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ML51/ML54/ML56
Sep. 01, 2020
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Rev 2.00
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ML51/M
L54
/M
L56
Series
Tec
hnical Reference
Manual
Port Pin
Input
Figure 6.4-3 Input-Only Mode Structure
Open-Drain Mode
The open-drain mode turns off all pull-high transistors and only drives the pull-low of the port pin when
the port latch is given by logic 0. If the port latch is logic 1, it behaves as if in input-only mode. To be
used as an output pin generally as R/W lines, an open-drain pin should add an external pull-high,
typically a resistor tied to V
DD
. User needs to take care that an open-drain pin with its port latch as
logic 1 should be given with a determined voltage level by external devices or resistors. A floating pin
will induce leakage current especially in Power-down mode.
Port Pin
Input
Port Latch
N
Figure 6.4-4 Open-Drain Mode Structure