Datasheet

LTC6655
18
6655fd
For more information www.linear.com/LTC6655
applicaTions inForMaTion
+ –
100k100k
SHIELD
SHIELDED CAN
1N4697
10V
AC LINE GROUND
1300µF
9V
100k* 10Ω*
+
–
1k*
200Ω*
2k
450Ω*
900Ω*
15V
15V
–15V
–15V
1µF
1µF
A1
LT1012
A2
LT1097
6655 F16
– INPUT
Q1
5
* = 1% METAL FILM ** = 1% WIREWOUND, ULTRONIX105A = 1N4148 = 2N4393 = 1/4 LTC202 SEE APPENDIX C FOR POWER, SHIELDING AND GROUNDING SCHEME
= TANTALUM,WET SLUG I
LEAK
< 5nA
SEE TEXT/APPENDIX B = POLYPROPELENE A4 330µF OUTPUT CAPACITORS = <200nA LEAKAGE AT 1V
DC
AT 25°C
Q1, Q2 = THERMALLY MATED 2SK369 (MATCH V
GS
10%)
OR LSK389 DUAL THERMALLY LAG SEE TEXT
A = 10
4
LOW NOISE
PRE-AMP
REFERENCE
UNDER TEST
0.15µF
750Ω*
10k
–15V
Q3
2N2907
Q2
0.022µF
1µF
**1.2k
SD
LTC6655
2.5V
IN
S
F
+
1µF
0.1µF
124k* 124k*
–
+
A3
LT1012
1M*
10k*
100Ω*330Ω*
IN OUT
ROOT-SUM-SQUARE
CORRECTION
SEE TEXT
330µF
16V
330µF
16V
+
+
330µF
16V
330µF
16V
+
–
A4
LT1012
0.1µF
0.1µF
10k
A = 100 AND
0.1Hz TO 10Hz FILTER
1µF
RST
+
–
A5
1/4 LT1058
–
+
A7
1/4 LT1058
1k
PEAK TO PEAK
NOISE DETECTOR
O TO 1V = O TO 1µV
+ PEAK
4.7k
P
P
1µF
RST
15V
0.1µF
+
–
A6
1/4 LT1058
–
+
A8
1/4 LT1058
1k
– PEAK
4.7k
10k
100k
100k
P
T
T
– +
DVM
TO OSCILLOSCOPE INPUT
VIA ISOLATED PROBE,
1V/DIV = 1µV/DIV,
REFERRED TO INPUT,
SWEEP = 1s/DIV
FROM OSCILLOSCOPE
SWEEP GATE OUTPUT
VIA ISOLATION
PULSE TRANSFORMER
RESET PULSE
GENERATOR
0.22µF
C2
RC2
+15V
+15V
CLR2
+15V
74C221
RST = Q2
+V
+15V
A2
B2
10k
BAT-85
BAT-85
10k
+
+
0.005µF
–15V
10k
0.005µF
Figure 17. Detailed Noise Test Circuitry. See Application Note 124.