TC7MBL3257CFT/FK/FTG

2008-07-17

8

Rise and Fall Times (tr / tf) of the TC7MBL3257C I/O Signals

The tr(out) and tf(out) values of the output signals are affected by the CR time constant of the input, which consists of

In practice, the tr(out) and tf(out) values are also affected by the circuit’s capacitance and resistance components other

than those of the TC7MBL3257C.

The tr(out) / tf(out) values can be approximated as follows. (Figure 3 shows the test circuit.)

Calculation example:

tr(out) (approx) = - ( 8 + 15 )E-12 ･ ( 120 + 8.5) ･ ln ( ( ( 3.0 - 0 ) – 1.5 ) / ( 3.0 – 0 ) )

≈ 2.1 ns

Calculation conditions:

Parameter

3.3 ± 0.3 V

2.5 ± 0.2 V

1.8 ± 0.15 V

Figure 3 Test Circuit

Measure

A/Bn

(Switch On)

TC7MBL3257C

Previous IC

Bn/A

tr(out)

Measure

Previous IC

GND

Waveform generated without the TC7MBL3257C

tf(out)

Waveform generated with the TC7MBL3257C added