GM5110 Просмотр технического описания (PDF) - Genesis Microchip

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GM5110

XGA/SXGA LCD Controller

Genesis Microchip 

*** Genesis Microchip Confidential ***

gm5110/20 Preliminary Data Sheet

CL1 = Cex1 + Cpcb + Cpin + Cpad + Cesd

Vdda

Vdda

Cex1

Cex2

Cpcb

Cshunt

Cpcb

141

TCLK

142

XTAL

CL2 = Cex1 + Cpcb + Cpin + Cpad + Cesd

Cpin

Cpad Cesd

gm5115

Internal Oscillator

Cpin

Cpad

Cesd

Approximate values:

CPCB ~ 2 pF to 10 pF (layout dependent)

Cpin ~ 1.1 pF

Cpad ~ 1 pF

Cesd ~ 5.3 pF

Cshunt ~ 9 pF

Figure 6.

Sources of Parasitic Capacitance

Some attention must be given to the details of the oscillator circuit when used with a crystal

resonator. The PCB traces should be as short as possible. The value of Cload that is specified

by the manufacturer should not be exceeded because of potential start up problems with the

oscillator. Additionally, the crystal should be a parallel resonate-cut and the value of the

equivalent series resistance must be less then 90 Ohms.

4.1.2 Using an External Clock Oscillator

Another option for providing the reference clock is to use a single-ended external clock

oscillator. When the gm5110/20 is in reset, the state of the ROM_ADDR13 (pin 10) is

sampled. If ROM_ADDR13 is pulled high by connecting to VDD through a pull-up resistor

(15KΩ recommended, 15KΩ maximum) then external oscillator mode is enabled. In this

mode the internal oscillator circuit is disabled and the external oscillator signal that is

connected to the TCLK pin (pin number 152) is routed to an internal clock buffer. This is

illustrated in Figure 7.

June 2002

13

C5110-DAT-01C

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