5/23
© 2022 ROHM Co., Ltd.
No. 64UG116E Rev.002
Feb.2022
User’s Guide
Table 1. RKX-A3-EVK-001 Main Features
1.3.2
Input / Output Power Configuration
1.3.2.1
VDD_SENSOR Select
The RKX-A3-EVK-001 gives users the flexibility to test sensors at different VDD and IO_VDD input voltages as well as providing a way to interface
sensors with both 5V platforms (e.g., Arduino UNO R3, or Infineon CY8CKIT-059) and 3.3V platforms (e.g., Raspberry Pi).
The VDD Sensor Select circuitry is shown in Figure 5. When the RKX-A3-EVK-001 is connected to a host platform, the input voltage to the board
is supplied on VBUS net and the green LED (LED1) will be ON. The VBUS voltage is then supplied as an input to the Voltage Regulator (VR1)
and is connected to the Single Poll Double Throw (SPDT) switch SW1. The purpose of the SW1 is to select the VDD voltage to the sensor that
will be connected to the RKX-A3-EVK-001 (VDD_SENSOR). One option for the VDD_SENSOR is the actual VBUS voltage. The second option
is the output voltage from the VR1 voltage regulator (VR1_OUT). The default configuration of the RKX-A3-EVK-001 is to select the output voltage
from the VR1 voltage regulator.
NOTE:
Care must be taken when switch SW1 is moved left to select VBUS voltage. For platforms like CY8CKIT-059 Prototyping Kit and Arduino
UNO R3, the VBUS voltage can be as high as 5V. Since many sensors including KX132-1211, are rated to 3.6V VDD max, overvoltage and
potential permanent damage may be done in cases when the 5V VBUS voltage is connected to VDD_SENSOR.
1
TP4 - Test Point 4 for VBUS (Host) input voltage measurement
12 TP1 - Test Point 1 for GND reference voltage measurements
2
LED2 - Orange LED is ON when VDD_SENSOR voltage is ON
13 J9 - Raspberry Pi 6-pin debug header
3
SW4 - Switch that connects VDD_SENSOR to VBUS/VR1_OUT
14 J8 - Raspberry Pi 40-pin dual-row header
4
LED1 - Green LED is ON when VBUS (Host) Voltage is provided
15 J15 - Infineon CY8CKIT-059 compatible header
5
SW1 - VDD_SENSOR select switch (VBUS or VR1_OUT)
16 J14 - Infineon CY8CKIT-059 compatible header
6.
J7 / R64 - VDD_Sensor current measurement header/bypass.
17 J4 - Arduino UNO R3 Compatible Digital Header (bottom mount)
7
SW3 - IO_VDD Select switch (VDD_SENSOR of VR2_OUT)
18 J6 - ROHM EVK EVB compatible header
8
SW2 - 7-position rotary switch to configure VR1_OUT voltage:
1 = 3.3V, 2 = 3.0V, 3 = 2.8V, 4 = 2.5V, 5 = 1.8V, 6 = 1.7V, 7 = 3.6V
19 J10 - ROHM Sensor Module 5-Pin Digital / 4-Pin Analog Header
9
TP3 - Test Point 3 for VDD_SENSOR voltage measurement.
20 J3 – Arduino UNO R3 Compatible Digital Header (bottom mount)
10
J1 - Arduino UNO R3 Compatible Power Header (bottom mount)
21 J11 - ROHM 7-Pin Digital Sensor (SPI) Header
11
J2 - Arduino UNO R3 Compatible Analog Header (bottom mount, even-
numbered pins).
22 J5 - ROHM EVK EVB ribbon cable compatible header
