MC33981BHFK Freescale Semiconductor, MC33981BHFK Datasheet - Page 25

• Manufacturer Part Number: MC33981BHFK
• Description: HF 4.0MOHM RDSON SWITCH
• Manufacturer: Freescale Semiconductor

used for the freewheeling phase. Typical values for external capacitors and resistors are given.
.
INTRODUCTION
frequency high-current high side switch. This device is a self-
protected silicon switch used to replace electromechanical
relays, fuses, and discrete circuits in power management
applications.
targeted applications. The automotive standard to measure
conducted and radiated emissions is provided. Concrete
measurements on the 33981 and improvements to reduce
electromagnetic emission are described.
DEVICE FEATURES
digitally controlled from a microcontroller (MCU) with
extended diagnostics, able to drive DC motors up to 60 kHz.
transient gate voltage in order to reach 4.0 m R
maximum at room temperature. In parallel, a charge pump is
implemented to offer continuous on-state capability. This
dual current supply of the high side MOSFET allows a duty
cycle from 5% to 100%. An external capacitor connected
between pins SR and GND is used to control the slew rate at
Analog Integrated Circuit Device Data
Freescale Semiconductor
Figure 20
This section relates the EMC capability for 33981, high
This section presents the key features of the device and its
This 33981 is a 4.0 m self-protected, high side switch
A bootstrap architecture has been used to provide fast
shows a typical application for the 33981. A brush DC motor is connected to the output. A low side gate driver is
V
PWR
Voltage regulator
Figure 20. 33981 Typical Application Diagram
EMC AND EMI RECOMMENDATIONS
TYPICAL APPLICATIONS
DS(ON)
MCU
V
DD
INTRODUCTION
A/D
A/D
I/O
I/O
I/O
I/O
1.0 k
1.0 k
V
DD
the output and, therefore, reduce electromagnetic
perturbations.
handled by an external freewheeling diode. To reduce global
power dissipation, the freewheeling diode can be replaced by
an external discrete MOSFET in low side configuration. The
IC integrates a gate driver that controls and protects this
external MOSFET in the event of short-circuit to battery. The
product manages the cross conduction between the internal
high side and the external low side when used in a half-bridge
configuration. The two MOSFETs can be controlled
independently when the CONF pin is at 0 V. To eliminates
fuses, the device is self-protected from severe short-circuits
(100 A typical) with an innovative over-current strategy.
of the load current through an MCU analog/digital converter
to facilitate closed-loop operation for motor speed control.
used by the MCU to monitor PC board temperature to
optimize the motor control and to protect the entire electronic
system. Therefore, an over-temperature shutdown feature
protects the IC against high overload condition.
10 k
10 k
10 k
2.2 nF
10 k
In standard configuration, the motor current recirculation is
The 33981 has a current feedback for real-time monitoring
The 33981 has an analog thermal feedback that can be
Figure 21
33 k
illustrates the typical application diagram.
SR
CONF
FS
INLS
EN
INHS
TEMP
CSNS
OCLS
33981
CBOOT
VPWR
GND
OUT
GLS
DLS
V
PWR
330 F
100 nF
100 nF
M
TYPICAL APPLICATIONS
INTRODUCTION
33981
25