STR752FR1H7 STMICROELECTRONICS [STMicroelectronics], STR752FR1H7 Datasheet - Page 46

• Manufacturer Part Number: STR752FR1H7
• Manufacturer: STMICROELECTRONICS [STMicroelectronics]

Electrical parameters
Table 22.
1. Resonator characteristics given by the crystal/ceramic resonator manufacturer.
2. For C
3. The relatively low value of the RF resistor offers a good protection against issues resulting from use in a humid
4. t
46/84
f
R
C
C
i
t
2
OSC4M
SU(OSC4M)
F
L1
L2
Symbol
high-frequency applications and selected to match the requirements of the crystal or resonator. C
same size. The crystal manufacturer typically specifies a load capacitance which is the series combination of C
PCB and MCU pin capacitance must be included when sizing C
combined pin and board capacitance).
environment, due to the induced leakage and the bias condition change. However, it is recommended to take this point into
account if the MCU is used in tough humidity conditions.
to 3.3V (<50µs) to a stabilized 4MHz oscillation is reached. This value is measured for a standard crystal resonator and it
can vary significantly with the crystal/ceramic resonator manufacturer.
SU(OSC4M)
(2)
L1
and C
(4)
is the typical start-up time measured from the moment V
4/8 MHz crystal / ceramic resonator oscillator (XT1/XT2)
The STR750 system clock or the input of the PLL can be supplied by a OSC4M which is a 4
MHz clock generated from a 4 MHz or 8 MHz crystal or ceramic resonator. If using an 8 MHz
oscillator, software set the XTDIV bit to enable a divider by 2 and generate a 4 MHz OSC4M
clock. All the information given in this paragraph are based on product characterisation with
specified typical external components. 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 start-up stabilization time. Refer to the crystal/ceramic resonator
manufacturer for more details (frequency, package, accuracy...).
4/8 MHz crystal / ceramic resonator oscillator (XT1/XT2)
Figure 21. Typical application with a 4 or 8 MHz crystal or ceramic resonator
Oscillator frequency
Feedback resistor
Recommended load
capacitance versus equivalent
serial resistance of the crystal or
ceramic resonator (R
XT2 driving current
Startup time at V
L2
it is recommended to use high-quality ceramic capacitors in the 5-pF to 25-pF range (typ.) designed for
WHEN RESONATOR WITH
INTEGRATED CAPACITORS
Parameter
DD_IO
S
)
(3)
power-up
C
L2
C
L1
4 MHz Crystal/Resonator Oscillator
connected on XT1/XT2 XTDIV=0
or
8 MHz Crystal/Resonator Oscillator
connected on XT1/XT2 XTDIV=1
R
V
DD_IO
S
RESONATOR
=200Ω
=3.3 V or 5.0 V
XT2
XT1
STR750Fxx STR751Fxx STR752Fxx STR755Fxx
L1
Conditions
and C
DD_IO
R
L2
F
is powered (with a quick V
(10 pF can be used as a rough estimate of the
V
Ref
DD
/2
i
AMPLIFIER
2
LINEAR
(1)
/2
XTDIV
FEEDBACK
Min
200
L1
LOOP
and C
DD_IO
Typ
240
425
STR75X
L2,
4
1
ramp-up from 0
f
are usually the
OSC4M
L1
Max
270
60
and C
L2
MHz
Unit
ms
kΩ
µA
pF
.