mc68hc705v12 Freescale Semiconductor, Inc, mc68hc705v12 Datasheet - Page 204

• Manufacturer Part Number: mc68hc705v12
• Description: M68hc05-based Mcu Hc05 Freescale Semiconductor
• Manufacturer: Freescale Semiconductor, Inc

Gauge Drivers
15.8 Mechanism Diagram
15.9 Gauge Power Supply
Advance Information
AUTOS — Automatic Mode Select Bit
The diagram in
connected to the coil driver pins and how some of the other pins should
be connected. The external components that have actual part numbers
are merely examples of suitable components. Other components with
similar operating characteristics also may be used.
The MC68HC705V12 contains most of the circuitry to provide the coil
drivers with a regulated supply that is necessary to drive the coil.
Referring to
the aid of an external P-channel enhancement mode MOSFET device
which serves as the series pass devices between a +12 V supply and
the V
V
whatever is required to produce a V
resistors R
GSUP.
This bit clears automatically once the scan cycle begins to service coil
11 (minor D). The bit will clear at the proper time, even if the minor D
gauge is not enabled in the GER, since the scan cycle time is not
affected by the enabling or disabling of the gauges. The bit is cleared
once coil 11 begins to be serviced because adequate time (2 * t
for the software (either interrupt driven or polled) to recognize the flag
and write new data to the CDR and CMR registers for the next scan
cycle should be provided. Note that after the scan cycle has finished,
a new scan cycle will not begin until this bit is set again. If a 1 is written
to this bit before it clears, the write will be ignored. In automatic mode,
this bit has no effect.
This bit selects whether the coil sequencer will operate in manual or
automatic mode.
V
Freescale Semiconductor, Inc.
GSUP
For More Information On This Product,
GSUP
1 = Automatic mode
0 = Manual mode
The drive to the gate of the external pass devices will be
* [R
G1
pin. Two external resistors also are used to set the level of
Figure
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G2
and R
Figure 15-14
/(R
Gauge Drivers
G1
15-3, the gauge drive voltage, V
G2
+R
should be chosen so that
G2
)] = 2.5
shows one way the gauge coils could be
GVREF
voltage of 2.5. The value of
MC68HC705V12
GSUP
, is derived with
—
Rev. 3.0
GCS
)