Typical Measurement
9
SNAU235 – May 2018
Copyright © 2018, Texas Instruments Incorporated
LMX2572LPEVM Evaluation Instructions
Figure 9. Calibration-Free Automatic Ramp Setting
Figure 10. Calibration-Free Automatic Ramp (CHDIV = 4)
3.2.3
Automatic Ramping
This ramping mode supports wider ramp frequency, but there are glitches in the middle of the ramp
because of the VCO calibrations that are required to ensure the continuity of the ramp.
Table 4. Automatic Ramp Example
PARAMETER
EXAMPLE VALUE
Ramping start frequency
4740 MHz
Ramping stop frequency
4860 MHz
Phase detector frequency
50 MHz
Ramp up / down time
1000 µs
RAMP_LIMIT_HIGH
5060 MHz
RAMP_LIMIT_LOW
4540 MHz
f
OSCin
100 MHz
CAL_CLK_DIV
0
RAMP_THRESH
40 MHz
Pause time for VCO calibration
500 µs