L99DZ70XP datasheet(24/47 Pages) STMICROELECTRONICS

24 / 47 page

Application information

L99DZ70XP

24/47

Doc ID 15162 Rev 3

Application information

3.1

Dual power supply: VS and VCC

The power supply voltage VS supplies the half bridges and the highside drivers. An internal

charge-pump is used to drive the highside switches. The logic supply voltage VCC 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.

3.2

Wake up and active mode / standby mode

After power up of VS and Vcc the device operates in standby-mode. Pulling the signal CSN

to low level wakes the device up and the analog part will be activated (active mode).

After at least 10µs, the first SPI communication is valid and bit 0 of the Control Register 0

can be used to set the EN-mode. If bit 0 is not set to 1, the device doesn't remain in the

active mode. After at least 256µs all latched data will be cleared and the inputs and outputs

are switched to high impedance. In standby mode the current at VS (VCC) is less than 6 µA

(5 µA) for CSN = high (DO in tristate).

3.3

Charge pump

In standby mode the chargepump is turned off. After enabling the device by SPI command

(bit0=1 Control Register 0) the oscillator starts and the voltage begins to increase. The

output drivers are enabled after at least 256 µs after CSN went to high.

3.4

Diagnostic functions

All diagnostic functions (over/under-current, power supply over-/undervoltage, temperature

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

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

set.

The filters are used to improve the noise immunity of the device. The under-current and

temperature warning functions are intended for information purpose and will not change the

state of the output drivers. On contrary, the over-current condition disables the

corresponding driver and thermal shutdown disables all drivers. 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.

L99DZ70XP Datasheet(PDF) 24 Page - STMicroelectronics