INN2605K TECHNICAL SUPPORT

Posted by: midhun on 06/01/2016

Friends

We have the following problems and doubts in our AC to DC Design(In the application notes provided from PI)

1. For what purpose 8.2v Zener is used? what if 6.8v is used there at the Bypass pin to primary auxillary pin?

2. While connecting load, the voltage and the current at the output continuosly fluctuates. How to rectify that?

Expecting your Support

Midhun

Files

INN2605K_12V_2A FULL SPEC.pdf (290.94 KB)

Comments

Hi,

The purpose of 8.2V Zener (VR1) is to provide the output over voltage protection. It should be selected based on your auxiliary winding output voltage such that it should not trigger OVP under normal operating conditions.

So I would check first with VR1 removed to see if the power supply is running stable. But have a 15V zener on the 12V output so that incase soemthing happens your power supply is protected.

Regards,

PI-NANO

Friends,

I am designing a power suply with IN2605K, OUT 24V x 20W.

I need to know about the VOUT PIN.

Can I connect this PIN directly to output voltage (24V)?

The especification is 15V to this PIN (Vout). Will I need a resistor divider?

Expecting your Support

Hi Marcelo,

Resistor divider will be lossy. We recommend to use a zener diode instead to clamp the voltage at the Vo pin at 15 V.

PI-AP

I have a doubt. My output is 24V. Do I need to use a Schottky diode more a shunt resistor or only a Schottky diode?

To prevent any damage to the IC, an external 1 A Schottky diode between the ISENSE and the SECONDARY GROUND pins is recommended for designs where a short-circuit at the power supply output may result in voltage at the IS pin in excess of 9 V. When this diode is used, the anode should be connected to the ISENSE pin and the cathode should be connected to the SECONDARY GROUND pin.

Thank you for last help!

Expecting your support.

Yes a schottky diode in parallel with the IS_GND sense resitor will be needed to prevent damage to the IC for Vo-Return shorts. The Schottky should be in the direction of the current flow, so the anode should be connected to the IS and the cathode should be connected to the secondary GND.