R5F21257SNFP#U0 Renesas Electronics America, R5F21257SNFP#U0 Datasheet - Page 103

• Manufacturer Part Number: R5F21257SNFP#U0
• Description: IC R8C/25 MCU FLASH 52LQFP
• Manufacturer: Renesas Electronics America
• Series: R8C/2x/25r

Specifications of R5F21257SNFP#U0

• Core Processor: R8C
• Core Size: 16/32-Bit
• Speed: 20MHz
• Connectivity: I²C, LIN, SIO, SSU, UART/USART
• Peripherals: POR, Voltage Detect, WDT
• Number Of I /o: 41
• Program Memory Size: 48KB (48K x 8)
• Program Memory Type: FLASH
• Ram Size: 2.5K x 8
• Voltage - Supply (vcc/vdd): 2.2 V ~ 5.5 V
• Data Converters: A/D 12x10b
• Oscillator Type: Internal
• Operating Temperature: -20°C ~ 85°C
• Package / Case: 52-LQFP
• For Use With: R0K521256S000BE - KIT EVAL STARTER FOR R8C/25
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Eeprom Size: -

R8C/24 Group, R8C/25 Group
Rev.3.00
REJ09B0244-0300
10.3
Figure 10.11
This clock is supplied by the XCIN clock oscillation circuit. This clock is used as the clock source for the CPU
clock, timer RA, and timer RE. The XCIN clock oscillation circuit is configured by connecting a resonator between
the XCIN and XCOUT pins. The XCIN clock oscillation circuit includes an on-chip a feedback resistor, which is
disconnected from the oscillation circuit in stop mode in order to reduce the amount of power consumed in the
chip. The XCIN clock oscillation circuit may also be configured by feeding an externally generated clock to the
XCIN pin.
Figure 10.11 shows Examples of XCIN Clock Connection Circuits.
During and after reset, the XCIN clock stops.
The XCIN clock starts oscillating when the CM04 bit in the CM0 register is set to 1 (XCIN-XCOUT pin).
To use the XCIN clock for the CPU clock source, set the CM07 bit in the CM0 register to 1 (XCIN clock) after the
XCIN clock is oscillating stably. To input an external clock to the XCIN pin, set the CM04 bit in the CM0 register
to 1 (XCIN-XCOUT pin) and leave the XCOUT pin open.
This MCU has an on-chip feedback resistor and on-chip resistor disable/enable switching is possible by the CM12
bit in the CM1 register.
In stop mode, all clocks including the XCIN clock stop. Refer to 10.5 Power Control for details.
XCIN Clock
Feb 29, 2008
External crystal oscillator circuit
NOTE:
1. Insert a damping resistor and feedback resistor if required. The resistance will vary depending on the oscillator and
XCIN
(on-chip feedback resistor)
the oscillation drive capacity setting. Use the value recommended by the manufacturer of the oscillator.
When the oscillation drive capacity is set to low, check that oscillation is stable. Also, if the oscillator manufacturer's
data sheet specifies that a feedback resistor be added to the chip externally, insert a feedback resistor between
XCIN and XCOUT following the instructions.
Examples of XCIN Clock Connection Circuits
CIN
MCU
Rf
Page 84 of 485
(1)
XCOUT
Rd
COUT
(1)
VCC
VSS
Externally derived clock
XCIN
External clock input circuit
(on-chip feedback resistor)
MCU
10. Clock Generation Circuit
XCOUT
Open