l9942 STMicroelectronics, l9942 Datasheet - Page 9

• Manufacturer Part Number: l9942
• Description: Integrated Stepper Motor Driver For Bipolar Stepper Motors With Microstepping And Programmable Current Profile
• Manufacturer: STMicroelectronics

L9942
2
2.1
2.2
2.3
2.4
2.5
Device description
Dual power supply: V
The power supply voltage V
drive the highside switches. The logic supply voltage V
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-on (V
V, typical) the circuit is initialized by an internally generated power-on-reset (POR). If the
voltage V
outputs are switched to tristate (high impedance) and the internal registers are cleared.
Standby-mode
The EN input has a pull-down resistor. The device is in standby mode if EN input isn't set to
a logic high level. All latched data will be cleared and the inputs and outputs are switched to
high impedance. In the standby mode the current at VS (VCC) is less than 3 µA (1µA) for
CSN = high (DO in tristate). If EN is set to a logic high level then the device will enter the
active mode. In the active mode the charge pump and the supervisor functions are
activated.
Diagnostic functions
All diagnostic functions (overload/-current, open load, power supply over-/under voltage,
temperature warning and thermal shutdown) are internally filtered (t
the condition has to be valid for a minimum time 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 bridge drivers. On contrary, the overload/-current and thermal
shutdown condition will disable the corresponding driver (overload/-current) or all drivers
(thermal shutdown), respectively. The microcontroller has to clear the status bit to reactivate
the bridge driver.
Over-voltage and under-voltage detection
If the power supply voltage VS rises above the over-voltage threshold V
20V), the outputs are switched to high impedance state to protect the load. When the
voltage VS drops below the intervillage threshold V
output stages are switched to the high impedance to avoid the operation of the power
devices without sufficient gate driving voltage (increased power dissipation). Error condition
is latched and the microcontroller needs to clear the status bits to reactivate the drivers.
Temperature warning and thermal shutdown
If junction temperature rises above T
detectable via the SPI. If junction temperature increases above the second threshold T
CC
decreases under the minimum threshold (V
S
supplies the half bridges. An internal charge-pump is used to
S
and V
j TW
CC
a temperature warning flag is set which is
increases from under voltage to V
CC
SUV OFF
CC
POR ON
(stabilized) is used for the logic
(UV-switch-OFF voltage), the
= 2.45 V, typical), the
GL
= 32µs, typical) and
Device description
SOV OFF
POR OFF
(typical
= 2.60
j SD
9/40
,