MSP430F2274-EP_11 Datasheet, PDF (33/80 Pages) Texas Instruments – MIXED SIGNAL MICROCONTROLLER

MSP430F2274-EP
www.ti.com
SLAS614D – SEPTEMBER 2008 – REVISED MAY 2011
Crystal Oscillator (LFXT1) Low-Frequency Modes – Electrical Characteristics^{(1) (2)}
over recommended ranges of supply voltage and operating free-air temperature (unless otherwise noted)
PARAMETER
f_LFXT1,LF
LFXT1 oscillator
crystal frequency, LF
mode 0, 1
TEST CONDITIONS
XTS = 0, LFXT1Sx = 0 or 1
T_A
–55°C to
105°C
V_CC
1.8 V to 3.6 V
MIN TYP
32,768
f_LFXT1,LF,
logic
LFXT1 oscillator
logic-level
square-wave input
frequency, LF mode
XTS = 0, LFXT1Sx = 3
–55°C to
125°C
1.8 V to 3.6 V
10,000 32,768
OA_LF
Oscillation allowance
for LF crystals
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
–55°C to
105°C
–55°C to
105°C
500
200
XCAPx = 0
1
C_L,eff
Integrated effective
load capacitance,
LF mode⁽³⁾
XTS = 0
XCAPx = 1
XCAPx = 2
–55°C to
105°C
5.5
8.5
XCAPx = 3
11
Duty
Cycle
f_Fault,LF
LF mode
Oscillator fault
frequency threshold,
LF mode ⁽⁴⁾
XTS = 0, Measured at
P1.4/ACLK,
f_LFXT1,LF = 32,768 Hz
XTS = 0, LFXT1Sx = 3⁽⁵⁾
–55°C to
125°C
–55°C to
125°C
2.2 V/3 V
2.2 V/3 V
30
50
10
MAX UNIT
Hz
50,000 Hz
kΩ
pF
70 %
10,000 Hz
(1) To improve EMI on the LFXT1 oscillator the following guidelines should be observed:
(a) Keep as short of a trace as possible between the device and the crystal.
(b) Design a good ground plane around the oscillator pins.
(c) Prevent crosstalk from other clock or data lines into oscillator pins XIN and XOUT.
(d) Avoid running PCB traces underneath or adjacent to the XIN and XOUT pins.
(e) Use assembly materials and praxis to avoid any parasitic load on the oscillator XIN and XOUT pins.
(f) If conformal coating is used, ensure that it does not induce capacitive/resistive leakage between the oscillator pins.
(g) 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.
(2) Use of the LFXT1 Crystal Oscillator with T_A > 105°C is not guaranteed. It is recommended that an external digital clock source or the
internal DCO is used to provide clocking.
(3) 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.
(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) Measured with logic-level input frequency, but also applies to operation with crystals with T_A < 105°C.
Internal Very-Low-Power, Low-Frequency Oscillator (VLO) – Electrical Characteristics
over recommended ranges of supply voltage and operating free-air temperature (unless otherwise noted)
PARAMETER
TEST
CONDITIONS
T_A
V_CC
MIN TYP MAX UNIT
f_VLO
VLO frequency
df_VLO/dT VLO frequency temperature drift
(1)
df_VLO/dV_CC VLO frequency supply voltage drift ⁽²⁾
–55°C to 85°C
125°C
–55°C to 125°C
25°C
2.2 V/3 V
2.2 V/3 V
2.2 V/3 V
1.8 V –
3.6V
4 12
0.5
4
20
kHz
22
%/°C
%/V
(1) Calculated using the box method:
I Version: [MAX(–55...85°C) – MIN(–55...85°C)]/MIN(55–...85°C)/[85°C – (–55°C)]
T Version: [MAX(–55...125°C) – MIN(–55...125°C)]/MIN(–55...125°C)/[125°C – (–55°C)]
(2) Calculated using the box method: [MAX(1.8...3.6 V) – MIN(1.8...3.6 V)]/MIN(1.8...3.6 V)/(3.6 V – 1.8 V)
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