
NXP Semiconductors
MPT612
Maximum power point tracking IC
MPT612
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NXP B.V. 2010. All rights reserved.
Product data sheet
Rev. 2 — 14 September 2010
16 of 16
The output divider can be set to divide by a factor of 2, 4, 8 or 16 to produce the output
clock. The minimum output divider value is 2 which gives a PLL output with a 50 % duty
cycle. The PLL is turned off and bypassed after a device reset and can be enabled using
the software. The program must configure and activate the PLL, wait for the PLL to lock
and then connect to the PLL as a clock source. The PLL settling time is 100 μs.
7.17.3 Reset and wake-up timer
The MPT612 reset has two sources; one from the RST pin and the other from the
watchdog reset.
The RST pin is a Schmitt trigger input pin with an additional glitch filter. Assertion of
device reset by any source starts the wake-up timer (see
Section 7.17.3.1
). This causes
the internal device reset to remain asserted until:
the external reset is deasserted
the oscillator is running
a fixed number of clocks have passed
the on-chip flash controller has completed its initialization
When the internal reset is removed, all of the processor core and peripheral registers are
been re-initialized to their reset values and the core begins executing from the reset
vector (address 0).
7.17.3.1 Wake-up timer description
The wake-up timer ensures that the oscillator and other analog functions required for
device operation are fully functional before the processor is allowed to execute
instructions. This is important during power on, all types of reset and whenever any of the
functions are turned off. Since the oscillator and other functions are turned off during
Power-down and in Deep power-down mode, a wake-up of the core from these modes
makes use of the wake-up timer.
The wake-up timer monitors the crystal oscillator to check when it is safe to begin code
execution. A stabilization time interval is required for the oscillator to produce a signal of
sufficient amplitude to drive the clock logic when power is applied to the device or an
event causes the chip to exit Power-down mode. The amount of time depends on many
factors, including:
the rate of V
DD
ramp up (in the case of power on),
the type of crystal, its electrical characteristics (if a quartz crystal is used), as well as
any other external circuitry (e.g., capacitors),
the characteristics of the oscillator under the existing ambient conditions