tc7mbl3245cft TOSHIBA Semiconductor CORPORATION, tc7mbl3245cft Datasheet - Page 8

• Manufacturer Part Number: tc7mbl3245cft
• Description: Low Voltage/low Capacitance Octal Bus Switch
• Manufacturer: TOSHIBA Semiconductor CORPORATION

Rise and Fall Times (tr / tf) of the TC7MBL3245C 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 (C
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 TC7MBL3245C.
The tr(out) / tf(out) values can be approximated as follows. (Figure 3 shows the test circuit.)
tr(out) / tf(out) (approx) = - ( C
Calculation example:
Calculation conditions:
tr(out) (approx) = - ( 7.5 + 15 )E-12 ･ ( 120 + 6.5) ･ ln ( ( ( 3.0 - 0 ) – 1.5 ) / ( 3.0 – 0 ) )
V
Output of the previous IC = digital (i.e., high-level voltage = V
CC
= 3.0V , C
≈ 2.0 ns
Previous IC
R
DRIVE
R
L
DRIVE
= 15pF , R
= output impedance of the previous IC
An/Bn
DRIVE
I/O
+ C
I/O
= 120Ω(output impedance of the previous IC), V
L
) and the on-resistance (R
TC7MBL3245C
) ･ (R
(Switch On)
Previous IC
R
DRIVE
Figure 3 Test Circuit
C
R
I/O
ON
DRIVE+
R
DRIVE
where, R
= output impedance of the previous IC
R
ON
Bn/An
DRIVE
) ･ ln ( ( ( V
8
CC
ON
is the output impedance of the previous-stage circuit.
; low-level voltage = GND)
) of the input.
Measure
Measure
Waveform generated with the TC7MBL3245C added
項目
OH
V
M
Waveform generated without the TC7MBL3245C
– V
OL
TC7MBL3245CFT/FK/FTG
3.3 ± 0.3 V
) – V
V
CC
M
tr(out)
M
/ 2
= 1.5V (V
) / ( V
V
M
OH
CC
– V
2.5 ± 0.2 V
V
/ 2)
OL
V
CC
CC
tf(out)
2008-09-01
) )
/ 2
V
M
V
GND
CC
1.8 ± 0.15 V
V
V
V
CC
OH
OL
/ 2