P9225-R Datasheet

© 2018 Integrated Device Technology, Inc.

17

November 12, 2018

R34

R33

Output Voltage

10kΩ

10kΩ

5.1V

14.7kΩ

10kΩ

5.2V

20kΩ

10kΩ

5.3V

34kΩ

10kΩ

5.4V

49.9kΩ

10kΩ

5.5V

8.3 SINK Pin

The P9225-R has an internal automatic DC clamping to protect the device in the event of high-voltage transients. The VRECT pin must be

shorted to SINK.

8.4 Rectifier Voltage – VRECT

The P9225-R uses a high

‐efficiencysynchronousrectifiertoconverttheACsignalfromthecoiltoaDCsignalontheVRECTpin.During

startup, the rectifier operates as a passive diode bridge. Once the voltage on VRECT exceeds the under-voltage lock-out (UVLO) level (see

Table 5), the rectifier will switch into full synchronous bridge rectifier mode. A total capacitance of 44µF is recommended to minimize the output

voltage ripple.

8.5 Over-Current Limit – ILIM

The P9225-R has a programmable current-limit function for protecting the device in the event of an over-current or short-circuit fault condition.

When the output current exceeds the programmed threshold, the P9225-R will limit the load current by reducing the output voltage. The current

limit should be set to 120% of the target maximum output current.

Connect the ILIM pin to the center tap of a resistor divider to set the current limit. Table 7 shows the resistor combination values for the resistor

divider for the ILIM setting. The default ILIM is set to 1.2A in the P9225-R Evaluation Board.

Table 7.

Setting the Current Limit

R38

R22

ILIM

10kΩ

47kΩ

0.8A

10kΩ

22kΩ

0.9A

10kΩ

OPEN

1.0A

10kΩ

10kΩ

1.1A

OPEN

10kΩ

1.2A

8.6 Interrupt Function – INT

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The P9225-R provides an open-drain, active-LOW interrupt output pin. It is asserted LOW when EN is HIGH or any of the following fault

conditions have been triggered: the die temperature exceeds 140°C, the external thermistor measurement exceeds the threshold (see section

8.9), or an over-current (OC) or over-voltage (OV) condition is detected (see sections 8.5 and 8 respectively).

During normal operation, the INT pin is pulled HIGH. This pin can be connected to the interrupt pin of a microcontroller. The fault condition

triggering the interrupt flag is available in the I2C interrupt register (see Table 13).