Datasheet

Electrical characteristics STM32F21xxx
128/175 DocID17050 Rev 9
6.3.24 Embedded reference voltage
The parameters given in Table 70 are derived from tests performed under ambient
temperature and V
DD
supply voltage conditions summarized in Table 13.
6.3.25 FSMC characteristics
Asynchronous waveforms and timings
Figure 54 through Figure 57 represent asynchronous waveforms and Table 71 through
Table 74 provide the corresponding timings. The results shown in these tables are obtained
with the following FSMC configuration:
• AddressSetupTime = 1
• AddressHoldTime = 1
• DataSetupTime = 1
• BusTurnAroundDuration = 0x0
In all timing tables, the
T
HCLK
is the HCLK clock period.
Table 70. Embedded internal reference voltage
Symbol Parameter Conditions Min
Typ
Max Unit
V
REFINT
Internal reference voltage –40 °C < T
A
< +105 °C 1.18 1.21 1.24 V
T
S_vrefint
(1)
1. Shortest sampling time can be determined in the application by multiple iterations.
ADC sampling time when
reading the internal reference
voltage
10 - - µs
V
RERINT_s
(2)
2. Guaranteed by design, not tested in production.
Internal reference voltage
spread over the temperature
range
V
DD
= 3 V - 3 5 mV
T
Coeff
(2)
Temperature coefficient - 30 50 ppm/°C
t
START
(2)
Startup time - 6 10 µs