Texas Instruments LMK00304 Evaluation Board LMK00304EVM/NOPB LMK00304EVM/NOPB 데이터 시트
제품 코드
LMK00304EVM/NOPB
6
LM
K00304EVM User’s Guide
March 2012
By default, 3.3 V is supplied to both VCC and VCCO rails by the onboard LDO regulator, U3. To power the
regulator, connect a 4 V
regulator, connect a 4 V
– 6 V input voltage and ground from an external power source to the terminal block,
J2, or SMA input labeled VCC_EXT.
To modify the EVM with a different power supply configuration, populate the resistor options as shown in
To modify the EVM with a different power supply configuration, populate the resistor options as shown in
. Then, apply the appropriate voltage(s) to the EVM power input(s).
If the EVM is configured for dual direct supplies, connect the 3.3 V supply and ground to VCC_EXT and the
2.5 V supply and ground to the SMA input labeled VCCO_EXT.
Decoupling capacitors and 0-ohm resistor footprints, which can accommodate ferrite beads, can be used to
isolate the EVM power input(s) from the device power pins.
Table 5: EVM Power Supply Configuration Options
LP3878 LDO
Regulator (U3)
3.3 V (DEFAULT)
LMZ10500
Switcher (U2)
3.3 V
Single
Direct Supply
3.3 V
Dual
Direct Supplies
3.3 V & 2.5 V
VCC_EXT port
(J2 or SMA)
Apply 4 V – 6 V
Apply 4 V – 5.5 V
Apply 3.3 V ± 5%
Apply 3.3 V ± 5%
VCCO_EXT port
(SMA)
Not used
Not used
Not used
Apply 2.5 V ± 5%
U2 Vout
Not used
3.3 V (VCC & VCCO)
Not used
Not used
U3 Vout
3.3 V (VCC & VCCO)
Not used
Not used
Not used
R131
OPEN
OPEN
OPEN
0
R132
0
0
0
0
R134
OPEN
0
OPEN
OPEN
R145
OPEN
0
OPEN
OPEN
R153
OPEN
OPEN
0
0
R155
0
OPEN
OPEN
OPEN
R156
0
OPEN
OPEN
OPEN
6.1. Independent Output Supply Voltages
On the bottom side of the EVM, resistor options provide flexibility to power each of the three individual output
supply pins (VCCOA, VCCOB, and VCCOC) from either VCC or VCCO rail. This is useful when 3.3 V and
2.5 V are both needed for separate output supplies.
For example, if Bank A outputs require 3.3 V LVPECL levels, Bank B outputs require 2.5 V LVPECL levels,
and REFout requires 2.5 V LVCMOS, then VCCOA can be connected to VCC (3.3 V) and VCCOB and
VCCOC can be connected to VCCO (2.5 V).
The EVM power supply needs to be modified to get 2.5 V on the VCCO rail, either using the VCCO_EXT
input or LMZ10500 switcher, per
supply pins (VCCOA, VCCOB, and VCCOC) from either VCC or VCCO rail. This is useful when 3.3 V and
2.5 V are both needed for separate output supplies.
For example, if Bank A outputs require 3.3 V LVPECL levels, Bank B outputs require 2.5 V LVPECL levels,
and REFout requires 2.5 V LVCMOS, then VCCOA can be connected to VCC (3.3 V) and VCCOB and
VCCOC can be connected to VCCO (2.5 V).
The EVM power supply needs to be modified to get 2.5 V on the VCCO rail, either using the VCCO_EXT
input or LMZ10500 switcher, per
. To configure LMZ10500 with 2.5 V output, set R138 to 150k and
R139 to 118k.
Note: When the LMZ10500 switcher is used to power the DUT and an ultra-low-noise clock source is used,
the higher output noise voltage of the switcher (compared to the LP3878-ADJ) can cause an slight increase
in the output phase noise floor at low offset frequencies as well as low-level spurs. The high PSRR of the
device helps to minimize supply-induced jitter.
Note: When the LMZ10500 switcher is used to power the DUT and an ultra-low-noise clock source is used,
the higher output noise voltage of the switcher (compared to the LP3878-ADJ) can cause an slight increase
in the output phase noise floor at low offset frequencies as well as low-level spurs. The high PSRR of the
device helps to minimize supply-induced jitter.