L9950

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3.1

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

tristate (high impedance) and the status registers are cleared.

3.2

Standby-Mode

The standby mode of the L9950 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 impedance. In the standby mode the

a very low quiescent current can 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 OUT6 without external free-wheeling diodes. The highside drivers OUT7 to OUT11 are intended to drive

resistive loads. Hence only a limited energy (E<1mJ) can be dissipated by the internal ESD-diodes in free-

wheeling 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-/undervoltage, temperature warning and ther-

mal 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 and ther-

mal shutdown condition will disable the corresponding driver (overload) or all drivers (thermal shutdown),

respectively. 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.

3.5

Overvoltage and Undervoltage Detection

the high impedance to avoid the operation of the power devices without sufficient gate driving voltage (in-

es return to the programmed state (input register 0: bit 20=0).

If the undervoltage/overvoltage recovery disable bit is set, the automatic turn-on of the drivers is deacti-

vated. The microcontroller needs to clear the status bits to reactivate the drivers. It is recommended to set

bit 20 to avoid a possible high current oscillation in case of a shorted output to GND and low battery volt-

age.

3.6

Temperature Warning and Thermal Shutdown

and power DMOS transistors of all output stages are switched off to protect the device. In order to reacti-

shutdown bit has to be cleared by the microcontroller.