PFS122
8bit MTP MCU with 12-bit R-Type ADC
5.5.1 Internal reference voltage (Vinternal R
)
The internal reference voltage Vinternal R is built by series resistance to provide different level of reference
voltage, bit 4 and bit 5 of gpcs register are used to select the maximum and minimum values of Vinternal R
and bit [3:0] of gpcs register are used to select one of the voltage level which is deivided-by-16 from the
defined maximum level to minimum level. Fig.5 to Fig.8 shows four conditions to have different reference
voltage Vinternal R. By setting the gpcs register, the internal reference voltage Vinternal R can be ranged from
(1/32)*VDD to (3/4)*VDD.
Case 1 : gpcs.5=0 & gpcs.4=0
16 stages
VDD
8R
8R
8R
gpcs.4=0
gpcs.4=1
gpcs.5=1
R
R
R
R
gpcs.5=0
MUX
gpcs[3:0]
V
internal R = (3/4) VDD ~ (1/4) VDD + (1/32) VDD
@ gpcs[3:0] = 1111 ~ gpcs[3:0] = 0000
1
4
(n+1)
32
V internal R
=
*
VDD +
*
VDD, n = gpcs[3:0] in decimal
Fig.5: Vinternal R hardware connection if gpcs.5=0 and gpcs.4=0
Case 2 : gpcs.5=0 & gpcs.4= 1
16 stages
VDD
8R
8R
8R
gpcs.4=0
gpcs.4=1
gpcs.5=1
R
R
R
R
gpcs.5=0
MUX
gpcs[3:0]
V internal R = (2/3) VDD ~ (1/24) VDD
@ gpcs[3:0] = 1111 ~ gpcs[3:0] = 0000
(n+1)
V internal R
=
*
VDD, n = gpcs[3:0] in decimal
24
Fig.6: Vinternal R hardware connection if gpcs.5=0 and gpcs.4=1
©Copyright 2020, PADAUK Technology Co. Ltd
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PDK-DS-PFS122-EN_V000-May 28, 2020
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