DF2148ATE20 Renesas Electronics America, DF2148ATE20 Datasheet - Page 680

• Manufacturer Part Number: DF2148ATE20
• Description: IC H8S MCU FLASH 128K 100-QFP
• Manufacturer: Renesas Electronics America
• Series: H8® H8S/2100r

Specifications of DF2148ATE20

• Core Processor: H8S/2000
• Core Size: 16-Bit
• Speed: 20MHz
• Connectivity: Host Interface, I²C, IrDA, SCI
• Peripherals: POR, PWM, WDT
• Number Of I /o: 74
• Program Memory Size: 128KB (128K x 8)
• Program Memory Type: FLASH
• Ram Size: 4K x 8
• Voltage - Supply (vcc/vdd): 4 V ~ 5.5 V
• Data Converters: A/D 8x10b; D/A 2x8b
• Oscillator Type: Internal
• Operating Temperature: -20°C ~ 75°C
• Package / Case: 100-TQFP, 100-VQFP
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Eeprom Size: -
• Other names: HD64F2148ATE20; HD64F2148ATE20

Section 20 A/D Converter
Permissible Signal Source Impedance
Analog input in this LSI is designed so that conversion precision is guaranteed for an input signal
for which the signal source impedance is 10 k (AVcc = 4.0 to 5.5 V, when
This specification is provided to enable the A/D converter’s sample-and-hold circuit input
capacitance to be charged within the sampling time; if the sensor output impedance exceeds 10 k
(AVcc = 4.0 to 5.5 V, when
to guarantee the A/D conversion precision.
However, if a large capacitance is provided externally, the input load will essentially comprise
only the internal input resistance of 10 k , and the signal source impedance is ignored.
But since a low-pass filter effect is obtained in this case, it may not be possible to follow an analog
signal with a large differential coefficient (e.g., 5 mV/µsec or greater).
When converting a high-speed analog signal, a low-impedance buffer should be inserted.
Influences on Absolute Precision
Adding capacitance results in coupling with GND, and therefore noise in GND may adversely
affect absolute precision. Be sure to make the connection to an electrically stable GND such as
AV
Care is also required to insure that filter circuits do not communicate with digital signals on the
mounting board, so acting as antennas.
Rev. 4.00 Sep 27, 2006 page 634 of 1130
REJ09B0327-0400
Sensor input
Note: Values are reference values.
SS
.
Sensor output
impedance,
up to 10 k
Low-pass
filter
C to 0.1 µF
Figure 20.11 Example of Analog Input Circuit
12 MHz), charging may be insufficient and it may not be possible
C
15 pF
This LSI
in
=
A/D converter
equivalent circuit
10 k
12 MHz) or less.
20 pF