NXP Semiconductors P89LPC9321 UM10310 - Manual (Page 31)

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User manual Rev. 2 — 1 November 2010 31 of 139
NXP Semiconductors
UM10310
P89LPC9321 User manual
4.4 Input-only configuration
The input port configuration is shown in Figure 12 . It is a Schmitt-triggered input that also
has a glitch suppression circuit.
(Please refer to the P89LPC9321 data sheet, Dynamic characteristics for glitch filter
specifications).
4.5 Push-pull output configuration
The push-pull output configuration has the same pull-down structure as both the open
drain and the quasi-bidirectional output modes, but provides a continuous strong pull-up
when the port latch contains a logic 1. The push-pull mode may be used when more
source current is needed from a port output.
The push-pull port configuration is shown in Figure 13 .
A push-pull port pin has a Schmitt-triggered input that also has a glitch suppression circuit.
(Please refer to the P89LPC9321 data sheet, Dynamic characteristics for glitch filter
specifications).
4.6 Port 0 and Analog Comparator functions
The P89LPC9321 incorporates two Analog Comparators. In order to give the best analog
performance and minimize power consumption, pins that are being used for analog
functions must have both the digital outputs and digital inputs disabled.
Fig 12. Input only.
002aaa916
input
data
port
pin
glitch rejection
Fig 13. Push-pull output.
002aaa917
port latch
data
input
data
port
pin
strong
glitch rejection
V DD
P
N