MOTOROLA ANALOG INTEGRATED CIRCUIT DEVICE DATA
33999
9
SYSTEM/APPLICATION INFORMATION
INTRODUCTION
The 33999 is designed and developed for automotive and
industrial applications. It is a 16-output power switch having
24-bit serial control. The 33999 incorporates SMARTMOS
technology having CMOS logic, bipolar/MOS analog circuitry,
and independent DMOS power output transistors. Many
benefits are realized as a direct result of using this mixed
technology.
Figure 1,
page 2
,
illustrates a simplified internal
block diagram of the 33999.
MCU INTERFACE DESCRIPTION
In operation the 33999 functions as a 16-output serial switch
serving as a microcontroller unit (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 33999 directly interfaces to an MCU, operating at
system clock serial frequencies up to 6.0 MHz using a Serial
Peripheral Interface (SPI) for control and diagnostic readout.
Figure 3
illustrates the basic SPI configuration between an
MCU and one 33999.
Figure 3. 33999 SPI Interface with Microcontroller
All inputs are compatible with 3.3 V/5.0 V CMOS logic levels
and incorporate positive logic. An input programmed to a logic
low state (< 0.8 V) has the corresponding output OFF.
Conversely, an input programmed to a logic high state (> 2.2 V)
has the output being controlled ON. Diagnostics is treated in a
similar manner—outputs with a fault will feed back (via SO) to
the microcontroller a logic [1], while normal operating outputs
will provide a logic [0].
The 33999 may be controlled and provide diagnostics using
a daisy chain configuration or in parallel mode.
Figure 4
shows
the daisy chain configuration using the 33999. Data from the
MCU is clocked daisy chain through each device while the Chip
Select bit (
CS
) is commanded low by the MCU. During each
clock cycle, output status from the daisy-chained 33999s is
being transferred back to the MCU via the Master In Slave Out
(MISO) line. On rising edge of
CS
, data stored in the input
register is then transferred to the output driver. Daisy chain
control of the 33999 requires 24 bits per device.
Figure 4. 33999 SPI System Daisy Chain
Multiple 33999 devices can be controlled in a parallel input
fashion using the SPI.
Figure 5
, page 10, illustrates potentially
32 loads being controlled by two dedicated parallel MCU ports
used for chip select.
MC68HCXX
Microcontroller
33999
24-Bit Shift Register
Shift Register
To Logic
Receive
Buffer
Parallel
Ports
MISO
SCLK
MOSI
SI
SO
RST
CS
PWM
MC68HCXX
Microcontroller
33999
Shift Register
Ports
Parallel
33999
SI
SO
SCLK
CS
RST
PWM
MISO
SCLK
PWM1
PWM2
MOSI
SI
SO
SCLK
CS
PWM
RST
F
Freescale Semiconductor, Inc.
Go to: www.freescale.com
n
.