HD64F3026X25 Renesas Electronics America, HD64F3026X25 Datasheet - Page 501

• Manufacturer Part Number: HD64F3026X25
• Description: MCU 3V 256K 100-TQFP
• Manufacturer: Renesas Electronics America
• Series: H8® H8/300Hr

Specifications of HD64F3026X25

• Core Processor: H8/300H
• Core Size: 16-Bit
• Speed: 25MHz
• Connectivity: SCI, SmartCard
• Peripherals: PWM, WDT
• Number Of I /o: 70
• Program Memory Size: 256KB (256K x 8)
• Program Memory Type: FLASH
• Ram Size: 8K x 8
• Voltage - Supply (vcc/vdd): 3 V ~ 3.6 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: -

7. Allowable Signal-Source Impedance
8. Effect on Absolute Accuracy
Sensor
input
The analog inputs of the H8/3024 Group are designed to assure accurate conversion of input
signals with a signal-source impedance not exceeding 10 k . The reason for this rating is that
it enables the input capacitor in the sample-and-hold circuit in the A/D converter to charge
within the sampling time. If the sensor output impedance exceeds 10 k , charging may be
inadequate and the accuracy of A/D conversion cannot be guaranteed.
If a large external capacitor is provided in single mode, then the internal 10-k input
resistance becomes the only significant load on the input. In this case the impedance of the
signal source is not a problem.
A large external capacitor, however, acts as a low-pass filter. This may make it impossible to
track analog signals with high dv/dt (e.g. a variation of 5 mV/µs) (figure 14.11). To convert
high-speed analog signals or to use scan mode, insert a low-impedance buffer.
Attaching an external capacitor creates a coupling with ground, so if there is noise on the
ground line, it may degrade absolute accuracy. The capacitor must be connected to an
electrically stable ground, such as AV
If a filter circuit is used, be careful of interference with digital signals on the same board, and
make sure the circuit does not act as an antenna.
Low-pass
filter
C up to 0.1 F
Sensor output impedance
Up to 10 k
Figure 14.11 Analog Input Circuit (Example)
SS
.
H8/3024 Group
Cin =
15 pF
Rev. 2.00 Sep 20, 2005 page 461 of 800
10 k
Equivalent circuit of
A/D converter
Section 14 A/D Converter
REJ09B0260-0200
20 pF