gm5120-H

A functional block diagram of gm5110/20 is illustrated below. Each of the functional units shown is described in the following sections.

The gm5110/20 features three clock inputs. All additional clocks are internal clocks derived from one or more of these:

1. Crystal Input Clock (TCLK and XTAL). This is the input pair to an internal crystal oscillator and corresponding logic. A 14.3 MHz TV crystal is recommended. Other crystal frequencies may be used, but require custom programming. This is illustrated in Figure 4 below.

Alternatively, a single-ended TTL/CMOS clock oscillator can be driven into the TCLK pin (leave XTAL as N/C in this case). This is illustrated in Figure 7 below. This option is selected by connecting a 10K pull-up to ROM_ADDR13 (refer to Table 18). See also Table 14.

2. DVI Differential Input Clock (RC+ and RC-)

3. Host Interface Transfer Clock (HCLK)

The gm5110/20 TCLK oscillator circuitry is a custom designed circuit to support the use of an external oscillator or a crystal resonator to generate a reference frequency source for the gm5110/20 device.