L9953 / L9953XP

Application information

Doc ID 14278 Rev 3

19/38

3

Application information

3.1

5 V) is used for the logic part and the SPI of the device.

Due to the independent logic supply voltage the control and status information will not be

lost, if there are temporary spikes or glitches on the power supply voltage. In case of power-

and the status registers are cleared.

3.2

Standby mode

The standby mode of the L9953 is activated by clearing the bit 23 of the Input Data Register

0. All latched data will be cleared and the inputs and outputs are switched to high

be achieved. If bit 23 is set, the device will be switched to active mode.

3.3

Inductive loads

Each half bridge is built by an internally connected highside and a lowside power DMOS

transistor. Due to the built-in reverse diodes of the output transistors, inductive loads can be

driven at the outputs OUT1 to OUT5 without external free-wheeling diodes. The highside

drivers OUT6 to OUT8 are intended to drive resistive loads. Hence only a limited energy

(E<1mJ) can be dissipated by the internal ESD-diodes in freewheeling condition. For

inductive loads (L>100

μH) an external free-wheeling diode connected to GND and the

corresponding output is needed.

3.4

Diagnostic functions

All diagnostic functions (over/open load, power supply over-/under voltage, temperature

warning and thermal shutdown) are internally filtered and the condition has to be valid for at

least 32 µs (open load: 1ms, respectively) before the corresponding status bit in the status

registers will be set. The filters are used to improve the noise immunity of the device. Open

load and temperature warning function are intended for information purpose and will not

change the state of the output drivers. On contrary, the overload condition will disable the

corresponding driver (over-current) and over temperature will switch off all drivers (thermal

shutdown). Without setting the over-current recovery bits in the Input Data register, the

microcontroller has to clear the over-current status bits to reactivate the corresponding

drivers.