MC68HC05V12 Datasheet, PDF (206/246 Pages) Freescale Semiconductor, Inc – HCMOS Microcontreller Unit

Gauge Drivers
Freescale Semiconductor, Inc.
• 12 is the number of coil drivers
• SF = % of max current driven in any coil; worse case for power
dissipation purposes, 0.707 (45^o) assumes sin/cos drive algorithm
• I_Coil(max) = maximum required coil current in each coil
15.12.3 Coil Inductance Limits
Since the MCU pins will drive the gauge coils directly without any
external voltage limiting devices, precautions must be taken to avoid
generating voltages and currents high enough to damage the MCU. The
high voltages generated by the inductive impedance of the coil will be
related directly to the coil drivers. This imposes a limit on the maximum
coil inductance referred to as L_Coil in the electrical specifications.
15.13 Operation in Wait Mode
During wait mode, the gauge driver module will continue to operate
normally. The gauges will continue to be driven to the currents and
directions that were last written to the CMR and CDR. In manual mode,
if the CPU will be put into wait mode between scan cycles, the SYNIE bit
in the SSCR should be set to enable the gauge module to generate an
interrupt request (which will take the CPU out of wait mode) to properly
service the gauge coils.
15.14 Operation in Stop Mode
During stop mode, the system clocks will stop operating. All bits in the
GER register will be cleared automatically when stop mode is entered.
No other bits in any other gauge module registers will be affected. The
gauge controller sequence and control logic will be reset/initialized such
that a new scan sequence will begin once the gauges are turned on
during the user’s stop mode recovery sequence.
Technical Data
Gauge Drivers
For More Information On This Product,
Go to: www.freescale.com
MC68HC05V12 — Rev. 2.0