© Koninklijke Philips Electronics N.V. 2005. All rights reserved.
User manual
Rev. 03 — 7 June 2005
36 of 139
Philips Semiconductors
UM10119
P89LPC938 User manual
5.4 Input-only configuration
The input port configuration is shown in
. It is a Schmitt-triggered input that also
has a glitch suppression circuit.
(Please refer to the
P89LPC938 data sheet, Dynamic characteristics
for glitch filter
specifications).
5.5 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
A push-pull port pin has a Schmitt-triggered input that also has a glitch suppression
circuit.
(Please refer to the
P89LPC938 data sheet, Dynamic characteristics
for glitch filter
specifications).
Fig 11. Open drain output.
002aaa915
port latch
data
input
data
glitch rejection
port
pin
Fig 12. Input only.
002aaa916
input
data
port
pin
glitch rejection