M62301SP/FP
Application Suggestion
1. 4-channel 11-bit A/D converter system
To microcomputer
5 V power supply
5V
10 k 10 k
1
2
20
19
18
To microcomputer
control pin
To counter
To
RESET
C
INT
680 pF
3
4
5
6
7
8
17
16
15
14
13
12
11
Input analog
voltage
M62301SP/FP
C
REF
4700 pF
50
µA
C
I
4700 pF
9
10
I
I
= 50
µA
R
I
24 k
Charge current I
I
=
1.22 V
24 kΩ
≈
50
µA
Note:
C
REF
: To stabilize reference voltage, be sure to connect capacitance of approximately 4700 pF.
C
INT
: We suggest that this capacitance be connected to prevent malfunction due to noise.
Use C
I
that leaks as slight current as possible. To prevent leak to the circuit board, we recommend
providing guard ring (7), (9).
Resolution depends on the number of microcomputer counter clock pulses that are generated while the INT output
status is "high" at the maximum input voltage 2.5 V (V
CC
– 2.5 V).
When the microcomputer counter clock frequency is 8 MHz, the resolution can be calculated by using the constant
calculated above, as follows;
4700 pF
×
(2.5 + 0.13)
50
µA
1
8M
≈
2
11
Therefore, the resolution of this system is approximately 11 bits.
REJ03D0861-0300 Rev.3.00 Mar 25, 2008
Page 6 of 11
RENESAS [ RENESAS TECHNOLOGY CORP ]
