tc7mbl3245s TOSHIBA Semiconductor CORPORATION, tc7mbl3245s Datasheet - Page 6

• Manufacturer Part Number: tc7mbl3245s
• Description: Low Voltage/low Capacitance Octal Bus Switch
• Manufacturer: TOSHIBA Semiconductor CORPORATION

Rise and Fall Times (tr / tf) of the TC7MBL3245S 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 TC7MBL3245S.
The tr(out) / tf(out) values can be approximated as follows. (Figure 3 shows the test circuit.)
Calculation example:
tr(out) / tf(out) (approx) = - ( C
tr(out) (approx) = - ( 12+ 15 )E-12 ･ ( 120 + 9) ･ ln ( ( ( 3.0 - 0 ) – 1.5 ) / ( 3.0 – 0 ) )
V
Calculation conditions:
Output of the previous IC = digital (i.e., high-level voltage = V
CC
= 3.0V , C
R
≈ 2.4ns
DRIVE
Previous IC
R
= output impedance of the previous IC
L
DRIVE
= 15pF , R
An/Bn
DRIVE
I/O
+ C
I/O
= 120 Ω (output impedance of the previous IC), V
) and the on-resistance (R
L
TC7MBL3245S
(Switch On)
Previous IC
R
) ･ (R
DRIVE
C
R
I/O
ON
R
where, R
DRIVE+
DRIVE
= output impedance of the previous IC
Figure 3 Test Circuit
R
DRIVE
ON
Bn/An
6
) ･ ln ( ( ( V
is the output impedance of the previous-stage circuit.
CC
ON
Parameter
; low-level voltage = GND)
) of the input.
Measure
Measure
V
M
OH
– V
TC7MBL3245SFT/FK/FTG
OL
Waveform generated with the TC7MBL3245S added
3.3 ± 0.3 V
) – V
Waveform generated without the TC7MBL3245S
V
CC
tr out
M
/ 2
M
= 1.5V(V
V
) / ( V
M
OH
CC
– V
2.5 ± 0.2 V
V
/ 2)
V
CC
OL
CC
2009-01-20
tf out
/ 2
) )
V
M
V
GND
CC
1.8 ± 0.15 V
V
V
V
CC
OH
OL
/ 2