Figure 3-3 Am186Cc/Ch/Cu Microcontroller Clocks - AMD Am186 CC User Manual

The Am186CC and Am186CH microcontrollers also include the transmitter/receiver clocks
CC CH
for each High-level Data Link Control (HDLC) channel.
In the Am186CC microcontroller, each HDLC channel receives its clock inputs directly from
CC
the external communication clock pins (TCLK _X and RCLK_X) in all modes except in GCI
mode. In GCI mode the external GCI communication clocks (TCLK_A and RCLK_A) are
first converted to an internal clocking format (analogous to PCM Highway) before
presentation to the HDLC. The system clock must be at least the same frequency as any
HDLC clock. The Am186CC microcontroller supports the following clock frequencies:
HDLC DCE mode supports clocks up to 10 MHz.
HDLC PCM mode supports clocks up to 10 MHz.
HDLC GCI mode supports a 1.536-MHz clock input. (System clock must be at least
twice the GCI clock.)
In the Am186CH HDLC microcontroller, each HDLC channel receives its clock inputs
CH
directly from the external communication clock pins (TCLK _X and RCLK_X) in all modes.
The system clock must be at least the same frequency as any HDLC clock. The Am186CH
HDLC microcontroller supports the following clock frequencies:
HDLC DCE mode supports clocks up to 10 MHz.
HDLC PCM mode supports clocks up to 10 MHz.
Figure 3-3 Am186CC/CH/CU Microcontroller Clocks
X1 X2
CC CU
USBX1 UXBX2
System Overview
Am186CC/CH/CC Microcontroller
PLL
PLL Bypass Mode
{CLKSEL2}–{CLKSEL1}
PLL
{USBSEL2}–{USBSEL1}
Am186™CC/CH/CU Microcontrollers User's Manual
CPU Clock
1x
2x
4x
48-MHz
USB Clock
2x
4x
CLKOUT
3-33