TTP-C2NF Communication Controller – Data Sheet

AS8202NF

Rev. 1.7, Copyright 2000-2007, austriamicrosystems AG and TTChip Entwicklungsgesellschaft mbH. All rights reserved.

14

VSS

10 MHz

Rd

Rf

Cext

Cext

VSS

10 MHz

square

wave

VDD

40 MHz

square

wave

Enabled PLL,

external quartz

Enabled PLL,

external oscillator

Disabled PLL,

external oscillator

Figure 6. Main clock setup

Rf will normally not be soldered, it is only provided to get maximum flexibility.

Cext, typ = 15/18 pF. Rd has to be calculated, if the measured drive level will be too high; if

drive level is ok, Rd = 0.

If using an external oscillator at 10 MHz with enabled internal PLL, the oscillator must have a

period of 100 ns with low jitter. Note that a crystal-based clock is recommended over a derived

clock (i.e., PLL-based) to allow best internal PLL performance.

Parameter

Conditions

Min

Typ

Max

Unit

R_osc10

Oscillation margin @ 10 MHz, Cload = 18 pF

0.95

1

1.62

1

kOhm

R_osc16

Oscillation margin @ 16 MHz, Cload = 18 pF

0.37

1

0.64

1

kOhm

R_osc20

Oscillation margin @ 20 MHz, Cload = 18 pF

0.24

1

0.41

1

kOhm

Note 1: Not tested during production.

Cload is the value of the external load capacitors towards ground. The total load capacitance seen by the quartz will be Cload_tot = (Cload + Cpar)/2.

Cpar is the equivalent parasitic capacitance of the oscillator cell inputs and the PCB and is derived from measurements to be about 3.5 … 4.0 pF.

The bus guardian clock has no internal PLL and must be connected to either a 16 MHz Quartz

or an external 16 MHz oscillator:

16 MHz

Rd

Rf

Cext

Cext

16 MHz

square

wave

external quartz

external oscillator

Figure 7. Bus Guardian clock setup

Both the XIN0/XOUT0 (main clock) and the XIN1/XOUT1 (bus guardian clock) cells support

driving a quartz crystal oscillation as well as clock input by an external oscillator.

Build-up Characteristics

Parameter

Symbol

Pin

Min

Typ

Max

Note

Oscillator startup time

(Main clock)

Tosc_startup0

XIN0/XOUT0

20 ms Quartz frequency: 10 MHz

Oscillator startup time

(Bus Guardian clock)

Tosc_startup1

XIN1/XOUT1

20 ms Quartz frequency: 16 MHz