LF155, LF156, LF355, LF356, LF357
SNOSBH0C –MAY 2000–REVISED MARCH 2013
www.ti.com
Figure 55. Fast Sample and Hold
Both amplifiers (A1, A2) have feedback loops individually closed with stable responses (overshoot negligible)
•
•
Acquisition time TA, estimated by:
•
•
•
LF156 develops full Sr output capability for VIN ≥ 1V
Addition of SW2 improves accuracy by putting the voltage drop across SW1 inside the feedback loop
Overall accuracy of system determined by the accuracy of both amplifiers, A1 and A2
Figure 56. High Accuracy Sample and Hold
•
•
By closing the loop through A2, the VOUT accuracy will be determined uniquely by A1.
–
No VOS adjust required for A2.
TA can be estimated by same considerations as previously but, because of the added
propagation delay in the feedback loop (A2) the overshoot is not negligible.
–
•
•
•
Overall system slower than fast sample and hold
R1, CC: additional compensation
Use LF156 for
–
–
Fast settling time
Low VOS
22
Submit Documentation Feedback
Copyright © 2000–2013, Texas Instruments Incorporated
Product Folder Links: LF155 LF156 LF355 LF356 LF357
TI [ TEXAS INSTRUMENTS ]
