LMX2541SQ2060E/NOPB National Semiconductor, LMX2541SQ2060E/NOPB Datasheet - Page 27

• Manufacturer Part Number: LMX2541SQ2060E/NOPB
• Description: IC PLL FREQ SYNTH W/VCO 36LLP
• Manufacturer: National Semiconductor
• Series: PowerWise®r
• Type: Clock/Frequency Synthesizer (RF)r

Specifications of LMX2541SQ2060E/NOPB

• Pll: Yes
• Input: Clock
• Output: Clock
• Number Of Circuits: 1
• Ratio - Input:output: 2:2
• Differential - Input:output: No/No
• Frequency - Max: 2.24GHz
• Divider/multiplier: Yes/No
• Voltage - Supply: 3.15 V ~ 3.45 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 36-LLP
• Frequency-max: 2.24GHz
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: LMX2541SQ2060E

Bench Test Setups
CHARGE PUMP CURRENTS TEST SETUP
The charge pump is tested in external VCO mode (MODE=1),
although it is no external VCO hooked up. The CPout pin
should be disconnected from the any external VCO tuning pin,
external loop filter, and also the Vtune pin on the device. A
signal is then applied to the OSCin pin to ensure that the R
counter is oscillating. This signal does not have to be clean
and the frequency is very critical. These currents at the CPout
pin are typically measured with a semiconductor parameter
analyzer.
Charge Pump Current Measurements
In order to test the TRI-STATE current, the CPT bit is set to
one and the current is measured. Aside from having no other
sources of leakage attached to this pin, it is also important
that the board be well cleaned before doing this test. The
temperature and voltage at the charge pump can then be var-
ied and the resulting leakage current is then recorded. Typi-
cally, the leakage currents are worst at higher temperatures
and higher charge pump voltages.
In order to test the source and sink currents, the CPT bit is
set to active mode and the frequency is programmed to some-
Leakage Current
Source Current
Measurement
Sink Current
PLL_R
X
1
1
PLL_N
4000
4000
X
27
thing much higher than can be achieved in order to force the
charge pump to rail. The reason why this is necessary is that
the duty cycle of the charge pump is not 100% unless it is
forced against one of the rails. If the charge pump polarity bit
(CPP) is set to positive, then the charge pump source current
is measured. To measure the sink current, the CPT bit is set
to negative. The part is then programmed and the charge
pump will rail in one direction. The semiconductor parameter
analyzer measures the current at a particular charge pump
voltage. The phase detector polarity bit, CPP, can be toggled
to test between the negative and positive charge pump gains.
In order to test leakage, set the TRI-STATE bit, CPT, to 1 so
that this can be measured. For the most accurate measure-
ments, it is desirable that the CPout and Vtune pin are not
shorted together for these measurements. Once these cur-
rents are measured, then the datasheet parameters can be
calculated.
A summary of these charge pump tests is given in the table
below.
0 - 31
0 - 31
CPG
X
1 (TRI-STATE)
0 (Active)
0 (Active)
CPT
0 (Negative)
1 (Positive)
CPP
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