MSP430X241X Datasheet, PDF (48/98 Pages) Texas Instruments – MIXED SIGNAL MICROCONTROLLER

MSP430x241x, MSP430x261x
MIXED SIGNAL MICROCONTROLLER
SLAS541A -- JUNE 2007 -- REVISED OCTOBER 2007
electrical characteristics over recommended ranges of supply voltage and operating free-air
temperature (unless otherwise noted) (continued)
crystal oscillator, LFXT1, low frequency modes (see Note 4)
PARAMETER
TEST CONDITIONS
VCC
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
32,768
Hz
LFXT1 oscillator logic
f_{LFXT1,LF,logic} level square wave input
frequency, LF mode
XTS = 0, LFXT1Sx = 3, XCAPx = 0
1.8 V to 3.6 V 10,000 32,768 50,000 Hz
OA_LF
C_L,eff
Oscillation allowance for
LF crystals
Integrated effective load
capacitance, LF mode
(see Note 1)
XTS = 0, LFXT1Sx = 0,
f_LFXT1,LF = 32,768 kHz,
C_L,eff = 6 pF
XTS = 0, LFXT1Sx = 0;
f_LFXT1,LF = 32,768 kHz, C_L,eff = 12 pF
XTS = 0, XCAPx = 0
XTS = 0, XCAPx = 1
XTS = 0, XCAPx = 2
XTS = 0, XCAPx = 3
500
kΩ
200
1
5.5
pF
8.5
11
Duty cycle LF mode
XTS = 0, Measured at P1.4/ACLK,
f_LFXT1,LF = 32,768 Hz
2.2 V/3 V
30
50
70 %
f_Fault,LF
Oscillator fault
frequency, LF mode
(see Note 3)
XTS = 0, LFXT1Sx = 3, XCAPx = 0
(see Note 2)
2.2 V/3 V
10
10,000 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 will set the fault flag, frequencies above the MAX specification will not set the fault flag.
Frequencies in between might set the flag.
4. To improve EMI on the LFXT1 oscillator the following guidelines should be observed.
-- 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.
5. Applies only if using an external logic-level clock source. Not applicable when using a crystal or resonator.
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