M62301SP/FP
Operating Description
(1) Decoder
Based on digital inputs to C0, C1, C2, the analog switch is set to on, and the input of "0" scale (GND input), input of
reference scale (reference voltage input), input to A1-A4, or discharge from integration capacitor (C
I
) is performed.
None of these operations is performed when the "mode 8" input is given:
Mode
C0
C1
C2
1
0
0
0
Discharge
2
1
0
0
GND
3
0
1
0
V
REF
4
1
1
0
A1
5
0
0
1
A2
6
1
0
1
A3
7
0
1
1
A4
8
1
1
1
—
(2) A/D conversion
Decoder selection mode
1
2
1
3
1
4 to 7
1
V
IN
+ 0.49 V
V (8)
V
REF
+ 0.49 V
0.49 V
0.36 V
T
GND
T
REF
T
IN
Multiplexer first selects V
GND
, obtaining minimum pulse T
GND
. It then selects V
REF
, obtaining reference pulse T
REF
.
Input is selected next, obtaining input pulse T
IN
. V
IN
is obtained by deducting T
GND
, as the offset, from T
REF
and T
IN
.
V
IN
= V
REF
•
T
IN
−
T
G
T
REF
−
T
G
By measuring voltage at the maximum input for approximately 500
µs
under the counter clock of 8 MHz, resolution
of approximately 12 bits can be obtained;
500
µs
125 ns
≈
2
12
Note: To ensure discharge from capacitor C
I
, the decoder input as in the above diagram should stay in mode 1 at least
for the period calculated above:
Tdi = (C
I
×
V
IAmax
+ 0.49
1 mA
)
It is not necessary to measure T
GND
, and T
REF
for each channel.
REJ03D0861-0300 Rev.3.00 Mar 25, 2008
Page 4 of 11
RENESAS [ RENESAS TECHNOLOGY CORP ]
