i can not get 1.7v voltage at pin21 and 0.7v voltage at pin22 of the ISL29501,but i can read and write all of registers over I2C interface,can someone give me a hand to figure the problem out?
Hello,
Thanks for reaching out Renesas Engineering Community.
Have you connected a 10K resistor between RSET pin and AVSS (GND)?
According to the datasheet of ISL29501 the RSET pin should be connected to a 10K resistor to AVSS(GND).
This resistor sets the bias current for the chip. If this resistor is not placed, the chip will not function properly.
The photodiode is reversed biased and the voltage across the photodiode is 1V.
Best Regards,
IK
Definitely,according to the datasheet of isl29501,i have connected a 10k resistor between RSET pin and AVSS pin,but i connect the pin20 and pin23 to the GND together,should i just connect pin20 and pin23 together and disconnect these two pins from GND?
Both pins should be connected to GND, I do not thins that this could have an impact on the functionality of the chip.
Could you please share a schematic of your connections to check?
Also what is the voltage you are measuring across the photodiode?
thanks for your reply,that is the schematic of my design,the voltage is measuring across the PD is about 0.1v ,so that the photodiode does not work,i would like to ask you for a check of my schematic and
figure this problem out.
Hello sir,
Thanks for sharing your schematic with me.
Please let me check it in more detail and come back to you with feedback.
Meanwhile can you please answer my questions on private message I sent to you?
Thanks and Regards,
Hello again,
Your schematic looks to be fine. However sharing with us a pdf file of your schematics would help more.
You can also take as reference the schematics provided from the EVK we provide for this sensor.
With a first look it seems that you don't have any important issue in your connections.
Can you please specify what is the power supply you give to the chip?
Also I would suggest to disconnect the photodiode and try to measure the voltage output on pins PDp and PDn to check if they match the specifications.
Have you tried also to make some basic I2C communication with the chip? For example reading the device ID?
Please make these tests to see if the chip is not malfunctioning and has not been damaged.
thank you IK,when i disconnect photodiode from this ISL29501,i still can not get 1.7v and 0.7v on the pin22 and pin 21.
when i power on my PCB, i can get this device id which is 0x0A,also other registers like Status register value which is 0x0F etc.
i can also write value 0xD7 to register 0xB0 to reset all registers value to default ,and try to read registers from 0x00 to 0xFF,i can get register values which are the same as the specification.
i think this chip must have been damaged,i'll try another one.
Yes if you have available one more chip, please make test in a new one to see how the voltage across the pins PDn and PDp is.
Also you can always have as reference the schematic provided in section 2.2.2 of the ISL290501 evaluation kit provided below:
https://www.renesas.com/en/document/mat/isl29501-cs-evkit1z-cat-shark-evaluation-kit-manual?r=1165656