MC33298 Motorola, MC33298 Datasheet - Page 9

• Manufacturer Part Number: MC33298
• Description: OCTAL SERIAL SWITCH (SPI Input/Output)
• Manufacturer: Motorola

Introduction
developed for automotive applications. It is an eight output
low side power switch having 8–bit serial control. The
MC33298 incorporates SMARTMOS
effective 2.0 CMOS logic, bipolar/MOS analog circuitry, and
independent state of the art double diffused MOS (DMOS)
power output transistors. Many benefits are realized as a
direct result of using this mixed technology. A simplified block
diagram of the MC33298 is shown in Figure 1.
current for their operation, structured MOS devices, since
they are voltage controlled, require only transient gate
charging current affording a significant decrease in power
consumption. The CMOS capability of the SMARTMOS
process allows significant amounts of logic to be
economically incorporated into the monolithic design. In
addition, bipolar/MOS analog circuits embedded within the
updrain power DMOS output transistors monitor and provide
fast, independent protection control functions for each
individual output. All outputs have internal 65 V at 0.5 A
independent output voltage clamps to provide fast inductive
turn–off and transient protection.
output transistors exhibiting very low drain to source “on”
resistance values (R DS(on)
control logic. Operational bias currents of less than 4.0 mA
(1.0 mA typical) with any combination of outputs “on” are the
result of using this mixed technology and would not be
possible with bipolar structures. To accomplish a comparable
functional feature set using a bipolar structure approach
would result in a device requiring hundreds of milliamperes of
internal bias and control current. This would represent a very
large amount of power to be consumed by the device itself
and not available for load use.
serial switch serving as a microcontroller (MCU) bus
expander and buffer with fault management and fault
reporting features. In doing so, the device directly relieves
the MCU of the fault management functions. The MC33298
directly interfaces to an MCU and operates at system clock
serial frequencies in excess of 2.0 MHz using a Synchronous
Peripheral Interface (SPI) for control and diagnostic readout.
MOTOROLA ANALOG IC DEVICE DATA
The MC33298 was conceived, specified, designed, and
Where bipolar devices require considerable control
The MC33298 uses high efficiency updrain power DMOS
In operation the MC33298 functions as an eight output
Microcontroller
MC68XX
SPI
SCLK
Parallel Port
MISO
IRQ
MOSI
0.45
SO
CSB
8 Outputs
MC33298
) and dense CMOS
technology having
SCLK
Figure 12. MC33298 SPI System Daisy Chain
SI
CIRCUIT DESCRIPTION
MC33298
SO
CSB
8 Outputs
MC33298
SCLK
Figure 11 shows the basic SPI configuration between an
MCU and one MC33298.
applications in the computer, telecommunications, and
industrial fields. It is parametrically specified over an input
“battery”/supply range of 9.0 V to 16 V but is designed to
operate over a considerably wider range of 5.5 V to 26.5 V.
The design incorporates the use of Logic Level MOSFETs as
output devices. These MOSFETs are sufficiently turned “on”
with a gate voltage of less than 5.0 V thus eliminating the
need for an internal charge pump. Each output is identically
sized and independent in operation. The efficiency of each
output transistor is such that with as little as 9.0 V supply
(V PWR ), the maximum R DS(on) of an output at room
temperature is 0.45
1.0
incorporate negative or inverted logic. Whenever an input is
programmed to a logic low state (< 1.0 V) the corresponding
low side switched output being controlled will be active low
and turned “on.” Conversely, whenever an input is
programmed to a logic high state (> 3.0 V), the output being
controlled will be high and turned “off.”
SI
The circuit can also be used in a variety of other
All inputs are compatible with 5.0 V CMOS logic levels and
Microcontroller
MC68HCXX
(0.5
Figure 11. SPI Interface with Microcontroller
Shift Register
Receive
Parallel
Buffer
Ports
SO
CSB
8 Outputs
typical) as V PWR is decreased to 5.5 V.
MC33298
SCLK
SI
MOSI
MISO
(0.35
Reset
CSB
SCLK
typical) and increases to only
SO
CSB
8 Outputs
SO
SI
MC33298
SCLK
Shift Register
SI
MC33298
Logic
To
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