![Infineon Technologies TC1784 User Manual Download Page 189](http://html.mh-extra.com/html/infineon-technologies/tc1784/tc1784_user-manual_2055446189.webp)
TC1784
System Control Unit (SCU)
User´s Manual
3-6
V1.1, 2011-05
32-bit SCU, V1.18
Figure 3-4
External Circuitry for Crystal / Ceramic Resonator operation
When using an external crystal / ceramic resonator, its frequency can be within the
allowed range (the values are listed in the Data Sheet). An external oscillator load
circuitry must be used, connected to both pins, XTAL1 and XTAL2. Additionally are
necessary, two load capacitances
C
1
and
C
2
, and depending on the crystal / ceramic
resonator type, a series resistor
R
2
to limit the current. A test resistor
R
Q
may be
temporarily inserted to measure the oscillation allowance (negative resistance) of the
oscillator circuitry.
R
Q
values are typically specified by the crystal / ceramic resonator
vendor. The
C
1
and
C
2
values shown in the Data Sheet can be used as starting points
for the negative resistance evaluation and for non-productive systems. The exact values
and related operating range are dependent on the crystal / ceramic resonator frequency
and have to be determined and optimized together with the crystal / ceramic resonator
vendor using the negative resistance method. Oscillation measurement with the final
target system is strongly recommended to verify the input amplitude at XTAL1 and to
determine the actual oscillation allowance (margin negative resistance) for the oscillator-
crystal / ceramic resonator system.
The oscillator can also be used in combination with a ceramic resonator. The final
circuitry must be also verified by the resonator vendor.
Oscillator Run Detection
ext_crystal_mode
OSC
C
1
C
2
XTAL1
XTAL2
with external Components
V
DDP
f
OSC
V
SS
R
2
R
Q
OSC
XTAL1
XTAL2
without external Components
V
DDP
f
OSC
V
SS
Summary of Contents for TC1784
Page 1: ...User s Manual V1 1 2011 05 Microcontrollers TC1784 32 Bit Single Chip Microcontroller ...
Page 3: ...User s Manual V1 1 2011 05 Microcontrollers TC1784 32 Bit Single Chip Microcontroller ...
Page 950: ...TC1784 Direct Memory Access Controller DMA User s Manual 11 132 V1 1 2011 05 DMA V3 03 ...
Page 1949: ...TC1784 General Purpose Timer Array GPTA v5 User s Manual 21 297 V1 1 2011 05 GPTA v5 V1 14 ...
Page 2350: ...w w w i n f i n e o n c o m Published by Infineon Technologies AG Doc_Number ...