78M6610+PSU/EK#1 Maxim Integrated, 78M6610+PSU/EK#1 Datasheet - Page 5

• Manufacturer Part Number: 78M6610+PSU/EK#1
• Description: Development Boards & Kits - Other Processors 78M6610 EVAL KIT
• Manufacturer: Maxim Integrated

Specifications of 78M6610+PSU/EK#1

• Rohs: yes
• Part # Aliases: 90-X6610#KK1

Upon reset or power-on, the 78M6610+PSU will automatically select the external clock, if available, after
1024 clock cycles of the internal oscillator, allowing the external crystal adequate time to start-up. After
power-on or during run-time, the 78M6610+PSU will automatically switch to the internal oscillator in the
event of a failure with the external oscillator (or crystal not mounted). This condition is also monitored by
the processor and available to the user in the ALARMS register.
The internal RC oscillator is trimmed and temperature compensated. It provides an accurate clock
source, however for applications requiring highest line frequency accuracy, the use of an external crystal
is recommended (only available in the 24-pin QFN package).
The 78M6610+PSU external clock circuitry requires a 20.000 MHz crystal. The circuitry includes two
18pF ceramic capacitors.
Alternatively, an external clock signal can be utilized instead of the crystal. In this case, the external clock
should be connected to the XOUT pin while the XIN pin should be connected to GNDD.
If the external crystal is not utilized (not mounted), the XOUT pin should be connected to GNDD and the
XIN pin left unconnected.
1.1 Clock Management
The 78M6610+PSU can be clocked by either the trimmed internal RC oscillator or by oscillator circuitry
that relies on an external crystal. The 78M6610+PSU hardware automatically handles the clock sources
logic and distributes the clock to the rest of the device.
self biasing and therefore an external resistor should NOT be connected across the crystal.
Rev 1
Figure 2
20.000MHz
shows the typical connection of the external crystal. This oscillator is
18pF
18pF
Figure 2: XTAL Connection
78M6610+PSU/B
XOUT
XIN
78M6610+PSU Data Sheet
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