My customer has the following inquiries, could you please comment them see below, Thanks.
1. There is any way to receive different default settings (from the factory) such as Buck1 to be 1.2V?
2. There is a way to use a selective i2c address to cascade multiple pca9420 devices on one bus?
3. Could you please confirm that LDO1 is only 1mA?
4. on page 3 at the datasheet @https://www.nxp.com/docs/en/data-sheet/PCA9420DS.pdf , the AGND1/2/3 connected to the GND, could you please explain why there is need for an analog ground and for shorting between them?
waiting for your kind response, Thanks in advance.
Please find my answer to your questions below:
[A1] The default value for SW1 _OUT_0[5:0] is set at 1.00V, but it should be MTP programmable, this means that you can change it via I2C.
I understand that your customer wants a different default preprogrammed version of the PMIC, maybe this can be arranged depending on the opportunity, for this task I recommend you to contact your local NXP Sales representative directly for a discussion about this topic.
[A2] There are only two option for i2c address on the PCA9420 device, the slave address is set as in table 6 of the datasheet, where Bit7 is fixed to ‘1’, Bit6 is fixed to ‘1’, Bit5 is fixed to ‘0’, Bit4 is configurable, Bit3 is fixed to ‘0’, Bit2 is fixed to ‘0’, Bit1 is fixed to ‘1’, and Bit0 is read/write bit.
Bit 4 should be reserved as MTP option, with its default value set as “0” but can be trimmed to “1” when needed.
If more than two are needed, maybe an I2C MUX device placed between the MPU and the PMICs can be an option.
[A3] Correct, LDO1 max output current is up to 1mA.
Take in mind that LDO1 is an Always-on LDO, so it is typically used to supply the VDD_AO1V8 pin of the i.MXRT600, which need a 1.8V supply for “always on” features (RTC, RESETN, LDO_ENABLE, PMIC_IRQ_N, PMIC_MODE0, and PMIC_MODE1).
[A4] Analog Grounds and Power Grounds, should not be connected on the top PCB layer. We recommend to separate the grounds so the PGND of the Switching regulators are short and the return pad/loop of the switching regulators are closed to the output components this way you avoid noise caused by the power switching all around the board.
AGNDs and PGND should be connected/shorted in PCB inner GND layer.