gain column. All
values of V
mance.
CM
0.600*
0.111
0.146
0.180
0.214
0.248
0.283
0.317
0.351
0.385
0.420
0.454
0.488
0.522
0.557
0.591
0.625
G=5
range equal to or less than this will give distortion-
CM
CM
Specifications ispPAC20
0.500*
is not 2.5V and the gain setting is greater than
0.093
0.121
0.150
0.178
0.207
0.236
0.264
0.293
0.321
0.350
0.378
0.407
0.435
0.464
0.492
0.521
IN
IN
G=6
where G is the gain setting and V
is V
less than this will give full rated perfor-
CM+
0.429*
0.080
0.104
0.128
0.153
0.177
0.202
0.226
0.251
0.275
0.300
0.324
0.349
0.373
0.398
0.422
0.447
G=7
= 5.0V - V
IN
0.375*
0.070
0.091
0.112
0.134
0.155
0.177
0.198
0.219
0.241
0.262
0.284
0.305
0.327
0.348
0.369
0.391
G=8
for a given V
CM–
IN
0.333*
IN+
is known, find the
0.062
0.081
0.100
0.119
0.138
0.157
0.176
0.195
0.214
0.233
0.252
0.271
0.290
0.309
0.328
0.347
CM
G=9
where 5V is the
- V
will be found
CM
CM–
CM–
IN–
for a given
0.300*
G=10
0.056
0.073
0.090
0.107
0.124
0.141
0.158
0.176
0.193
0.210
0.227
0.244
0.261
0.278
0.295
0.313
| and the
= 0.675V
to V
IN
is the
CM+
CM
IN