MSP430FR573 Datasheet, PDF (53/109 Pages) Texas Instruments – MIXED SIGNAL MICROCONTROLLER

MSP430FR573x
MSP430FR572x
www.ti.com
SLAS639D – JULY 2011 – REVISED AUGUST 2012
Crystal Oscillator, XT1, Low-Frequency (LF) Mode ⁽¹⁾
over recommended ranges of supply voltage and operating free-air temperature (unless otherwise noted)
ΔI_VCC.LF
f_XT1,LF0
PARAMETER
Additional current consumption
XT1 LF mode from lowest drive
setting
XT1 oscillator crystal frequency,
LF mode
TEST CONDITIONS
f_OSC = 32768 Hz, XTS = 0,
XT1BYPASS = 0, XT1DRIVE = {1},
C_L,eff = 9 pF, T_A = 25°C,
f_OSC = 32768 Hz, XTS = 0,
XT1BYPASS = 0, XT1DRIVE = {2},
T_A = 25°C, C_L,eff = 9 pF
f_OSC = 32768 Hz, XTS = 0,
XT1BYPASS = 0, XT1DRIVE = {3},
T_A = 25°C, C_L,eff = 12 pF
XTS = 0, XT1BYPASS = 0
V_CC
MIN TYP MAX UNIT
3V
60
3V
90
nA
3V
140
32768
Hz
f_XT1,LF,SW
XT1 oscillator logic-level square-
wave input frequency, LF mode
XTS = 0, XT1BYPASS = 1 ^{(2) (3)}
10 32.768
50 kHz
OA_LF
f_Fault,LF
Oscillation allowance for
LF crystals ⁽⁴⁾
XTS = 0,
XT1BYPASS = 0, XT1DRIVE = {0},
f_XT1,LF = 32768 Hz, C_L,eff = 6 pF
XTS = 0,
XT1BYPASS = 0, XT1DRIVE = {3},
f_XT1,LF = 32768 Hz, C_L,eff = 12 pF
Duty cycle, LF mode
XTS = 0, Measured at ACLK,
f_XT1,LF = 32768 Hz
Oscillator fault frequency, LF mode
(5)
XTS = 0 ⁽⁶⁾
210
kΩ
300
30
70 %
10
10000 Hz
t_START,LF
Startup time, LF mode ⁽⁷⁾
f_OSC = 32768 Hz, XTS = 0,
XT1BYPASS = 0, XT1DRIVE = {0},
T_A = 25°C, C_L,eff = 6 pF
3V
f_OSC = 32768 Hz, XTS = 0,
XT1BYPASS = 0, XT1DRIVE = {3},
T_A = 25°C, C_L,eff = 12 pF
C_L,eff
Integrated effective load
capacitance, LF mode ^{(8) (9)}
XTS = 0
1000
ms
1000
1
pF
(1) To improve EMI on the XT1 oscillator, the following guidelines should be observed.
(a) Keep the trace between the device and the crystal as short as possible.
(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.
(2) When XT1BYPASS is set, XT1 circuits are automatically powered down. Input signal is a digital square wave with parametrics defined in
the Schmitt-trigger Inputs section of this data sheet.
(3) Maximum frequency of operation of the entire device cannot be exceeded.
(4) Oscillation allowance is based on a safety factor of 5 for recommended crystals. The oscillation allowance is a function of the XT1DRIVE
settings and the effective load. In general, comparable oscillator allowance can be achieved based on the following guidelines, but
should be evaluated based on the actual crystal selected for the application:
(a) For XT1DRIVE = {0}, C_L,eff ≤ 6 pF.
(b) For XT1DRIVE = {1}, 6 pF ≤ C_L,eff ≤ 9 pF.
(c) For XT1DRIVE = {2}, 6 pF ≤ C_L,eff ≤ 10 pF.
(d) For XT1DRIVE = {3}, 6 pF ≤ C_L,eff ≤ 12 pF.
(5) 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.
(6) Measured with logic-level input frequency but also applies to operation with crystals.
(7) Includes startup counter of 4096 clock cycles.
(8) Requires external capacitors at both terminals.
(9) Values are specified by crystal manufacturers. Include parasitic bond and package capacitance (approximately 2 pF per pin).
Recommended values supported are 6 pF, 9 pF, and 12 pF. Maximum shunt capacitance of 1.6 pF.
Copyright © 2011–2012, Texas Instruments Incorporated
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