MC33996 データシートの表示（PDF） - Freescale Semiconductor

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MC33996

16 Output Switch with SPI Control

Freescale Semiconductor 

FUNCTIONAL DESCRIPTION

OPERATIONAL MODES

OPERATIONAL MODES

On each SPI communication, a 24 bit command word is

sent to the 33996 and 24 bit fault word is received from the

33996. The Most Significant Bit (MSB) is sent and received

first.

Command Register Definition:

0 = Output Command Off

1 = Output Command On

SO Definition:

0 = No fault

1 = Fault

Table 5. Fault Operation

Over-temperature

Over-current

Output “ON’ Open Load Fault

Output “OFF’” Open Load Fault

Device Shutdowns

Over-voltage

Over-temperature

Over-current

Serial Output (SO) Pins Reports

Fault reported by Serial Output (SO) pin.

SO pin reports short to battery/supply or over-current condition.

Not reported.

SO pin reports output “OFF’” open load condition.

Total device shutdown at VPWR = 27.5 V to 35 V. Resumes normal operation with proper voltage.

Upon recovery all outputs assume previous state or OFF based on the Overvoltage bit in the Global

Shutdown/Retry Control Register.

Only the output experiencing an over-temperature fault shuts down. Output may auto-retry or remain

off according to the control bits in the Global Shutdown/Retry Control Register.

Output will remain in current limit 0.9 A to 2.5 A until thermal limit is reached. When thermal limit is

reached, device will enter over-temperature shutdown. Output will operate as programmed in the

Global Shutdown/Retry Control Register. Fault flag in SO Response word will be set.

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 6.0MHz using a Serial

Peripheral Interface (SPI) for control and diagnostic readout.

Figure 9 shows the basic SPI configuration between an

MCU and one 33996.

MC68HCXX

Microcontroller

Shift Register

MOSI

MISO

33996

SI

24-Bit Shift Register

SO

Receive

Buffer

Parallel

Ports

SCLK

RST

CS

PWM

To Logic

Analog Integrated Circuit Device Data

Freescale Semiconductor

Figure 9. 33996 SPI Interface with Microcontroller

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

and incorporate positive logic. An input that is programmed to

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

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

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

33996

11

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