Datasheet

LM12L458
www.ti.com SNAS085B –JULY 1999–REVISED MARCH 2013
Excessive output capacitance on the digital lines. The current required to charge the capacitance on the
digital outputs can cause noise on the supply bus within the LM12L458, causing internal supply "bounce" even
when the external supply pin is pretty stable. The current required to discharge the output capacitance can cause
die ground "bounce". Either of these can cause noise to be induced at the analog inputs, resulting in conversion
errors.
Output capacitance should be limited as much as possible. A series 100Ω resistor in each digital output line,
located very close to the output pin, will limit the charge and discharge current, minimizing the extent of the
conversion errors.
Improper CS decoding. If address decoder is used, care must be exercised to ensure that no "runt" (very
narrow) pulse is produced on the CS line when trying to address another device or memory. Even sub-
nanosecond spikes on the CS line can cause the chip to be reprogrammed in accordance with what happens to
be on the data lines at the time. The result is unexpected operation. The worst case result is that the device is
put into the "Test" mode and the on-board EEPROM that corrects linearity is corrupted. If this happens, the only
recourse is to replace the device.
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