Datasheet

MSP430x22x2, MSP430x22x4
MIXED SIGNAL MICROCONTROLLER
SLAS504B − JULY 2006 − REVISED JULY 2007
39
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
POST OFFICE BOX 1443 • HOUSTON, TEXAS 77251−1443
electrical characteristics over recommended ranges of supply voltage and operating free-air
temperature (unless otherwise noted) (continued)
crystal oscillator, LFXT1, high frequency modes (see Note 5)
PARAMETER TEST CONDITIONS VCC MIN TYP MAX UNIT
f
LFXT1,HF0
LFXT1 oscillator crystal frequency,
HF mode 0
XTS = 1, LFXT1Sx = 0 1.8 V − 3.6 V 0.4 1 MHz
f
LFXT1,HF1
LFXT1 oscillator crystal frequency,
HF mode 1
XTS = 1, LFXT1Sx = 1 1.8 V − 3.6 V 1 4 MHz
LFXT1 ill t t l f
1.8 V − 3.6 V 2 10
f
LFXT1,HF2
LFXT1 oscillator crystal frequency,
HF mode 2
XTS = 1, LFXT1Sx = 2
2.2 V − 3.6 V 2 12
MHz
f
LFXT1
,
HF2
HF
mo
d
e
2
XTS
1,
LFXT1Sx
2
3.0 V − 3.6 V 2 16
MHz
LFXT1 oscillator logic level
1.8 V − 3.6 V 0.4 10
f
LFXT1,HF,lo
g
ic
LFXT1
oscillator
logic
level
square-wave input frequency,
XTS = 1, LFXT1Sx = 3
2.2 V − 3.6 V 0.4 12
MHz
f
LFXT1
,
HF
,
logic
square wave
input
frequency,
HF mode
XTS
1,
LFXT1Sx
3
3.0 V − 3.6 V 0.4 16
MHz
O
XTS = 0, LFXT1Sx = 0,
f
LFXT1,HF
= 1 MHz, C
L,eff
= 15 pF
2700
OA
HF
Oscillation allowance for HF
crystals
(see Figure 18 and Figure 19)
XTS = 0, LFXT1Sx = 1
f
LFXT1,HF
= 4 MHz, C
L,eff
= 15 pF
800
W
(
see
Fi
gure
18
an
d
Fi
gure
19)
XTS = 0, LFXT1Sx = 2
f
LFXT1,HF
= 16 MHz, C
L,eff
= 15 pF
300
C
L,eff
Integrated effective load
capacitance, HF mode
(see Note 1)
XTS = 1 (see Note 2) 1 pF
Duty Cycle
HF mode
XTS = 1, Measured at P1.4/ACLK,
f
LFXT1,HF
= 10 MHz
2.2 V/3 V 40 50 60
%
Duty Cycle HF mode
XTS = 1, Measured at P1.4/ACLK,
f
LFXT1,HF
= 16 MHz
2.2 V/3 V 40 50 60
%
f
Fault,HF
Oscillator fault frequency, HF mode
(see Note 4)
XTS = 1, LFXT1Sx = 3
(see Notes 3)
2.2 V/3 V 30 300 kHz
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. Requires external capacitors at both terminals. Values are specified by crystal manufacturers.
3. Measured with logic level input frequency but also applies to operation with crystals.
4. Frequencies below the MIN specification set the fault flag, frequencies above the MAX specification do not set the fault flag.
Frequencies in between might set the flag.
5. To improve EMI on the LFXT1 oscillator the following guidelines should be observed.
− Keep as short a trace as possible between the device and the crystal.
− 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.