DB3264 Rev 3

17/24

L99UDL01

Device description

22

operation can be entered.

2.5.3

Normal mode

The L99UDL01 exits Standby mode and enters Normal mode when the CSN pin is pulled

This delay has to do with the charge pump and 3V3 regulator stabilization. When these

voltages have reached their proper levels, the SDO pin is pulled low from a tri-stated

condition. At that point, logic is operating, all circuits are activated and the SPI controller can

be used to update the register configuration.

When coming out from Standby, the configuration registers are set to their default values. In

this startup phase, the Charge Pump circuit starts to work. When the charge pump rises

above the CPLOW threshold actuation can be initiated via EN_OUT pin or via an

appropriate SPI frame. The CPLOW bit is not cleared until the register is read and cleared.

2.5.4

Emergency override mode

Emergency override mode is a crash override mechanism that will interrupt any current

actuation command in progress and drives outputs according to the programmed values in

the command and configuration registers.

This mode also overrides all protections. In an Emergency override mode the device will not

latch off if an overcurrent threshold is exceeded. Instead of latching off the driver and

reporting a fault the output will continue to retry as in normal current regulation mode.

All faults will be reported while not acted upon.

Emergency override mode is initiated when a (1, 0) is entered in the EMCY bits (register

01H). All other bit configurations result in normal operation.

When emergency override is enabled all current actuation activity will stop. To initiate a new

actuation routine the OUT_ON bit must be set or the EN_OUT pin must be toggled.

2.6

Diagnostics and protections

2.6.1

Shorted load detection

All integrated drivers are protected for shorts to ground or supply by a simple over current

longer than the filter time the faulted output(s) will be latched off.

If a shorted condition occurs after an output is active only the filtering time applies to the

latch-off action.

The fault will be reported in the fault register (register 10H). The Global fault Functional

Error 1 bit (FE1) will also be set.

concept applies to have three outputs in parallel.