Table 27-22. Hibernation External Oscillator (XOSC) Input Characteristics (continued)
Unit
Max
Nom
Min
Parameter Name
Parameter
pF
-
0.5
-
PCB stray shunt capacitance
b
C
PCB
pF
4
-
-
Total shunt capacitance
b
C
SHUNT
kΩ
50
-
-
Crystal effective series resistance,
OSCDRV
= 0
c
ESR
kΩ
75
-
-
Crystal effective series resistance,
OSCDRV
= 1
c
µW
0.25
-
-
Oscillator output drive level
DL
ms
1500
e
600
-
Oscillator startup time, when using a crystal
d
T
START
V
-
-
2.64
CMOS input high level, when using an external
oscillator with Supply > 3.3 V
V
IH
f
V
-
-
0.8 *
Supply
CMOS input high level, when using an external
oscillator with 1.8 V ≤ Supply ≤ 3.3 V
V
0.2 * Supply
-
-
CMOS input low level, when using an external oscillator
with 1.8 V ≤ Supply ≤ 3.63 V
V
IL
f
mV
1390
960
360
CMOS input buffer hysteresis, when using an external
oscillator with 1.8 V ≤ Supply ≤ 3.63 V
V
HYS
f
%
70
-
30
External single-Ended (Bypass) reference duty cycle
DC
HIBOSC_EXT
a. The HIB XOSC pins are non-failsafe and must follow the limits detailed in “Non-Power I/O Pins” on page 1851.
b. See information below table.
c. Crystal ESR specified by crystal manufacturer.
d. Oscillator startup time is specified from the time the oscillator is enabled to when it reaches a stable point of oscillation
such that the internal clock is valid.
e. Only valid for recommended supply conditions. Measured with
OSCDRV
bit set (high drive strength enabled, 24 pF).
f. Specification is relative to the larger of V
DD
or V
BAT
.
The load capacitors added on the board, C
1
and C
2
, should be chosen such that the following
equation is satisfied (see Table 27-22 on page 1837 for typical values).
■ C
L
= load capacitance specified by crystal manufacturer
■ C
L
= (C
1
*C
2
)/(C
1
+C
2
) + C
PKG
+ C
PCB
■ C
SHUNT
= C
PKG
+ C
PCB
+ C
0
(total shunt capacitance seen across
XOSC0
,
XOSC1
)
■ C
PKG
, C
PCB
as measured across the
XOSC0
,
XOSC1
pins excluding the crystal
■ Clear the
OSCDRV
bit in the
Hibernation Control (HIBCTL)
register for C
1,2
≤ 18 pF; set the
OSCDRV
bit for C
1,2
> 18 pF.
■ C
0
= Shunt capacitance of crystal specified by the crystal manufacturer
27.9.5
Main Oscillator Specifications
Table 27-23. Main Oscillator Input Characteristics
a
Unit
Max
Nom
Min
Parameter Name
Parameter
MHz
25
-
4
b
Parallel resonance frequency
F
MOSC
MHz
120
-
0
External clock reference (PLL in BYPASS mode)
F
REF_XTAL_BYPASS
pF
24
-
12
External load capacitance on
OSC0
,
OSC1
pins
c
C
1
, C
2
pF
-
0.5
-
Device package stray shunt capacitance
c
C
PKG
June 18, 2014
1838
Texas Instruments-Production Data
Electrical Characteristics