MC68HC705JP7 Datasheet, PDF (130/242 Pages) Motorola, Inc – HCMOS Microcontroller Unit

Freescale Semiconductor, Inc.
Analog Subsystem
V_CAP
V_X
t_DIS
t_DIS
(MIN)
t_DIS
(MIN)
V_MAX
t_CHG
V_X = ^{tCHG x ICHG}
C_EXT
CHG
COMP2
(TCAP)
TOF
OCF
ICF
0
1
2
31
2
Point
Action
Software/Hardware Action Dependent Variable(s)
Begin initial discharge and select mode 2
0
by clearing CHG and ATD1 and setting
ATD2 in the ACR. Also set ICEN bit in
Software write
ACR and IEDG bit in TCR.
Software
1 V_CAP falls to V_SS.
Wait out minimum t_DIS time.
V_MAX, I_DIS, C_EXT
2
Stop discharge and begin charge when
the next TOF sets the CHG control bit in
ACR.
Timer TOF sets the CHG control
bit in the ACR.
Free-running timer
counter overflow, f_OSC
V_CAP rises to V_X and comparator 2
output trips, setting CPF2 and CMP2, ^{Wait out t}CHG ^time.
3 which causes an ICF from the timer and Timer ICF clears the CHG control V_X, I_CHG, C_EXT
clears the CHG control bit in ACR. Must bit in the ACR.
clear CPF2 to trap next CPF2 flag.
Figure 8-10. A/D Conversion — TOF/ICF Control (Mode 2)
Advance Information
130
MC68HC705JJ7 • MC68HC705JP7 — REV 4
Analog Subsystem
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