DF71251AD50FPV Renesas Electronics America, DF71251AD50FPV Datasheet - Page 521

• Manufacturer Part Number: DF71251AD50FPV
• Description: MCU RISC FLASH 32K 8K 64LQFP
• Manufacturer: Renesas Electronics America
• Series: SuperH® SH Tinyr

Specifications of DF71251AD50FPV

• Core Processor: SH-2
• Core Size: 32-Bit
• Speed: 50MHz
• Connectivity: SCI
• Peripherals: POR, PWM, WDT
• Number Of I /o: 37
• Program Memory Size: 32KB (32K x 8)
• Program Memory Type: FLASH
• Ram Size: 8K x 8
• Voltage - Supply (vcc/vdd): 4 V ~ 5.5 V
• Data Converters: A/D 8x10b
• Oscillator Type: External
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 64-LQFP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Eeprom Size: -

13.7
13.7.1
Operation of the A/D converter can be disabled or enabled using the standby control register. The
initial setting is for operation of the A/D converter to be halted. Register access is enabled by
clearing module standby mode. For details, refer to section 19, Power-Down Modes.
13.7.2
This LSI's analog input is designed such that conversion accuracy is guaranteed for an input signal
for which the signal source impedance is 1 kΩ or less. 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 1 kΩ, charging may be insufficient and it may not be
possible to guarantee A/D conversion accuracy. However, for A/D conversion in single mode with
a large capacitance provided externally, the input load will essentially comprise only the internal
input resistance of 10 kΩ, and the signal source impedance is ignored. However, as 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/μs or greater) (see figure 13.7). When converting a high-speed
analog signal or converting in scan mode, a low-impedance buffer should be inserted.
13.7.3
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
AVss.
Care is also required to insure that filter circuits do not interfere in the accuracy by the printed
circuit digital signals on the mounting board (i.e, acting as antennas).
Usage Notes
Module Standby Mode Setting
Permissible Signal Source Impedance
Influences on Absolute Accuracy
Rev. 5.00 Mar. 06, 2009 Page 501 of 770
REJ09B0243-0500