Datasheet

MSP430F42xA
MIXED SIGNAL MICROCONTROLLER
SLAS587 -- FEBRUARY 2008
27
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
electrical characteristics over recommended operating free-air temperature (unless otherwise
noted) (continued)
crystal oscillator, LFXT1 oscillator (see Notes 1 and 2)
PARAMETER TEST CONDITIONS V
CC
MIN TYP MAX UNIT
OSCCAPx = 0h 3V 0
C
Inte
g
rated in
p
ut ca
p
acitance
OSCCAPx = 1h
3V 10
p
F
C
XIN
I
n
t
e
g
r
a
t
e
d
i
n
p
u
t
c
a
p
a
c
i
t
a
n
c
e
(see Note 4)
OSCCAPx = 2h
3V 14
pF
OSCCAPx = 3h 3V 18
OSCCAPx = 0h 3V 0
C
Inte
g
rated out
p
ut ca
p
acitance
OSCCAPx = 1h
3V 10
p
F
C
XOUT
I
n
t
e
g
r
a
t
e
d
o
u
t
p
u
t
c
a
p
a
c
i
t
a
n
c
e
(see Note 4)
OSCCAPx = 2h
3V 14
pF
OSCCAPx = 3h 3V 18
V
IL
I
n
p
t
l
e
e
l
s
a
t
X
I
N
s
e
e
N
o
t
e
3
3
V
V
SS
0.2×V
CC
V
V
IH
Input levels at XIN seeNote3 3
V
0.8×V
CC
V
CC
V
NOTES: 1. The parasitic capacitance from the package and board may be estimated to be 2pF. The effective load capacitor for the crystal is
(C
XIN
xC
XOUT
)/(C
XIN
+C
XOUT
). It is independent of XTS_FLL.
2. To improve EMI on the low-power LFXT1 oscillator, particularly in the LF mode (32 kHz), the following guidelines must be
observed:
• Keep as short a trace as possible between the ’F42xA and the crystal.
• Design a good ground plane around oscillator pins.
• Prevent crosstalk from other clock or data lines into oscillator pins XIN and XOUT.
• Avoid running PCB traces underneath or adjacent to XIN an XOUT pins.
• Use assembly materials and praxis to avoid any parasitic load on the oscillator XIN and XOUT pins.
• If conformal coating is used, ensure that it does not induce capacitive/resistive leakage between the oscillator pins.
• Do not route the XOUT line to the JTAG header to support the serial programming adapter as shown in other documentation.
This signal is no longer required for the serial programming adapter.
3. Applies only when using an external logic-level clock source. XTS_FLL must be set. Not applicable when using a crystal or resonator.
4. External capacitance is recommended for precisi on real-time clock applications, OSCCAPx = 0h.