maxq7667 Maxim Integrated Products, Inc., maxq7667 Datasheet - Page 21

• Manufacturer Part Number: maxq7667
• Description: 16-bit, Risc, Microcontroller-based, Ultrasonic Distance-measuring System
• Manufacturer: Maxim Integrated Products, Inc.

The MAXQ7667 includes three 16-bit timers/counters
with programmable I/O (Figure 9). Each timer is a Type
2 timer implemented in the MAXQ
timer is an autoreload 16-bit timer/counter offering the
following functions:
The MAXQ7667 oscillator module supplies the system
clock for the µC core and all of the peripheral modules.
The high-frequency oscillator operates with a 1MHz to
16MHz crystal. Use the internal RC oscillator as the
system clock for applications that do not require pre-
cise timing. See Section 15 of the MAXQ7667 User’s
Guide .
The MAXQ7667 supports the following master clock
sources:
MAXQ is a registered trademark of Maxim Integrated Products, Inc.
• 8-bit/16-bit timer/counter
• Up/down autoreload
• Counter function of external pulse
• Capture
• Compare
• Internal high-frequency oscillator drives an exter-
nal 1MHz–16MHz crystal or ceramic resonator
______________________________________________________________________________________
Ultrasonic Distance-Measuring System
Type 2 Timers/Counters
16-Bit, RISC, Microcontroller-Based,
®
family. The Type 2
Clock Sources
The MAXQ7667 requires a crystal with the following
specifications:
Frequency: 1MHz–16MHz
C
Drive level: 5µW
Series resonance resistance: 30Ω (max)
Note: Quartz crystal vendors often specify series reso-
nance resistance (R1). Series resonance resistance is
the resistance observed when the resonator is in the
series resonant condition. When a resonator is used in
the parallel resonant mode with an external load capac-
itance, as is the case with the MAXQ7667 oscillator cir-
cuit, the effective resistance at the loaded frequency of
oscillation is:
For typical shunt capacitance (CO) and load capaci-
tance (C
tially exceeds R1 by a factor of 2.
LOAD
• Internal, fast-starting, 13.5MHz RC oscillator
• External 4MHz–16MHz clock input
(default oscillator at startup and in the event the
external crystal fails)
: 6pF (min)
LOAD
) values, the effective resistance poten-
R1 x (1 + (CO/C
LOAD
))
Crystal Selection
2
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