M30260F6AGP#U3 Renesas Electronics America, M30260F6AGP#U3 Datasheet - Page 231

• Manufacturer Part Number: M30260F6AGP#U3
• Description: IC M16C MCU FLASH 48K 48LQFP
• Manufacturer: Renesas Electronics America
• Series: M16C™ M16C/Tiny/26r

Specifications of M30260F6AGP#U3

• Core Processor: M16C/60
• Core Size: 16-Bit
• Speed: 20MHz
• Connectivity: I²C, IEBus, SIO, UART/USART
• Peripherals: DMA, PWM, Voltage Detect, WDT
• Number Of I /o: 39
• Program Memory Size: 48KB (48K x 8)
• Program Memory Type: FLASH
• Ram Size: 2K x 8
• Voltage - Supply (vcc/vdd): 2.7 V ~ 5.5 V
• Data Converters: A/D 12x10b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 48-LQFP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Eeprom Size: -

M
R
R
14.5 Output Impedance of Sensor under A/D Conversion
e
E
1
. v
J
6
Figure 14.5.1 Analog Input Pin and External Sensor Equivalent Circuit
0
C
2
9
2 /
0 .
B
To carry out A/D conversion properly, charging the internal capacitor C shown in Figure 14.5.1 has to be
completed within a specified period of time. T (sampling time) as the specified time. Let output imped-
ance of sensor equivalent circuit be R0, microcomputer’s internal resistance be R, precision (error) of
the A/D converter be X, and the A/D converter’s resolution be Y (Y is 1024 in the 10-bit mode, and 256
in the 8-bit mode).
Figure 14.5.1 shows analog input pin and externalsensor equivalent circuit. When the difference be-
tween VIN and VC becomes 0.1LSB, we find impedance R0 when voltage between pins. VC changes
from 0 to VIN-(0.1/1024) VIN in timer T. (0.1/1024) means that A/D precision drop due to insufficient
capacitor chage is held to 0.1LSB at time of A/D conversion in the 10-bit mode. Actual error however is
the value of absolute precision added to 0.1LSB. When f(XIN) = 10MHz, T=0.3 s in the A/D conversion
mode with sample & hold. Output inpedance R0 for sufficiently charging capacitor C within time T is
determined as follows.
Thus, the allowable output impedance of the sensor circuit capable of thoroughly driving the A/D con-
verter turns out of be approximately 13.9k .
0
0
6
2
A
0
F
2
G
e
0 -
b
o r
VC is generally VC = VIN{1-e
And when t = T,
Hence,
T = 0.3 s, R = 7.8k , C = 1.5pF, X = 0.1, and Y = 1024. Hence,
R0 = -
1 .
2
u
0
, 5
0
p
2
(
0
M
0
1
7
1.5X10
6
NOTES:
C
page 212
Sensor equivalent
circuit
1. Reference value
2 /
R0 = -
V
6
0.3X10
IN
, A
-
-12
C(R0+R)
M
•ln
VC=VIN-
e
1
C•ln
R
1
f o
6
0
c(R0+R)
-6
C
1024
0.1
3
2 /
2
T
9
6
T = ln
, B
1
Y
X
Microcomputer
M
R (7.8k )
Y
T
X
c(R0+R)
C (1.5pF)
=
1
- 7.8 X 10
- R
6
Y
C
X
1
VIN=VIN(1-
X
Y
2 /
(1)
(1)
6
) T
t
}
3
V
C
13.9 X 10
X
Y
Sampling time
Sample-and-hold function enabled:
Sample-and-hold function disabled:
)
3
3
AD
2
AD
14. A/D Converter