L99H02 datasheet(25/51 Pages) STMICROELECTRONICS

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DS12547 Rev 6

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L99H02

Device description

3.1

Dual power supply: VS and VCC

The power supply Vs supplies the charge pump and the gate drivers. An internal charge-

pump is used to drive the high-side switches and the low-side switches. The supply voltage

VCC (3.3 V / 5 V) is used for the logic part, the SPI of the device and for the output stage of

the current sense amplifier. Due to the independent logic supply voltage the control and the

status information is not lost, even if the supply voltage VS is switched-off. In case of power-

on (VCC increases from undervoltage to VPOR OFF = 2.5 V, typical) the circuit is initialized by

an internally generated power-on reset (POR). If the voltage VCC decreases under the

minimum threshold (VPOR ON = 2.2 V, typical), the outputs are switched-off and the status

and the control registers are reset to default values.

3.2

Standby mode (EN)

The L99H02 is activated with enable input high. For enable input floating (not connected) or

VEN = 0 V the device is in standby mode. In standby mode all latched data are cleared and

inputs and outputs are switched-off. In standby mode the current at VS is less than 5 µA

(1 µA) for CSN = high (DO in tristate). If VCC > VPOR OFF and EN = high the device enters

the active mode.

In active mode the diagnostic functions are active. In fact gate drivers and charge pump

status will depend on the fault flags. For example if the device enters in active mode with

VS>VSOV the charge pump will be disabled.

3.3

H-bridge control (DIR, PWM, bit FW)

The DIR and PWM inputs control the drivers of the external H-bridge transistors. The motor

direction can be chosen with the DIR input, the duty cycle and frequency with the PWM

input. With the SPI bits FW and FW-PAS 4 different free wheeling modes (2 active and 2

passive) can be selected by using the high-side transistors or the low-side transistors.

Unconnected inputs are defined by internal pull-down current.

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