adsp-21483 Analog Devices, Inc., adsp-21483 Datasheet - Page 23

• Manufacturer Part Number: adsp-21483
• Description: Sharc Processor
• Manufacturer: Analog Devices, Inc.

Preliminary Technical Data
Clock Input
Table 15. Clock Input
1
2
3
4
5
6
Clock Signals
The ADSP-2148x can use an external clock or a crystal. See the
CLKIN pin description in
configure the processor to use its internal clock generator by
connecting the necessary components to CLKIN and XTAL.
Figure 7
Parameter
Timing Requirements
t
t
t
t
t
f
t
Applies only for CLK_CFG1–0 = 00 and default values for PLL control bits in PMCTL.
Applies only for CLK_CFG1–0 = 01 and default values for PLL control bits in PMCTL.
Any changes to PLL control bits in the PMCTL register must meet core clock timing specification t
See
Actual input jitter should be combined with ac specifications for accurate timing analysis.
Jitter specification is maximum peak-to-peak time interval error (TIE) jitter.
VCO
CK
CKL
CKH
CKRF
CCLK
CKJ
5, 6
4
Figure 4 on page 21
3
shows the component connections used for a crystal
CLKIN Period
CLKIN Width Low
CLKIN Width High
CLKIN Rise/Fall (0.4 V to 2.0 V)
CCLK Period
VCO Frequency
CLKIN Jitter Tolerance
CLKIN
for VCO diagram.
C1
22pF
Table 9 on Page
CLKIN
*TYPICAL VALUES
t
CKH
25 MHz
R1
1M *
Y1
14. Programs can
ADSP-2148x
t
Rev. PrA | Page 23 of 66 | March 2010
CK
XTAL
Fundamental Mode Crystal Operation
Figure 7. Recommended Circuit for
t
CKL
R2
47 *
C2
22pF
Figure 6. Clock Input
Min
22.8
11
11
2.85
200
–250
ADSP-21483/21486/21487/21488/21489
R2 SHOULD BE CHOSEN TO LIMIT CRYSTAL
DRIVE POWER. REFER TO CRYSTAL
MANUFACTURER’S SPECIFICATIONS
1
operating in fundamental mode. Note that the clock rate is
achieved using a 25 MHz crystal and a PLL multiplier ratio 16:1
(CCLK:CLKIN achieves a clock speed of 400 MHz). To achieve
the full core clock rate, programs need to configure the multi-
plier bits in the PMCTL register.
350 MHz
CCLK
.
Max
100
45
45
3
10
700
+250
2
t
CKJ
Min
20
10
10
2.5
200
–250
1
400 MHz
Max
100
45
3
10
800
+250
45
2
Unit
ns
ns
ns
ns
ns
MHz
ps