AM3874_16 Datasheet, PDF (189/358 Pages) Texas Instruments – Sitara ARM Processors

www.ti.com
AM3874, AM3871
SPRS695D – SEPTEMBER 2011 – REVISED JANUARY 2016
Table 8-13. SERDES_CLKN/P AC Coupling Capacitors Recommendations (continued)
PARAMETER
SERDES_CLKN/P AC coupling capacitor package size⁽¹⁾⁽²⁾
MIN
TYP
0402
MAX
0603
UNIT
EIA
(1) L x W, 10 Mil units, that is, a 0402 is a 40 x 20 Mil surface mount capacitor.
(2) The physical size of the capacitor should be as small as practical. Use the same size on both lines in each pair placed side-by-side.
The differential clock source is required to meet the REFCLK AC Specifications outlined in the PCI-
EXPRESS CARD ELECTROMECHANICAL SPECIFICATION, REV. 2.0, at the input to the AC coupling
capacitors.
In addition, LVDS clock sources that are compliant to the above specification, but with the following
exceptions, are also acceptable:
Table 8-14. Acceptable Exceptions to the REFCLK AC Specifications for LVDS Clock Sources
PARAMETER
V_IH
Differential High-Level Input Voltage
V_IL
Differential Low-Level Input Voltage
MIN
125
-1000
MAX
1000
-125
UNIT
mV
mV
8.4.3 AUD_CLKINx Input Clocks
External clock inputs can optionally be provided at the AUD_CLKIN0/1/2 pins to serve as a reference
clocks for the following modules:
• McASP3/4/5
• McBSP
• TIMER1/2/3/4/5/6/7/8
8.4.4 CLKIN32 Input Clock
An external 32768-Hz clock input can optionally be provided at the CLKIN32 pin to serve as a reference
clock in place of the RTCDIVIDER clock for the following Modules:
• RTC
• GPIO0/1/2/3
• TIMER1/2/3/4/5/6/7/8
• ARM Cortex-A8
• SYNCTIMER
The CLKIN32 source must meet the timing requirements shown in Table 8-18.
8.4.5 External Input Clocks
There are three pins referred to as AUD_CLKIN0,1,2 which are used as optional sources for HDMI I2S,
McASP, McBSP and TIMER1-8. The maximum IO pin frequency for these three input clocks is 50MHz.
8.4.6 Output Clocks Select Logic
The device includes two selectable general-purpose clock outputs (CLKOUT0 and CLKOUT1). The source
for these output clocks is controlled by the CLKOUT_MUX register in the Control Module (see Figure 8-
11).
Copyright © 2011–2016, Texas Instruments Incorporated
Power, Reset, Clocking, and Interrupts 189
Submit Documentation Feedback
Product Folder Links: AM3874 AM3871