msp430f2121irge Microchip Technology Inc., msp430f2121irge Datasheet - Page 27

• Manufacturer Part Number: msp430f2121irge
• Description: Msp430
• Manufacturer: Microchip Technology Inc.

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)
NOTES: 1. Includes parasitic bond and package capacitance (approximately 2pF per pin).
f LFXT1,HF0
f LFXT1,HF1
f LFXT1,HF2
f LFXT1,HF2
f LFXT1,HF,logic wave input frequency,
f LFXT1,HF,logic
OA HF
C L,eff
Duty Cycle
Duty Cycle
f Fault,HF
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 will set the fault flag, frequencies above the MAX specification will not set the fault flag.
5. To improve EMI on the LFXT1 oscillator the following guidelines should be observed.
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.
Frequencies in between might set the flag.
−
−
−
−
−
−
−
LFXT1 oscillator crystal frequency,
HF mode 0
LFXT1 oscillator crystal frequency,
HF mode 1
LFXT1 oscillator crystal frequency,
LFXT1 oscillator crystal frequency,
HF mode 2
HF mode 2
LFXT1 oscillator logic level square
LFXT1 oscillator logic level square
wave input frequency,
HF mode
HF mode
Oscillation Allowance for HF
crystals
(refer to Figure 14 and Figure 15)
(refer to Figure 14 and Figure 15)
Integrated effective Load
Capacitance, HF mode
(see Note 1)
HF mode
HF mode
Oscillator fault frequency, HF mode
(see Note 4)
Keep as short of 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.
PARAMETER
POST OFFICE BOX 655303
XTS = 1, LFXT1Sx = 0
XTS = 1, LFXT1Sx = 1
XTS = 1, LFXT1Sx = 2
XTS = 1, LFXT1Sx = 2
XTS = 1, LFXT1Sx = 3
XTS = 1, LFXT1Sx = 3
XTS = 0, LFXT1Sx = 0,
f LFXT1,HF = 1 MHz,
C L,eff = 15 pF
XTS = 0, LFXT1Sx = 1
f LFXT1,HF = 4 MHz,
C L,eff = 15 pF
XTS = 0, LFXT1Sx = 2
f LFXT1,HF = 16 MHz,
C L,eff = 15 pF
XTS = 1 (see Note 2)
XTS = 1, Measured at P1.4/ACLK,
f LFXT1,HF = 10 MHz
XTS = 1, Measured at P1.4/ACLK,
f LFXT1,HF = 16 MHz
XTS = 1, LFXT1Sx = 3
(see Notes 3)
TEST CONDITIONS
•
DALLAS, TEXAS 75265
MIXED SIGNAL MICROCONTROLLER
SLAS439C − SEPTEMBER 2004 − REVISED JULY 2006
1.8 V − 3.6 V
1.8 V − 3.6 V
1.8 V − 3.6 V
2.2 V − 3.6 V
3.0 V − 3.6 V
1.8 V − 3.6 V
2.2 V − 3.6 V
3.0 V − 3.6 V
2.2 V/3 V
2.2 V/3 V
2.2 V/3 V
VCC
MIN
0.4
0.4
0.4
0.4
40
40
30
1
2
2
2
2700
TYP
800
300
MSP430x21x1
50
50
1
MAX
300
10
12
16
10
12
16
60
60
1
4
UNIT
MHz
MHz
MHz
MHz
MHz
MHz
MHz
MHz
kHz
pF
%
%
W
W
W
27