JN517X Datasheet, PDF (42/100 Pages) NXP Semiconductors – Supports multiple network stacks

NXP Semiconductors
JN517x
IEEE802.15.4 Wireless Microcontroller
For example, generating approximately half the number of pulses that make up a
complete conversion period will produce a voltage on the RC output of V_DD, provided the
RC time constant is chosen correctly. During a conversion, the pulses will be
pseudo-randomly dispersed throughout the cycle in order to produce a steady voltage on
the output of the RC network.
The output signal is asserted for the number of clock periods defined in the high register,
with the total period being 2¹⁷ cycles. For the same value in the high register, the pattern
of pulses on subsequent cycles is different, due to the pseudo-random distribution.
The delta-sigma converter output can operate in a Return-To-Zero (RTZ) or a
Non-Return-to-Zero (NRZ) mode. The NRZ mode allows several pulses to be output next
to each other. The RTZ mode ensures that each pulse is separated from the next by at
least one period. This improves linearity if the rise and fall times of the output are different
to one another. Essentially, the output signal is low on every other output clock period, and
the conversion cycle time is twice the NRZ cycle time, that is 2¹⁸ clocks. The integrated
output will only reach half V_DDD in RTZ mode, since even at full scale only half the cycle
contains pulses. Figure 29 and Figure 30 illustrate the difference between RTZ and NRZ
for the same programmed number of pulses.



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Fig 29. Return-To-Zero mode in operation
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Fig 30. Non-Return-to-Zero mode
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9.10.1.5 Example timer/counter application
Figure 31 shows an application of the JN517x timers to provide closed loop speed control.
PWM1 is configured in PWM mode to provide a variable mark-space ratio switching
waveform to the gate of the NFET. This in turn controls the power in the DC motor.
Timer0 is configured to count the rising edge events on the CLK/GATE pin over a constant
period. This converts the tacho pulse stream output into a count proportional to the motor
speed. This value is then used by the application software executing the control algorithm.
If necessary for other functionality, then the unused IO associated with the timers could be
used as general-purpose DIO.
JN517X
Product data sheet
All information provided in this document is subject to legal disclaimers.
Rev. 2.0 — 8 November 2016
© NXP Semiconductors N.V. 2016. All rights reserved.
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