PCA9420 - VIN tolerance

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PCA9420 - VIN tolerance

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shai_b
Senior Contributor I

Hello team,

My customer is planning to use our #PCA9420 pmic as his main DC/DC and LDO and today he using a 4xAA battery setup which leads to Vin 6.2v once the batteries are new (in the future they will use a rechargeable battery).

Please advise if it okay to use PCA9420 in such a use case Vin could be 6.2v? 

Thanks in advance

Regards,

Shai 

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reyes
NXP TechSupport
NXP TechSupport

Hi Shai,

 

According to table 74 of the datasheet, the MAX limiting value for VIN pin for the PCA9420 is up to 20V, however, table 76 of the datasheet mention that the recommended operating voltage is up to 5.5V.

Reason is because the Over Voltage Protection circuit, you can I2C program it at 5.5V or 6V using the VIN_OVP_SEL:

0: 5.50V

1: 6.0V

Note: The current default value for VIN_OVP_SEL is set at 5.5V, but it should be MTP programmable

 

VINOVP Accuracy: Input over- voltage protection threshold is -3.5 / +3.5 %.

The 6.2V you want to use as the main power is within this accuracy (if VIN_OVP_SEL is selected t 6.0V + the 3.5% of accuracy, we get up to 6.21V), however, it is very closed to the limit and above the recommended vale, so I would not recommend it, but I would suggest that you perform some tests and check if it worked for your application.


Most likely, in your test you will be getting OVP interrupts (VIN_STATUS = 10: VIN is invalid. VIN>VIN_OVP).

In such case, condition 4 would happened (section 8.10.3 of the datasheet) and all enabled power rails will be off after power up until VIN goes below its VIN OVP hysteresis (typ 100mV).

 

Note: If VIN is greater than 6V, the voltage rating on the capacitor of 2.2µF/10V shall be changed to a higher voltage than a maximum voltage in applications.

 

Regards,

Jose

NXP Semiconductors

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