MAX14886EVKIT+ Maxim Integrated, MAX14886EVKIT+ Datasheet - Page 4

• Manufacturer Part Number: MAX14886EVKIT+
• Description: Video ICs 1
• Manufacturer: Maxim Integrated

Specifications of MAX14886EVKIT+

• Operating Supply Voltage: 3.3 V
• Number Of Channels: 2

MAX14886 Evaluation Kit
The device outputs are open-collector differential switches,
steering currents through the connector and cables into
a 50I HDMI load biased at +3.3V. A high-bandwidth
DC-coupled probe with a 50I load biased at +3.3V
(e.g., Tektronix P7313) is therefore best suited to evaluate
the device’s performance. If such a probe is not avail-
able, a common AC-coupled 50I instrument with SMA
connectors, such as a scope or vector network ana-
lyzer (VNA), can still be used to evaluate the device’s
performance in the characterization circuit.
In the default configuration of the characterization circuit
section, a high-frequency bias-T (250MHz to 1GHz),
consisting of RF inductors (L1, L2) and low-ESR capaci-
tors (C38, C39), is connected to the U4 device outputs.
The bias-T produces a 50I DC impedance biased
at VCC and high impedance in the 250MHz to 1GHz
high-frequency range. When a 50I SMA instrument
is AC-coupled, the device load closely resembles the
HDMI monitor. In practice, frequencies below 250MHz
(e.g., HDMI clock) result in “sloping top waveforms” due
to the termination-impedance frequency dependence
and cannot be evaluated here.
For the best evaluation results, and to measure the
device’s performance at HDMI clock frequencies below
4
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Testing
250MHz, use a high-bandwidth DC-coupled probe with
a 50I load biased at +3.3V (e.g., Tektronix P7313). Start
by removing L1 and L2 and replace C38 and C39 with
0I 0402 resistors. Use the same DC-coupled probe to
evaluate the device’s performance with double HDMI
termination. Reconfigure the EV kit as follows: replace
L1/L2 with 200I 0603 resistors, R25/R26 and C38/C39
with 0I 0402 resistors, and R18 with a 3kI 0402 resistor.
Always bias the DC-coupled probe at +3.3V first and
then connect it to P6 and P7 on the EV kit with the SMA
cables. Next apply a +3.3V supply to the VCC1 and GND
PCB pads on the EV kit and enable the U4 device by
positioning jumper JU4 in the 1-2 position. Consult the
probe manual for proper measurement procedures.
The bottom half of the EV kit provides a set of calibra-
tion traces that can be used for further analysis. The
lengths and shapes of the calibration traces from the
SMA connectors (P8, P9) are matched to the traces
going from the SMA connectors (P4, P5) to the U4
device of the inputs of the characterization circuit. Each
calibration trace includes a 0.1FF 0402 DC-blocking
capacitor and a 50I load termination exactly matching
the characterization circuit section components.
Calibration Traces