Datasheet

DS12556 Rev 2 111/201
STM32H750VB STM32H750IB STM32H750XB Electrical characteristics
189
Figure 14. Typical application with an 8 MHz crystal
1. R
EXT
value depends on the crystal characteristics.
Low-speed external clock generated from a crystal/ceramic resonator
The low-speed external (LSE) clock can be supplied with a 32.768 kHz crystal/ceramic
resonator oscillator. All the information given in this paragraph are based on
characterization results obtained with typical external components specified in
Table 43. In
the application, the resonator and the load capacitors have to be placed as close as
possible to the oscillator pins in order to minimize output distortion and startup stabilization
time. Refer to the crystal resonator manufacturer for more details on the resonator
characteristics (frequency, package, accuracy).
ai17530b
OSC_OU T
OSC_IN
f
HSE
C
L1
R
F
STM32
8 MHz
resonator
Resonator with
integrated capacitors
Bias
controlled
gain
R
EXT
(1)
C
L2
Table 43. Low-speed external user clock characteristics
(1)
Symbol Parameter Operating conditions
(2)
Min Typ Max Unit
F Oscillator frequency - - 32.768 - kHz
I
DD
LSE current
consumption
LSEDRV[1:0] = 00,
Low drive capability
-290 -
nA
LSEDRV[1:0] = 01,
Medium Low drive capability
-390 -
LSEDRV[1:0] = 10,
Medium high drive capability
-550 -
LSEDRV[1:0] = 11,
High drive capability
-900 -
Gm
critmax
Maximum critical crystal
gm
LSEDRV[1:0] = 00,
Low drive capability
--0.5
µA/V
LSEDRV[1:0] = 01,
Medium Low drive capability
- - 0.75
LSEDRV[1:0] = 10,
Medium high drive capability
--1.7
LSEDRV[1:0] = 11,
High drive capability
--2.7
t
SU
(3)
Startup time VDD is stabilized - 2 - s
1. Guaranteed by design.
2. Refer to the note and caution paragraphs below the table, and to the application note AN2867 “Oscillator design guide for
ST microcontrollers.
3. t
SU
is the startup time measured from the moment it is enabled (by software) to a stabilized 32.768k Hz oscillation is
reached. This value is measured for a standard crystal resonator and it can vary significantly with the crystal manufacturer.
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