Datasheet

0
1
Sys_32k_in
32.5 kHz
Fixed
Divider
/800
0
1
Latch
Sys_clk=
26 MHz
JTAG Overrides
for DFT
1
Sys_clk
PowerOn Reset
Sys_32k
Sys_xtalin
Sys_xtalout
Sys_boot7
AM3517, AM3505
SPRS550E –OCTOBER 2009–REVISED MARCH 2013 www.ti.com
Figure 4-2. 32-kHz Clock Generation
The AM3517/05 outputs externally two clocks:
• sys_clkout1 can output the oscillator clock (26 MHz) at any time.
• sys_clkout2 can output the oscillator clock, core_clk, 96 MHz or 54 MHz. It can be divided by 2, 4, 8,
or 16 and its off state polarity is programmable.
4.1 Oscillator
The sys_xtalin (26 MHz) oscillator provides the primary reference clock for the device. The on-chip
oscillator requires an external crystal connected across the sys_xtalin and sys_xtalout pins, along with two
load capacitors, as shown in Figure 4-3. The external crystal load capacitors must be connected only to
the oscillator ground pin (VSSOSC). Do not connect to board ground (VSS).
Note: If an external oscillator is to be used, the external oscillator clock signal should be connected to the
sys_xtalin pin with a 1.8V amplitude. The sys_xtalout should be left unconnected and the VSSOSC signal
should be connected to board ground (VSS).
92 Clock Specifications Copyright © 2009–2013, Texas Instruments Incorporated
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