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Hardware Preparation and Installation
MC92602 Reduced Interface SerDes Design Verification Board User’s Guide, Rev. 3
Freescale Semiconductor
2-3
The +3.3-V, +1.8-V, and +V
DDQ
supplies are accessible via connection posts.
Note that these regulators
should be set to voltage limits within the operating ranges described in the
MC92602 Quad 1.25 Gbaud
Reduced Interface SerDes Reference Guide.
Failure to operate within these ranges could cause damage to
the MC92602. Freescale will not guarantee MC92602 operation beyond the ranges specified. The R12V,
R22V, and R22V1 potentiometers will be factory set for +3.3, +1.8, and +1.5 V, respectively.
2.3.3
HSTL Voltage Reference Regulator
The HSTL I/O has a voltage reference that must be adjusted to set the logic high/low switch point. For a
n1.5 V on the +1.5-V, V
DDQ
supply, R22V2 should be set such that the voltage at the
HSTL_VREF test point is +0.75 V. For those systems whose HSTL voltage will be +1.8 V, this
potentiometer should be set to +0.9 V. The R22V2 potentiometer is typically factory set for +0.8 V.
2.4
Reference Clock Source
Through a combination of clock buffers, a reference clock is supplied to the MC92602 and several SMA
output connectors. The input reference clock for the MC92602 can be supplied using either an onboard
crystal oscillator, or by directly driving an external reference clock into the board’s clock buffer circuit via
SMA connector, CLK_IN. The clock circuitry for the MC92602DVB is shown in
Figure 2-2
.
Figure 2-2. MC92602DVB Clock Circuitry
Y2
Y1
EN
EN
EN
CLK_0
REF_CLK_P
CLK
CLK
DIV 1/2
CSEL
DIV 1/2
DIV by 1
REF_CLK_N
1
7
SW1
U2
U3
MC100ES6222
MPC9456
250-MHz
Oscillator
+
+
CLK_1
CLK_IN
3.3V_CLK_OUT1
3.3V_CLK_OUT2
3.3V_CLK_OUT3
3.3V_CLK_OUT4
2
3
4
5
6
1.5V_CLK_OUT5
1.5V_CLK_OUT6
DIV 1/2
U4 MC100ES8111
PECL
to
HSTL
Buffer
Содержание MC92602
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