L9966 datasheet(21/122 Pages) STMICROELECTRONICS

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Current Sources

The FlexInput is equipped with a set of programmable and configurable current sources that can pull up or pull

down the input line.

The pull up current sources can pull up the input line to three different levels:

•

VPRE, the internal clamped high voltage rail

•

5V_REF, the internal generated 5 V rail

•

VVAR, the internal generated and programmable variable voltage level

The strength of the current and the voltage limit (pull up only) can be configured by register CURR_SRC_CTRL_x

for the channel configuration and DWT_VOLT_SRC_LSF_CTRL for VVAR output voltage setting.

The current sources can be controlled in order to configure a dewetting function. Both dewetting current and

actuation time are selectable via SPI; dewetting time (DWT[2:0] bit of DWT_VOLT_SRC_LSF_CTRL register)

is shared among the channels while current value setting (CV_DW_1, CV_DW_0 bit of CURR_SRC_CTRL_x

registers) is specific for each one.

The dewetting function is disabled by default. If enabled, the dewetting function is triggered according to the

following conditions, see Figure 12:

•

If IO_x is configured as pull up, then a falling edge on IO_x detected by the comparator will start dewetting.

•

If IO_x is configured as pull down, then a rising edge on IO_x detected by the comparator will start

dewetting.

Figure 12. Dewetting activation

GADG0501181049PS

After that the configured dewetting time is expired, the current turns back to the value defined in the

CURR_SRC_CTRL_x registers bit CV[2:0].

L9966

Current Sources

DS12459 - Rev 10

page 21/122

L9966 Arkusz danych(PDF) 21 Page - STMicroelectronics