AMIC110 Datasheet, PDF (96/214 Pages) Texas Instruments – Sitara Processors

AMIC110
SPRS971A – AUGUST 2016 – REVISED SEPTEMBER 2016
6.2 Clock Specifications
www.ti.com
NOTE
The ZCE package is not supported for this family of devices.
6.2.1 Input Clock Specifications
The AMIC110 device has two clock inputs. Each clock input passes through an internal oscillator which
can be connected to an external crystal circuit (oscillator mode) or external LVCMOS square-wave digital
clock source (bypass mode). The oscillators automatically operate in bypass mode when their input is
connected to an external LVCMOS square-wave digital clock source. The oscillator associated with a
specific clock input must be enabled when the clock input is being used in either oscillator mode or bypass
mode.
The OSC1 oscillator provides a 32.768-kHz reference clock to the real-time clock (RTC) and is connected
to the RTC_XTALIN and RTC_XTALOUT terminals. This clock source is referred to as the 32K oscillator
(CLK_32K_RTC) in the AM335x and AMIC110 Sitara Processors Technical Reference Manual. OSC1 is
disabled by default after power is applied. This clock input is optional and may not be required if the RTC
is configured to receive a clock from the internal 32k RC oscillator (CLK_RC32K) or peripheral PLL
(CLK_32KHZ) which receives a reference clock from the OSC0 input.
The OSC0 oscillator provides a 19.2-MHz, 24-MHz, 25-MHz, or 26-MHz reference clock which is used to
clock all non-RTC functions and is connected to the XTALIN and XTALOUT terminals. This clock source is
referred to as the master oscillator (CLK_M_OSC) in the AM335x and AMIC110 Sitara Processors
Technical Reference Manual. OSC0 is enabled by default after power is applied.
For more information related to recommended circuit topologies and crystal oscillator circuit requirements
for these clock inputs, see Section 6.2.2.
6.2.2 Input Clock Requirements
6.2.2.1 OSC0 Internal Oscillator Clock Source
Figure 6-9 shows the recommended crystal circuit. TI recommends that preproduction printed-circuit board
(PCB) designs include the two optional resistors R_bias and R_d in case they are required for proper oscillator
operation when combined with production crystal circuit components. In most cases, R_bias is not required
and R_d is a 0-Ω resistor. These resistors may be removed from production PCB designs after evaluating
oscillator performance with production crystal circuit components installed on preproduction PCBs.
The XTALIN terminal has a 15- to 40-kΩ internal pulldown resistor which is enabled when OSC0 is
disabled. This internal resistor prevents the XTALIN terminal from floating to an invalid logic level which
may increase leakage current through the oscillator input buffer.
96
Power and Clocking
Submit Documentation Feedback
Product Folder Links: AMIC110
Copyright © 2016, Texas Instruments Incorporated