Datasheet

LT6003/LT6004/LT6005
15
600345fd
APPLICATIONS INFORMATION
Figure 4. Adaptive Filter
S1
S
COMP
OUT
BA
S1: FAIRCHILD FSA1157
V
CC
= 1.8V TO 5V
I
CC
= 10µA, RISING TO 20µA
WITH LARGE SIGNAL
600345 F04
–
+
A2
1/4 LT6005
10M
V
CC
V
OUT
V
IN
–
+
A3
1/4 LT6005
249k
200k
249k
10M
10M
10k
10M
–
+
A4
1/4 LT6005
249k
249k
LT6700-2
–
INB
–
INA
V
S
V
CC
V
CC
GND
OUTB OUTA
–
+
A1
1/4 LT6005
1M
ADAPTIVE FILTER IMPROVES INHERENT TRADE-OFF OF SETTLING TIME VS NOISE FILTERING. SMALL SIGNAL DC STEPS
SETTLE WITH A 20ms TIME CONSTANT FOR AN 8Hz NOISE BANDWIDTH. LARGE STEP SIGNALS (>10mV) CAUSE S1 TO
TURN ON, SPEEDING UP THE TIME CONSTANT TO 1ms, FOR IMPROVED SETTLING. AS THE OUTPUT SETTLES BACK TO
WITHIN 10mV, 51 TURNS OFF AGAIN, RESTORING THE 20ms TIME CONSTANT, FOR IMPROVED FILTERING.
0.1µF
V
IN
100mV/DIV
V
OUT
50mV/DIV
COMP
OUT
5V/DIV
2ms/DIV
600345 F04b
Figure 5. Precision 1.25µA Current Source
I
LOAD
=
V
S
= V
LOAD
+ 2V
600345 F05
V
S
V
S
+
–
LT6003
R1
1M
V
LOAD
LOAD
1.25V
R1
I
LOAD
R2
390k
LT1389-1.25