tc7mb3125c TOSHIBA Semiconductor CORPORATION, tc7mb3125c Datasheet - Page 7

• Manufacturer Part Number: tc7mb3125c
• Description: Low Capacitance Quad Bus Switch
• Manufacturer: TOSHIBA Semiconductor CORPORATION

Rise and Fall Times (tr / tf) of the TC7MB3125C
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 TC7MB3125C, 3126C.
The tr / tf (out) values can be approximated as follows. (Figure 3 shows the test circuit.)
tr / tf out (approx) = - ( C
Calculation example:
Calculation conditions:
tr out (approx) = - ( 8 + 15 )E-12 ･ ( 120 + 5.5) ･ ln ( ( ( 4.5 - 0 ) – 2.25 ) / ( 4.5 – 0 ) )
V
Output of the previous IC = digital (i.e., high-level voltage = V
CC
= 4.5V , C
≈ 2.0 ns
Previous IC
R
DRIVE
R
L
DRIVE
= output impedance of the previous IC
= 15pF , R
I/O
+ C
An/Bn
DRIVE
L
) ･ (R
I/O
= 120Ω(output impedance of the previous IC), V
) and the on-resistance (R
TC7MB3125C
TC7MB3126C
(Switch On)
Previous IC
R
DRIVE+
DRIVE
Figure 3
C
R
I/O
ON
R
DRIVE
R
where, R
= output impedance of the previous IC
ON
) ･ ln ( ( ( V
Bn/An
DRIVE
Test Circuit
7
ON
is the output impedance of the previous-stage circuit.
CC
OH
，
; low-level voltage = GND)
) of the input.
3126C I/O Signals
Parameter
TC7MB3125C,3126CFT/FK/FTG
Measure
Measure
– V
Waveform generated with the TC7MB3125C,3126C added
V
OL
M
Waveform generated without the TC7MB3125C,3126C
) – V
M
) / ( V
5.0 ± 0.5 V
M
tr out
V
= 2.25V (V
V
CC
OH
CC
V
M
/ 2
– V
OL
CC
) )
/ 2)
tf out
2011-01-11
V
M
V
CC
GND
V
V
OH
OL