PCA9306: VREF1 and EN configuration

Evan Wang

Genius 11160 points

Part Number: PCA9306

Hi All,

May I have your help to check the below schematic?

We notice the VREF1 voltage level is abnormal.

Might related to the EN and VREF1 design.

1. May I know whether we can use external signal to control the EN pin? How?

2. May I know whether we can add 200k ohm on VERF1? Will it affect the internal structure? Why?

Looking forward to your reply.

Thank you.

0 Clemens Ladisch over 3 years ago

Guru 319720 points

1. The EN pin can be pulled low with an open-drain or open-collector signal.

2. VREF1 must be connected directly to the power supply. During normal operation, a small current flows into VREF2 and out of VREF1.

0 Danny Bacic over 3 years ago

Chia,

Clemens is correct.

In addition, is R1228 populated? You would need this 0 Ω resistor to connect EN to V_REF2 for proper biasing of the EN pin.

Best,

Danny

Interface forum