PC33991DHSLASHR2 datasheet(28/36 Pages) MOTOROLA

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33991

MOTOROLA ANALOG INTEGRATED CIRCUIT DEVICE DATA

Figure 9. Full Steps (CCW)

RTZ Output

The non-driven coil is analyzed determining the state of the

motor during an RTZ event. The 33991multiplexes the coil

voltages and provides the signal from the non-driven coil to the

RTZ pin.

Default Mode

Default mode refers to the state of the 33991after an internal

or external reset and prior to SPI communication. An internal

reset occurs during VDD power-up. An external reset is initiated

by the RST pin driven to a logic [0]. With the exception of the

RTZCR full step time, all of the specific pin functions and internal

registers will operate as though all of the addressable

configuration register bits were set to logic [0]. This means for

example, all of the outputs will be disabled after a power-up or

external reset, SO flag ST6 is set, indicating an under voltage

event. Anytime an external reset is exerted and the default is

restored, all configuration parameters, e.g., clock calibration,

maximum speed, RTZ parameters, etc. are lost and must be

reloaded.

Fault Logic Requirements

The 33991device indicates each of the following faults as

they occur:

• Over temperature fault

• Out-of-range voltage faults

• Clock outofspec

Over current faults are not reported directly. It is likely, however,

an over current condition will become a thermal issue and be

reported.

Over Temperature Fault Requirements

The 33991incorporates over temperature protection

circuitry, shutting off the affected Gauge Driver when excessive

temperatures are measured. In the event of a thermal overload,

the affected gauge driver is automatically disabled. The over

temperature fault is flagged via ST0 and/or ST1. Its respective

flag continues to be set until the affected gauge is successfully

re-enabled, provided the junction temperature has fallen below

the hysteresis level.

Over Voltage Fault Requirements

The device is capable of surviving VPWR voltages within the

maximum specified in the Maximum Ratings table. VPWR levels

resultinginanOver Voltage Shut Down condition canresultin

uncertain pointer positions. Therefore, the pointer position

should be re-calibrated. The master is then notified of an over

voltage event via the ST6 flag on the SO pin. Over voltage

detection and notification occurs regardless of whether the

gauge(s) are enabled or disabled.

Note:

There is no way to distinguish between an over voltage fault

and an under voltage fault from the status bits. If there is no external

means for the microcontroller to determine the fault type, the gauges

should be routinely enabled following the transition to logic [0] of ST6.

Imax

Icoil

SINE

COSINE

Freescale Semiconductor, Inc.

For More Information On This Product,

Go to: www.freescale.com

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