MOTOROLA ANALOG INTEGRATED CIRCUIT DEVICE DATA

33996

9

SYSTEM/APPLICATION INFORMATION

INTRODUCTION

The 33996 is designed and developed for automotive and

industrial applications. It is a 16-output power switch having

24-bit serial control. The 33996 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. A simplified internal block diagram of the 33996 is

shown in Figure 1, page 2.

MCU INTERFACE DESCRIPTION

In operation the 33996 functions as a 16-output 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 33996 directly interfaces to an MCU and operates at

system clock serial frequencies up to 6.0 MHz using a Serial

Peripheral Interface (SPI) for control and diagnostic readout.

Figure 3 shows the basic SPI configuration between an MCU

and one 33996.

Figure 3. 33996 SPI Interface with Microcontroller

All inputs are compatible with 3.3 V/5.0 V CMOS logic levels

and incorporate positive logic. An input that is programmed to a

logic low state (< 0.8 V) will have the corresponding output

OFF. Conversely, an input programmed to a logic high state

(> 2.2 V) will have the output being controlled ON. Diagnostics

is treated in a similar manner—outputs with a fault will feedback

(via SO) to the MCU a logic [1], while normal operating outputs

will provide a logic [0].

The 33996 may be controlled and provide diagnostics using

a daisy chain configuration or in parallel mode. Figure 4 shows

the daisy chain configuration using the 33996. Data from the

MCU is clocked daisy chain through each device while the Chip

clock cycle, output status from the daisy-chained 33996s is

being transferred back to the MCU via the Master In Slave Out

register is transferred to the output driver. Daisy chain control of

the 33996 requires 24 bits per device.

Multiple 33996 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.

Figure 4. 33996 SPI System Daisy Chain

33996

MC68HCXX

Microcontroller

Receive

Buffer

Parallel

Ports

To Logic

24-Bit Shift Register

Shift Register

MOSI

SI

MISO

SO

SCLK

RST

CS

PWM

MC68HCXX

Microcontroller

33996

Shift Register

Ports

Parallel

33996

SI

SO

SCLK

CS

RST

PWM

MISO

SCLK

PWM1

PWM2

MOSI

SI

SO

SCLK

CS

RST

PWM

Freescale Semiconductor, Inc.

For More Information On This Product,

Go to: www.freescale.com