Datasheet

Table Of Contents
ADSP-21362/ADSP-21363/ADSP-21364/ADSP-21365/ADSP-21366
Rev. J | Page 17 of 60 | July 2013
The product of CLKIN and PLLM must never exceed 1/2
f
VCO
(max) in Table 11 if the input divider is not enabled
(INDIV = 0).
The product of CLKIN and PLLM must never exceed f
VCO
(max) in Table 11 if the input divider is enabled
(INDIV = 1).
The VCO frequency is calculated as follows:
f
VCO
= 2 × PLLM × f
INPUT
f
CCLK
= (2 × PLLM × f
INPUT
) ÷ (2 × PLLN)
where:
f
VCO
= VCO output
PLLM = Multiplier value programmed in the PMCTL register.
During reset, the PLLM value is derived from the ratio selected
using the CLK_CFG pins in hardware.
PLLN = 1, 2, 4, 8 based on the PLLD value programmed on the
PMCTL register. During reset this value is 1.
f
INPUT
= Input frequency to the PLL.
f
INPUT
= CLKIN when the input divider is disabled or
f
INPUT
= CLKIN ÷ 2 when the input divider is enabled
Note the definitions of the clock periods that are a function of
CLKIN and the appropriate ratio control shown in Table 9. All
of the timing specifications for the ADSP-2136x peripherals are
defined in relation to t
PCLK
. Refer to the peripheral specific sec-
tion for each peripheral’s timing information.
Figure 5 shows core to CLKIN relationships with external oscil-
lator or crystal. The shaded divider/multiplier blocks denote
where clock ratios can be set through hardware or software
using the power management control register (PMCTL). For
more information, refer to the ADSP-2136x SHARC Processor
Hardware Reference.
Table 9. Clock Periods
Timing
Requirements Description
t
CK
CLKIN Clock Period
t
CCLK
Processor Core Clock Period
t
PCLK
Peripheral Clock Period = 2 × t
CCLK
Figure 5. Core Clock and System Clock Relationship to CLKIN
CLKOUT (TEST ONLY)*
LOOP
FILTER
PLL
f
VCO
÷ (2 × PLLM)
VCO
PLL
DIVIDER
PMCTL
(2 × PLLN)
f
VCO
f
CCLK
CLK_CFGx/
PMCTL (2 × PLLM)
CLKIN
PCLK
XTAL
CLKIN
DIVIDER
RESETOUT
DELAY OF
4096 CLKIN
CYCLES
RESET
BUF
BUF
PMCTL
(INDIV)
PMCTL
(PLLBP)
BYPASS
MUX
PIN MUX
DIVIDE
BY 2
RESETOUT
PMCTL (CLKOUTEN)
CCLK
CORERST
*CLKOUT (TEST ONLY) FREQUENCY IS THE SAME AS f
INPUT.
THIS SIGNAL IS NOT SPECIFIED OR SUPPORTED FOR ANY DESIGN.
f
INPUT