STR912FAZ46 STMicroelectronics, STR912FAZ46 Datasheet - Page 68

• Manufacturer Part Number: STR912FAZ46
• Description: ARM966E-S™ 16/32-Bit Flash MCU with Ethernet, USB, CAN, AC motor control, 4 timers, ADC, RTC, DMA
• Manufacturer: STMicroelectronics

Specifications of STR912FAZ46

• Arm966e-s Risc Core: Harvard architecture, 5-stage pipeline, Tightly-Coupled Memories (SRAM and Flash)

Electrical characteristics
7.7.3
Note:
Caution:
68/102
Figure 16. Typical application with an external clock source
RTC clock generated from a crystal/ceramic resonator
The RTC (Real-Time Clock) can be supplied with a 32.768 kHz crystal/ceramic resonator
oscillator. All the information given in this paragraph is based on characterization results
obtained with typical external components specified in
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).
For CL1 and CL2 it is recommended to use high-quality ceramic capacitors in the 5 pF to 16
pF range, selected to match the requirements of the crystal or resonator. CL1 and CL2, are
usually the same size. The crystal manufacturer typically specifies a load capacitance which
is the series combination of CL1 and CL2.
Load capacitance CL has the following formula:
where Cstray is the pin capacitance and board or trace PCB-related capacitance. Typically,
it is between 2 pF and 7 pF.
Never use a resonator with a load capacitance of 12.5 pF.
Example: if you choose a resonator with a load capacitance of CL = 6 pF, and Cstray = 2 pF,
then CL1 = CL2 = 8 pF.
Conditions: V
Table 20.
1. Refer to
2. Data based on bench measurements, not tested in production.
V
t
START(RTC)
STUP(RTC)
Symbol
R
g
M
F
Table 14
V
V
X1H
X1L
RTC oscillator electrical characteristics
DDQ
EXTERNAL
CLOCK SOURCE
External feedback resistor
Oscillator start voltage
Oscillator transconductance
Oscillator Start-up Time
for min. value of V
= 2.7 - 3.6 V, V
t
r(T1)
Parameter
CL = CL1 x CL2 / (CL1 + CL2) + Cstray
T
X1
hi-Z
Doc ID 13495 Rev 6
DD_LVD+
DD
t
f(X1)
= 1.65 - 2 V, T
(2)
X2_CPU
X1_CPU
90%
10%
(2)
Start-up
V
conditions
DD
Test
stable
t
w(X1H)
A
= -40 / 85 °C unless otherwise specified.
Table 20
I
V
L
DD_LVD+
t
w(X1L)
Min
1.8
f
OSC
STR91xF
&
(1)
Table
Value
Typ
22
21. In the
STR91xFAxxx
Max
1
µA/Volts
Unit
MΩ
V
S