DRA790 Datasheet, PDF (164/436 Pages) Texas Instruments – Infotainment Applications Processor

DRA790, DRA791
DRA793, DRA797
SPRS968A – AUGUST 2016 – REVISED FEBRUARY 2017
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NAME
t_sX
Table 5-20. Oscillator Switching Characteristics—Crystal Mode (continued)
Start-up time
DESCRIPTION
MIN
TYP
MAX
4
UNIT
ms
5.9.4.1.3.2 OSC1 Input Clock
A 1.8-V LVCMOS-Compatible Clock Input can be used instead of the internal oscillator to provide the
SYS_CLKIN2 clock input to the system. The external connections to support this are shown in, Figure 5-
14. The xi_osc1 pin is connected to the 1.8-V LVCMOS-Compatible clock sources. The xo_osc1 pin is left
unconnected. The vssa_osc1 pin is connected to board ground (vss).
Device
xi_osc1
xo_osc1
vssa_osc1
NC
SPRS906_CLK_07
Figure 5-14. 1.8-V LVCMOS-Compatible Clock Input
Table 5-21 summarizes the OSC1 input clock electrical characteristics.
Table 5-21. OSC1 Input Clock Electrical Characteristics—Bypass Mode
NAME
DESCRIPTION
MIN
TYP
MAX
UNIT
f
Frequency
Range from 12 to 38.4
MHz
C_IN
Input capacitance
I_IN
Input current (3.3V mode)
t_sX
Start-up time⁽¹⁾
2.819
4
3.019
6
See⁽²⁾
3.219
pF
10
µA
ms
(1) To switch from bypass mode to crystal or from crystal mode to bypass mode, there is a waiting time about 100 μs; however, if the chip
comes from bypass mode to crystal mode the crystal will start-up after time mentioned in Table 5-20, t_sX parameter.
(2) Before the processor boots up and the oscillator is set to bypass mode, there is a waiting time when the internal oscillator is in
application mode and receives a wave. The switching time in this case is about 100 μs.
Table 5-22 details the OSC1 input clock timing requirements.
NAME
CK0
CK1
Table 5-22. OSC1 Input Clock Timing Requirements
1/
t_c(xiosc1)
DESCRIPTION
Frequency, xi_osc1
t_w(xiosc1) Pulse duration, xi_osc1 low or high
t_j(xiosc1) Period jitter⁽¹⁾, xi_osc1
t_R(xiosc1) Rise time, xi_osc1
t_F(xiosc1) Fall time, xi_osc1
MIN
TYP
MAX
Range from 12 to 38.4
0.45 ×
t_c(xiosc1)
0.55 ×
t_c(xiosc1)
0.01 ×
t_c(xiosc1)
(3)
5
5
UNIT
MHz
ns
ns
ns
ns
164 Specifications
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