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UM10601
All information provided in this document is subject to legal disclaimers.
© NXP B.V. 2012. All rights reserved.
Preliminary user manual
Rev. 1.0 — 7 November 2012
157 of 313
NXP Semiconductors
UM10601
Chapter 13: LPC800 Analog comparator
13.5.1 Reference voltages
The voltage ladder can use two reference voltages, from the VDDCMP or the V
DD
pin.
The voltage ladder selects one of 32 steps between the pin voltage and V
SS
inclusive. The
voltage on VDDCMP should not exceed that on V
DD
.
13.5.2 Settling times
After the voltage ladder is powered on, it requires stabilization time until comparisons
using it are accurate. Much shorter settling times apply after the LADSEL value is
changed and when either or both voltage sources are changed. Software can deal with
these factors by repeatedly reading the comparator output until a number of readings yield
the same result.
13.5.3 Interrupts
The interrupt output comes from edge detection circuitry in this module. Rising edges,
falling edges, or both edges can set the COMPEDGE bit and thus request an interrupt.
COMPEDGE and the interrupt request are cleared when software writes a 1 to
EDGECLR.
Fig 20. Comparator block diagram
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