L9659 datasheet(26/51 Pages) STMICROELECTRONICS

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Functional description

L9659

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Doc ID 022048 Rev 2

the current exceeds the specified level. After a POR or software reset the L9659 will reset all

8 measurement registers to all ‘0’s.

A “real-time” current measurement status of all the channels is available. If a current limit

status request is sent then the L9659 will report in the next SPI transfer whether the current

is above or below IMEAS for each of the channels. The current status results can be read at

any time and will correctly report whether current is flowing. The content of the internal

current status register is captured on the falling edge of chip select during the SPI response.

The internal status register is updated at a nominal sample time of 25µs and is independent

of SPI transfers.

For this circuit there is continuously being performed compensation of the comparator to

remove offset errors, which is independent from SPI commands. The compensation is being

performed every 12.8µs based on the internal clock.

3.4.3

Fire enable (FEN) function description

The Fire Enable (FEN) function is the result of the FENx input OR’d with the internal FEN

latch. If the FEN latch is not enabled and the FENx pin is low then activation of the FET

drivers are disabled except as indicated during the MOS test. All internal diagnostic

functions, and results, will be available through the serial interface. This pin must be pulled

high to initiate the FEN latch function (if programmed) and enable firing of the FET drivers.

There are four FEN function blocks

●

FEN Function 1 is FEN1 input OR’d with FEN1 latch timer and used for enabling

channels 0 & 1

●

FEN Function 2 is FEN1 input OR’d with FEN2 latch timer and used for enabling

channels 2 & 3

●

FEN Function 3 is FEN1 input OR'd with FEN3 latch timer and used for enabling

channels 4 & 5

●

FEN Function 4 is FEN1 input OR'd with FEN4 latch timer and used for enabling

channels 6 & 7

The FEN function will be considered active when the pin is active (‘1’ or high) for more than

12 microseconds. Tolerance range for the filter used is 12 to 16 µsecs.

When the FENx input is active, ‘1’, the FEN function will be active. When the FENx input

state transitions from ‘1’ to ‘0’, the programmable latching function will hold the FEN

function active until the timeout of the FEN timer. The programmable latch and hold

function will be capable of delays of 0ms, 128 ms, 256 ms, and 512 ms. There are 4

independent timers with the timer for FEN1 associated with channels 0 & 1, timer for FEN2

associated with channels 2 & 3, timer for FEN3 associated with channels 4 & 5, timer for

FEN4 associated with channels 6 & 7. The timer is reset to the programmed time when

the FENx pin transitions from ‘0’ to ‘1’. The programmable counter delay will be set

through a SPI command.

L9659 Datasheet(PDF) 26 Page - STMicroelectronics

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