LTC1966HMS8-PBF View Datasheet(PDF) - Linear Technology
Part Name
Description
Manufacturer
LTC1966HMS8-PBF Datasheet PDF : 38 Pages
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LTC1966
Applications Information
7. Output is noisy with >10kHz inputs.
– This is a fundamental characteristic of this topol-
ogy. The LTC1966 is designed to work very well
with inputs of 1kHz or less. It works okay as high
as 1MHz, but it is limited by aliased ∆Σ noise.
Solution: Bandwidth limit the input or digitally filter
the resulting output.
8. Large errors occur at crest factors approaching, but
less than 4.
– Insufficient averaging.
Solution: Increase CAVE. See Crest Factor and AC + DC
Waveforms section for discussion of output droop.
9. Screwy results, errors > spec limits, typically 1% to 5%.
– High impedance (85kΩ) and high accuracy (0.1%)
require clean boards! Flux residue, finger grime, etc.
all wreak havoc at this level.
Solution: Wash the board.
Helpful Hint: Sensitivity to leakages can be reduced
significantly through the use of guard traces.
KEEP BOARD CLEAN
10. Gain is low by ≅1% or more, no other problems.
– Probably due to circuit loading. With a DMM or
a 10× scope probe, ZIN = 10MΩ. The LTC1966
output is 85kΩ, resulting in – 0.85% gain error.
Output impedance is higher with the DC accurate
post filter.
Solution: Remove the shunt loading or buffer the
output.
– Loading can also be caused by cheap averaging
capacitors.
Solution: Use a high quality metal film capacitor
for CAVE.
LOADING DRAGS DOWN GAIN
LTC1966
5
VOUT
85k
6
OUT RTN
mV
DCV
10M
DMM
200mVRMS IN
–0.85%
1966 TS10
LTC1966
1966fb
33
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