ADuC841/ADuC842/ADuC843
Rev. 0 | Page 78 of 88
TIMING SPECIFICATIONS1, 2, 3
Table 41. AVDD =2.7 V to 3.6 V or 4.75 V to 5.25 V, DVDD = 2.7 V to 3.6 V or 4.75 V to 5.25 V; all specifications TMIN to TMAX,
unless otherwise noted
Parameter
32.768 kHz External Crystal
ADuC842/ADuC843 CLOCK INPUT (External Clock Driven XTAL1)
Min
Typ
Max
Unit
tCK
XTAL1 Period
30.52
s
tCKL
XTAL1 Width Low
6.26
s
tCKH
XTAL1 Width High
6.26
s
tCKR
XTAL1 Rise Time
9
ns
tCKF
XTAL1 Fall Time
9
ns
1/tCORE
ADuC842/ADuC843 Core Clock Frequency4
0.131
16.78
MHz
tCORE
ADuC842/ADuC843 Core Clock Period5
0.476
s
tCYC
ADuC842/ADuC843 Machine Cycle Time6
0.059
0.476
7.63
s
1 AC inputs during testing are driven at DVDD – 0.5 V for a Logic 1 and 0.45 V for Logic 0. Timing measurements are made at VIH min for Logic 1 and VIL max for Logic 0, as
shown in Figure 87.
2 For timing purposes, a port pin is no longer floating when a 100 mV change from load voltage occurs. A port pin begins to float when a 100 mV change from the
loaded VOH/VOL level occurs, as shown in Figure 87.
3 CLOAD for all outputs = 80 pF, unless otherwise noted.
4 ADuC842/ADuC843 internal PLL locks onto a multiple (512 times) of the 32.768 kHz external crystal frequency to provide a stable 16.78 MHz internal clock for the
system. The core can operate at this frequency or at a binary submultiple called Core_Clk, selected via the PLLCON SFR.
5 This number is measured at the default Core_Clk operating frequency of 2.09 MHz.
6 ADuC842/ADuC843 machine cycle time is nominally defined as 1/Core_CLK.
Parameter
Variable External Crystal
ADuC841 CLOCK INPUT (External Clock Driven XTAL1)
Min
Typ
Max
Unit
tCK
XTAL1 Period
62.5
1000
ns
tCKL
XTAL1 Width Low
20
ns
tCKH
XTAL1 Width High
20
ns
tCKR
XTAL1 Rise Time
20
ns
tCKF
XTAL1 Fall Time
20
ns
1/tCORE
ADuC841 Core Clock Frequency
0.131
20
MHz
tCORE
ADuC841 Core Clock Period
0.476
s
tCYC
ADuC841 Machine Cycle Time
0.05
0.476
7.63
s
t
CKH
t
CKL
t
CK
t
CKF
t
CKR
03260-0-085
Figure 86. XTAL1 Input
DVDD – 0.5V
0.45V
0.2DVDD + 0.9V
TEST POINTS
0.2DVDD – 0.1V
VLOAD – 0.1V
VLOAD
VLOAD + 0.1V
TIMING
REFERENCE
POINTS
VLOAD – 0.1V
VLOAD
VLOAD – 0.1V
03260-0-086
Figure 87. Timing Waveform Characteristics