L6910 datasheet(7/21 Pages) STMICROELECTRONICS

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L6910A L6910

Figure 3. High Side driver peak current. Vboot-Vphase = 12V (right) Vboot-Vphase = 5V (left)

Figure 4. Low Side driver peak current. VCC = 12V (right) VCC = 5V (left)

Monitoring and Protections

The output voltage is monitored by means of pin FB. If it is not within ±10% (typ.) of the programmed value, the

powergood output is forced low.

The device provides overvoltage protection, when the voltage sensed on pin FB reaches a value 17% (typ.)

greater than the reference the OSC pin is forced high (3V typ.) and the lower driver is turned on as long as the

over-voltage is detected.

Overcurrent protection is performed by the device comparing the drop across the high side MOS, due to the

RDSON, with the voltage across the external resistor (ROCS) connected between the OCSET pin and drain of the

upper MOS. Thus the overcurrent threshold (IP) can be calculated with the following relationship:

Where the typical value of IOCS is 200µA. To calculate the ROCS value it must be considered the maximum

RdsON (also the variation with temperature) and the minimum value of IOCS. To avoid undesirable trigger of

overcurrent protection this relationship must be satisfied:

CH1 = High Side Gate CH4 = Gate Current

CH1 = Low Side Gate CH4 = Gate Current

OCS

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ds O N

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