Universal Peripheral Interface User's Manual

UPI-C42/UPI-L42
DRIVING FROM AN EXTERNAL SOURCE
290414–18
NOTE:
See XTAL1 Configuration Table.
290414–19
Rise and Fall Times Should Not
Exceed 10 ns. Resistors to V
CC
are Needed to Ensure V
IH
e
3.5V
if TTL Circuitry is Used.
LC OSCILLATOR MODE
L C NOMINAL
f
e
1
2q
0
LC
Ê
45 H 20 pF 5.2 MHz
120 H 20 pF 3.2 MHz
C
Ê
e
C
a
3Cpp
2
Cpp
j
5–10 pF
Pin-to-Pin Capacitance
290414–20
Each C Should be Approximately 20 pF, including Stray Capacitance.
CRYSTAL OSCILLATOR MODE
290414–21
C1 5 pF (STRAY 5 pF)
C2 (CRYSTAL
a
STRAY) 8 pF
C3 20–30 pF INCLUDING STRAY
Crystal Series Resistance Should
be Less Than 30X at 12.5 MHz.
XTAL1 Configuration Table
XTAL1 Connection
1) to Ground
2) 10 KX Resistor
3) Not Connected
to Ground
Not recommended for CHMOS Recommended configuration for Low power configuration
designs. Causes approximately designs which will use both recommended for CHMOS only
16 mA of additional current flow NMOS and CHMOS parts. This designs to provide lowest
through the XTAL1 pin on UPI- configuration limits the additional possible power consumption.
C42 and approximately 11 mA of current through the XTAL1 pin to This configuration will not work
additional current through XTAL1 approximately 1 mA, while with the NMOS device.
on the UPI-L42. maintaining compatibility with the
NMOS device.
20