NCN5192NGEVB
http://onsemi.com
7
Clock Generation
NCN5192 is operated on a clock signal of either
460.8 kHz, 921.6 kHz or 1.84 MHz. The NCN5192NGEVB
has two options for providing this clock signal. The first
method is by using a ceramic resonator or a crystal with the
internal oscillator. The standard populated option is a Token
ZTACC1.84MG ceramic resonator, loaded with two 27 pF
capacitors.
Alternatively, a clock signal can be provided externally
when R
37
is removed and R
24
is populated by a resistor of
0
W
. This signal can be provided by a microcontroller or any
other external oscillator circuit. The module uses less power
when clock signal is applied externally, as this allows the
modem to shut down the oscillator circuit. A typical current
consumption witnessed by utilizing an external oscillator is
70-100
m
A less. However, care must be taken that this
external signal has the required frequency accuracy (1%).
Duty cycle of the clock signal is specified between 40%
and 60%. No errors were observed during testing in
operation between 20% and 80% duty cycle. However,
operation on such very small or very large duty cycle is not
recommended, due to the possibility of timing errors that
may occur under specific circumstances (including, but not
limited to, temperature variations).
Figure 7. Clock Generation Circuit
(Resonator Option)
Figure 8. Clock Generation Circuit
(External Clock)
UART Interface IDC
1
Figure 9. UART Interface (IDC
1
)
Table 4. MICROCONTROLLER INTERFACE
Pin Number
Signal
Type
Description
1
RESETB
Open Drain
Reset Signal from the Voltage Supervisor, Open Drain with Pull-up, Active Low
3
CD
Output
Carrier Detect
5
RxD
Input
Receive from Microcontroller
7
TxD
Output
Transmit towards Microcontroller
9
RTSB
Input
Request to Send, Active Low
2, 10
VDD
Power
3 V Nominal
4, 6, 8
GND
Power
Ground
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