STM32L021D4 datasheet(89/114 Pages) STMICROELECTRONICS

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STM32L021x4

Electrical characteristics

SPI characteristics

Unless otherwise specified, the parameters given in the following tables are derived from

tests performed under ambient temperature, fPCLKx frequency and VDD supply voltage

conditions summarized in Table 17.

Refer to Section 6.3.12: I/O current injection characteristics for more details on the

input/output alternate function characteristics (NSS, SCK, MOSI, MISO).

Table 63. SPI characteristics in voltage Range 1 (1)

Symbol

Parameter

Conditions

Min

Typ

Max

Unit

fSCK

1/tc(SCK)

SPI clock frequency

Master mode

MHz

Slave mode receiver

Slave mode Transmitter

1.71<VDD<3.6V

12(2)

Slave mode Transmitter

2.7<VDD<3.6V

16(2)

Duty(SCK)

Duty cycle of SPI clock

frequency

Slave mode

tsu(NSS)

NSS setup time

Slave mode, SPI presc = 2

4Tpclk

th(NSS)

NSS hold time

Slave mode, SPI presc = 2

2Tpclk

tw(SCKH)

tw(SCKL)

SCK high and low time

Master mode

Tpclk-2

Tpclk

Tpclk+2

tsu(MI)

Data input setup time

Master mode

tsu(SI)

Slave mode

th(MI)

Data input hold time

Master mode

3.5

th(SI)

Slave mode

ta(SO

Data output access time

Slave mode

tdis(SO)

Data output disable time

Slave mode

tv(SO)

Data output valid time

Slave mode 1.71<VDD<3.6V

Slave mode 2.7<VDD<3.6V

tv(MO)

Master mode

th(SO)

Data output hold time

Slave mode

th(MO)

Master mode

1. Guaranteed by characterization results, not tested in production.

2. The maximum SPI clock frequency in slave transmitter mode is determined by the sum of tv(SO) and tsu(MI) which has to fit

into SCK low or high phase preceding the SCK sampling edge. This value can be achieved when the SPI communicates

with a master having tsu(MI) = 0 while Duty(SCK) = 50%.

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