Datasheet

MSP430F41x2
MIXED SIGNAL MICROCONTROLLER
SLAS648E -- APRIL 2009 -- REVISED MARCH 2011
35
POST OFFICE BOX 655303  DALLAS, TEXAS 75265
electrical characteristics over recommended operating free-air temperature (unless otherwise
noted)
crystal oscillator, LFXT1, low-frequency modes (see Note 4)
PARAMETER TEST CONDITIONS V
CC
MIN TYP MAX UNIT
f
LFXT1,LF
LFXT1 oscillator crystal
frequency, LF mode 0, 1
XTS = 0, LFXT1Sx = 0 or 1 1.8 V to 3.6 V 32768 Hz
O
A
Oscillation allowance
f
or
XTS = 0, LFXT1Sx = 0,
f
LFXT1,LF
= 32768 kHz,
C
L,eff
=6pF
500
k
Ω
O
A
LF
O
s
c
i
l
l
a
t
i
o
n
a
l
l
o
w
a
n
c
e
f
o
r
LF crystals
XTS = 0, LFXT1Sx = 0,
f
LFXT1,LF
= 32768 kHz,
C
L,eff
=12pF
200
kΩ
XTS = 0, XCAPx = 0 1
C
Integrated effective load
c
a
p
a
c
i
t
a
n
c
e
L
F
m
o
d
e
XTS = 0, XCAPx = 1 5.5
p
F
C
L,eff
capacitance, LF mode
(
s
e
e
N
o
t
e
1
)
XTS = 0, XCAPx = 2 8.5
pF
(
s
e
e
N
o
t
e
1
)
XTS = 0, XCAPx = 3 11
Duty cycle LF mode
XTS = 0,
Measured at P1.6/ACLK,
f
LFXT1,LF
= 32768Hz
2.2 V/3 V 30 50 70 %
f
Fault,LF
Oscillator fault frequency,
LF mode (see Note 3)
XTS = 0, XCAPx = 0.
LFXT1Sx = 3 (see Note 2)
2.2 V/3 V 10 10000 Hz
NOTES: 1. Includes parasitic bond and package capacitance (approximately 2 pF per pin).
Since the PCB adds additional capacitance it is recommended to verify the correct load by measuring the ACLK frequency. For a
correct setup the effective load capacitance should always match the specification of the used crystal.
2. Measured with logic level input frequency but also applies to operation with crystals.
3. Frequencies below the MIN specification set the fault flag, frequencies above the MAX specification do not set the fault flag, and
frequencies in between might set the flag.
4. To improve EMI on the LFXT1 oscillator the following guidelines should be observed.
-- Keep the trace between the device and the crystal as short as possible.
-- Design a good ground plane around the oscillator pins.
-- Prevent crosstalk from other clock or data lines into oscillator pins XIN and XOUT.
-- Avoid running PCB traces underneath or adjacent to the XIN and 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.