ZHCSH13B October 2017 – January 2019 LMX2572
PRODUCTION DATA.
Manual ramping is enabled when the user sets RAMP_EN = 1 and RAMP_MANUAL = 1. In this mode, the ramp is clocked by the rising edges applied to the RampClk pin. The size of the frequency change is defined by RAMP0_INC and RAMP1_INC. If a LOW is seen at the RampDir pin on the rising edge of RampClk, the output frequency will be incremented by RAMP0_INC. On the contrary, the output frequency will be incremented by RAMP1_INC if a HIGH is captured. If a rising edge is seen on the RampClk pin while the VCO is calibrating, then this rising edge is ignored. The frequency for the RampClk must be limited to a frequency of 250 kHz or less, and the rising edge of the RampDir signal must be targeted to the falling edge of the RampClk pin. The necessary register fields for use in manual ramping mode are shown in Table 138.