公开(公告)号：DE69507126T2

公开(公告)日：1999-05-27

申请号：DE69507126

申请日：1995-05-23

Applicant: ST MICROELECTRONICS SRL

Inventor： FUCILI GIONA ,  NESSI MAURIZIO

IPC: H02P7/03 ,  H02P7/00

Abstract: Masking of switching noise is implemented in the driving system of an "H" bridge stage by exploiting the periodic signal generated by a PWM control circuit (normally present in the control system for controlling the "H" bridge in an open-loop mode) for masking the decay time of the disturbances caused by the switching from off-to-on of a first pair of switches of the bridge that drive a current in a certain direction through the load. This is implemented by keeping high for a preset period of time the periodic signal generated by the PWM circuit and varying the duty-cycle of the signal for regulating the mask time in function of the load characteristics. The system further comprises the masking of the decay interval of the disturbances caused by the switching from on-to-off of the first pair of switches and from off-to-on of the other pair of switches that provide a current ricirculation path of the energy stored in the reactance of the load, for a preset number of clock cycles, thus impeding any subsequent switching for the duration of this second mask. This second mask may be realised in different ways. The use of an up-counter and a programmable comparator been preferred.

公开(公告)号：DE69414820D1

公开(公告)日：1999-01-07

申请号：DE69414820

申请日：1994-02-28

Applicant: ST MICROELECTRONICS SRL

Inventor： CHRAPPAN FRANCESCO ,  NESSI MAURIZIO ,  SALINA ALBERTO

IPC: H03F3/20 ,  H02P25/034 ,  H03F1/32 ,  H03F3/30 ,  H03F3/347

Abstract: The operation of externally connected output power transistors of a class AB amplifier is controlled without employing any external sensing resistance of the output current by driving an externally connected power transistor through a level shifting buffer and employing a limiting network composed of an integrated transistor driven by the output of a signal amplifying stage and a resistance connected in series with its drain. The buffer stage shifts the level of the driving signal of the external power transistor by a value equal to the threshold voltage of the integrated transistor of the limiting network thus ensuring the turn-off of the external power transistor under quiescent conditions.

公开(公告)号：DE69313833T2

公开(公告)日：1998-01-22

申请号：DE69313833

申请日：1993-05-31

Applicant: ST MICROELECTRONICS SRL

Inventor： NESSI MAURIZIO

IPC: H02P6/08 ,  H03K17/042 ,  H03K17/16 ,  H03K17/04

Abstract: A fast-discharge switch (M1) is controlled by a comparator (M2) sensing the voltage difference between the output node and the input node of a driving integrator stage that controls the slew-rate of a power switching output transistor (MP). The fast-discharge switch turns off automatically when the output power transistor reaches (in the case of a MOS transistor) or exits (in the case of a bipolar transistor) saturation. The circuit of the invention accelerates the discharge thus reducing the turn-off delay and is insensitive of load conditions and does not affect the performance of the integrating (driver) stage that control the slew-rate.