MSP430FR5994 Datasheet, PDF (36/166 Pages) Texas Instruments – Mixed-Signal Microcontrollers

MSP430FR5994, MSP430FR59941, MSP430FR5992, MSP430FR5964, MSP430FR5962
SLASE54 – MARCH 2016
www.ti.com
Low-Frequency Crystal Oscillator, LFXT⁽¹⁾ (continued)
over recommended ranges of supply voltage and operating free-air temperature (unless otherwise noted)
C_LFXIN
PARAMETER
Integrated load capacitance at
LFXIN terminal^{(5) (6)}
TEST CONDITIONS
V_CC
MIN TYP MAX UNIT
2
pF
C_LFXOUT
Integrated load capacitance at
LFXOUT terminal^{(5) (6)}
2
pF
t_START,LFXT
Start-up time⁽⁷⁾
f_Fault,LFXT
Oscillator fault frequency^{(8) (9)}
f_OSC = 32768 Hz
LFXTBYPASS = 0, LFXTDRIVE = {0},
T_A = 25°C, C_L,eff = 3.7 pF
f_OSC = 32768 Hz
LFXTBYPASS = 0, LFXTDRIVE = {3},
T_A = 25°C, C_L,eff = 12.5 pF
3.0 V
3.0 V
800
ms
1000
0
3500 Hz
(5) This represents all the parasitic capacitance present at the LFXIN and LFXOUT terminals, respectively, including parasitic bond and
package capacitance. The effective load capacitance, C_L,eff can be computed as C_IN x C_OUT / (C_IN + C_OUT), where C_IN and C_OUT is the
total capacitance at the LFXIN and LFXOUT terminals, respectively.
(6) Requires external capacitors at both terminals to meet the effective load capacitance specified by crystal manufacturers. Recommended
effective load capacitance values supported are 3.7 pF, 6 pF, 9 pF, and 12.5 pF. Maximum shunt capacitance of 1.6 pF. The PCB adds
additional capacitance, so it must also be considered in the overall capacitance. Verify that the recommended effective load capacitance
of the selected crystal is met.
(7) Includes start-up counter of 1024 clock cycles.
(8) Frequencies above the MAX specification do not set the fault flag. Frequencies in between the MIN and MAX specification may set the
flag. A static condition or stuck at fault condition will set the flag.
(9) Measured with logic-level input frequency but also applies to operation with crystals.
HFXTCLK (see Table 5-5) is a high-frequency oscillator that can be used with standard crystals or
resonators in the 4‑MHz to 24-MHz range. When in bypass mode, HFXTCLK can be driven with an
external square-wave signal.
Table 5-5. High-Frequency Crystal Oscillator, HFXT⁽¹⁾
over recommended ranges of supply voltage and operating free-air temperature (unless otherwise noted)
I_DVCC.HFXT
f_HFXT
PARAMETER
HFXT oscillator crystal current
HF mode at typical ESR
HFXT oscillator crystal
frequency, crystal mode
TEST CONDITIONS
f_OSC = 4 MHz,
HFXTBYPASS = 0, HFXTDRIVE = 0,
HFFREQ = 1⁽²⁾, T_A = 25°C,
C_L,eff = 18 pF, typical ESR, C_shunt
f_OSC = 8 MHz,
HFXTBYPASS = 0, HFXTDRIVE = 1,
HFFREQ = 1, T_A = 25°C,
C_L,eff = 18 pF, typical ESR, C_shunt
f_OSC = 16 MHz,
HFXTBYPASS = 0, HFXTDRIVE = 2,
HFFREQ = 2, T_A = 25°C,
C_L,eff = 18 pF, typical ESR, C_shunt
f_OSC = 24 MHz,
HFXTBYPASS = 0, HFXTDRIVE = 3,
HFFREQ = 3, T_A = 25°C,
C_L,eff = 18 pF, typical ESR, C_shunt
HFXTBYPASS = 0, HFFREQ = 1 ^{(2) (3)}
HFXTBYPASS = 0, HFFREQ = 2⁽³⁾
HFXTBYPASS = 0, HFFREQ = 3⁽³⁾
V_CC
MIN TYP
75
120
3.0 V
190
250
4
8.01
16.01
MAX UNIT
µA
8
16 MHz
24
(1) To improve EMI on the HFXT oscillator the following guidelines should be observed.
• Keep the traces 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 HFXIN and HFXOUT.
• Avoid running PCB traces underneath or adjacent to the HFXIN and HFXOUT pins.
• Use assembly materials and processes that avoid any parasitic load on the oscillator HFXIN and HFXOUT pins.
• If conformal coating is used, make sure that it does not induce capacitive or resistive leakage between the oscillator pins.
(2) HFFREQ = {0} is not supported for HFXT crystal mode of operation.
(3) Maximum frequency of operation of the entire device cannot be exceeded.
36
Specifications
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