P89LPC938 NXP Semiconductors, P89LPC938 Datasheet - Page 25

• Manufacturer Part Number: P89LPC938
• Description: The P89LPC938 is a single-chip microcontroller, available in low cost packages, based ona high performance processor architecture that executes instructions in two to four clocks,six times the rate of standard 80C51 devices
• Manufacturer: NXP Semiconductors

Philips Semiconductors
9397 750 14051
Product data sheet
7.13.1.3 Input-only configuration
7.13.1.4 Push-pull output configuration
7.13.2 Port 0 analog functions
7.13.3 Additional port features
7.14 Power monitoring functions
An open-drain port pin has a Schmitt triggered input that also has a glitch suppression
circuit.
The input-only port configuration has no output drivers. It is a Schmitt triggered input that
also has a glitch suppression circuit.
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. A push-pull port pin has a
Schmitt triggered input that also has a glitch suppression circuit.
The P89LPC938 incorporates two Analog Comparators. In order to give the best analog
function performance and to minimize power consumption, pins that are being used for
analog functions must have the digital outputs and digital inputs disabled.
Digital outputs are disabled by putting the port output into the Input-Only
(high-impedance) mode.
Digital inputs on Port 0 may be disabled through the use of the PT0AD register, bits 1:5.
On any reset, PT0AD[1:5] defaults to ‘0’s to enable digital functions.
After power-up, all pins are in Input-Only mode. Please note that this is different from
the LPC76x series of devices.
Every output on the P89LPC938 has been designed to sink typical LED drive current.
However, there is a maximum total output current for all ports which must not be
exceeded. Please refer to
specifications.
All ports pins that can function as an output have slew rate controlled outputs to limit noise
generated by quickly switching output signals. The slew rate is factory-set to
approximately 10 ns rise and fall times.
The P89LPC938 incorporates power monitoring functions designed to prevent incorrect
operation during initial power-up and power loss or reduction during operation. This is
accomplished with two hardware functions: Power-on detect and brownout detect.
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•
After power-up, all I/O pins except P1.5, may be configured by software.
Pin P1.5 is input only. Pins P1.2 and P1.3 and are configurable for either input-only or
open-drain.
Rev. 01 — 25 February 2005
Table 10 “DC electrical characteristics”
8-bit microcontroller with 10-bit A/D converter
© Koninklijke Philips Electronics N.V. 2005. All rights reserved.
P89LPC938
for detailed
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