Renesas QB-MINI2 User Manual page 112

CHAPTER
(1) Automatically switching the reset signal via series resistor
Figure 5-3 illustrates the reset pin connection described in 5.1.2 Circuit connection example.
This connection is designed assuming that the reset circuit on the target system contains an N-ch open-drain
buffer (output resistance: 100Ω or less).
RESET_IN/OUT of MINICUBE2 is inverted, so observe the conditions described below in Remark.
Figure 5-3. Circuit Connection with Reset Circuit That Contains Buffer
MINICUBE2 MINICUBE2
RESET_OUT RESET_OUT
RESET_IN RESET_IN
Remark Make the resistance of at least R1 ten times that of R2, R1 being 10 kΩ or more.
Pull-up resistor R2 is not required if the buffer of the reset circuit consists of CMOS output.
The circuit enclosed by a dashed line is not required when only flash programming is performed.
Figure 5-4 illustrates the circuit connection for the case where the reset circuit on the target system contains
no buffers and the reset signal is only generated via resistors or capacitors. Design the circuit, observing the
conditions described below in Remark.
Figure 5-4. Circuit Connection with Reset Circuit That Contains No Buffers
MINICUBE2 MINICUBE2
RESET_OUT RESET_OUT
RESET_IN RESET_IN
Remark Make the resistance of at least R1 ten times that of R2, R1 being 10 kΩ or more.
The circuit enclosed by a dashed line is not required when only flash programming is performed.
110
5 HOW TO USE MINICUBE2 WITH 78K0S MICROCONTROLLER
The VDD or GND level may be unstable when the logic of
Target device Target device
_RESET _RESET
R1 R1
Target device Target device
R1 R1
User's Manual U18371EJ5V0UM
Reset connector Reset connector
V V
DD DD
R2 R2 Buffer Buffer
Reset connector Reset connector
_RESET _RESET
V V
DD DD
V V
DD DD
R2 R2