GMZAN3 Datasheet, PDF (21/53 Pages) List of Unclassifed Manufacturers – XGA ALALOG INTERFACE LCD MONITOR CONTROLLER

gmZAN3 Preliminary Data Sheet
minimum signal level of about 50-mV peak to peak to function correctly. The output of the comparator is
buffered and then distributed to the gmZAN3 circuits.
3.3 Volts
~ 2 Volts
250 mV peak to peak
to
1000 mV peak to peak
time
Figure 6.
Internal Oscillator Output
One of the design parameters that must be given some consideration is the value of the loading capacitors
used with the crystal as shown in Figure 7. The loading capacitance (C_load) on the crystal is the
combination of C_L1 and C_L2 and is calculated by C_load = ((C_L1 * C_L2) / (C_L1 + C_L2)) + C_shunt. The shunt
capacitance C_shunt is the effective capacitance between the XTAL and TCLK pins. For the gmZAN3 this is
approximately 9 pF. C_L1 and C_L2 are a parallel combination of the external loading capacitors (C_ex), the
PCB board capacitance (C_pcb), the pin capacitance (C_pin), the pad capacitance (C_pad), and the ESD
protection capacitance (C_esd). The capacitances are symmetrical so that C_L1 = C_L2 = C_ex + C_PCB + C_pin +
C_pad + C_ESD. The correct value of C_ex must be calculated based on the values of the load capacitances.
Approximate values are provided in Figure 7.
CL1 = Cex1 + Cpcb + Cpin + Cpad + Cesd
Vdda
Cex1
Vdda
Cex2
Cpcb
Cshunt
Cpcb
111
TCLK
110
XTAL
CL2 = Cex1 + Cpcb + Cpin + Cpad + Cesd
Cpin
Cpad Cesd
gmZAN3
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
C0523-DAT-01G
21
Genesis Microchip Confidential
http://www.genesis-microchip.com
July 2003