HDM8515 Datasheet, PDF (30/75 Pages) Hynix Semiconductor – DVB/DSS Compliant Receiver

3.7 Clock Generation PLL
An integrated VCO is locked to MxN times a reference frequency provided by a external clock.
1.Determining Output Frequency
Fully programmable feedback and reference divider capability allows virtually any frequency
to be generated, not just simple multiples of reference frequency.
There are two status exist
(1) PLL Disable mode : The PLL is bypassed and the external clock is directly connected to the
Internal clock.
(2) PLL Enable mode : The internal clock is connected to the generated clock of the PLL.
1.1 PLL disable mode
PLL control setting is as follows
TDM (Bit 7 of 0x23 register) is set to one and BYPASS (Bit 4 of 0x23 register) is set to one.
1.2 Normal Frequency mode
Output frequency range is limited to 160MHz.
PLL control setting is as follows:
TDM (Bit 7 of 0x23 register) is set to zero, and BYPASS (Bit 4 of 0x23 register) is set to
zero.
At this condition, the output frequency, F(ck), is actually determined by the following
equation.
F(ref) x (Feedback divisor)
F(ck) = ----------------------------------------------
(Reference divisor)
F(ck) : Frequency of output
F(ref): Frequency of reference input
Feedback divisor : M[13:0]+2 , (0x25 and 0x26 registers)
Reference divisor : N[7:0]+1 , (0x27 register)
1.3 Extended Frequency mode
Output frequency range is limited to 320MHz.
PLL control setting is as follows
TDM (Bit 7 of 0x23 register) is set to zero, and BYPASS (Bit 4 fo 0x23 register) is set to
one.
At this condition, the output frequency, F(ck), is actually determined by the following
Equation
F(ref) x (Feedback divisor) x (Pre divisor)
F(ck) = --------------------------------------------------------
(Reference divisor)
Pre divisor : 2^p[1:0]+1 , P is Bit 2 and 3 of 0x23 register
2. PLL Control Parameter setting
Besides of M (Feedback divisor), N (Reference divisor), P (Pre divisor) , You must determine vc
(VCO range control vector), lfm (Loop filter mode selector), icp (Charge pump bias current
control
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