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Programmable Hardware Manual (PHM)
© Tibbo Technology Inc.
5.2.1.9
Power, Reset, PLL Control, MD Button, and Mode Lines
The EM1001 consumes around 250mA @ 3.3V of current (PLL on, 100BaseT mode,
all onboard LEDs on).
There are two ways to power the EM1001.
Powering through the regulator
The onboard switching regulator has the 8-20V input range and delivers enough
current to power the EM1001 itself, the
Wi-Fi add on, PLUS external loads
with up to 1A of combined current.
To use the regulator, connect the power source to the power jack or GND and VIN
pins. The power jack and GND/VIN are wired in parallel, with no diodes or any other
circuitry between them.
The regulator has a single diode in front of it. The diode will protect the regulator if
the power is accidentally connected in reverse.
External loads can be powered through the 3.3V pin. When the board is powered
through the regulator, this pin serves as a power output. Up to 1A of current is
available with the WA2000 installed, 1.3A available if the WA2000 is not installed.
Using direct 3.3V power
It is also possible to power the EM1001 through the GND and 3.3V lines. In this case
the 3.3V pin serves as a power input and the regulator is bypassed. The 3.3V power
source should be regulated to at least +/-10%.
Board reset
Proper external reset is not required. The EM1001 has a reliable power-on reset
circuit with brown-out detection. You can optionally connect a reset button or
some other reset-generating circuit to the RST pin. This will allow you to generate
"external" resets. The RST line has active HIGH polarity. If you are not using the
RST line you can leave it unconnected.
PLL
The main clock frequency of the EM1001 is generated by the 11.0592MHz crystal
connected to the onboard PLL circuit. When the PLL is off, the EM1001 is clocked at
11.0592MHz. When the PLL is on, the main clock is eight times higher- 88.4736MHz.
Naturally, with PLL turned on the EM1001 works 8 times faster and consumers more
current (250mA @ 3.3V with PLL on vs. 130mA with PLL off). Main clock frequency
also affects the baudrates of
when in the UART mode, as well as the
frequency produced by the
.