PC33882R2 datasheet(17/31 Pages) FREESCALE

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Analog Integrated Circuit Device Data

Freescale Semiconductor

33882

FUNCTIONAL DESCRIPTION

FUNCTIONAL PIN DESCRIPTION

to 32 bits. The first word sent is command verification data

fed through the two 33882 ICs. Data returned in the 32 bits is

the two fault status bytes, followed by the first word sent. Bits

sent out are sampled on rising SCLK edges at the input pin

of the next IC in the daisy chain.

Note Because SO pins of the 33882 ICs are tri-stated,

any device receiving its SPI data from a previous 33882 IC

SO pin in a daisy chain will not receive data if the MODE pin

is low. This prohibits setting SPI-controlled channels ON with

a SPI command while the MODE pin is low. Therefore, all

channels remain OFF when the MODE pin changes from low

to high at vehicle power-up.

MODE

OPERATION

During normal operation output channels are controlled by

either the Serial Input control bits or the parallel input pins. If

the MODE pin is pulled high:

• Serial input control is disabled.

• Parallel input pins IN0 to IN5 are ignored.

• The SO pin is tri-stated.

OUT0 and OUT1, OUT2 and OUT3, and OUT4 and OUT5

are controlled by the IN0 & IN1, IN2 & IN3, and IN4 & IN5

pins, respectively. When a 10 k

Ω pull-up resistor is used, a

logic high on the MODE pin or an open serial output pin is

flagged by the SPI when all bits are returned as logic [1]s.

Although a logic high on the MODE pin disables serial

control of outputs, data can still be clocked into the serial

input register. This allows programming of a desired state for

the outputs taking effect only when the MODE pin returns to a

logic low. For applications using the SO pin, daisy chaining is

permitted, but if the MODE pin is high, writing to other than the

first IC in a daisy chain is not possible because the serial

outputs are tri-stated.

OUTPUT DRIVERS

The high power OUT0 to OUT5 outputs are active

clamped, low side switches driving 1.0 A typical or less loads.

The low-power OUT6 and OUT7 outputs are unclamped low-

side switches driving 30 mA typical or less loads. All outputs

are individually protected from short circuit or short-to-battery

conditions and transient voltages. The outputs are also

protected by short-circuit device shutdown. Each output

individually detects and reports open load/short-to-ground

and short-circuit/short-to-battery faults.

FAULT SENSE/PROTECTION CIRCUITRY

Each output channel individually detects shorted loads/

short-to-battery while the output is ON and open load/short-

to-ground while the output is OFF. OUT0 to OUT5 may also

be programmed via SPI bits 6 and 7 to detect open loads and

shorts-to-ground while the output is ON. Whenever a short or

open fault condition is present on a particular output channel,

its fault bit in the internal fault register indicates the fault with

a logic [1].

When a fault ends, its fault bit remains set until the SPI

normal condition. When the CS pin is pulled low for serial

communication, the fault bits in the internal fault register

latch, preventing erroneous status transmissions and the

forthcoming communication reports this latched fault status.

The SO pin serial output data for 8-bit SPI mode are the fault

status register bits.

For 16-bit SPI mode and SO pin (non-daisy chained) use,

a transmitted double command provides the fault byte

followed by the first byte of the double command, becoming

a command verification. The status is sent back to the IC for

fault monitoring. Diagnostic interpretation of the following

fault types can be accomplished using the procedure

described in the paragraph entitled Extensive Fault

Diagnostics:

• Communication error

• Open load/short-to-ground

• Short-to-battery or short-circuit

When serial communication is ended, the CS pin returns

high, opening the fault status register to new fault information

and tri-stating the SO pin.

Two fault conditions initiate protective action by the device:

• A short-circuit or short-to-battery on a particular output will

cause that output to go into a low duty cycle operation until

the fault condition is removed or the input to that channel

turns OFF.

• A short-circuit condition causes all channels to shut down,

ignoring serial and parallel inputs to the device.

To be detected and reported as a fault, a fault condition

must last a specified time (fault sense time or fault mask

time). This prevents any normal switching transients from

causing inadvertent fault status indications.

Fault status information should be ignored for VBAT levels

outside the 9.0 V to 17 V range. The fault reporting may

appear to function properly but may not be 100 percent

reliable.

SHORT-CIRCUIT/SHORT-TO-BATTERY SENSING

AND PROTECTION

When an output is turned ON, if the drain current limit is

reached, the current remains at the limit until the short-circuit

sense time, tSS, has elapsed. At this time, the affected output

will shut down and its fault status bit switches to a logic [1].

The output goes into a low duty cycle operation as long as the

short-circuit condition exists and the input to that channel is

ON.

This duty cycle is defined by the sense and refresh times.

If a short occurs after the output is ON, the fault sense time

indicates the fault and enters the low duty cycle mode at

much less than tSS. The duty cycle is low enough to keep the

driver from exceeding its thermal capabilities. When the short

is removed, the driver resumes normal operation at the next

retry, but the fault status bit does not return to a normal

logic [0] state until it is read from the SPI. When the CS pin of

this device is pulled low, the fault status bits are latched, after

which any new fault information is not a part of this serial

communication event.

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