LMP8358MA NSC [National Semiconductor], LMP8358MA Datasheet - Page 23

• Manufacturer Part Number: LMP8358MA
• Description: Zero-Drift, Programmable Instrumentation Amplifier with Diagnostics
• Manufacturer: NSC [National Semiconductor]

Frequency Compensation (Serial)
The gain-bandwidth compensation is set to one of five levels
under program control. The amount of compensation can be
decreased to maximize the available bandwidth as the gain
of the amplifier is increased. The compensation level is se-
lected by setting bits COMP[2:0] of the control register with
000b, 001b, 010b, 011b, or 1xxb.
pensation (Register bits 5:3)
Input Multiplexer and Polarity Switch (Serial)
The Input Multiplexer Selection bits MUX[1:0] and Polarity bit
POL can be used to set the inputs of the LMP8358 to the
Polarity Reversal
When MUX[1:0] = 00b and POL = 0b the LMP8358 has the
input of a normal instrumentation amplifier. The input for the
LMP8358 is defined as Gain × (V
the input for the LMP8358 is defined as Gain × (V
Polarity reversal can be used to do system level calibration,
Gain\COMP [2:0]
10
20
50
100
200
500
1000
User Defined Gain
GBW Product
MUX1
0
0
1
1
MUX0
0
1
0
1
Diff Input for POL = 0
shows the bandwidths achieved
+IN
Table 9. Input Multiplexer and Polarity (Register bits 8:6)
Bandwidth
000
930 kHz
385 kHz
160 kHz
80 kHz
38 kHz
16 kHz
8 kHz
> 10x
8 MHz
Table 8. Frequency Com-
Table 8. Frequency Compensation (Register bits 5:3)
− V
−IN
). When POL = 1b,
−IN
001
n/a
n/a
460 kHz
225 kHz
95 kHz
40 kHz
22 kHz
> 30x
24 MHz
– V
+IN
).
23
at the selectable gain and compensation settings. Note that
for gains 10X and 20X, the recommended compensation set-
ting is 000b. For the gain setting 50X, compensation settings
may be 000b and 001b. Gain settings 100X and 200X may
use the three bandwidth compensation settings 000b, 001b,
and 010b. At gains of 500X and 1000X, all bandwidth com-
pensation ranges may be used. Note that for lower gains, it is
possible to under compensate the amplifier into instability.
states shown in
ister bits
for example, to compensate for thermocouple voltages, resid-
ual offset of the LMP8358, or offsets of the sensor or ADC.
Short Inputs
When MUX[1:0] = 01b and POL = 0b both inputs are con-
nected to the +IN pin of the LMP8358. The –IN pin is left
010
n/a
n/a
n/a
640 kHz
195 kHz
85 kHz
50 kHz
> 100x
80 MHz
Diff Input for POL = 1
8:6).
Table 9. Input Multiplexer and Polarity (Reg-
011
n/a
n/a
n/a
n/a
n/a
130 kHz
89 kHz
> 300x
240 MHz
1xx
74 kHz
37 kHz
16 kHz
8 kHz
4 kHz
1.5 kHz
0.8 kHz
> 1x
0.8 MHz
(For external filter cap)
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