TC7MBL3245CFT(EL) Ver la hoja de datos (PDF) - Toshiba

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TC7MBL3245CFT(EL)

CMOS Digital Integrated Circuits Silicon Monolithic

Toshiba 

TC7MBL3245CFT

12. Rise and Fall Time (tr/tf)

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 TC7MBL3245CFT.

The tr(out)/tf(out) values can be approximated as follows. (Figure 12.1, Table 12.1 shows the test circuit.)

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

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

Calculation example:

tr(out) (approx) = - (7.5 + 15) E - 12  (120 + 6.5)  ln (((3.0 - 0) - 1.5) / (3.0 - 0)) ≈ 2.0 ns

Calculation conditions:

VCC = 3.0 V, CL = 15 pF, RDRIVE = 120 Ω (output impedance of the previous IC), VM = 1.5 V (VCC/2)

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

Fig. 12.1 Calculation Circuit

Characteristics

VM

Table 12.1 Calculation Circuit

VCC = 3.3 ± 0.3 V

VCC/2

VCC = 2.5 ± 0.2 V

VCC/2

VCC = 1.8 ± 0.15 V

VCC/2

©2017

Toshiba Electronic Devices & Storage Corporation

6

2017-10-03

Rev.3.0

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