STR711FR0 STMicroelectronics, STR711FR0 Datasheet - Page 43

• Manufacturer Part Number: STR711FR0
• Description: ARM-Based Flash microcontrollers with USB
• Manufacturer: STMicroelectronics

Specifications of STR711FR0

• 5 Power Saving Modes: SLOW, WAIT, LPWAIT, STOP and STANDBY modes
• Conversion Range: 0 to 2.5 V

STR71xF
OSC32K crystal / ceramic resonator oscillator
The STR7 RTC clock can be supplied with a 32 kHz Crystal/Ceramic resonator oscillators.
All the information given in this paragraph are based on characterization results 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 resonator manufacturer
for more details (frequency, package, accuracy...).
Table 20.
Notes:
1. The oscillator selection can be optimized in terms of supply current using an high quality resonator with
2.
Figure 15. Typical application with a 32 kHz crystal
t
SU(OSC32KHZ)
WHEN RESONATOR WITH
INTEGRATED CAPACITORS
small R
32 kHz oscillation is reached. This value is measured for a standard crystal resonator and it can vary
significantly with the crystal manufacturer
t
SU(OSC32KHZ)
Symbol
C
C
R
g
i
2
L1
L2
m
F
S
value for example MSIV-TIN32.768kHz. Refer to crystal manufacturer for more details
32K oscillator characteristics (f
2)
is the start-up time measured from the moment it is enabled (by software) to a stabilized
C
Feedback resistor
Recommended load capacitance
versus equivalent serial resistance
of the crystal (R
RTCXT2 driving current
Oscillator Transconductance
startup time
L2
C
L1
32 kHz
RESONATOR
Parameter
S
)
1)
RTCXT1
RTCXT2
R
OSC32K=
F
i
2
R
V
V
V
33
IN
S
33
=40K Ω
=V
=3.3 V
32.768 kHz)
is stabilized
Conditions
SS
FEEDBACK
LOOP
STR710
Electrical parameters
f
OSC32K
12.5
Typ
2.7
3.2
8
5
µA/V
Unit
MΩ
pF
µA
s
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