MC33880DW View Datasheet(PDF) - Motorola => Freescale
Part Name
Description
Manufacturer
MC33880DW Datasheet PDF : 24 Pages
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Freescale Semiconductor, Inc.
FAULT OPERATION
On each SPI communication, an 8-bit command word is sent
to the 33880 and an 8-bit fault word is received from the 33880.
The Most Significant Bit (MSB) is sent and received first (see
below).
MSB
LSB
OUT8 OUT7 OUT6 OUT5 OUT4 OUT3 OUT2 OUT1
Command Register Definition:
0 = Output Command Off
1 = Output Command On
Fault Register Definition:
0 = No fault
1 = Fault.
Table 1. Fault Operation
Serial Output (SO) Pins Reports
Overtemperature
Fault reported by Serial Output (DO) pin.
Overcurrent
DO pin reports short to battery/supply or overcurrent condition.
Output ON Open Load Fault
Not reported.
Output OFF Open Load Fault
DO pin reports output OFF open load condition.
Device Shutdowns
Overvoltage
Total device shutdown at VPWR = 25 V to 30 V. Resumes normal operation with proper voltage. All outputs
assuming the previous state upon recovery from overvoltage.
Overtemperature
Only the output experiencing an overtemperature fault shuts down. Output assumes previous state upon
recovery from overtemperature.
APPLICATIONS
Power Consumption
The 33880 device has been designed with one sleep and
one operational mode. In the sleep mode (VDD ≤ 2.0 V), the
current consumed by VPWR pin is less than 25 µA. To place the
33880 in the sleep mode, turn all outputs off, then remove
power from VDD and the EN (enable) input pin. Prior to
removing power from the device, it is recommended all control
inputs from the microcontroller are low. During normal
operation, 4.0 mA will be drawn from the VDD supply and 12 mA
from the VPWR supply.
Paralleling of Outputs
Using MOSFETs as output switches allows the connection of
any combination of outputs together. RDS(ON) of MOSFETs
have an inherent positive temperature coefficient, providing
balanced current sharing between outputs without destructive
operation. The device can even be operated with all outputs tied
together. This mode of operation may be desirable in the event
the application requires lower power dissipation or the added
capability of switching higher currents. Performance of parallel
operation results in a corresponding decrease in RDS(ON) while
the outputs OFF open load detect currents and the output
current limits increase correspondingly (by a factor of eight if all
outputs are paralleled). Paralleling outputs from two or more
different IC devices are possible but not recommended.
Fault Logic Operation
Fault logic of the 33880 device has been greatly simplified
over other devices using SPI communications. As command
word one is being written into the shift register, a fault status
word is being simultaneously written out and received by the
MCU. Regardless of the configuration, with no outputs faulted,
all status bits being received by the MCU will be zero. When
outputs are faulted (off state open circuit or on state short
circuit/overtemperature), the status bits being received by the
MCU will be one. The distinction between open circuit fault and
short circuit/overtemperature is completed via the command
word. For example, when a zero command bit is sent and a one
fault is received in the following word, the fault is open/short-to-
battery for high-side drive or open/short to ground for low-side
drive. In the same manner, when a one command bit is sent and
a one fault is received in the following word the fault is a short-
to-ground/overtemperature for high-side drive or short-to-
battery/overtemperature for low-side drive. The timing between
two write words must be greater than 300 µs to allow adequate
time to sense and report the proper fault status.
MOTOROLA ANALOG INTEGRATED CIRFCoUrITMDEoVrIeCEIDnAfoTArmation On This Product,
Go to: www.freescale.com
33880
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