TC7MB3257CFTG Ver la hoja de datos (PDF) - Toshiba

Número de pieza

componentes Descripción

Fabricante

TC7MB3257CFTG

TOSHIBA CMOS Digital Integrated Circuit Silicon Monolithic

Toshiba 

TC7MB3257CFT/FK/FTG

Rise and Fall Times (tr / tf) of the TC7MB3257C 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

the switch terminal capacitance (CI/O) and the on-resistance (RON) of the input.

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 TC7MB3257C.

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

tr(out) / tf(out) (approx) = - ( CI/O + CL ) ･ (RDRIVE+ RON) ･ ln ( ( ( VOH – VOL ) – VM) / ( VOH – VOL ) )

Calculation example:

where, RDRIVE is the output impedance of the previous-stage circuit.

tr(out) (approx) = - ( 8.5 + 15 )E-12 ･ ( 120 + 3) ･ ln ( ( ( 4.5 - 0 ) – 2.25 ) / ( 4.5 – 0 ) )

≈ 2.0 ns

Calculation conditions:

VCC = 4.5 V , CL = 15 pF , RDRIVE = 120 Ω (output impedance of the previous IC), VM = 2.25 V (VCC / 2)

Output of the previous IC = digital (i.e., high-level voltage = VCC; low-level voltage = GND)

Previous IC

RDRIVE

Waveform generated without the TC7MB3257C

Measure

VCC

GND

Previous IC

RDRIVE

A/Bn

RDRIVE = output impedance of the previous IC

TC7MB3257C

CI/O

(Switch On)

Bn/A

RON

Waveform generated with the TC7MB3257C added

Measure

VM

tr(out)

VM

tf(out)

VOH

VOL

RDRIVE = output impedance of the previous IC

Parameter

VM

VCC

5.0 ± 0.5 V

VCC / 2

Figure 3 Test Circuit

7

2011-02-10

Share Link: