XRP9710 Datasheet, PDF(28/36 Page) Exar Corporation – Dual 6A Programmable Power Module

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XRP9710 Datasheet, PDF (28/36 Pages) Exar Corporation – Dual 6A Programmable Power Module

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XRP9710 and XRP9711

Dual 6A Programmable Power Module

by the following equation where the range for

N is 1 to 63:

í µí± â í µí°¿í µí±í µí°µ(í µí±í µí±) â 105

í µí±í µí±í µí±(%) = í µí±í µí±¡í µí±í µí±í µí±í µí±í µí±¡ (í µí±)

When the OVP level is reached and the fault is

generated, the host will be notified by the

SUPPLY_FAULT_EVENT interrupt generated by

the controller. The host then can use an I2C

command to check which channel is at fault.

In addition, OVP fault can be monitored

through GPIO0.

A user can choose one of three options in

response to an OVP event: shutdown the

faulting channel, shut down faulting channel

and perform auto-restart of the channel, or

restart the chip.

Note: The Channel Fault Action response is

the same for an OVP or OCP event.

OCP

A user defined OCP fault level is set with 10

mA increments in PA 5.1. PA 5.1 uses

calculations to give the user the approximate

DC output current entered in the current limit

field. However the actual current limit trip

value programmed into the part is limited to

280mV as defined in the electrical

characteristics. The maximum value the user

can program is limited by Rdson of the

synchronous Power FET and current

monitoring ADC range. For example, using a

synchronous FET with RDSON of 30mâ¦, and the

wider ADC range, the maximum current limit

programmed would be:

In the case of shutting down the faulting

channel and auto-restarting, the user has an

option to specify startup timeout (the time in

which the fault is validated) and hiccup

timeout (the period after which the controller

will try to restart the channel) periods in 1

msec increments with a maximum value of

255 msec.

280í µí±í µí±

The current is sampled approximately 30ns

before the low side MOSFET turns off, so the

actual measured DC output current in this

example would be 9.33A plus approximately

half the inductor ripple.

An OCP Fault is considered to have occurred

only if the fault threshold has been tripped in

four consecutive switching cycles. When the

switching frequency is set to the 4x multiplier,

the current is sampled only every other cycle.

As a result it can take as many as eight

switching cycles for an over current event to

28/36

Rev. 1.0.1

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