Table 4. Power-on and reset sequence timings

Name

Description

Conditions Min Typ Max Units

tHL

Minimum time for reset active after power-up

-

0

-

-

μs

SVCC

VCC rising slope (from 10% to 90% of nominal value)

-

-

-

5

V/μs

tWL Reset

Pulse width for reset(1)

-

5

-

-

μs

tR/tF Reset

Reset rise and fall time

VCC > VPOR

-

-

1

μs

tI2C_READY Delay for STSAFE-A120 to accept I²C commands after a reset sequence.

-

-

4.5

20

ms

1. Any low pulse (from 1 to 0, then 0 to 1) shorter than 5 μs is ignored.

7.2.5

Power consumption optimization

When the STSAFE-A120 is not in use, it is possible to decrease its power consumption by removing the power

supply properly.

This could be achieved by using a transistor to pilot the STSAFE-A120 power supply, or by using a GPIO able to

provide an ICC-PROC current that respects the STSAFE-A120 powering conditions as illustrated in

Section 6: Electrical integration.

Note:

The RESET signal must remain low when power is removed.

7.3

DC characteristics

The following tables provide the detailed description of the DC operating conditions of STSAFE-A120 from 2.7 V

to 5.5 V voltages.

Table 5. DC operating specifications and input parameters

Name

Description

Conditions

Min

Typ

Max

Units

VIH

Input high voltage (CLK, RESET, I/O)

-

0.7 x Vcc

-

Vcc

V

VIL

Input low voltage (CLK, RESET, I/O)

-

0

-

0.2 x Vcc

V

IIH

Input high current, high impedance (SDA)

0.7xVCC < VIH < VCC

-1

-

1

μA

Input high current, high impedance (CLK)

0.7xVCC < VIH < VCC

-100

-

200

nA

Input high current, pull-down (RST)

0.7xVCC < VIH < VCC

3

7

15

μA

IIL

Input low current, high impedance (SDA)

0V< VIL < 0.2xVCC

-1

-

1

μA

Input low current, high impedance (CLK)

0V< VIL < 0.2xVCC

-100

-

100

nA

Input low current, pull-down (RST)

0V< VIL < 0.2xVCC

-1

1.5

10

μA

VOL

Output low voltage (I/O)

IOL = 6 mA

-

-

460

mV

CIN1

SCL input capacitance

VIN = 0 to VCC Max

-

-

30

pF

CIN2

SDA input capacitance

VIN = 0 to VCC Max

-

-

30

pF

Note:

VCC MAX is the maximum VCC as defined in Table 3. Power supply specifications.

STSAFE-A120

Electrical characteristics

DS14609 - Rev 1

page 22/38