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UM11029
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© NXP Semiconductors N.V. 2017. All rights reserved.
User manual
Rev. 1.0 — 16 June 2017
470 of 515
NXP Semiconductors
UM11029
Chapter 27: LPC84x Digital-to-Analog Converter (DAC)
27.3 Architecture
27.4 Pin description
gives a brief summary of each of DAC related pins.
Fig 62. DAC control with DMA interrupt and timer
CNTVAL
COUNTER
PRE-BUFFER
MUX
CR
LD
LD
LD
EN
16
16
pbus
pbus
set_intrpt
dblbuf_ena
cnt_ena
ena_cnt_and_dblbuf
pbus_wr_to_CR
1
0
pbus
pbus
pbus_wr_to_CR
zero
DAC value
3
2
1
0
S
C
set_intrpt
pbus
pbus_wr_to_CR
DMA_ena
intrptDMA_req
Table 457. D/A Pin Description
Pin
Type
Description
DAC_OUT
Output
Analog Output.
After the selected settling time after the CR is written with a new value, the
voltage on this pin (with respect to V
SSA
) is VALUE
((V
REFP
)/1024). Note that DAC_OUT is
disabled when the CPU is in Deep-sleep, Power-down, or Deep Power-down modes.
V
REFP
Reference
Voltage Reference.
This pin provides a voltage reference level for the ADC and DAC. Note:
V
REFP
should be tied to VDD(3V3) if the ADC and DAC are not used.
V
DDA
, V
SSA
Power
Analog Power and Ground.
These should typically be the same voltages as V
DD
and V
SS
,
but should be isolated to minimize noise and error.
Note: V
DDA
should be tied to VDD(3V3)
and V
SSA
should be tied to V
SS
if the ADC and DAC are not used.