ST7232A datasheet(128/157 Pages) STMICROELECTRONICS

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ST7232A

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12.8 I/O PORT PIN CHARACTERISTICS

12.8.1 General Characteristics

Subject to general operating conditions for VDD, fOSC, and TA unless otherwise specified.

Notes:

1. Data based on characterization results, not tested in production.

2. Hysteresis voltage between Schmitt trigger switching levels. Based on characterization results, not tested.

3. When the current limitation is not possible, the VIN maximum must be respected, otherwise refer to IINJ(PIN) specifica-

tion. A positive injection is induced by VIN>VDD while a negative injection is induced by VIN<VSS. Refer to Section 12.2.2

on page 114 for more details.

4. Configuration not recommended, all unused pins must be kept at a fixed voltage: using the output mode of the I/O for

example and leaving the I/O unconnected on the board or an external pull-up or pull-down resistor (see Figure 66). Static

peak current value taken at a fixed VIN value, based on design simulation and technology characteristics, not tested in

production. This value depends on VDD and temperature values.

5. The RPU pull-up equivalent resistor is based on a resistive transistor (corresponding IPU current characteristics de-

scribed in Figure 67).

6. To generate an external interrupt, a minimum pulse width has to be applied on an I/O port pin configured as an external

interrupt source.

Figure 66. Unused I/O Pins configured as input

Figure 67. Typical IPU vs. VDD with VIN=VSS

Symbol

Parameter

Conditions

Min

Typ

Max

Unit

VIL

Input low level voltage (standard voltage

devices)1)

0.3xVDD

VIH

Input high level voltage 1)

0.7xVDD

Vhys

Schmitt trigger voltage hysteresis 2)

0.7

IINJ(PIN)

Injected Current on Flash device pin PB0

VDD=5V

0+4

Injected Current on other I/O pins

±4

ΣI

INJ(PIN)

3) Total injected current (sum of all I/O and

control pins)

±25

Ilkg

Input leakage current

VSS ≤ VIN ≤ VDD

±1

µA

Static current consumption induced by each

floating input pin

Floating input mode4)

200

RPU

Weak pull-up equivalent resistor 5)

VIN=VSS

VDD=5V

120

250

Ω

CIO

I/O pin capacitance

tf(IO)out

Output high to low level fall time 1)

CL=50pF

Between 10% and

90%

tr(IO)out

Output low to high level rise time 1)

tw(IT)in

External interrupt pulse time 6)

1tCPU

10k

Ω

UNUSED I/O PORT

ST7XXX

10k

Ω

UNUSED I/O PORT

ST7XXX

VDD

Note: I/O can be left unconnected if it is configured as output

greater EMC robustness and lower cost.

(0 or 1) by the software. This has the advantage of

22.5

33.5

4.5

55.5

Vdd(V)

Ta=1 40°C

Ta=9 5°C

Ta=2 5°C

Ta=-45 °C

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