Software Control
10
SLAU374B – December 2011 – Revised May 2016
Copyright © 2011–2016, Texas Instruments Incorporated
TSW308x Evaluation Module
Perform the following steps to configure the PLL.
1. Enable PLL.
2. Uncheck
PLL reset
and
PLL sleep
.
3. Set
M
and
N
ratio such that F
DAC
= (M)/(N) × Fref.
4. For the DAC3482, DAC3484, and DAC34H84, set the
prescaler
such that the F
DAC
× prescaler is within
3.3 GHz and 4 GHz.
5. For the DAC34SH84, set the
prescaler
such that the F
DAC
× prescaler is within 2.7 GHz and 3.3 GHz.
6. Set
VCO Bias Tune
to 1.
7.
Charge Pump
setting
(a) If stability (P × M) is less than 120, then set to
Single
.
(b) If stability (P × M) is greater than 120, then set to
Double
or install external loop filter.
8. Adjust the
Freq. Tune (Coarse)
accordingly. For additional information, see the relevant DAC348x data
sheet.
2.2.2
Digital Tab Control Options
Figure 6. Digital Tab Control Options – DAC348x
●
Interpolation: allows control of the data rate versus DAC sampling rate ratio (that is, data rate ×
interpolation = DAC sampling rate).
●
Digital Mixer: allows control of the coarse mixer function.
Note: If fine mixer (NCO) is used, the Enable Mixer button must be checked, and the coarse
mixer must be bypassed. See the following NCO bullet for detail.