33874 Datasheet, PDF (29/37 Pages) Freescale Semiconductor, Inc – Quad High-Side Switch (Quad 35 mΩ)

TYPICAL APPLICATION
STANDALONE MODE
This section consists of evaluating the MC33874
standalone capability.
CONFIGURATION WITHOUT MCU
The standalone mode is intended for customers who
desire to plug the device and then immediately “play” with it,
without having to connect it to a microcontroller. It also
provides an easy way to evaluate the main electrical features.
Without the Microcontroller to select programmable
parameters and get full diagnosis via the SPI, the MC33874
runs with all parameters set to default.
The input SPI pins and VDD must be connected to ground.
Fail safe mode and watchdog timeout must be disabled by
connecting the FSI to GND.
All protection functions are available without SPI
communication. Nevertheless, any configuration is possible
without an MCU to communicate by SPI. Some functions still
enable, but diagnosis is reduced. Available functions and
default parameters are detailed next.
FUNCTIONING WITHOUT MCU
Without an MCU, SPI communication is not possible. Fail
safe mode and watchdog timeout are not useful functions
without an MCU, but still enable. Wake/Sleep mode is used
to minimize current consumption during sleep mode. IN pins
control the corresponding outputs and FS output is active (at
0 V) when a default occurs.
The tables 1 and 2 illustrate the available functions without
SPI and default parameters.
Table 1. Available Functions
Function
With SPI
Without SPI
Wake/Sleep mode
Output ON/OFF control
Over temperature protection
Over voltage protection
Under voltage protection
Over current protection
Open load, battery disconnect, reverse
battery, ground disconnect protections
Fault diagnosis
Current sense
Watchdog timeout
Configurable slew rate
Analog temperature feedback
Available
Available
Via SPI or IN pin
Only with IN pin
Available, can be unlatched
Available
Available, can be disabled
Available, always enable
Available, can be disabled
Available, always enable
Available, configurable (with 8 low levels and Available, always enable with default values
2 high levels), can be disabled
Available
Available
Full diagnosis with report by SPI and fault
status pin (/FS)
Available, 2 configurable ratios
Available, 4 configurable timings
2 slew rate modes
Available
Limited fault diagnosis with Fault status pin
only
Not available
Available, default value
Default slew rate mode
Available
Table 2. Default SPI-configurable parameters
Configulable parameter
Default typical value
Over voltage protection
Under voltage protection
Over current protection
Over current low level
Over current high level
Over current detect blanking time
Current sense
Watchdog time timeout
Slew rate mode
Enable
Enable
Enable
OCLO0
OCHI0
t_OCLO0
Disable
T_WDTO0
Slow mode
Table 2 illustrates default parameters after resetting or
applying supply voltage to the MC33874. Levels and timings
are typical values.
Analog Integrated Circuit Device Data
Freescale Semiconductor
33874
29