L99MOD50XP datasheet(21/42 Pages) STMICROELECTRONICS

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DS12615 Rev 4

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L99MOD50XP

Application information

3.1

Dual power supply: VS and VCC

The power supply voltage VS supplies the half bridges and the high-side drivers. An internal

charge-pump is used to drive the high-side 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 is not 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 is 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 256 μs all latched data are 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 charge-pump 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: 1 ms) 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 don’t change the

state of the output drivers. On the 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.

3.5

Overvoltage and undervoltage detection at VS

If the power supply voltage VS rises above the overvoltage threshold VSOV OFF (typical

21 V), the outputs OUT1 to OUT11 are switched to high impedance state to protect the load.

When the voltage VS drops below the undervoltage threshold VSUV OFF (UV-switch-OFF

voltage), the output stages are switched to high impedance to avoid the operation of the

power devices without sufficient gate driving voltage (increased power dissipation). If the

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