Detailed Description
The MAX3674 EV kit simplifies evaluation by providing
the hardware and software needed to evaluate all the
MAX3674 functions. A microcontroller (Microchip
PIC16C745) and I/O port expander (MAX7312) allow
the user to set control pins and read/write registers with
software. The on-board 16MHz crystal and integrated
oscillator generate the PLL reference clock.
Alternatively, an external clock source can be connect-
ed to the REF_CLK input to serve as the reference
clock. LED D1 switches on when the LOCK output is
high, indicating the PLL is locked.
The microcontroller is powered by the USB port +5V
supply. LED D2 switches on when USB power is
detected. The MAX3674 and I/O port expander are
powered by the +3.3V supply. The EV kit also includes
the MAX3373 level translator that interfaces the I2C
clock and data lines from the microcontroller to the
MAX3674 and I/O port expander, and is powered by
both supplies. The USB cable and +3.3V supply can
be connected to the EV kit in any sequence.
Master Reset
It is recommended to press the RESET button after
every power-up.
LVPECL Clock Outputs
The LVPECL clock outputs (QA, QA, QB, QB) have on-
board bias-Ts that provide DC biasing and AC-couple
the signal to allow direct connection to 50Ω-terminated
test equipment. Unused outputs should be terminated
to prevent reflections on the transmission lines.
Reference Clock Input
The REF_CLK input (J17) accepts sinusoidal or square-
wave clocks with frequencies between 15MHz and
20MHz, and swings up to 3.3VP-P. This input has a 50Ω
DC termination to ground and is AC-coupled to an on-
board buffer. The buffer is used to square the clock
signal applied to the REF_CLK input pin.
I2C Slave Address
Jumper J5 is used to set the two selectable address
bits (ADR0 and ADR1). The EV kit software performs a
search at power-up to determine which of the four pos-
sible slave addresses is being used.
EV Kit Software
The EV kit software provides an easy way to set opera-
tional modes and read/write internal registers
(Figure 1). Refer to the MAX3674 data sheet for
detailed descriptions of the MAX3674 functions and
guidance on selecting dividers settings. Note that when
the Programming Interface is set to I2C, the settings
for dividers P, NA, NB, and Mare configured within the
MAX3674 after pressing the LOAD button.
Evaluates: MAX3674
MAX3674 Evaluation Kit
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